Mass flow controller (MFC) having self-calibration function and calibration method

Abstract

Disclosed are a mass flow controller (MFC) having self-calibration function and a calibration method. The MFC comprises a control body (1), wherein the control body (1) is provided with a measurement channel (11) and a calibration channel (12); two ends of the control body (1) are rotatably provided with a first calibration disc (2) and a second calibration disc (3) having the same structure; the first calibration disc (2) and the second calibration disc (3) are each provided with through holes (101) corresponding to the measurement channel (11) and the calibration channel (12); the first calibration disc (2) and the second calibration disc (3) are each rotatably provided with a first electrode assembly and a second electrode assembly in one through hole (101); the first electrode assembly and the second electrode assembly are both elliptical; and the control body (1) is further provided with a switching assembly for synchronously driving the first calibration disc (2) and the second calibration disc (3) to rotate, and a power mechanism for driving the first electrode assembly and the second electrode assembly to rotate. The problem of prolonged production shutdown caused by the need to disassemble a single electrode assembly for calibration is avoided, facilitating improvement to production efficiency.

Description

MFC mass flow controller with self-calibration function and calibration method TECHNICAL FIELD

[0001] The present application relates to the technical field of flow control, in particular to an MFC mass flow controller with self-calibration function and a calibration method. BACKGROUND

[0002] An MFC mass flow controller is a kind of device that measures the mass flow of fluid through a mass flow sensor and controls the flow control valve on the pipeline according to the measurement result to ensure that the mass flow of the pipeline is within the preset range.

[0003] A thermal mass flow controller is a kind of device that measures the mass flow of fluid in the pipeline by setting an electrode assembly composed of a first heating electrode and a second non-heating electrode in the fluid pipeline, the temperature of the first heating electrode is higher than the temperature of the fluid, and the fluid carries the heat on the first heating electrode to the second heating electrode during the flow process, so that the temperature of the second heating electrode rises, and the mass flow of the fluid in the pipeline can be measured by measuring the temperature difference between the first heating electrode and the second heating electrode. TECHNICAL PROBLEM

[0004] Since the electrode assembly is in the fluid pipeline, after the mass flow controller works for a long time, the impurities in the fluid will adhere to the surface of the electrode assembly, which reduces the heat transfer coefficient between the electrode assembly and the fluid, causing measurement error.

[0005] When the mass flow controller is working, the working temperature of the first heating electrode is higher than that of the second heating electrode, so the impurities adhered to the surface of the first heating electrode are more, which causes the difference in the heat transfer coefficient between the first heating electrode and the second heating electrode and the fluid, further increasing the measurement error. Therefore, the thermal mass flow controller needs to be calibrated manually regularly, and when the measurement error is too large, the heating electrode needs to be disassembled and cleaned, which is complicated and needs to be stopped for a long time, reducing the production efficiency. TECHNICAL SOLUTION

[0006] The purpose of the present application is to overcome the above-mentioned shortcomings, provide an MFC mass flow controller with self-calibration function and a calibration method, which avoids the problem of long-time shutdown caused by disassembly for calibration of a single electrode assembly, and is beneficial to improve the production efficiency.

[0007] To achieve the above-mentioned purpose, the specific scheme of the present application is as follows:

[0008] The first aspect of the present application provides a self-calibration function MFC mass flow controller, comprising a control body, the control body is provided with a measuring channel and a calibration channel, the control body is rotatably provided with a first calibration disc and a second calibration disc which are the same structure at both ends of the control body, the first calibration disc and the second calibration disc are both provided with through holes corresponding to the measuring channel and the calibration channel, and the first calibration disc and the second calibration disc are both rotatably provided with a first electrode assembly and a second electrode assembly in one of the through holes; the first electrode assembly and the second electrode assembly are both in an elliptical shape.

[0009] The control body is also provided with a switching assembly for synchronously driving the first calibration disc and the second calibration disc to rotate and a power mechanism for driving the first electrode assembly and the second electrode assembly to rotate.

[0010] Optionally, the first electrode assembly comprises a first heating electrode capable of generating heat and a first temperature probe arranged in the first heating electrode, and the second electrode assembly comprises a second heating electrode incapable of generating heat and a second temperature probe arranged in the second heating electrode.

[0011] Optionally, the first calibration disc and the second calibration disc each further comprise a disc body, the disc body is provided with a central sliding hole, a sliding block is arranged in the central sliding hole, the sliding block is provided with a strip-shaped hole corresponding to the first electrode assembly and the second electrode assembly respectively, and the two through holes are symmetrically distributed on both sides of the central sliding hole; the sliding block is in transmission connection with the power mechanism.

[0012] The first heating electrode and the second heating electrode are each sleeved with a swing arm, the swing arm is provided with a first clamping pin at the distal end, and the first clamping pin is movably embedded in the corresponding strip-shaped hole.

[0013] Optionally, the peripheral surface of the disc body is provided with a spiral groove; the switching assembly comprises a dial rod which is slidingly arranged on the control body, and the dial rod is provided with a second clamping pin at both ends, and the second clamping pin is movably embedded in the spiral groove.

[0014] The switching assembly further comprises a push rod which is arranged on the control body, and the output end of the push rod is connected with the dial rod.

[0015] Optionally, the first heating electrode and the second heating electrode are each sleeved with a friction ring which is in frictional contact with the disc body.

[0016] Optionally, the power mechanism comprises a power motor, a one-way transmission assembly and first and second driving rods, the one-way transmission assembly is connected with the output end of the power motor, and the first and second driving rods are slidingly arranged on the control body and distributed on both sides of the one-way transmission assembly.

[0017] One end of the first driving rod is connected with the one-way transmission assembly, the other end of the first driving rod is movably embedded in the central sliding hole of the first calibration disc and in transmission connection with the sliding block; one end of the second driving rod is connected with the one-way transmission assembly, and the other end of the second driving rod is movably embedded in the central sliding hole of the second calibration disc and in transmission connection with the sliding block.

[0018] Optionally, the one-way transmission assembly comprises a transmission shaft, and a first driving disc and a second driving disc rotatably sleeved on the transmission shaft; the transmission shaft movably has a first pawl and a second pawl; the first driving disc and the second driving disc are each provided with an outer ratchet and an inner ratchet, the disc surface of the first driving disc is provided with a first cam groove, and the disc surface of the second driving disc is provided with a second cam groove; the first pawl is in one-way engagement with the inner ratchet of the first driving disc, and the second pawl is in one-way engagement with the inner ratchet of the second driving disc; the other end of the first driving rod and the other end of the second driving rod are each provided with a third pin, the third pin of the first driving rod is movably embedded in the first cam groove, and the third pin of the second driving rod is movably embedded in the second cam groove.

[0019] The control body is provided with a first elastic sheet and a second elastic sheet corresponding to the positions of the first driving disc and the second driving disc respectively for one-way engagement with the outer ratchets.

[0020] Optionally, the transmission shaft is provided with a guide hole corresponding to the first pawl and the second pawl in the radial direction respectively, the first pawl and the second pawl are slidably arranged in the corresponding guide holes respectively, and the first pawl and the second pawl are connected with the transmission shaft through springs respectively.

[0021] Optionally, one end of the control body corresponding to the measuring channel is connected with a flow control valve; one end of the control body corresponding to the calibration channel is connected with a density measuring device and a constant displacement pump; the control body is further provided with a control module connected with the flow control valve, the density measuring device and the constant displacement pump.

[0022] The second aspect of the present application provides a calibration method of an MFC mass flow controller based on the self-calibration function, which specifically comprises the following steps:

[0023] S1, the electrode assembly to be calibrated in the measuring channel is switched into the calibration channel through the switching assembly, and the calibrated electrode assembly in the calibration channel is switched into the measuring channel at the same time;

[0024] S2, after the electrode assembly to be calibrated enters the calibration channel, the constant displacement pump delivers fluid medium into the calibration channel at a constant volume flow rate, and the density measuring device sends density data to the control module; the control module obtains the mass flow rate Q1 in the calibration channel according to the density and the volume flow rate of the fluid medium;

[0025] S3, the mass flow rate Q2 of the fluid medium in the calibration channel is measured by the electrode assembly to be calibrated;

[0026] The control module compares the mass flow rate Q1 and the mass flow rate Q2; when the difference AQ between the mass flow rate Q1 and the mass flow rate Q2 is greater than the precision error range; the power mechanism drives the electrode assembly to be calibrated to rotate, and adjusts the projection area of the electrode assembly to be calibrated on the cross section of the calibration channel;

[0027] S4, repeating step S3 until the mass flow rate Q2 measured by the electrode assembly to be calibrated is equal to the mass flow rate Q1, the power mechanism stops adjusting, thereby completing the calibration of the mass flow controller. Advantages

[0028] The present application has the advantages that: the present application sets two liquid flow channels of calibration channel and measurement channel, sets the first calibration disc and the second calibration disc, sets the first electrode assembly and the second electrode assembly in an elliptical shape, thereby switching the electrode assembly of the first calibration disc and the electrode assembly of the second calibration disc between the two liquid flow channels through the switching assembly, adjusting the projection area of the first electrode assembly and the second electrode assembly on the calibration channel cross section through the power mechanism, realizing the calibration of the first electrode assembly and the second electrode assembly, realizing the calibration and measurement of the electrode assembly simultaneously, and achieving the purpose of calibrating the measurement error of the electrode assembly caused by impurity adhesion, avoiding the problem of long time production stop caused by the disassembly of the single electrode assembly for calibration, and being beneficial to improve the production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0029] Fig. 1 is a structural schematic diagram of the present application;

[0030] Fig. 2 is a sectional schematic diagram of the present application;

[0031] Fig. 3 is a partial enlarged schematic diagram of A in Fig. 2;

[0032] Fig. 4 is a sectional schematic diagram of another perspective of the present application;

[0033] Fig. 5 is a partial enlarged schematic diagram of B in Fig. 4;

[0034] Fig. 6 is a structural schematic diagram of the first calibration disc or the second calibration disc of the present application;

[0035] Fig. 7 is a sectional schematic diagram of the first calibration disc or the second calibration disc of the present application;

[0036] Fig. 8 is a structural schematic diagram of the power mechanism of the present application;

[0037] Fig. 9 is a sectional schematic diagram of part of the structure of the power mechanism of the present application;

[0038] Explanation of reference signs: 1, control body; 11, measurement channel; 12, calibration channel; 13, first elastic sheet; 14, second elastic sheet; 2, first calibration disc; 3, second calibration disc; 41, push rod; 42, lever; 421, second latch; 51, power motor; 521, transmission shaft; 5211, first pawl; 5212, second pawl; 5213, spring; 522, first driving disc; 5221, first cam groove; 523, second driving disc; 5231, second cam groove; 53, first driving rod; 54, second driving rod; 55, third latch; 6, flow control valve; 7, density measurer; 8, quantitative pump; 9, control module; 10, disc body; 101, through hole; 102, central sliding hole; 103, helical groove; 201, first hot electrode; 202, first temperature probe; 301, second hot electrode; 302, second temperature probe; 40, sliding block; 401, strip-shaped hole; 50, swing arm; 501, first latch; 60, friction ring. Embodiment of the present application

[0039] The present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, which are not intended to limit the scope of the present application.

[0040] As shown in FIGS. 1-9, the MFC mass flow controller with self-calibration function according to the present embodiment comprises a control body 1, which is provided with a measurement channel 11 and a calibration channel 12. Installation notches are provided at both ends of the control body 1, and a first calibration disc 2 and a second calibration disc 3, which are identical in structure, are rotatably arranged in the installation notches, respectively. The first calibration disc 2 and the second calibration disc 3 are both provided with through holes 101 corresponding to the measurement channel 11 and the calibration channel 12, and a first electrode assembly and a second electrode assembly are rotatably arranged in one of the through holes 101 of the first calibration disc 2 and the second calibration disc 3, respectively. The first electrode assembly and the second electrode assembly are both elliptical in shape, so as to adjust the projection area of the first electrode assembly and the second electrode assembly on the cross section of the calibration channel 12.

[0041] The control body 1 is further provided with a switching assembly for synchronously driving the first calibration disc 2 and the second calibration disc 3 to rotate, and a power mechanism for driving the first electrode assembly and the second electrode assembly to rotate.

[0042] One end of the control body 1 corresponding to the measurement channel 11 is connected with a flow control valve 6. One end of the control body 1 corresponding to the calibration channel 12 is connected with a density measurer 7 and a quantitative pump 8. The control body 1 is further provided with a control module 9 connected with the flow control valve 6, the density measurer 7 and the quantitative pump 8.

[0043] Specifically, in actual use, the MFC mass flow controller of the embodiment is connected to the pipeline to be measured at the measuring channel 11, and the calibration channel 12 is connected to the same pipeline as the fluid medium conveyed in the measuring channel 11. Initially, the first electrode assembly and the second electrode assembly on the first calibration disc 2 are placed in the measuring channel 11, and the first electrode assembly and the second electrode assembly on the second calibration disc 3 are placed in the calibration channel 12. The first electrode assembly and the second electrode assembly on the first calibration disc 2 measure the fluid medium in the measuring channel 11. Initially, the long axis direction of the first electrode assembly is set along the vertical direction, and the long axis direction of the second electrode assembly is set along the horizontal direction. At this time, the projection area of the first electrode assembly on the cross section of the calibration channel 12 or the measuring channel 11 is the largest, and the projection area of the second electrode assembly on the cross section of the calibration channel 12 or the measuring channel 11 is the smallest, as shown in FIG. 2.

[0044] When the measurement accuracy of the first electrode assembly and the second electrode assembly on the first calibration disc 2 is reduced due to the attachment of impurities, the electrode assembly on the first calibration disc 2 is the electrode assembly to be calibrated, the electrode assembly on the second calibration disc 3 is the calibrated electrode assembly, and calibration is needed. When calibration is needed, the first calibration disc 2 and the second calibration disc 3 are rotated by the switching assembly, so that the electrode assembly to be calibrated on the first calibration disc 2 is placed in the calibration channel 12, and the calibrated electrode assembly on the second calibration disc 3 is placed in the measuring channel 11. Thus, the calibrated electrode assembly on the second calibration disc 3 measures the fluid medium in the measuring channel 11, and sends the measurement data to the control module 9. The control module 9 controls the opening of the flow control valve 6, so that the mass flow in the measuring channel 11 meets the preset threshold range.

[0045] At this time, the constant volumetric flow of the fluid medium with known temperature and pressure and the same as the fluid medium in the measuring channel 11 is conveyed to the calibration channel 12 by the quantitative pump 8. The density of the fluid medium in the calibration channel 12 is measured by the density measuring device 7, and the density data is sent to the control module 9. The control module 9 obtains the mass flow Q1 in the calibration channel 12 according to the density data and the volumetric flow of the fluid medium. At the same time, the mass flow Q2 of the fluid medium in the calibration channel 12 is measured by the electrode assembly to be calibrated on the first calibration disc 2. The control module 9 compares the mass flow Q2 with the mass flow Q1.

[0046] If the difference AQ between the mass flow rate Q2 and the mass flow rate Q1 is greater than the precision error range of the mass flow controller, the power mechanism drives the to-be-calibrated electrode assembly on the first calibration disc 2 to rotate, while the calibrated electrode assembly on the second calibration disc 3 remains unchanged, so that the projection area of the first electrode assembly on the cross section of the calibration channel 12 is reduced, the projection area of the second electrode assembly on the cross section of the calibration channel 12 is increased, the second electrode assembly receives more fluid medium, compensates for the heat exchange with the fluid medium in the calibration channel 12 due to the reduction of the first electrode assembly covered by impurities, adjusts the orientation of the first electrode assembly and the second electrode assembly, that is, adjusts the orientation of the to-be-calibrated electrode assembly, and repeats the above adjustment process until the mass flow rate Q2 is equal to the mass flow rate Q1, at which time the power mechanism stops adjusting, at which time the first electrode assembly and the second electrode assembly on the first calibration disc 2 remain in the adjusted state, thereby completing the calibration of the first electrode assembly and the second electrode assembly on the first calibration disc 2.

[0047] When the measurement accuracy of the first electrode assembly and the second electrode assembly on the second calibration disc 3 is reduced due to the attachment of impurities, the electrode assembly on the second calibration disc 3 is the to-be-calibrated electrode assembly, the electrode assembly on the first calibration disc 2 is the calibrated electrode assembly, and calibration is needed, the calibrated electrode assembly on the first calibration disc 2 is placed in the measurement channel 11 and the to-be-calibrated electrode assembly on the second calibration disc 3 is placed in the calibration channel 12 again through the switching assembly, and then the orientation of the to-be-calibrated electrode assembly of the second calibration disc 3 is adjusted according to the calibration process of the calibrated electrode assembly of the first calibration disc 2, and the to-be-calibrated electrode assembly of the second calibration disc 3 is calibrated.

[0048] The embodiment sets two liquid flow channels of the calibration channel 12 and the measurement channel 11, and rotates the first calibration disc 2 and the second calibration disc 3, sets the first electrode assembly and the second electrode assembly in an elliptical shape, so that the electrode assembly of the first calibration disc 2 and the electrode assembly of the second calibration disc 3 are switched between the two liquid flow channels through the switching assembly, and the projection area of the first electrode assembly and the second electrode assembly on the cross section of the calibration channel 12 is adjusted by the power mechanism, so as to realize the calibration of the first electrode assembly and the second electrode assembly, realize the synchronization of the calibration and measurement of the electrode assembly, and achieve the purpose of calibrating the measurement error of the electrode assembly caused by the attachment of impurities, thereby avoiding the problem of long-term production stop caused by the calibration of a single electrode assembly which needs to be disassembled, and improving the production efficiency.

[0049] As shown in FIG. 2, FIG. 3, FIG. 6 and FIG. 7, the MFC mass flow controller in the embodiment includes, in some embodiments, a first electrode assembly including a first heating electrode 201 capable of generating heat and a first temperature probe 202 disposed in the first heating electrode 201, and a second electrode assembly including a second heating electrode 301 incapable of generating heat and a second temperature probe 302 disposed in the second heating electrode 301. The embodiment measures the temperature of the first heating electrode 201 by the first temperature probe 202, measures the temperature of the second heating electrode 301 by the first temperature probe 202, and measures the mass flow of the fluid medium in the measurement channel 11 by the temperature difference between the first temperature probe 202 and the second temperature probe 302.

[0050] As shown in FIG. 2 to FIG. 7, the MFC mass flow controller in the embodiment includes, in some embodiments, the first calibration disc 2 and the second calibration disc 3 each further including a disc body 10 provided with a central sliding hole 102, a sliding block 40 disposed in the central sliding hole 102, a strip-shaped hole 401 corresponding to the first electrode assembly and the second electrode assembly respectively formed in the sliding block 40, two through holes 101 symmetrically distributed on both sides of the central sliding hole 102, and the sliding block 40 in transmission connection with a power mechanism; the first heating electrode 201 and the second heating electrode 301 each are sleeved with a swing arm 50, and the swing arm 50 is provided at an end thereof with a first clamping pin 501 movably embedded in the corresponding strip-shaped hole 401.

[0051] Specifically, when the first electrode assembly and the second electrode assembly need to be calibrated, the power mechanism drives the sliding block 40 to slide, and the sliding block 40 drives the swing arm 50 of the first heating electrode 201 and the swing arm 50 of the second heating electrode 301 to swing in the sliding process by cooperation of the strip-shaped hole 401 and the first clamping pin 501, so as to make the first heating electrode 201 and the second heating electrode 301 rotate, change the projection area of the first heating electrode 201 and the second heating electrode 301 on the cross section of the calibration channel 12, and realize calibration of the first heating electrode 201 and the second heating electrode 301.

[0052] As shown in FIG. 4 and FIG. 6, the MFC mass flow controller in the embodiment includes, in some embodiments, a helical groove 103 provided on the peripheral surface of the disc body 10; the switching assembly includes a dial rod 42 slidingly disposed on the control body 1, and the dial rod 42 is provided at both ends thereof with a second clamping pin 421 movably embedded in the helical groove 103; the switching assembly further includes a push rod 41 disposed on the control body 1, and the output end of the push rod 41 is connected with the dial rod 42.

[0053] Specifically, when the first calibration disc 2 and the second calibration disc 3 need to be switched, the push rod 41 pushes the dial rod 42 to slide, the second clamping pin 421 at both ends of the dial rod 42 passes through the helical groove 103, and the first calibration disc 2 and the second calibration disc 3 are driven to rotate, so as to realize switching of the first calibration disc 2 and the second calibration disc 3.

[0054] It should be noted that the middle of the dial lever 42 extends a connecting arm, which is fixedly connected with the output end of the push rod 41.

[0055] As shown in FIG. 3 and FIG. 7, the MFC mass flow controller described in the embodiment, in some embodiments, the first hot electrode 201 and the second hot electrode 301 are both sleeved with a friction ring 60 in friction contact with the disc body 10. The embodiment sets the friction ring 60 so that the first hot electrode 201 and the second hot electrode 301 can be reliably kept in an adjusted state to ensure the calibration effect.

[0056] As shown in FIG. 4, FIG. 5, FIG. 8 and FIG. 9, the MFC mass flow controller described in the embodiment, in some embodiments, the power mechanism includes a power motor 51, a one-way transmission assembly and first and second drive rods 53 and 54, the one-way transmission assembly is connected with the output end of the power motor 51, and the first and second drive rods 53 and 54 are slidingly arranged on the control body 1 and distributed on both sides of the one-way transmission assembly.

[0057] One end of the first drive rod 53 is connected with the one-way transmission assembly, and the other end of the first drive rod 53 is slidingly arranged in the center sliding hole 102 of the first calibration disc 2 and in transmission connection with the sliding block 40. One end of the second drive rod 54 is connected with the one-way transmission assembly, and the other end of the second drive rod 54 is slidingly arranged in the center sliding hole 102 of the second calibration disc 3 and in transmission connection with the sliding block 40.

[0058] Specifically, when the first electrode assembly and the second electrode assembly of the first calibration disc 2 need to be adjusted in the projection area of the first hot electrode 201 and the second hot electrode 301 on the cross section of the calibration channel 12, the power motor 51 is counterclockwise rotated to drive the first drive rod 53 to slide through the one-way transmission assembly, the first drive rod 53 drives the sliding block 40 to slide, thereby driving the first hot electrode 201 and the second hot electrode 301 of the first calibration disc 2 to rotate, so as to adjust the projection area of the first hot electrode 201 and the second hot electrode 301 on the cross section of the calibration channel 12, thereby achieving the purpose of calibration.

[0059] When the first electrode assembly and the second electrode assembly of the second calibration disc 3 need to be adjusted in the projection area of the first hot electrode 201 and the second hot electrode 301 on the cross section of the calibration channel 12, the power motor 51 is clockwise rotated to drive the second drive rod 54 to slide through the one-way transmission assembly, the second drive rod 54 drives the sliding block 40 to slide, thereby driving the first hot electrode 201 and the second hot electrode 301 of the second calibration disc 3 to rotate, so as to adjust the projection area of the first hot electrode 201 and the second hot electrode 301 on the cross section of the calibration channel 12, thereby achieving the purpose of calibration.

[0060] As shown in FIG. 5, FIG. 8 and FIG. 9, the MFC mass flow controller in the embodiment includes a one-way transmission assembly, which in some embodiments includes a transmission shaft 521, a first driving disc 522 and a second driving disc 523 rotatably sleeved on the transmission shaft 521; the transmission shaft 521 movably has a first pawl 5211 and a second pawl 5212; the first driving disc 522 and the second driving disc 523 are both provided with outer ratchet teeth and inner ratchet teeth, the first driving disc 522 is provided with a first cam groove 5221 on the disc surface, and the second driving disc 523 is provided with a second cam groove 5231 on the disc surface; the first pawl 5211 is in one-way engagement with the inner ratchet teeth of the first driving disc 522, and the second pawl 5212 is in one-way engagement with the inner ratchet teeth of the second driving disc 523; the control body 1 is provided with a first elastic sheet 13 and a second elastic sheet 14 corresponding to the positions of the first driving disc 522 and the second driving disc 523 respectively for one-way engagement with the outer ratchet teeth.

[0061] Specifically, the slope directions of the inner ratchet teeth and the outer ratchet teeth of the first driving disc 522 are opposite, the slope directions of the inner ratchet teeth of the second driving disc 523 and the outer ratchet teeth of the first driving disc 522 are the same, the slope directions of the outer ratchet teeth of the second driving disc 523 and the inner ratchet teeth of the first driving disc 522 are the same, and the slope directions of the first pawl 5211 and the second pawl 5212 are opposite.

[0062] When the first driving rod 53 needs to be driven to slide, the power motor 51 drives the transmission shaft 521 to rotate counterclockwise, the first pawl 5211 is in one-way engagement with the inner ratchet teeth of the first driving disc 522, the first pawl 5211 transmits power to the first driving disc 522, so that the transmission shaft 521 drives the first driving disc 522 to rotate counterclockwise through the first pawl 5211, the first elastic sheet 13 does not lock the first driving disc 522, and the first driving disc 522 drives the first driving rod 53 to move through the first cam groove 5221, so as to adjust the projection area of the first hot electrode 201 and the second hot electrode 301 of the first calibration disc 2 on the cross section of the calibration channel 12; at this time, the second elastic sheet 14 is in one-way engagement with the first driving disc 522 to lock, and since the second pawl 5212 is in one-way engagement with the inner ratchet teeth of the second driving disc 523, there is no power transmission between the second pawl 5212 and the second driving disc 523, so that the second driving disc 523 does not rotate when the transmission shaft 521 rotates counterclockwise;

[0063] When the second driving rod 54 needs to be driven to slide, the power motor 51 drives the transmission shaft 521 to rotate clockwise, at this time, the first elastic sheet 13 is in one-way engagement with the first driving disc 522, and the first pawl 5211 and the first driving disc 522 do not transmit power, at this time, the first driving disc 522 does not rotate with the transmission shaft 521, and the second elastic sheet 14 does not lock the second driving disc 523, and the second pawl 5212 and the second driving disc 523 transmit power, so that the transmission shaft 521 drives the second driving disc 523 to rotate clockwise through the second pawl 5212, and the second driving disc 523 drives the second driving rod 54 to move through the second cam groove 5231, so as to adjust the projection area of the first hot electrode 201 and the second hot electrode 301 of the second calibration disc 3 in the cross section of the calibration channel 12.

[0064] By setting the first pawl 5211 and the second pawl 5212 on the transmission shaft 521, the first pawl 5211 is in one-way engagement with the inner ratchet teeth of the first driving disc 522, the second pawl 5212 is in one-way engagement with the inner ratchet teeth of the second driving disc 523, the first elastic sheet 13 is in one-way engagement with the outer ratchet teeth of the first driving disc 522, and the second elastic sheet 14 is in one-way engagement with the outer ratchet teeth of the second driving disc 523, so that the power motor 51 can independently control the calibration of the first calibration disc 2 and the second calibration disc 3 through the rotation direction, which simplifies the structure and reduces the control difficulty.

[0065] As shown in FIG. 9, the MFC mass flow controller provided in the embodiment can correspond to the first pawl 5211 and the second pawl 5212, which are respectively provided with guide holes in the radial direction, and the first pawl 5211 and the second pawl 5212 are respectively arranged in the corresponding guide holes, and the first pawl 5211 and the second pawl 5212 are respectively connected with the transmission shaft 521 through springs 5213. In the embodiment, the spring 5213 is arranged to make the first pawl 5211 and the second pawl 5212 respectively have a tendency to be in one-way engagement with the inner ratchet teeth of the first driving disc 522 and the inner ratchet teeth of the second driving disc 523 under the elastic force of the spring 5213.

[0066] As shown in FIGS. 1 to 9, the embodiment further provides a calibration method based on the above-mentioned MFC mass flow controller, which specifically includes the following steps:

[0067] In step S1, the electrode assembly to be calibrated in the measurement channel 11 is switched into the calibration channel 12 through the switching assembly, and the calibrated electrode assembly in the calibration channel 12 is switched into the measurement channel 11, the mass flow of the fluid medium in the measurement channel 11 is measured by using the calibrated electrode assembly, and the measurement data is sent to the control module 9, the control module 9 controls the opening degree of the flow control valve 6, so that the mass flow of the pipeline to be measured meets the set threshold range.

[0068] In this step, the calibration and measurement of the electrode assembly are synchronized by switching between the two sets of electrode assemblies, avoiding the problem of long-term production stoppage caused by the disassembly of the electrode assembly for calibration.

[0069] Step S2, after the electrode assembly to be calibrated enters the calibration channel 12, the constant volume flow of the fluid medium with known temperature and pressure is delivered to the calibration channel 12 by the quantitative pump 8, the density of the fluid medium in the calibration channel 12 is measured by the density measuring device, and the density data is sent to the control module 9; the control module 9 obtains the mass flow Q1 in the calibration channel 12 according to the fluid medium density and the volume flow;

[0070] Step S3, the mass flow Q2 of the fluid medium in the calibration channel 12 is measured by the electrode assembly to be calibrated, and the mass flow Q2 and the mass flow Q1 are compared;

[0071] When the difference AQ between the mass flow Q2 and the mass flow Q1 is greater than the precision error range of the mass flow controller; the power mechanism drives the electrode assembly to be calibrated to rotate, and adjusts the projection area of the electrode assembly to be calibrated on the cross section of the calibration channel 12;

[0072] Step S4, repeat step S3 until the mass flow Q2 measured by the electrode assembly to be calibrated is equal to the mass flow Q1, and the power mechanism stops adjusting, thereby completing the calibration of the mass flow controller.

[0073] The above is only one preferred embodiment of the present application, so equivalent changes or modifications made according to the structure, features and principles described in the patent application of the present application are included in the protection scope of the patent application of the present application.

Claims

1. A self-calibrating function MFC mass flow controller characterized by, The control body is provided with a measuring channel and a calibration channel, and two first calibration discs and two second calibration discs are rotatably arranged at two ends of the control body and have the same structure. The control body is further provided with a switching assembly for synchronously driving the first calibration discs and the second calibration discs to rotate and a power mechanism for driving the first electrode assemblies and the second electrode assemblies to rotate.

2. A self-calibrating function MFC mass flow controller according to claim 1, wherein, The first electrode assemblies and the second electrode assemblies are both in an elliptical shape.

3. A self-calibrating function MFC mass flow controller according to claim 2, wherein, The first calibration discs and the second calibration discs are further provided with disc bodies, the disc bodies are provided with central sliding holes, sliding blocks are arranged in the central sliding holes, the sliding blocks are respectively provided with strip-shaped holes corresponding to the first electrode assemblies and the second electrode assemblies, and two through holes are symmetrically arranged on two sides of the central sliding hole. The sliding blocks are in transmission connection with the power mechanism.

4. A self-calibrating function MFC mass flow controller according to claim 3, wherein, The first electrode assemblies and the second electrode assemblies are both provided with friction rings in frictional contact with the disc bodies. The power mechanism comprises a power motor, a one-way transmission assembly and first and second driving rods, the one-way transmission assembly is connected with an output end of the power motor, and the first and second driving rods are slidably arranged on the control body and are arranged on two sides of the one-way transmission assembly.

5. A self-calibrating function MFC mass flow controller as defined in claim 3, wherein, One end of the first driving rod is connected with the one-way transmission assembly, the other end of the first driving rod is slidably arranged in the central sliding hole of the first calibration disc and is in transmission connection with the sliding block, one end of the second driving rod is connected with the one-way transmission assembly, and the other end of the second driving rod is slidably arranged in the central sliding hole of the second calibration disc and is in transmission connection with the sliding block.

6. A self-calibrating function MFC mass flow controller as defined in claim 3, wherein, The one-way transmission assembly comprises a transmission shaft and first and second driving discs rotatably arranged on the transmission shaft. The transmission shaft is movably provided with first and second pawls.

7. A self-calibrating function MFC mass flow controller as defined in claim 6, wherein, The first and second driving discs are both provided with outer and inner ratchet teeth, the disc surface of the first driving disc is provided with a first cam groove, and the disc surface of the second driving disc is provided with a second cam groove. The first pawl is in one-way engagement with the inner ratchet teeth of the first driving disc, the second pawl is in one-way engagement with the inner ratchet teeth of the second driving disc, the other ends of the first and second driving rods are both provided with third clamping pins, the third clamping pin of the first driving rod is slidably arranged in the first cam groove, and the third clamping pin of the second driving rod is slidably arranged in the second cam groove. The control body is provided with first and second elastic sheets corresponding to positions of the first and second driving discs and in one-way engagement with the outer ratchet teeth.

8. A self-calibrating function MFC mass flow controller as defined in claim 7, wherein, The transmission shaft is provided with a guide hole in the radial direction corresponding to the first and second pawls, the first and second pawls are slidingly arranged in the corresponding guide hole, and the first and second pawls are connected with the transmission shaft through a spring.

9. A self-calibrating functional MFC mass flow controller according to any one of claims 1 to 8, characterized in that, The control body is connected with a flow control valve at one end corresponding to the measuring channel; the control body is connected with a density measuring device and a quantitative pump at one end corresponding to the calibration channel; the control body is further provided with a control module connected with the flow control valve, the density measuring device and the quantitative pump.

10. A method of calibrating a mass flow controller based on the self-calibration function of claim 9, characterized in that, The method comprises the following steps: S1, switching the electrode assembly to be calibrated in the measuring channel into the calibration channel through the switching assembly, and simultaneously switching the calibrated electrode assembly in the calibration channel into the measuring channel; S2, after the electrode assembly to be calibrated enters the calibration channel, the quantitative pump delivers fluid medium into the calibration channel at a constant volume flow rate, and the density measuring device sends density data to the control module; the control module obtains the mass flow rate Q1 in the calibration channel according to the fluid medium density and the volume flow rate; S3, the mass flow rate Q2 of the fluid medium in the calibration channel is measured by the electrode assembly to be calibrated; The control module compares the mass flow rate Q1 and the mass flow rate Q2; when the difference AQ between the mass flow rate Q1 and the mass flow rate Q2 is greater than the precision error range; the power mechanism drives the electrode assembly to be calibrated to rotate, and adjusts the projection area of the electrode assembly to be calibrated on the cross section of the calibration channel; S4, repeat step S3 until the mass flow rate Q2 measured by the electrode assembly to be calibrated is equal to the mass flow rate Q1, and the power mechanism stops adjusting, thereby completing the calibration of the mass flow controller.

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