A high-precision flow measuring instrument based on the principle of laminar pressure difference

Abstract

The application discloses a high-precision flow measuring instrument based on laminar flow pressure difference principle and relates to the technical field of flow meters.The high-precision flow measuring instrument based on laminar flow pressure difference principle measures the fluid static pressure difference by measuring capillary pressure measuring pipes at two ends of a pipeline, drives a laser emitter to swing by a piston rod, captures the light spot position change by an image sensor after multiple reflections of light, and calculates the flow by combining the Hagen-Poiseuille law.The instrument innovatively introduces adjustable spring force design, is suitable for different pressure ranges, optimizes the light path and prolongs the optical path by a concave-convex lens, improves the detection sensitivity, reduces the interference by a light shield and horizontal placement, and guarantees the stability.Compared with a traditional flow meter, the instrument is more suitable for flow measurement under low flow laminar flow conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flow meter, in particular to a high-precision flow measuring instrument based on laminar flow pressure difference principle. BACKGROUND

[0002] The flow measuring instrument in the prior art often adopts a differential pressure flow meter as the mainstream form, which generates a pressure difference by setting a throttling device (such as a orifice plate, a nozzle) in the pipeline, and then calculates the flow of the fluid according to the pressure difference. However, this method has significant drawbacks: the introduction of the throttling device will interfere with the flow state of the fluid in the pipeline, destroy the original stable laminar flow condition, and make the fluid change from laminar flow to turbulent flow or transitional flow state. Since the flow rate is low and the flow is parallel under the laminar flow condition, the relationship between the pressure difference and the flow is more linear and predictable, but the change of the flow state caused by the throttling device significantly reduces the measurement accuracy at low flow rates, especially in scenarios that require high-precision measurement. This limitation limits the application effect of the differential pressure flow meter in the laminar flow environment, and it is difficult to meet the demand for accurate measurement of stable and low flow rate fluid flow. SUMMARY

[0003] In order to overcome the defects of the prior art, the present application provides the following technical scheme: a high-precision flow measuring instrument based on laminar flow pressure difference principle, comprising a measuring pipeline, two ends of the measuring pipeline are both inserted and sealedly installed with capillary pressure measuring pipes along the radial direction of the measuring pipeline, the two capillary pressure measuring pipes are arranged in a horizontal manner, each capillary pressure measuring pipe is slidably inserted and sealedly fitted with a piston rod, one end of the piston rod located outside the measuring pipeline is fixedly installed with a top head, the top head is in contact with one end of the capillary pressure measuring pipe located outside the measuring pipeline, a laser emitter capable of swinging is arranged on the top head in a lapping manner, the light emitted by the laser emitter is reflected to an image sensor through a plurality of reflecting mirrors, and the image sensor is used for detecting the swing angle of the light emitted by the laser emitter; the light emitted by the two laser emitters can be projected and irradiated onto the image sensor, the light emitted by one of the laser emitters passes through an obliquely arranged light beam splitter to irradiate onto the image sensor, and the light emitted by the other laser emitter is reflected by the light beam splitter to irradiate onto the image sensor.

[0004] Preferably, one end of each capillary pressure measuring pipe located outside the measuring pipeline is fixedly installed with an extension bracket and a laser emitter bracket, the laser emitter is rotatably installed on the laser emitter bracket, one end of the extension bracket away from the measuring pipeline is slidably installed with two guide sliding rods parallel to the axial direction of the capillary pressure measuring pipe, one end of each guide sliding rod close to the capillary pressure measuring pipe is fixedly installed with a contact block, and the contact block is in sliding contact with the laser emitter.

[0005] Preferably, an adjusting compression spring plate is sleeved and slid on the corresponding two guide sliding rods on each extension support, an adjusting screw rod is rotatably installed on the adjusting compression spring plate, the adjusting screw rod is in threaded transmission cooperation with the end of the extension support away from the capillary pressure measuring pipe, a spring is circumferentially arranged on each guide sliding rod, and the two ends of the spring are fixedly connected with the adjusting compression spring plate and the abutting block.

[0006] Preferably, a pin is fixedly installed on the top head, the pin and the shell of the laser emitter are elastically connected through a rubber drawstring, and the laser emitter and the top head are kept in contact at all times.

[0007] Preferably, concave lens supports are fixedly installed at positions where the outer surface of the measuring pipe is located between the two capillary pressure measuring pipes, concave lenses are fixedly installed on the concave lens supports, convex lenses are arranged on the sides of the concave lenses, and the concave lenses and the convex lenses are used for adjusting the angle of light emitted by the laser emitter.

[0008] Preferably, convex lens support supporting sliding rods and adjusting motors are also fixedly installed on the concave lens supports, a convex lens support is sleeved and slid on the convex lens support supporting sliding rod, an adjusting lead screw that is in threaded transmission cooperation with the convex lens support is fixedly installed on the output shaft of the adjusting motor, and a convex lens is fixedly installed on the convex lens support, used for adjusting the distance between the convex lens and the concave lens.

[0009] Preferably, the image sensor, the light beam splitter, and all the reflecting lenses are fixedly installed between the opposite surfaces of the two light-shielding covers, the two light-shielding covers are fixedly installed on the circumferential surface of the measuring pipe, and the adjusting screw rod extends to the outside of the light-shielding cover.

[0010] Preferably, a plurality of reflecting lenses are arranged to lengthen the distance between the light emitted by the laser emitter and the image sensor, and increase the sensitivity of the image sensor in detection, wherein the light beam splitter splits the light emitted by the laser emitter at a ratio of 50:50.

[0011] Preferably, flanges are fixedly installed at the two ends of the measuring pipe.

[0012] Compared with the prior art, the present application has the following beneficial effects: (1) The high-precision flow measuring instrument based on the laminar flow pressure difference principle can accurately detect the small pressure difference between the two ends of the measuring pipeline through the cooperation of the laser emitter and the image sensor. The sliding of the piston rod drives the laser emitter to swing, and the light is amplified after multiple reflections, so that the image sensor can capture the small light spot position difference. This design significantly improves the sensitivity and accuracy of flow measurement, especially for low flow rate and stable laminar flow state; (2) The instrument can optimize the incident angle of the light emitted by the laser emitter through the combination of the concave lens and the convex lens and the adjustment of the position of the convex lens driven by the adjusting motor, so as to ensure that the light can still be vertically irradiated to the image sensor after being reflected by multiple mirror lenses. This light path optimization design not only prolongs the light propagation distance to improve the detection sensitivity, but also reduces the signal loss caused by light deflection, ensuring the stability and reliability of the measurement; (3) The present application directly detects the static pressure difference between the two ends of the measuring pipeline through the capillary pressure measuring pipe, avoiding the use of throttling devices and other structures that can interfere with fluid flow, so as to ensure that the fluid in the pipeline always maintains a stable laminar flow state. Under the laminar flow condition, the linear relationship between pressure difference and flow rate is fully utilized, and the high sensitivity detection of the laser emitter and the image sensor significantly improves the measurement accuracy. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is a schematic diagram of the overall structure of the present application.

[0014] Figure 2 It is a sectional view of the measuring pipeline of the present application.

[0015] Figure 3 It is Figure 2 It is a schematic diagram of the structure at A.

[0016] Figure 4 It is a schematic diagram of the structure at the blocking block of the present application.

[0017] Figure 5 It is a position distribution diagram of the mirror lens of the present application.

[0018] In the figure: 101-measuring pipeline; 102-flange plate; 103-shade; 104-image sensor; 105-light beam splitter; 106-mirror lens; 107-capillary pressure measuring pipe; 108-elongated support; 109-adjusting screw; 110-guiding slide rod; 111-adjusting spring plate; 112-spring; 113-blocking block; 114-laser emitter; 115-laser emitter support; 116-top head; 117-piston rod; 118-concave lens support; 119-adjusting motor; 120-concave lens; 121-convex lens; 122-convex lens support; 123-convex lens support support slide rod; 124-adjusting screw; 125-rubber pull belt; 126-pintle. DETAILED DESCRIPTION

[0019] The technical solutions of the present application are further illustrated below in conjunction with the accompanying drawings. Figures 1-5 The technical solutions of the present application are further illustrated below in conjunction with the accompanying drawings.

[0020] The application provides a high-precision flow measuring instrument based on the laminar pressure difference principle, which comprises a measuring pipeline 101, two capillary pressure measuring pipes 107 are inserted and sealingly installed at the two ends of the measuring pipeline 101 along the radial direction of the measuring pipeline 101, the two capillary pressure measuring pipes 107 are arranged horizontally, a piston rod 117 is slidingly inserted and sealingly matched in each capillary pressure measuring pipe 107, a top head 116 is fixedly installed at one end of the piston rod 117 outside the measuring pipeline 101, the top head 116 is in contact with one end of the capillary pressure measuring pipe 107 outside the measuring pipeline 101, a swingable laser emitter 114 is lapped and arranged on the top head 116, the light emitted by the laser emitter 114 is reflected to an image sensor 104 through a plurality of reflecting mirror pieces 106, and the image sensor 104 is used for detecting the swing angle of the light emitted by the laser emitter 114; the light emitted by the two laser emitters 114 can be projected and irradiated on the image sensor 104, the light emitted by one of the laser emitters 114 passes through an obliquely arranged light beam splitter 105 and is irradiated on the image sensor 104, and the light emitted by the other laser emitter 114 is irradiated on the image sensor 104 after being reflected by the light beam splitter 105. An extension support 108 and a laser emitter support 115 are fixedly installed at one end of each capillary pressure measuring pipe 107 outside the measuring pipeline 101, the laser emitter 114 is rotatably installed on the laser emitter support 115, two guide sliding rods 110 parallel to the axial direction of the capillary pressure measuring pipe 107 are slidingly installed at one end of the extension support 108 away from the measuring pipeline 101, a contact block 113 is fixedly installed at one end of the two guide sliding rods 110 close to the capillary pressure measuring pipe 107, and the contact block 113 is in sliding contact with the laser emitter 114. An adjusting spring plate 111 is slidingly sleeved on the corresponding two guide sliding rods 110 on each extension support 108, an adjusting screw rod 109 is rotatably installed on the adjusting spring plate 111, the adjusting screw rod 109 is in threaded transmission cooperation with one end of the extension support 108 away from the capillary pressure measuring pipe 107, a spring 112 is arranged around each guide sliding rod 110, and the two ends of the spring 112 are fixedly matched with the adjusting spring plate 111 and the contact block 113. A pin 126 is fixedly installed on the top head 116, the pin 126 is elastically connected between the housing of the laser emitter 114 and the top head 116 through a rubber pull belt 125, so that the laser emitter 114 and the top head 116 always keep in contact. A concave lens support 118 is fixedly installed on the outer surface of the measuring pipeline 101 at the positions of the two capillary pressure measuring pipes 107, a concave lens 120 is fixedly installed on the concave lens support 118, a convex lens 121 is arranged on the side of the concave lens 120, and the concave lens 120 and the convex lens 121 are used for adjusting the angle of the light emitted by the laser emitter 114.The concave lens holder 118 is also fixedly installed with a convex lens holder support sliding rod 123 and an adjusting motor 119, wherein the convex lens holder support sliding rod 123 is slidably sleeved with a convex lens holder 122, the output shaft of the adjusting motor 119 is fixedly installed with an adjusting screw rod 124 which is in threaded transmission cooperation with the convex lens holder 122, the convex lens 121 is fixedly installed on the convex lens holder 122, and is used for adjusting the distance between the convex lens 121 and the concave lens 120. The image sensor 104, the light beam splitter 105 and all the reflecting mirror lenses 106 are fixedly installed between the opposite surfaces of the two light shielding covers 103, the two light shielding covers 103 are fixedly installed on the circumferential surface of the measuring pipeline 101, and the adjusting screw rod 109 extends to the outside of the light shielding cover 103. A plurality of reflecting mirror lenses 106 are arranged to prolong the distance between the light emitted by the laser emitter 114 and the image sensor 104, and increase the sensitivity of the image sensor 104, wherein the light beam splitter 105 splits the light emitted by the laser emitter 114 at a strength of 50:50. The flanges 102 are fixedly installed at both ends of the measuring pipeline 101.

[0021] The working principle of the high-precision flow measuring instrument based on the principle of laminar flow pressure difference is as follows: the measuring pipeline 101 is connected in series through the flange plate 102 in the pipeline where the flow needs to be detected, and the light shield 103 is placed (preferably horizontally, which can reduce the error caused by gravity, and the specific requirement depends on the required measurement accuracy). When the fluid passes through the measuring pipeline 101 (the longer the length of the measuring pipeline 101, the higher the detection accuracy), the velocity of the fluid inside the measuring pipeline 101 is detected by measuring the static pressure difference of the fluid at both ends of the measuring pipeline 101, because laminar flow refers to the state that the fluid flows in parallel layers in the pipeline, the flow rate is low and stable. Under the condition of laminar flow, the pressure difference at both ends of the pipeline is proportional to the flow rate (Hagen-Poiseuille law). That is, when the flow rate inside the measuring pipeline 101 increases, the pressure at the upstream end of the fluid will be greater than that at the downstream end, which will result in a difference in the pressure inside the two capillary pressure measuring tubes 107, so the sliding distance of the piston rod 117 inside the two capillary pressure measuring tubes 107 is different, and the two piston rods 117 need to overcome the elastic force of the corresponding springs 112 (the elastic force of the springs 112 can be adjusted by rotating the adjusting screw 109, and the rotation of the adjusting screw 109 will move along the axial direction of the extension bracket 108, so as to adjust the pressure of the two springs 112 by adjusting the pressure spring plate 111 to squeeze or relax, so as to adjust the pressure applied to the piston rod 117, that is, when the static pressure inside the measuring pipeline 101 reaches a certain value, the piston rod 117 can be driven to move, thereby adjusting the range of measurable fluid static pressure).The piston rod 117 slides inside the capillary pressure measuring tube 107 to drive the top head 116 to move synchronously, the movement of the top head 116 drives the laser emitter 114 to swing on the laser emitter support 115, and then changes the angle of the light emitted by the laser emitter 114. When there is no fluid movement in the measuring pipe 101, the pressures detected by the two capillary pressure measuring tubes 107 are the same, that is, the angles of the two laser emitters 114 swinging are the same. At this time, the control adjustment motor 119 is adjusted, the output shaft of the adjustment motor 119 drives the adjustment lead screw 124 to rotate, the adjustment lead screw 124 drives the convex lens support 122 to slide along the axis of the convex lens support sliding rod 123, the movement of the convex lens support 122 drives the convex lens 121 to move away from or close to the concave lens 120, thereby changing the incident angle of the light emitted by the laser emitter 114 on the first mirror 106. Due to the difference in pressure range, the size of the incident angle will be much larger than the angle difference between the two laser emitters 114 driven by the pressure difference between the two ends of the measuring pipe 101 (because the length of the measuring pipe 101 is limited). By adjusting the distance between the concave lens 120 and the convex lens 121, the incident angle of the light emitted by the laser emitter 114 on the first mirror 106 is adjusted, so that the light received on the image sensor 104 is as vertical as possible. Because the light emitted by the laser emitter 114 is reflected by multiple mirrors 106 to the image sensor 104, a slight swing of the laser emitter 114 will cause the light to be outside the image sensor 104 and cannot be received by the image sensor 104. After adjustment, there will be two light spots on the image sensor 104, respectively from the light emitted by the two laser emitters 114. When there is liquid flow in the measuring pipe 101, there is a pressure difference between the two capillary pressure measuring tubes 107, and the swing between the two laser emitters 114 will be different, resulting in different positions of the light emitted by the two laser emitters 114 on the image sensor 104. The distance between the two light spots (actually the sum of the respective offsets of the light spots emitted by each laser emitter 114 on the image sensor 104, which needs to be calculated separately) is detected by the image sensor 104. The distance between the two light spots is proportional to the pressure difference between the two capillary pressure measuring tubes 107, which is converted into a pressure difference, and then the pressure difference is converted into a flow rate by the Hagen-Poiseuille law.

Claims

1. A high-precision flow measuring instrument based on the principle of laminar flow pressure difference, characterized in that: It includes the measuring pipeline (101), both ends of the measuring pipeline (101) are inserted and sealedly installed with capillary pressure gauges (107) along the radial direction of itself, the two capillary pressure gauges (107) are arranged in a horizontal manner, a piston rod (117) is slidably and sealingly fitted in each capillary pressure gauge (107), a top head (116) is fixedly installed at one end of the piston rod (117) outside the measuring pipeline (101), the top head (116) is in contact with one end of the capillary pressure gauge (107) outside the measuring pipeline (101), a laser emitter (114) capable of swinging is lapped and arranged on the top head (116), the light emitted by the laser emitter (114) is reflected to an image sensor (104) through a plurality of reflecting lenses (106), and the image sensor (104) is used for detecting the swing angle of the light emitted by the laser emitter (114); The light emitted by the two laser emitters (114) can be projected and irradiated onto the image sensor (104), wherein the light emitted by one of the laser emitters (114) passes through an obliquely arranged light beam splitter (105) and is irradiated onto the image sensor (104), and the light emitted by the other laser emitter (114) is irradiated onto the image sensor (104) after being reflected by the light beam splitter (105).

2. The high-precision flow measuring instrument based on the principle of laminar flow pressure difference according to claim 1, characterized in that: An extension bracket (108) and a laser emitter bracket (115) are fixedly installed at one end of each capillary pressure gauge (107) outside the measuring pipeline (101), wherein the laser emitter (114) is rotatably installed on the laser emitter bracket (115), two guide sliding rods (110) parallel to the axial direction of the capillary pressure gauge (107) are slidably installed at one end of the extension bracket (108) away from the measuring pipeline (101), and a contact block (113) is fixedly installed at one end of the two guide sliding rods (110) close to the capillary pressure gauge (107), and the contact block (113) is in sliding contact with the laser emitter (114).

3. The high-precision flow measuring instrument based on the principle of laminar flow differential pressure according to claim 2, characterized in that: An adjusting spring plate (111) is slidably sleeved on the corresponding two guide sliding rods (110) of each extension bracket (108), an adjusting screw rod (109) is rotatably installed on the adjusting spring plate (111), the adjusting screw rod (109) is in threaded transmission cooperation with one end of the extension bracket (108) away from the capillary pressure gauge (107), a spring (112) is arranged around each guide sliding rod (110), and both ends of the spring (112) are fixedly connected with the adjusting spring plate (111) and the contact block (113).

4. The high-precision flow measuring instrument based on the principle of laminar flow differential pressure according to claim 3, characterized in that: A pin (126) is fixedly installed on the top head (116), the pin (126) and the shell of the laser emitter (114) are elastically connected through a rubber drawstring (125), so that the laser emitter (114) and the top head (116) always maintain a contact state.

5. The high-precision flow measuring instrument based on the principle of laminar flow differential pressure according to claim 4, characterized in that: The outer surface of the measuring pipe (101) is fixedly installed with a concave lens support (118) at the positions of the two capillary pressure gauges (107), and the concave lens support (118) is fixedly installed with a concave lens (120). The concave lens (120) is provided with a convex lens (121) on the side, and the concave lens (120) and the convex lens (121) are used to adjust the angle of the light emitted by the laser emitter (114).

6. The high-precision flow measuring instrument based on the principle of laminar flow differential pressure according to claim 5, characterized in that: The concave lens support (118) is also fixedly installed with a convex lens support supporting slide rod (123) and an adjusting motor (119). The convex lens support supporting slide rod (123) is slidably sleeved with a convex lens support (122), and the output shaft of the adjusting motor (119) is fixedly installed with an adjusting lead screw (124) in threaded transmission cooperation with the convex lens support (122). The convex lens (121) is fixedly installed on the convex lens support (122) and is used to adjust the distance between the convex lens (121) and the concave lens (120).

7. The high-precision flow measuring instrument based on the principle of laminar flow differential pressure according to claim 6, characterized in that: The image sensor (104), the light beam splitter (105) and all the reflecting lenses (106) are fixedly installed between the opposite faces of the two light shields (103), and the two light shields (103) are fixedly installed on the circumferential surface of the measuring pipe (101), and the adjusting screw rod (109) extends to the outside of the light shield (103).

8. The high-precision flow measuring instrument based on the principle of laminar flow differential pressure according to claim 7, characterized in that: A plurality of reflecting lenses (106) are arranged to lengthen the distance between the light emitted by the laser emitter (114) and the image sensor (104), and to increase the sensitivity of the image sensor (104). The light beam splitter (105) splits the light emitted by the laser emitter (114) at a strength of 50:

50.

9. The high-precision flow measuring instrument based on the principle of laminar flow differential pressure according to claim 8, characterized in that: The two ends of the measuring pipe (101) are fixedly installed with flanges (102).

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