High-precision flow measuring instrument based on laminar flow pressure difference principle

Abstract

The invention discloses a high-precision flow measuring instrument based on a laminar flow pressure difference principle, and relates to the technical field of flowmeters. According to the high-precision flow measuring instrument based on the laminar flow pressure difference principle, the fluid static pressure difference is detected through the capillary pressure measuring pipes at the two ends of the measuring pipeline, the piston rod is used for driving the laser transmitter to swing, after light is subjected to multiple reflection, the light spot position change is captured through the image sensor, and the flow is calculated in combination with the Harroot-Poiseuille law. The instrument innovatively introduces an adjustable spring force design to adapt to different pressure ranges; the light path is optimized and prolonged through the concave-convex lens, and the detection sensitivity is improved; the horizontal arrangement of the light shield reduces interference and ensures stability. Compared with a traditional flow meter, the flow meter is more suitable for flow measurement under the low-flow-speed laminar flow condition.

Description

Technical Field

[0001] The invention relates to the technical field of flowmeters, in particular to a high-precision flow measuring instrument based on the laminar pressure difference principle. Background Art

[0002] Flow measurement instruments in the prior art often use differential pressure flowmeters as the mainstream form, which generate a pressure difference by setting a throttling device (such as an orifice plate, a nozzle) in the pipeline, and then calculate the flow rate of the fluid based on the pressure difference. However, this method has significant disadvantages: the introduction of the throttling device will interfere with the flow state of the fluid in the pipeline, destroy the originally stable laminar flow conditions, and cause the fluid to change from laminar flow to turbulent or transitional flow. Due to the low flow velocity and parallel flow under laminar conditions, the relationship between the pressure difference and the flow rate is more linear and predictable, and the flow state change caused by the throttling device causes the measurement accuracy to drop significantly at low flow rates, especially in scenarios that require high-precision measurements. This limitation limits the application effect of differential pressure flowmeters in laminar flow environments, and it is difficult to meet the needs of accurate measurement of stable, low-velocity fluid flow. Summary of the invention

[0003] In order to overcome the defects of the above-mentioned prior art, the present invention provides the following technical solutions: a high-precision flow measuring instrument based on the laminar pressure difference principle, comprising a measuring pipeline, both ends of the measuring pipeline are sealed and plugged with capillary pressure measuring tubes along the radial direction of the measuring pipeline, the two capillary pressure measuring tubes are arranged horizontally, and each capillary pressure measuring tube is slidably plugged and sealed with a piston rod inside, and the piston rod is fixedly installed with a head at one end of the piston rod located on the outside of the measuring pipeline, and the head is in contact with the end of the capillary pressure measuring tube located on the outside of the measuring pipeline. A swingable laser emitter is overlapped and arranged on the head, and the light emitted by the laser emitter is reflected to an image sensor through multiple reflective lenses, and the image sensor is used to detect the swing angle of the light emitted by the laser emitter; the light emitted by the two laser emitters can be projected onto the image sensor, the light emitted by one laser emitter passes through an inclined light beam splitter and is irradiated onto the image sensor, and the light emitted by the other laser emitter is reflected by the light beam splitter and is irradiated onto the image sensor.

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

[0005] Preferably, adjusting spring plates are slidably sleeved on the corresponding two guiding slide bars on each extension bracket. An adjusting screw rod is rotatably installed on the adjusting spring plate. The adjusting screw rod is in threaded driving cooperation with one end of the extension bracket away from the capillary pressure gauge tube. Springs are disposed around each guiding slide bar. Two ends of the spring are fixedly cooperated with the adjusting spring plate and the abutting block.

[0006] Preferably, a pin is fixedly installed on the top head. The pin is elastically connected with the outer shell of the laser emitter through a rubber strap, so as to keep the laser emitter in contact with the top head all the time.

[0007] Preferably, concave lens brackets are fixedly installed at positions of the outer surface of the measuring pipe corresponding to the two capillary pressure gauge tubes. Concave lenses are fixedly installed on the concave lens brackets. A convex lens is disposed on the side of the concave lens. The concave lens and the convex lens are used for adjusting the angle of the light emitted by the laser emitter.

[0008] Preferably, a convex lens bracket support slide bar and an adjusting motor are further fixedly installed on the concave lens bracket. A convex lens bracket is slidably sleeved on the convex lens bracket support slide bar. An adjusting screw rod in threaded driving cooperation with the convex lens bracket is fixedly installed on the output shaft of the adjusting motor. The convex lens is fixedly installed on the convex lens bracket, so as to adjust 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 provided to extend the distance between the light emitted by the laser emitter and the image sensor, and improve the detection sensitivity of the image sensor. The light beam splitting intensity of the light beam splitter for the light emitted by the laser emitter is 50:50.

[0011] Preferably, flange plates are fixedly installed at both ends of the measuring pipe.

[0012] The present invention has the following beneficial effects compared with the prior art: (1) The high-precision flow measurement instrument based on the laminar flow pressure difference principle of the present invention can accurately detect the tiny pressure difference at both ends of the measurement pipeline through the cooperation of a laser emitter and an image sensor. The sliding of the piston rod drives the laser emitter to swing, and the light is amplified in angle after multiple reflections, enabling the image sensor to capture the difference in the positions of tiny light spots. This design significantly improves the sensitivity and accuracy of flow measurement, especially suitable for low-flow-rate and stable laminar flow states; (2) Through the combination of a concave lens and a convex lens and the adjustment of the position of the convex lens driven by an adjustment motor, this instrument can optimize the incident angle of the light emitted by the laser emitter to ensure that the light can still be perpendicularly irradiated onto the image sensor after being reflected by multiple reflecting lenses. This optimized optical path design not only extends the light propagation distance to improve detection sensitivity but also reduces signal loss caused by light skew, ensuring the stability and reliability of measurement; (3) The present invention directly detects the static pressure difference at both ends of the measurement pipeline through a capillary pressure measuring tube, avoiding the use of structures such as throttling devices that would interfere with fluid flow, thereby ensuring that the fluid in the pipeline always maintains a stable laminar flow state. Under laminar flow conditions, the linear relationship between pressure difference and flow rate is fully utilized, combined with the highly sensitive detection of the laser emitter and the image sensor, significantly improving the measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0014] Figure 2 is a cross-sectional view of the measurement pipeline of the present invention.

[0015] Figure 3 is Figure 2 a schematic diagram of the structure at position A in

[0016] Figure 4 is a schematic diagram of the structure at the abutting block of the present invention.

[0017] Figure 5 is a distribution diagram of the positions of the reflecting lenses of the present invention.

[0018] In the figure: 101 - measurement pipeline; 102 - flange; 103 - light-shielding cover; 104 - image sensor; 105 - light beam splitter; 106 - reflecting lens; 107 - capillary pressure measuring tube; 108 - extension bracket; 109 - adjustment screw; 110 - guiding slide bar; 111 - adjustment spring plate; 112 - spring; 113 - abutting block; 114 - laser emitter; 115 - laser emitter bracket; 116 - top head; 117 - piston rod; 118 - concave lens bracket; 119 - adjustment motor; 120 - concave lens; 121 - convex lens; 122 - convex lens bracket; 123 - support slide bar for convex lens bracket; 124 - adjustment lead screw; 125 - rubber strap; 126 - pin. Detailed implementation manners

[0019] The following will be combined with the attached Figures 1-5 drawings, and the technical solutions of the present invention will be further described through specific implementation manners.

[0020] The present invention provides a high-precision flow measurement instrument based on the principle of laminar flow pressure difference, including a measurement pipeline 101. At both ends of the measurement pipeline 101, capillary pressure measurement tubes 107 are hermetically inserted and installed along the radial direction of the pipeline itself. The two capillary pressure measurement tubes 107 are arranged horizontally. Inside each capillary pressure measurement tube 107, a piston rod 117 is slidably inserted and hermetically fitted. One end of the piston rod 117 located outside the measurement pipeline 101 is fixedly installed with a top head 116. The top head 116 is in contact and cooperation with the end of the capillary pressure measurement tube 107 located outside the measurement pipeline 101. A swingable laser emitter 114 is lapped on the top head 116. The light emitted by the laser emitter 114 is reflected by a plurality of reflecting lenses 106 onto an image sensor 104. The image sensor 104 is used to detect the swing angle of the light emitted by the laser emitter 114. The light emitted by the two laser emitters 114 can both be projected and irradiated onto 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 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. At one end of each capillary pressure measurement tube 107 located outside the measurement pipeline 101, an extension bracket 108 and a laser emitter bracket 115 are fixedly installed. Among them, the laser emitter 114 is rotatably installed on the laser emitter bracket 115. At one end of the extension bracket 108 away from the measurement pipeline 101, two guiding slide rods 110 parallel to the axial direction of the capillary pressure measurement tube 107 are slidably installed. At one end of the two guiding slide rods 110 close to the capillary pressure measurement tube 107, a contact block 113 is fixedly installed. The contact block 113 is in contact and sliding cooperation with the laser emitter 114. On the corresponding two guiding slide rods 110 of each extension bracket 108, an adjusting spring plate 111 is slidably sleeved. An adjusting screw 109 is rotatably installed on the adjusting spring plate 111. The adjusting screw 109 is in threaded transmission cooperation with the end of the extension bracket 108 away from the capillary pressure measurement tube 107. A spring 112 is arranged around each guiding slide rod 110. The two ends of the spring 112 are fixedly fitted 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 to the outer shell of the laser emitter 114 through a rubber strap 125, so as to keep the laser emitter 114 and the top head 116 in contact state all the time. On the outer surface of the measurement pipeline 101 at the positions of the two capillary pressure measurement tubes 107, concave lens brackets 118 are fixedly installed. A concave lens 120 is fixedly installed on the concave lens bracket 118. A convex lens 121 is arranged on the side of the concave lens 120. The concave lens 120 and the convex lens 121 are used to adjust the angle of the light emitted by the laser emitter 114.A convex lens support slide rod 123 and an adjustment motor 119 are also fixedly installed on the concave lens support 118. A convex lens support 122 is slidably sleeved on the convex lens support slide rod 123. An adjustment lead screw 124 that is in threaded transmission cooperation with the convex lens support 122 is fixedly installed on the output shaft of the adjustment motor 119. A 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. The image sensor 104, the beam splitter 105, and all the reflecting lenses 106 are fixedly installed between the opposite surfaces of the two light shields 103. The two light shields 103 are fixedly installed on the circumferential surface of the measuring pipeline 101, and the adjustment screw rod 109 extends to the outside of the light shield 103. A plurality of reflecting lenses 106 are provided to extend the distance of the light emitted by the laser emitter 114 to the image sensor 104 and increase the detection sensitivity of the image sensor 104. The beam splitting intensity of the light emitted by the laser emitter 114 by the beam splitter 105 is 50:50. Flange plates 102 are fixedly installed at both ends of the measuring pipeline 101.

[0021] The working principle of a high-precision flow measurement instrument based on the laminar flow pressure difference principle disclosed by the present invention is as follows: The measurement pipeline 101 is serially installed in the pipeline where the flow needs to be detected through the flange 102, and the light-shielding cover 103 is placed (it is preferably placed horizontally to reduce the error caused by gravity, specifically depending on the required measurement accuracy). When the fluid passes through the measurement pipeline 101 (the longer the length of the measurement pipeline 101, the higher the detection accuracy), the velocity of the fluid inside the measurement pipeline 101 is detected by measuring the static pressure difference of the fluid at both ends of the measurement pipeline 101. This is because laminar flow refers to the state where the fluid flows in parallel layers in the pipeline, with a relatively low and stable flow velocity. Under laminar flow conditions, the pressure difference at both ends of the pipeline is proportional to the flow velocity (Hagen-Poiseuille's law). That is to say, when the flow velocity inside the measurement pipeline 101 increases, the pressure at the upstream end of the fluid will be greater than the pressure at the downstream end, which will cause a difference in the pressure inside the two capillary pressure gauges 107. Therefore, the sliding distances of the piston rods 117 inside the two capillary pressure gauges 107 are different. The two piston rods 117 need to overcome the elastic forces of their respective corresponding springs 112 (the elastic forces of the springs 112 can be adjusted by rotating the adjusting screw 109. When the adjusting screw 109 rotates, it moves along its own axial direction on the extension bracket 108, thereby squeezing or relaxing the two springs 112 through the adjusting spring plate 111 to adjust the pressure applied to the piston rods 117. That is to say, when the static pressure inside the measurement pipeline 101 reaches what value, it can push the piston rod 117 to move, and further adjust the range of the static pressure of the fluid that can be measured).The sliding of the piston rod 117 inside the capillary manometer tube 107 will drive the synchronous movement of the head 116. The movement of the head 116 will push the laser emitter 114 to swing on the laser emitter bracket 115, and then change the angle of the light emitted by the laser emitter 114. When there is no fluid movement inside the measurement pipe 101, the pressures detected by the two capillary manometer tubes 107 are the same, that is, the angles of swing of the two laser emitters 114 are the same. At this time, the control adjustment motor 119 is controlled. 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 bracket 122 to slide along the axial direction of the convex lens bracket support slide bar 123. The movement of the convex lens bracket 122 will drive the convex lens 121 to move away from or close to the concave lens 120, so as to change the incident angle of the light emitted by the laser emitter 114 on the first reflecting lens 106. Due to the different pressure ranges, the size of this incident angle will be much larger than the angle difference between the two laser emitters 114 caused by the pressure difference at both ends of the measurement pipe 101 (because the length of the measurement 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 reflecting lens 106 is adjusted, so that the light received on the image sensor 104 is as vertical as possible. Because the distance that the light emitted by the laser emitter 114 is reflected by multiple reflecting lenses 106 to the image sensor 104 is very long, a slight swing of the laser emitter 114 will cause the light to irradiate outside the image sensor 104 and cannot be received by the image sensor 104. After the adjustment is completed, there will be two light spots on the image sensor 104, which come from the light emitted by the two laser emitters 114 respectively. When there is liquid flow inside the measurement pipe 101, there is a pressure difference inside the two capillary manometer tubes 107, and there will be a difference in the swing between the corresponding two laser emitters 114, resulting in different positions of the light irradiated by the two laser emitters 114 on the image sensor 104. The distance between the two light spots is detected by the image sensor 104 (actually the sum of the respective offsets of the light spots irradiated by each laser emitter 114 on the image sensor 104, which needs to be calculated separately). The distance between the two light spots is proportional to the pressure difference between the two capillary manometer tubes 107. It is converted into a pressure difference, and then the pressure difference is converted into a flow rate through the Hagen-Poiseuille law.

Claims

1. A high-precision flow measurement instrument based on the principle of laminar flow pressure difference, characterized in that: The measuring pipe (101) comprises a measuring pipe (101), both ends of the measuring pipe (101) are plugged and sealed with capillary pressure measuring tubes (107) along the radial direction of the measuring pipe (101), the two capillary pressure measuring tubes (107) are arranged horizontally, each capillary pressure measuring tube (107) is slidably plugged and sealed with a piston rod (117) inside, one end of the piston rod (117) located outside the measuring pipe (101) is fixedly installed with a head (116), the head (116) contacts and cooperates with one end of the capillary pressure measuring tube (107) located outside the measuring pipe (101), and a swingable laser emitter (114) is overlapped and arranged, the light emitted by the laser emitter (114) is reflected to the image sensor (104) through a plurality of reflective lenses (106), and the image sensor (104) is used to detect the swing angle of the light emitted by the laser emitter (114); The light emitted by the two laser emitters (114) can both be projected onto the image sensor (104), wherein the light emitted by one of the laser emitters (114) passes through an inclined light beam splitter (105) and is irradiated onto the image sensor (104), and the light emitted by the other laser emitter (114) is reflected by the light beam splitter (105) and is irradiated onto the image sensor (104).

2. The high-precision flow measurement instrument based on the laminar flow differential pressure principle according to claim 1, wherein: An extension bracket (108) and a laser emitter bracket (115) are fixedly mounted on one end of each capillary pressure measuring tube (107) located outside the measuring pipe (101), wherein the laser emitter (114) is rotatably mounted on the laser emitter bracket (115), and two guide slide bars (110) parallel to the axis of the capillary pressure measuring tube (107) are slidably mounted on one end of the extension bracket (108) away from the measuring pipe (101), and a resistance block (113) is fixedly mounted on one end of the two guide slide bars (110) close to the capillary pressure measuring tube (107), and the resistance block (113) is in contact and sliding cooperation with the laser emitter (114).

3. The high-precision flow measurement instrument based on the laminar flow pressure difference principle according to claim 2, characterized in that: An adjusting spring plate (111) is provided on the sliding sleeve of the two corresponding guide slide bars (110) on each extension bracket (108), and an adjusting screw (109) is rotatably mounted on the adjusting spring plate (111). The adjusting screw (109) is threadedly matched with one end of the extension bracket (108) away from the capillary pressure measuring tube (107). A spring (112) is arranged around each guide slide bar (110), and both ends of the spring (112) are fixedly matched with the adjusting spring plate (111) and the abutment block (113).

4. The high-precision flow measurement instrument based on the laminar flow pressure difference principle according to claim 3, wherein: A pin (126) is fixedly mounted on the top head (116), and the pin (126) is elastically connected to the housing of the laser emitter (114) via a rubber pull belt (125) so as to keep the laser emitter (114) and the top head (116) in contact at all times.

5. The high-precision flow measurement instrument based on the laminar flow pressure difference principle according to claim 4, characterized in that: At the positions of the two capillary manometers (107) where the outer surface of the measuring pipe (101) is located, concave lens brackets (118) are fixedly installed. A concave lens (120) is fixedly installed on the concave lens bracket (118). A convex lens (121) is arranged on the side of the concave lens (120). 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 measurement instrument based on the laminar flow differential pressure principle according to claim 5, wherein: A convex lens bracket support slide rod (123) and an adjustment motor (119) are also fixedly installed on the concave lens bracket (118). A convex lens bracket (122) is slidably sleeved on the convex lens bracket support slide rod (123). An adjustment lead screw (124) that is in threaded transmission cooperation with the convex lens bracket (122) is fixedly installed on the output shaft of the adjustment motor (119). The convex lens (121) is fixedly installed on the convex lens bracket (122) and is used to adjust the distance between the convex lens (121) and the concave lens (120).

7. The high-precision flow measurement instrument based on the laminar flow differential pressure principle 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 surfaces of the two light shields (103). The two light shields (103) are fixedly installed on the circumferential surface of the measuring pipe (101), and the adjustment screw (109) extends to the outside of the light shield (103).

8. The high-precision flow measurement instrument based on the laminar flow pressure difference principle according to claim 7, wherein: A plurality of reflecting lenses (106) are provided to extend the distance between the light emitted by the laser emitter (114) and the image sensor (104), and increase the sensitivity of the detection of the image sensor (104). The light beam splitting intensity of the light beam splitter (105) for the light emitted by the laser emitter (114) is 50:

50.

9. The high-precision flow measurement instrument based on the laminar flow pressure difference principle according to claim 8, characterized in that: Flange plates (102) are fixedly installed at both ends of the measuring pipe (101).

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