In-tube liquid detecting device and holding structure thereof

Abstract

To provide a device for detecting a liquid in a pipe capable of detecting the presence or absence of the liquid in the pipe without being affected by air bubbles / liquid dripping / liquid droplets even when the air bubbles / liquid dripping / liquid droplets are generated in a part of the pipe.SOLUTION: One or a plurality of sets of light projecting parts and light receiving parts are arranged along the outer periphery of a cylindrical pipe in the cross-sectional direction orthogonal to the axial direction of the pipe, and the form of the measuring surface of the device for detecting the liquid in the pipe is formed into a cylindrical curved surface having a radius adapted to the maximum outer diameter to be measured of the outer diameter of the cylindrical pipe. One or more sets of light changing means are provided between the light projecting unit and the cylindrical tube and between the light receiving unit and the cylindrical tube, respectively, the light changing means having an inner surface facing the cylindrical tube and formed in a surface shape different from an outer diameter of the cylindrical tube so as to emit light toward the cylindrical tube at a predetermined angle.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a liquid detection device for detecting liquids in a tube and a gripping structure thereof, and more specifically to a liquid detection device for detecting liquids in a tube optically from the outside to determine whether or not liquid is present in a cylindrical tube with a circular cross section, and a gripping structure for easily and stably attaching the liquid detection device for detecting liquids in a tube to the side of the cylindrical tube. [Background technology]

[0002] As a method for detecting the liquid level inside a container that stores a liquid 2, for example, as shown in Figure 1, a cylindrical pipe 3 that branches off from the bottom of the liquid storage container 1 is installed upright parallel to the side of the liquid storage container 1, and the liquid level inside the liquid storage container 1 is indirectly measured by detecting the presence or absence of liquid inside the cylindrical pipe 3 at a predetermined position (height) that connects the liquid storage container 1 to the cylindrical pipe 3.

[0003] Therefore, the present applicant has developed and manufactured an in-pipe liquid detection device for detecting the liquid level inside a hollow cylindrical pipe, as a liquid leakage sensor and liquid leakage detection system, as described in Patent Publication No. 4474664 (Patent Document 1).

[0004] Furthermore, with the liquid detection device for a pipe described in Patent Document 1, even if the diameter of the cylindrical pipe in which the liquid is detected is different, it is possible to detect the presence or absence of liquid in the pipe using the same detection device, within the range of pipe diameters that are expected to be used in advance, without adjusting the projection angle of the light-emitting part of the detection device or replacing the device itself. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4474664 Summary of the Invention [Problem to be solved by the invention]

[0006] Furthermore, the invention described in Patent Document 1 above does not require that the cylindrical tube to be detected be made of a transparent material, as long as it is made of a light-transmitting material such as a translucent material through which light can pass. It operates and detects very stably even when bubbles, drips, or droplets are present inside the tube from the outside of the tube onto which the light is projected. Furthermore, even if the outer diameter of the cylindrical tube to which the device is attached differs by 20% or more between large-diameter and small-diameter tubes, the exact same measuring device body can be used, and the device is easy to install and does not require any skill.

[0007] On the other hand, in order to make the most of the above advantages, it is desirable to reduce production costs and power consumption even further.

[0008] For example, in the invention described in Patent Document 1, the inner surface of the device main body on the side that is attached to the cylindrical tube is used both as an optical path changing means and as a part that fastens the device main body, and as shown in Figure 2(A), light emitted from the light-emitting unit is refracted by light-refracting unit A on the light-emitting side, and the refracted light is emitted from the cylindrical inner surface of the main body (case) to the air side, and is incident as transmitted light that detects the presence or absence of liquid in the air inside the hollow cylindrical tube at a substantially constant detection angle, is refracted inside the cylindrical tube, and is incident on the cylindrical inner surface of the main body on the light-receiving side. The incident light is then refracted by light-refracting unit B on the light-receiving side and is incident on the light-receiving unit.

[0009] Here, on the light projection side, for example, as shown in Figure 2(B), parallel light rays (incident light) from the light projection part are refracted on the cylindrical inner surface of light refraction part A and emitted into the air side, but the parallel light rays incident on light refraction part A have different angles of incidence at each point of incidence on the cylindrical inner surface, so the refracted light A for each light ray has the characteristic of spreading. Therefore, the amount of light incident on the cylindrical tube is attenuated compared to the light incident on light refraction part A.

[0010] On the other hand, the liquid presence / absence determination means for detecting liquid in the tube determines the presence / absence based on the intensity (amount of light) of refracted light reaching the light receiving unit, so the greater the amount of light incident on the light receiving unit, the greater the dynamic range of liquid presence / absence.

[0011] Therefore, the invention of Patent Document 1 has a problem in that the amount of refracted light on the light-projecting side is attenuated because it passes through the inner surface of the cylindrical shape that matches the cylindrical tube of the light-refracting portion A.

[0012] Furthermore, in the invention described in Patent Document 1, when attaching the liquid-detection device to the side of a cylindrical tube, for example, as shown in FIG. 3, cylindrical tube 3 is placed between a saddle-shaped fastener and the device main body, and a rod screw protruding from the device main body 4 side is inserted through a through-hole provided in the fastener, and cylindrical tube 3 is pressed and clamped between device main body 4 and the saddle-shaped fastener using a screwable fastening means such as a wing nut, thereby tightly fixing it in place.

[0013] Such a saddle-shaped fastener has the effect of reducing light incidence from the back of the cylindrical tube 3 as viewed from the device main body 4, thereby improving the dynamic range of liquid detection. However, if it is possible to align the central axis of the cylindrical tube with the central axis of the device main body when installing the cylindrical tube, it is desirable to further improve installation operability.

[0014] Therefore, the present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a liquid detection device in a pipe that maintains the advantages of the liquid detection device in a pipe described in Patent Document 1, such as the fact that it does not require adjustment of the projection angle of the light-projecting unit even if the pipe diameter is different, that it can be used even if the pipe is not made of a transparent material as long as the pipe is made of a light-transmitting material such as a translucent material that allows light to pass through, and that it operates / detects very stably even if air bubbles / liquid drips / droplets are generated inside the pipe from the outside of the pipe that projects light, that the exact same sensor main body can be used even if the outer diameter of the cylindrical pipe to which the device is attached differs by 20% or more between a large diameter pipe and a small diameter pipe, and that the installation of the device is simple and does not require skill, while also achieving reduced production costs, further saving on power consumption, and improved installation operability. [Means for solving the problem]

[0015] In order to solve the above problems, the present invention provides an in-pipe liquid detection device that detects the presence or absence of liquid in a cylindrical pipe by arranging one or more pairs of a light projecting unit and a light receiving unit along the outer periphery of the cylindrical pipe in a cross-sectional direction perpendicular to the axial direction of the cylindrical pipe, and the shape of the measurement surface of the housing of the in-pipe liquid detection device is formed into a cylindrical curved surface having a radius that matches the outer diameter of the cylindrical pipe to the largest outer diameter to be measured, and the inner surface facing the cylindrical pipe is formed into a front curved surface so that light is emitted at a predetermined angle toward the cylindrical pipe between the light projecting unit and the cylindrical pipe, and between the light receiving unit and the cylindrical pipe. One or more sets of light changing means each having a surface shape different from the outer diameter of the cylindrical tube are provided, and the transmitted light is refracted / projected via the light projecting unit and the light path changing means so that the transmitted light for detecting the presence or absence of the liquid is refracted and incident at a substantially constant detection angle from the outside of the cylindrical tube into the air inside the hollow cylindrical tube, and when there is no liquid in the air inside the hollow cylindrical tube, the refracted light is directly received by the light path changing means and the light receiving unit. a plurality of sets of the light-emitting units and the light-receiving units are arranged in the same cross-sectional direction so that, when the liquid is present in the optical path, the refracted light passes through the liquid and does not directly reach the light-receiving units; and a liquid presence / absence determining means is provided for processing the outputs of the plurality of light-receiving units to detect the presence or absence of liquid in the tube; when the cylindrical tube has the largest outer diameter and there is no liquid inside the hollow cylindrical tube, the optical path changing means causes the transmitted light for detection to pass through the air inside the hollow cylindrical tube; and a front light source is provided on the side where the liquid detection device is attached from the center of the cylindrical tube to the front light source; a geometric equation and an optical equation are simultaneously used to calculate the fixed positions of the light-emitting unit and the light-receiving unit so that the transmitted light for detection is transmitted; further, when the outer diameter of the cylindrical tube is the smallest outer diameter tube to be measured and there is no liquid inside the hollow cylindrical tube, the transmitted light for detection passes through the air via the optical path changing means and is then incident on the cylindrical tube, and the transmitted light for detection passes through the air inside the hollow cylindrical tube; and then the transmitted light for detection that has passed through the air from the cylindrical tube is propagated to the light-receiving unit via the optical path changing means;When the transmitted light for detection passes through the air inside the hollow cylindrical tube, the fixed positions of the light-emitting unit and the light-receiving unit are calculated by simultaneously solving geometric equations and optical equations so that the transmitted light for detection passes from the cylindrical center of the cylindrical tube to the side on which the liquid-detecting device is attached, and for the light-emitting unit and light-receiving unit attachment positions at preset spatial fixed positions, the fixed positions of the light-emitting unit and the light-receiving unit calculated when the outer diameter of the cylindrical tube is the maximum tube diameter and the fixed positions of the light-emitting unit and the light-receiving unit calculated when the outer diameter of the cylindrical tube is the minimum diameter are calculated, and for tubes with various outer diameters, when there is no liquid inside the hollow of the tube, the fixed positions of the light-emitting unit and / or the light-receiving unit are changed to positions where the light-emitting unit and the light-receiving unit at the preset spatial fixed positions can stably receive the main beam of the refracted and transmitted light, and and a fastener for fixing the spatial arrangement of the cylindrical tube and the light-emitting unit and the light-receiving unit so that the axis of the cylindrical tube maintains a predetermined positional relationship with the light-emitting unit and the light-receiving unit even if the outer diameter of the cylindrical tube changes, and the device is characterized in that the device is able to detect the presence or absence of liquid in the tube by using the plurality of sets of light-emitting units and light-receiving units, even if air bubbles / liquid drips / droplets occur on part of the tube surface, without being affected by the air bubbles / liquid drips / droplets, by the plurality of sets of light-emitting units and light-receiving units.

[0016] Furthermore, the above problem is solved more effectively when the predetermined angle is a substantially constant emission angle that is neither divergent nor convergent, and the surface shape that is different from the outer diameter of the cylindrical tube is a flat surface.

[0017] Furthermore, the above problem is solved more effectively by the light-changing means having convex surfaces on the upper and lower surfaces of the housing of the light-changing means that fit into the housing of the liquid-detecting device, and by the housing having an opaque / light-blocking material formed in advance between the light-emitting unit and the light-receiving unit on the inside of the housing of the light-changing means to prevent transmitted light from the light-emitting unit from being directly received by the light-receiving unit.

[0018] The above problem is further solved by a gripping structure for gripping the in-pipe liquid detection device to the side of the cylindrical tube, wherein the housing of the in-pipe liquid detection device consists of an upper shell body and a lower shell body, the upper shell body is provided with an upper band guide, and the lower shell body is provided with a lower band guide, and a saddle band is arranged along the axial direction of the cylindrical tube on the side of the cylindrical tube opposite the housing of the in-pipe liquid detection device, and by wrapping cable ties from each of the upper band guide and the lower band guide so as to surround the outside of the saddle bands arranged on the side of the cylindrical tube and tying the cable ties, thereby gripping the in-pipe liquid detection device to the side of the cylindrical tube, or by providing the saddle band with a band pass-through shape through which the cable ties can pass, or by tying with the cable ties being performed on the side of the cylindrical tube by a saddle band locking portion. [Effects of the Invention]

[0019] In the present invention, for example, the shape of the measurement surface of the housing of the in-tube liquid detection device is formed into a cylindrical curved surface having a radius that matches the outer diameter of the cylindrical tube to the maximum outer diameter of the object to be measured, while between the light-emitting unit and the cylindrical tube, and between the light-receiving unit and the cylindrical tube, a light-modifying means is provided in which the inner surface facing the cylindrical tube is formed into a surface shape different from the outer diameter of the cylindrical tube so that light is emitted toward the cylindrical tube at an approximately constant emission angle that does not diffuse or converge.

[0020] Therefore, by holding a cylindrical tube on the measurement surface side of the housing of the tube liquid detection device, and at the same time giving the light changing means side the same angle of incidence and refraction of the light beam from the light projecting unit, or by giving the light beam a characteristic of narrowing the difference in refraction angle, it is possible to increase the amount of light incident on the light receiving unit and improve the ability to determine whether or not liquid is present in the tube.

[0021] In addition, in this invention, the shape of the measurement surface of the housing of the liquid detection device for a pipe is formed into a cylindrical curved surface with a radius that matches the outer diameter of the cylindrical pipe to be measured, and a structure is adopted in which the cylindrical pipe is fixed to the main body of the liquid detection device for a pipe using two band-shaped tightening devices on the upper and lower sides of the liquid detection device for a pipe, a band guide provided toward the center of the cylindrical pipe fixing part of the main body of the liquid detection device for a pipe, and a saddle band on the back of the cylindrical pipe that is sandwiched between the cable tie and the cylindrical pipe.

[0022] Therefore, with this gripping structure, the central axis of the measurement surface of the main body of the liquid detection device in a tube can be automatically aligned with the central axis of the cylindrical tube, regardless of the diameter of the cylindrical tube, and this can be done extremely easily by using a cable tie. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a cross-sectional view showing a cylindrical pipe attached to a liquid storage tank and a liquid detection device disposed therein. [Figure 2] 1A and 1B are diagrams showing the optical paths in Patent Document 1, where (A) is a conceptual diagram of the entire device as seen from above, and (B) is an enlarged view showing the optical paths around the light refraction section. [Figure 3] FIG. 1 is a perspective view of a case where the liquid-detecting device in Patent Document 1 is simply mounted in a cylindrical shape. [Figure 4] 1A and 1B are diagrams showing optical paths according to the present invention, in which (A) is a conceptual diagram of the entire device as seen from above, and (B) is an enlarged view showing optical paths around a light refraction section. [Figure 5]1A and 1B are enlarged views showing the optical path around a prism having an engagement portion according to the present invention for engaging with the housing of a liquid-detection device, where (A) is formed with a cylindrical surface as described in Patent Document 1, and (B) is formed with a flat surface according to the present invention. [Figure 6] 1A and 1B are enlarged views showing simulation results showing the optical path around a prism having an engagement portion according to the present invention, where (A) shows a prism having a cylindrical surface as described in Patent Document 1, and (B) shows a prism having a flat surface according to the present invention. [Figure 7] 1A to 1C are diagrams showing an example of a housing of a liquid-detection device according to the present invention, in which (A) is a front view showing the measurement unit side, (B) is a top view, and (C) is a rear view. [Figure 8] 1A and 1B are top views showing examples of winding a cable tie according to the present invention, in which (A) and (B) show examples of band guides that protrude from the upper and lower shells, and (C) and (D) show examples of band guides provided inside the upper and lower shells. Also, (A) and (C) show examples of winding a cable tie around a large-diameter cylindrical pipe, and (B) and (D) show examples of winding a cable tie around a small-diameter cylindrical pipe. [Figure 9] This shows an example in which a band guide is provided inside each of the upper and lower shells, where (A) is a front view showing the measurement section, (B) is a view of the band guide section from the top and bottom, (C) is a perspective view of the light-changing means on the light-emitting and light-receiving sides within the detection device, and (D) is a rear view. [Figure 10] 10A and 10B are perspective views showing an example of stacking multiple detection devices on a cylindrical tube, where FIG. 10A is a view from the detection device side and FIG. 10B is a view from the band fastener 43b side. [Figure 11] FIG. 10 is a top view showing an example in which the band guide is provided away from the measuring section side in the present invention. [Figure 12] 1A and 1B are diagrams showing an example of the configuration of a binding band, in which (A) is a top view and (B) is a side view. [Figure 13](A) is an oblique view showing an example in which a band guide is provided inside each of the upper and lower shells, and a circular insertion hole is also provided in the saddle band; (B) is a plan view showing an example in which a band-passing shape is provided in the saddle band for inserting a cable tie; and (C) is a cross-sectional view of the part in (A) where the band is wound. [Figure 14] 1 is a diagram illustrating the entire optical path from the light projecting unit 52 to the light receiving unit 54 of the present invention, with the angular coordinates at each refraction point as the center. [Figure 15] 1 is a diagram showing the entire optical path from the light projecting unit 52 to the light receiving unit 54 of the present invention, with the position coordinates of each refraction point as the center. [Figure 16] 10 is a diagram showing the relationship between the light projecting unit 52, the optical path changing means 407, and the case inner diameter r1 of the present invention. FIG. [Figure 17] 10 is a diagram showing the relationship between incident light P1-P2 and refracted light 123 at the refraction point P2 of the optical path changing means 407. FIG. [Figure 18] 10 is a diagram showing the optical path along which transmitted light propagates from the refraction point P2 of the optical path changing means 407 to the outer refraction point P3 of the cylindrical tube 3. FIG. [Figure 19] 1 is a diagram showing an optical path when refracted light propagates inside a cylindrical tube 3 at an outer refraction point P3. [Figure 20] 1 is a diagram showing the optical path of refracted light propagating inside the tubing of a cylindrical tube 3. FIG. [Figure 21] 10 is a diagram showing the optical path of refracted light at an inner refraction point P4 of a cylindrical tube 3. FIG. [Figure 22] 10 is a diagram showing the optical path of refracted light propagating inside the hollow cylindrical tube 3 and refracting inside the tube material at an inner refraction point P5. [Figure 23] 1 is a diagram showing the optical path of refracted light propagating inside the tubing of a cylindrical tube 3 to the outside. [Figure 24] 10 is a diagram showing the optical path of refracted light propagating to the outside of a cylindrical tube 3 at an outer refraction point P6. [Figure 25] 10 is a diagram showing the optical path along which transmitted light propagates from a refraction point P6 on the outside of the cylindrical tube 3 to a refraction point P7 of the optical path changing means 411. FIG. [Figure 26]10 is a diagram showing an optical path along which refracted light propagates inside the optical path changing means 411 at a refraction point P7. [Figure 27] 10 is a diagram showing an optical path along which refracted light propagates from a refraction point PP of the optical path changing means 411 to the light receiving section 54. FIG. [Figure 28] 1 is a cross-sectional view showing the optical path of a liquid detection device 4 according to the present invention when mounted in a cylindrical tube of medium outer diameter. [Figure 29] 1 is a cross-sectional view showing the optical path when the liquid detection device 4 according to the present invention is mounted in a cylindrical tube with a maximum outer diameter. [Figure 30] This is a horizontal cross-sectional view of an in-pipe liquid detection device 4b in which the light-emitting unit / light-receiving unit of the present invention are arranged asymmetrically so that the error between the fixed positions for the largest outer diameter tube and the smallest outer diameter tube is within a predetermined error ε. [Figure 31] FIG. 10 is a diagram showing an example of a configuration in which a plurality of light-emitting / light-receiving sections are arranged on the outer periphery of a tube and a plurality of liquid-detecting optical systems are provided according to the present invention. [Figure 32] 10 is a diagram showing the travel path of the projection light for liquid detection when the inside of the tube is filled with liquid. FIG. [Figure 33] This figure shows another example of a configuration in which multiple light-emitting / light-receiving units of the present invention are arranged on the outer periphery of a tube and multiple optical systems for liquid detection are provided, and is an example in which multiple integrally formed light-emitting / light-receiving units are arranged in two locations. DETAILED DESCRIPTION OF THE INVENTION

[0024] The in-pipe liquid detection device and its gripping structure according to the present invention will be described in more detail below with reference to the drawings.

[0025] The drawings referred to below are illustrative of the outline of the present invention, and the detailed structures, proportions, and notations of common structures may be exaggerated or omitted in a schematic manner to facilitate understanding.

[0026] In addition, since the present invention is an improvement of the invention described in Patent Document 1, the basic configuration is based on that invention. Therefore, the description of Patent Document 1 will be cited as necessary in the explanation.

[0027] Since the present invention relates to an in-pipe liquid detection device and its gripping structure, the features of the main body of the in-pipe liquid detection device will be described first.

[0028] In the present invention, for example, as shown in Figure 4(A), the shape of the measurement surface of the housing of the detection device main body 41 (42) (internal structure 41F (42F) of the measurement surface) and the shape of the inner surface side of the optical path changing means are separated and made to have mutually different shapes.

[0029] That is, the shape of the measurement surface of the housing of the in-pipe liquid detection device is formed into a cylindrical curved surface having a radius that matches the maximum outer diameter of the cylindrical pipe to be measured.

[0030] On the other hand, the light-changing means has an inner surface facing the cylindrical tube formed in a surface shape different from the outer diameter of the cylindrical tube so that light is emitted at a predetermined angle toward the cylindrical tube between the light-emitting unit and the cylindrical tube, and between the light-receiving unit and the cylindrical tube.

[0031] Therefore, in the present invention, by configuring in this manner, for example, when the inner surface of the light-changing means is configured to be flat, the incident light from the light-projecting unit is refracted at the flat inner surface between the main body of the light-refracting unit A and the cylindrical tube, as shown in Figure 4(B).

[0032] In this case, the angle of incidence and the angle of refraction of each ray become the same, and the refracted light emitted from the light refraction section A enters the cylindrical tube as parallel rays with the same angle of refraction.

[0033] Therefore, in the present invention, the incident angle and refraction angle of the light beam from the light-emitting unit are made the same, or the difference between the refraction angles of each light beam is made narrow, thereby making it possible to increase the amount of light incident on the light-receiving unit and improve the performance of determining whether or not liquid is present in the tube.

[0034] FIG. 5 is a light path diagram comparing a prism having an engaging portion 407F according to the present invention for engaging with the housing of the liquid-detection device as an example of such light changing means (407, 411) with a cylindrical surface as described in Patent Document 1 (FIG. 5(A)) and a prism having a flat surface according to the present invention (FIG. 5(B)).

[0035] As shown in FIG. 5(A), in a prism having a cylindrical surface, three incident rays (L=0 and L=±1.0) are diffused by passing through the cylindrical surface.

[0036] On the other hand, as shown in Figure 5(B), in a prism with a flat surface, the three incident lights (L = 0 and L = ±1.0) do not diffuse even when passing through the flat surface, so by reducing the spread in this way, it is possible to reduce the attenuation of the received light intensity.

[0037] Therefore, according to the present invention, the attenuation of the amount of refracted light emitted from the light-emitting body is smaller than in the conventional method described in Patent Document 1, which has the advantage of improving the ability to determine the presence or absence of liquid.

[0038] Figure 6 shows these advantages through simulation, with Figure 6(A) showing the light-changing means with a cylindrical inner surface facing the cylindrical tube, and Figure 6(B) showing a flat surface. Here, the dotted line in the figure represents the cross section of a cylindrical tube made of quartz glass (n=1.459) with a diameter of 6 mm (inner thickness of 1 mm), and the chain line represents the ray of L=0 in Figure 5, the one-dot chain line represents the ray of L=+1.0, and the two-dot chain line represents the ray of L=-1.0.

[0039] In all of the examples shown in Figure 6, the light ray with L=0 is nearly horizontal inside the cylindrical tube and enters the light receiving section normally. In the case of L=-1.0, when the inner surface of Figure 6(A) is cylindrical, the light ray does not enter the inner surface of the cylindrical tube. Also, there is a light path where the light undergoes total reflection in the range from L=0 to L=-1, and there is a possibility that the totally reflected light may enter the light receiving section, which is not desirable.

[0040] On the other hand, when the inner surface is cylindrical, even when L = -1, the light is incident on the inner surface of the cylindrical tube φ6 mm, and there is no light path for total reflection at L = ±1 mm. Therefore, from the results of the simulation, it can be seen that a light-changing means with a flat inner surface facing the cylindrical tube, as shown in Figure 6(B), is preferable because it can stabilize the light-receiving characteristics.

[0041] Furthermore, in the present invention, as described above, the light modifying means provided between the light projecting unit and the cylindrical tube and the light modifying means provided between the light receiving unit and the cylindrical tube are each configured with a separately constructed prism. These prisms have the engaging portion of the present invention for engaging with the housing of the liquid-detection device, as described above. Additionally, a light-opaque / light-shielding material is formed in advance on the inside of the housing of the light modifying means, between the light projecting unit and the light receiving unit, to prevent transmitted light from the light projecting unit from being directly received by the light receiving unit.

[0042] Therefore, in the present invention, such a configuration can facilitate manufacturing and further improve optical characteristics.

[0043] Next, an invention relating to a gripping structure of an in-pipe liquid detection device will be described. In the present invention, for example, as shown in Fig. 7, the housing of the in-pipe liquid detection device consists of an upper shell body on the upper side and a lower shell body on the lower side, and an upper surface (upper side) band guide 41UBG is provided on the upper surface of the upper shell facing upward, and a lower surface (lower side) band guide 42DBG is provided on the lower surface of the lower shell facing downward. Here, Fig. 7 is a drawing showing the outer shape of the in-pipe liquid detection device, with Fig. 7(A) being a front view showing the measurement surface side, Fig. 7(B) being a top view, and Fig. 7(C) being a back view. Furthermore, on the cylindrical tube side, a structure is adopted in which a saddle band 44 of any width is arranged on the side of the cylindrical tube opposite the housing of the in-tube liquid detection device, along the axial direction of the cylindrical tube, so as to surround a portion of that side of the cylindrical tube 3, as shown in Figures 8(A) and 8(B), for example.

[0044] Therefore, when attempting to grip the in-pipe liquid detection device to the side of a cylindrical pipe, for example, as shown in Figures 8(A) and 8(B), the side of the band guide locking portion RT provided on each of the upper (upper side) band guide 41UBG and the lower (lower side) band guide 42DBG, opposite the cylindrical pipe 3, can be slid, and a cable tie 43 can be wrapped around the outside of the saddle band 44 arranged on the side of the cylindrical pipe 3, and the cable tie 43 can be fastened with a locking device 43b, thereby gripping the in-pipe liquid detection device to the side of the cylindrical pipe 3.

[0045] In this case, the upper band guide 41UBG and the lower band guide 42DBG may be, for example, approximately quadrilateral in shape as shown in Figures 7, 8(A), and 8(B), and may have holes (42UBGH, 42DBGH) through which the cable tie 43 can be inserted and band guide engaging portions RT, etc., as long as they can slidably engage the cable tie 43 on the in-pipe liquid detection device side.

[0046] In addition, the width of the saddle band may be, for example, at least half the circumference of the cylindrical tube, so as to cover more than half of the side surface of the cylinder, thereby preventing the binding band 43 from coming into contact with the side surface of the cylindrical tube 3.

[0047] In addition, in the above example, the upper and lower band guides (41UBG, 42DBG) are provided facing upward and downward from the upper and lower shells, but it is also possible to provide them inside the upper and lower shells, as shown in Figures 8(C) and 8(D), so that the upper and lower shells are configured in a flat manner.

[0048] Figure 9 shows an example in which a band guide is provided inside each of the upper and lower shells in this way, where (A) is a front view showing the measurement section, (B) is a view of the band guide section from the top and bottom, (C) is a perspective view of the light-changing means on the light-emitting and light-receiving sides within the detection device, and (D) is a rear view.

[0049] In this way, when band guides are provided inside each of the upper and lower shells, as shown in Figure 9(A), the upper band guide portion 41UBG and the lower band guide portion 42DBG are configured inside the respective housings without protruding from the housings, and each has hole portions (42UBGH, 42DBGH) inside thereof through which the cable tie 43 can be inserted, and the band guide engagement portion RT is configured in an approximately cylindrical shape in the vertical direction.

[0050] When winding the cable tie 43, as shown in Figure 8(C), Figure 8(D) or Figure 9(B), the cable tie 43 is wound by sliding it along the side of the band guide locking portion RT from one of the pair of holes provided in each of the upper and lower housings to the other, and the cable tie 43 is tightened and locked by the locking device 43b on the side of the cylindrical tube 3 via the saddle band 44.

[0051] Therefore, when such a configuration is used, it is possible to easily stack and arrange multiple in-pipe liquid detection devices (4, 5) in the axial direction of the cylindrical pipe by configuring the entire in-pipe liquid detection device in a plane, as shown in Figure 10. Here, Figure 10 is a perspective view showing an example of stacking and arranging multiple detection devices on a cylindrical pipe, Figure 10(A) is a view from the detection device side, and Figure 10(B) is a view from the band fastener 43b side.

[0052] In addition, it is generally desirable to position the upper and lower band guides on the upper and lower shells away from the measurement unit of the liquid-in-pipe detection device main body, as shown in Figure 11. This is because positioning them away from each other naturally provides stability, from the perspective of preventing misalignment of the central axis and the central axis of the liquid-in-pipe detection device main body. However, in practice, as the length of the cable ties increases, the cylindrical tube may easily move laterally from the central axis of the housing, so the position is determined according to the material of the housing and the cylindrical tube for which it is intended to be used. In addition, the fastening position of the cable tie fastening device 43b will differ depending on whether the band guide is provided on the upper or lower surface (external) of each upper or lower shell body or on the interior of each upper or lower shell body, but each has the following characteristics.

[0053] In other words, when a band guide is provided on the outside of each upper and lower shell, as shown in Figure 7, the band guide structure is approximately square and has holes (41UBGH, 42DBGH) through which the cable tie can be inserted that protrude to the outside, so that the cable tie 43 can be temporarily passed around the band guide (41UBG, 42DBG) and the outside of the cylindrical tube 3, making the gripping operation easier.

[0054] On the other hand, if band guides are provided inside the upper and lower shells, as shown in Figure 9, the cable tie is locked on the saddle band 44 side, so although the temporary threading as described above is not possible, it is effective for slidably holding the cable tie 43 to the housing. Furthermore, in the case of small diameters in particular, by binding on the cylindrical tube 3 side, it is possible to hold the cylindrical tube 3 more stably. Next, the binding band 43 used in the present invention is not particularly limited in configuration as long as it can hold or secure the housing to the cylindrical tube, and commercially available ones can be used.

[0055] Therefore, for example, it is possible to use a cable tie that has a cable tie body 43 and a cable tie fastener 43b integrated into one unit, as shown in the top view and side view of Figures 12(A) and (B).

[0056] Next, the saddle band 44 used in the present invention covers the back of the cylindrical tube with a material that blocks external light to prevent external light from entering the measurement section of the detection device body from the back of the cylindrical tube and reducing the liquid detection performance of the measurement section.

[0057] The saddle band is made of a flexible material such as silicone resin, which prevents the cable tie from slipping when gripping the cylindrical tube and the housing. The cable tie's locking portion has a ratchet structure, and the band length changes with each ratchet step. Therefore, by using such a flexible material, it is possible to absorb the drawback of slight distortion of the cable tie when fastening the cylindrical tube and the housing.

[0058] In a practical example, for example, an opaque silicone resin sheet with a one-sided adhesive sticker about 2 mm thick can be cut to fit the diameter of the cylindrical pipe and attached.

[0059] Furthermore, even if a single-sided adhesive seal is not used for the saddle band 44, in order to prevent the cable tie 43 from shifting position, a band retaining shape 44H for the cable tie 43 may be provided, for example, by providing two insertion holes corresponding to one cable tie, as shown in Figure 13.

[0060] Here, Figure 13 shows another different configuration example according to the present invention, where Figure 13(A) is an oblique view showing an example in which band guides are provided inside each of the upper and lower shells, and in which, for example, a circular insertion hole 44H is provided in the saddle band 44, Figure 13(B) is a plan view showing an example in which a band passing shape 44H for inserting a cable tie is provided in the saddle band 44, and Figure 13(C) is a cross-sectional view of the part in Figure 13(A) where the band is wound around. Furthermore, as will be described later, depending on the arrangement of the light-emitting section 52 and the light-receiving section 54, it is also possible to provide a groove-shaped notch in the saddle band 44 to reduce the amount of excess light incident on the light-receiving section 54.

[0061] Therefore, in the present invention, by using such a gripping structure, it is possible to naturally align the center axis of the cylindrical tube and the center axis of the main body of the liquid detection device in a tube during the bundling process when installing the cylindrical tube, and further, since screwing or the like is no longer necessary, it is also possible to improve installation operability.

[0062] Next, the housing of the in-pipe liquid detection device according to the present invention will be described.

[0063] The present invention can basically use a housing similar to that of Patent Document 1, but is not necessarily limited to this and other configurations can also be adopted.

[0064] Therefore, for example, as shown in Figure 7, the housings (case bodies) 41, 42 of the in-pipe liquid detection device are configured to be able to be fitted together so that they can be divided into two parts, upper and lower, at the center, and an upper band guide 41UBG is provided on the upper surface of the upper shell body 41 on the upper side, and a lower band guide 42DBG is provided on the lower surface of the lower shell body 42 on the lower side.

[0065] 7(A), the cylindrical tube side of the case body serves as the measurement surface of this in-pipe liquid detection device, and this measurement surface has a cylindrical curved surface 462 formed thereon with a radius r1 adapted to the maximum tube diameter D44a of the cylindrical tube 3 to which this liquid level detection device can be attached, and a predetermined width in the axial direction. This cylindrical curved surface 462 is provided with openings (52H, 54H) for transmitting light to the light-emitting unit 52 and the light-receiving unit 54, and the material of the case other than the opening side is preferably made of an opaque material that completely blocks, or blocks at least 50% or more of, the wavelength of the light source emitted from the light-emitting means of the light-emitting unit (in the present invention, a single light-emitting element may be used, or multiple light-emitting elements may be used with each light-emitting element set at a predetermined projection angle).

[0066] The case body also contains a circuit board 50 that controls the light-emitting unit 52 and the light-receiving unit 54 and mounts a liquid presence / absence determination means 55 (not shown) that processes the output of the light-receiving unit 54 to detect the presence or absence of liquid in the cylindrical tube (for example, it may be composed of an operational amplifier, an inverting amplifier, etc., or an MPU (microprocessor)).

[0067] These circuit boards, etc. incorporate the light conversion means, etc. of the present invention, and fit and clamp the upper and lower shells together to perform assembly and sensitivity adjustment, such as light reception level. After completing these adjustments, it is also possible to inject a silicone filler, etc. (not shown), to seal the device for waterproofing and explosion protection. In the case of Patent Document 1 by the present applicant, the holding surface of the cylindrical tube and the light input / output surface of the measurement unit were common, so the silicone filler was injected to prevent a decrease in detection performance due to unnecessary extraneous light from outside the main unit. However, in the present invention, the main body housing case can be made of a different, more light-blocking material than the prism of the measurement unit, making the injection of silicone filler unnecessary for light-blocking purposes.

[0068] There are no particular restrictions on the materials that can be used to construct the case body, and various engineering plastics and ceramic components can be used, but it is desirable to color it black as appropriate to prevent harmful reflected light, etc. Furthermore, as the light-emitting means of the light-projecting unit 52 of the present invention, light source means such as a commonly used LED (semiconductor light-emitting diode), an infrared laser light-emitting element, or an optical fiber (including a light-projecting lens system) can be used, and light is emitted / projected from such light source means, but if an explosion-proof structure is particularly required, the light-projecting unit 52 and the light-receiving unit 54 may be configured to consist only of optical components such as glass or plastic optical fibers and an imaging / focusing lens system, and the circuit board 50 etc. may be provided inside a remote explosion-proof structure, with optical transmission means such as optical fiber relaying / connecting them, and electrical signals may be processed by a remote electrical circuit board not shown.

[0069] When a single light-emitting element is used, it is usually possible to use one having a wide light-emitting projection angle, and when forming multiple light-projecting sections as described below, the projection light output from a single light-emitting element having a wide light-emitting projection angle may be branched to each of predetermined projection angles by an optical path changing means such as a prism, or multiple light-emitting elements (such light source means as LEDs, infrared laser light-emitting elements, optical fibers (including projection lens systems) and the like can be used as such light-emitting elements) may be arranged at predetermined projection angles to form multiple light-projecting sections. On the other hand, the light receiving unit 54 can be made up of a photoelectric conversion element of a MOS structure or a CCD structure (one or more sets of photoelectric conversion elements can be associated with each light projecting unit), an optical fiber (including a focusing lens system), etc., but if an explosion-proof structure is particularly required, the light projecting unit 52 and the light receiving unit 54 may be made up of only an optical system such as a glass or plastic optical fiber (one or more sets of photoelectric conversion elements can be associated with each light projecting unit). Next, with reference to Figures 14 to 27, the operation of a liquid detection optical system using a single light-emitting element 52 with a wide projection angle and a single light-receiving element 54 in the above configuration will be described, citing the description in Patent Document 1.

[0070] First, FIG. 14, which roughly corresponds to the center of FIG. 4(A), shows an enlarged view of the entire main part of the optical path from the light projecting unit 52 to the light receiving unit 54 in the liquid-detecting device 4 (4s) of the present invention. The refractive index of the optical path changing means 407, 411, whose cross section of the joining surface 406 to the cylindrical tube 3 (1b) is flat, is n1, the center of the flat plate is O0, the refractive index of the cylindrical tube 3 is n2, the outer diameter of the cylindrical tube 3 that is smaller than the maximum outer diameter r1 is r2, the inner diameter is r3, and the center is O0. The point is O3, the maximum outer diameter of the cylindrical tube 3 to which the liquid-level detection device 4s of the present invention can be attached is r1, and its center is the origin O0 (0,0) of the x-y coordinate system. The y-axis is the line connecting the origin O0 and the intersection P0 between the mounting surface 408 of the light-projecting unit 52 of the optical path changing means 407 and the mounting surface 412 of the light-receiving unit 54 of the optical path changing means 411. The distance between the origin and the intersection P0 is represented by the coordinate (0,-y0), and the direction perpendicular to the y-axis at the origin O0 is represented by the x-axis. The fixed position of the light-projecting unit 52 to the mounting surface 408 is represented by the coordinate P1 (-x1,-y1), and the fixed position of the light-receiving unit 54 to the mounting surface 412 is represented by the coordinate P8 (x8,-y8). Thus, the angle θ1 formed by the origin O0 and points P0 and P1 is defined, and the angle θ31 formed by the origin O0 and points P0 and P8 is similarly defined.

[0071] As shown in FIG. 14, the light-projecting unit 52 / light-receiving unit 54 are preferably installed / fixed in a spatial positional relationship such that the optical center of the transmitted light is blocked by the convex protrusion 450 of the case body 42, which functions as an opaque / light-blocking material, and its cylindrical upper surface 451, and the projected light does not directly enter the light-receiving unit 54 from the light-projecting unit 52, thereby improving the S / N ratio of the light-receiving element 54. When the refracted / transmitted light 145 (or the straight line P4-P5) inside the cylindrical tube 3 passes through approximately parallel to the straight line P1-P8 connecting the optical centers of the light-projecting unit 52 and the light-receiving unit 54, this relationship can be satisfied by arranging the optical centers P1, P8 of the light-projecting unit 52 and the light-receiving unit 54 below the cylindrical upper surface 451, respectively. Next, the main part of the optical path from light-projecting unit 52 to light-receiving unit 54 will be described with reference to Figures 14 and 15. First, when the main luminous flux of the light-emitting means (including an LED or optical fiber) of light-projecting unit 52, which forms an angle θ1 with the horizontal plane from point P1, is projected perpendicularly onto mounting surface 408 in Figure 4(A), it travels straight through and transmits through the interior of optical path changing means 407 arranged within the case, and is incident on point P2 on planar cross section 406 shown in Figure 14 at an incident angle θ2, and is refracted into the air at point P2 at a refraction angle θ3. Furthermore, as the light travels straight through the air at a refraction angle θ3, it enters the outer surface of the cylindrical tube 3, which has a curvature radius of r2, at a point P3 at an incident angle θ4, is refracted inside the cylindrical tube 3, which has a refractive index of n2, at a refraction angle θ5, continues traveling straight, and enters point P4 on the inner circular cross section, which has a curvature radius of r3, at an incident angle θ6, and is refracted into the air inside the hollow cylindrical tube 3 at a refraction angle θ7. Next, the light travels straight through the air inside the hollow cylindrical tube 3 at a refraction angle θ7, enters the inner surface of the cylindrical tube 3, which has a curvature radius of r3, at a position of point P5 at an incident angle θ8, is refracted inside the cylindrical tube 3, which has a refractive index of n2, at a refraction angle θ9, continues straight, and enters the outer surface of the cylindrical tube 3, which also has a curvature radius r2, at a position of point P6 at an incident angle θ10, is refracted into the air outside the cylindrical tube 3 at a refraction angle θ11, continues straight through the air, and enters point P7 on the planar cross section 406 of the optical path changing means 411 located inside the case body at an incident angle θ12, continues straight through the interior of the optical path changing means 411, which has a refractive index of n1, and enters the light receiving unit mounting surface 412 at a position of point P8 at an incident angle θ14, from which it is received by the light receiving unit 54, which forms an angle θ31 with the horizontal plane. The coordinates of each refraction point of the above optical path P1-P2-P3-P4-P5-P6-P7-P8 are expressed as point P2 = (-x2, -y2), point P3 = (-x3, -y3), point P4 = (-x4, y4), point P5 = (x5, -y5), point P6 = (x6, -y6), and point P7 = (x7, -y7), respectively, as shown in Figure 15. Thus, when the maximum outer diameter r1 of cylindrical tube 3 is fixed at a predetermined size, the angle θ1 formed by optical path changing means 407 with the horizontal plane is also determined and fixed at a predetermined size, and the mounting position P1 (-x1, -y1) of light projecting unit 52 on mounting surface 408 is set at a fixed position in a spatial positional relationship such that projected light does not directly enter light receiving unit 54 from light projecting unit 52, the object of the present invention is to realize a cylindrical tube 3 having an outer diameter r2 and an inner diameter r3 smaller than the maximum outer diameter r1 of the tube, even if the outer diameter r2 and the inner diameter r3 vary to various values, so that light 145 refracted and transmitted through the interior of cylindrical tube 3 when there is no liquid 2 can be transmitted through the cylindrical tube 3 at the light receiving unit mounting position P8 in a predetermined position. This question can be substituted with the following: Is there a position where the main beam of refracted and transmitted light can be stably received even when the light-receiving unit mounting position P8 is a spatially fixed position set for this purpose? If so, what are the values ​​of the set angles θ1 and θ31 of the optical path changing means, and the values ​​of the mounting position P1(-x1, -y1) of the light-projecting unit 52 and the mounting position P8(x8, -y8) of the light-receiving unit 54 when the maximum outer diameter r1 of the cylindrical tube 3 is fixed to a predetermined size? In conclusion, as will be described later, there are an infinite number of such positional relationships between the light-projecting unit and the light-receiving unit, and a specific method for determining these relationships will be described in detail below. First, Figures 14 to 27 show an example in which refracted / transmitted light 145 (or straight line P4-P5) inside cylindrical tube 3 is transmitted obliquely, not parallel, to straight line P1-P8 connecting the optical centers of light-projecting unit 52 and light-receiving unit 54. In this case, if the maximum outer diameter r1 of cylindrical tube 3 is fixed to a predetermined size, the angle θ1 of optical path changing means 407 is also determined and fixed to a predetermined size, and the mounting position P1 (-x1, -y1) of light-projecting unit 52 on mounting surface 408 is also set to a fixed position, the coordinates x1 and y1 cannot be changed independently, and the liquid detection When the cylindrical tube to which the liquid detection device is attached has the largest outer diameter, the fixed positions of the light-emitting unit and the light-receiving unit are calculated by simultaneously setting up geometric equations and optical equations so that the transmitted light for liquid detection can pass through on the side below the center of the cylinder where the liquid-detecting device is attached.When the cylindrical tube to which the liquid-detecting device is attached has the smallest outer diameter, the fixed positions of the light-emitting unit and the light-receiving unit are calculated by simultaneously setting up geometric equations and optical equations so that the transmitted light for liquid detection can pass through on the side below the center of the cylinder where the liquid-detecting device is attached.

[0072] Specifically, the following geometric equation holds between the radius r1, angle θ1, and y coordinate y0 of the intersection point P0, and the coordinate values ​​x1, y1 of the point P1 shown in FIGS. y0 = y1 + x1·cot(θ1) ···(1) Next, if the coordinate values ​​x2, y2 of point P2 shown in Figures 15 and 16 are expressed using the coordinate values ​​x1, y1 of point P1, the optical path P1-P2 forms an angle θ1 with the x-axis, and the optical path P1-P2 also intersects with the circumference of an inner radius r1, so the following geometric equation holds between the coordinate values ​​x1, y1 of point P1 and the coordinate values ​​x2, y2 of point P2. y1 = (x1-x2)·tan(θ1) + y2 ···(2) Since point P2 is on the circumference of the cylindrical tube 3 with the maximum radius r1, TIFF2026009443000002.tif8150Next, at the position of point P2 shown in Figure 17, the following geometric equation holds between the angle θ20 that the radius P2-O0 makes with the y-axis, the angle of incidence θ2, the angle of refraction θ3, and the angle θ21 that the refracted light l23 into air makes with the x-axis. Since point P2 is on the circumference of a circle with radius r1, TIFF2026009443000003.tif7150 Also, if the intersection point of a line passing through point P1 and parallel to the x-axis and the y-axis is P10, and the intersection point of a line passing through point P1 and parallel to the x-axis and the line O0-P2 is P11, then the angle P2P11P10 is equal to θ1 + θ2, and since the triangle O0P11P10 is a right-angled triangle, TIFF2026009443000004.tif8150 The following optical equation holds between the incident angle θ2 and the refraction angle θ3 using the refractive index n1 of the optical path changing means 407. sin(θ3) / sin(θ2) = n1 ···(6) Furthermore, the angle that the line O0-P2 makes with the x-axis at point P2 is equal to θ3+θ21, so TIFF2026009443000005.tif7150In addition, in Figure 17, if point P1 is set at an angle θ20 > 45 degrees and positioned higher as shown at the position of point P1a, and the angle θ2 < 0.0, for example, the refracted light l2a3 into the air at the position of point P2a will propagate upward from the straight line P2a-O0, and the light receiving position will change from the fourth quadrant to the second quadrant, which is generally not desirable. Next, if the coordinate values ​​x3, y3 of point P3 shown in Figure 18 are expressed using the coordinate values ​​x2, y2 of point P2, the optical path P2-P3 forms an angle θ21 with the x axis, and the optical path P2-P3 also intersects with the circumference of the cylindrical tube 3 with an outer radius r2, so the following geometric equation holds between the coordinate values ​​x2, y2 of point P2 and the coordinate values ​​x3, y3 of point P3. From the linear condition, y2 = (x2-x3)·tan(θ21) + y3 ···(8) Since point P3 is on the circumference of a circle with radius r2, TIFF2026009443000006.tif7150 Next, at the position of point P3 shown in Figure 19, the following geometric equation holds between the angle θ21 that the optical path P2-P3 makes with the x-axis, the angle θ22 that the radius P3-O3 makes with the y-axis, the incident angle θ4, the refraction angle θ5, and the angle θ23 that the refracted light l34 into the cylindrical tube 3 makes with the x-axis. Since point P3 is on the circumference of a circle with radius r2, TIFF2026009443000007.tif7150 Also, let P12 be the point where the line O3-P3 intersects with a line that passes through point P2 and is parallel to the x-axis, and let P13 be the point where the line that passes through point P2 and is parallel to the x-axis intersects with the y-axis. Then, the angle P3P12P13 is equal to θ21 + θ4, and since the triangle O3P12P13 is a right triangle, TIFF2026009443000008.tif6150The following optical equation holds between the incident angle θ4 and the refraction angle θ5 based on the refractive index n2. sin(θ5) / sin(θ4) = n2 ···(12) Furthermore, as shown in FIG. 20, the angle that the line O3-P3 makes with the x-axis at point P3 is equal to θ5+θ23, so TIFF2026009443000009.tif7150Next, if the coordinate values ​​x4, y4 of point P4 shown in Figure 20 are expressed in terms of the coordinate values ​​x3, y3 of point P3, the optical path P3-P4 forms an angle θ23 with the x axis, and the optical path P3-P4 also intersects with the circumference of the cylindrical tube 3 with an inner radius r3, so the following geometric equation holds between the coordinate values ​​x3, y3 of point P3 and the coordinate values ​​x4, y4 of point P4.From the linearity condition, y3 = (x3-x4)·tan(θ23) + y4 ···(14) Since point P4 is on the circumference of a circle with radius r3, TIFF2026009443000010.tif7150Next, at the position of point P4 shown in Figure 21, the following geometric equation holds between the angle θ23 that the optical path P3-P4 makes with the x-axis, the angle θ24 that the radius P4-O3 makes with the y-axis, the incident angle θ6, the refraction angle θ7, and the angle θ25 that the refracted light P4-P5 into the air inside the cylindrical tube 3 makes with the x-axis. Since point P4 is on the circumference of a circle with radius r3, TIFF2026009443000011.tif7150Also, let P14 be the point where the line O3-P4 intersects with a line parallel to the x-axis, and let P15 be the point where this line parallel to the x-axis intersects with the y-axis. Then, the angle P4P14P15 is equal to θ23+θ6, and since the triangle O3P14P15 is a right triangle, TIFF2026009443000012.tif7150The following optical equation holds between the incident angle θ6 and the refraction angle θ7 based on the refractive index n2 of the cylindrical tube 3. sin(θ7) / sin(θ6) = n2 ···(18) Furthermore, the angle that the line O3-P4 makes with the x-axis at point P4 is equal to θ7+θ25, so TIFF2026009443000013.tif7150 Next, if the coordinate values ​​x5, y5 of point P5 shown in Figure 22 are expressed using the coordinate values ​​x4, y4 of point P4, the optical path P4-P5 forms an angle θ25 with the x axis, and the optical path P4-P5 also intersects with the circumference of the cylindrical tube 3 with an inner radius r3, so the following geometric equation holds between the coordinate values ​​x4, y4 of point P4 and the coordinate values ​​x5, y5 of point P5. From the linear condition, y4 = y5 + (x4+x5)·tan(θ25) ···(20) Since point P5 is on the circumference of a circle with radius r3, TIFF2026009443000014.tif7150Next, at the position of point P5 shown in Figure 22, the following geometric equation holds between the angle θ25 that the optical path P4-P5 makes with the x-axis, the angle θ26 that the radius P5-O3 makes with the y-axis, the incident angle θ8, the refraction angle θ9, and the angle θ27 that the refracted light l56 into the material with refractive index n2 inside the cylindrical tube 3 makes with the x-axis. Since point P5 is on the circumference of a circle with radius r3, TIFF2026009443000015.tif6150Also, if the point where a line passing through point P5 and parallel to the x-axis intersects with the y-axis is P16, then the angle P4P5P16 is equal to θ25, and since the triangle O3P5P16 is a right triangle, TIFF2026009443000016.tif7150The following optical equation holds between the incident angle θ8 and the refraction angle θ9 based on the refractive index n2. sin(θ8) / sin(θ9) = n2 ···(24) Furthermore, the angle that the line O3-P5 makes with the x-axis at point P5 is equal to θ9+θ27, so TIFF2026009443000017.tif7150 Next, if the coordinate values ​​x6, y6 of point P6 shown in Figure 23 are expressed as the coordinate values ​​x5, y5 of point P5, the optical path P5-P6 forms an angle θ27 with the x axis, and the optical path P5-P6 also intersects with the circumference of the cylindrical tube 3 with an outer radius r2, so the following geometric equation holds between the coordinate values ​​x5, y5 of point P5 and the coordinate values ​​x6, y6 of point P6. From the linear condition, y6 = (x6-x5)·tan(θ27) + y5 ···(26) Since point P6 is on the circumference of a circle with radius r2, TIFF2026009443000018.tif6150Next, the following geometric equation holds between the coordinate values ​​x6, y6 at the position of point P6 shown in Figure 24, the angle θ27 that the optical path P5-P6 makes with the x-axis, the angle θ28 that the radius P6-O3 makes with the y-axis, the incident angle θ10, the refraction angle θ11, and the angle θ29 that the refracted light 167 makes with the x-axis from the material with refractive index n2 inside the cylindrical tube 3 into the air. Since point P6 is on the circumference of a circle with radius r2, TIFF2026009443000019.tif6150Also, if the point where a line passing through point P6 and parallel to the x-axis intersects with the y-axis is P17, then the angle P5P6P17 is equal to θ27, and since the triangle O3P6P17 is a right triangle, TIFF2026009443000020.tif7150The following optical equation holds between the incident angle θ10 and the refraction angle θ11 using the refractive index n2. sin(θ11) / sin(θ10) = n2 ···(30) Furthermore, the angle that the line O3-P6 makes with the x-axis at point P6 is equal to θ11 + θ29, so TIFF2026009443000021.tif7150 Next, if the coordinate values ​​x7, y7 of point P7 shown in Figure 25 are expressed as the coordinate values ​​x6, y6 of point P6, the optical path P6-P7 forms an angle θ29 with the x axis, and the optical path P6-P7 also intersects with the inner plane of the optical path changing means 411 on the maximum tube diameter r1 of the cylindrical tube 3, so the following geometric equation holds between the coordinate values ​​x6, y6 of point P6 and the coordinate values ​​x7, y7 of point P7. y7 = (x7-x6)·tan(θ29) + y6 ···(32) Since point P7 is on the circumference of a circle with radius r1, TIFF2026009443000022.tif8150Next, the following geometric equation holds between the coordinate values ​​x7, y7 at the position of point P7 shown in Figure 26, the angle θ29 that the optical path P6-P7 makes with the x-axis, the angle θ30 that the radius P7-O0 makes with the y-axis, the incident angle θ12, the refraction angle θ13, and the angle θ31 that the refracted light l78 from air to the component with refractive index n1 inside the optical path changing means 411 makes with the x-axis. Since point P7 is on the circumference of a circle with radius r1, TIFF2026009443000023.tif7150Also, if the point where a line passing through point P7 and parallel to the x-axis intersects with the y-axis is P18, then the angle P6P7P18 is equal to θ29, and since triangle O0P7P18 is a right triangle, TIFF2026009443000024.tif7150The following optical equation holds between the incident angle θ12 and the refraction angle θ13 based on the refractive index n1. sin(θ12) / sin(θ13) = n1 ···(36) Furthermore, the angle that the line O0-P7 makes with the x-axis at point P7 is equal to θ13 + θ31, so TIFF2026009443000025.tif7150 Next, if the coordinate values ​​x8, y8 of point P8 shown in Figure 27 are expressed as the coordinate values ​​x7, y7 of point P7, the optical path P7-P8 forms an angle θ31 with the x axis, and the optical path P7-P8 intersects with the mounting plane 412 of the optical path changing means 411, so the following geometric equation holds between the coordinate values ​​x7, y7 of point P7 and the coordinate values ​​x8, y8 of point P8. From the straight line condition, y8 = (x8-x7)·tan(θ31) + y7 ···(38) And so, Condition 1) When the maximum outer diameter r1 of the cylindrical tube 3 (1 b) is fixed and the angles θ1 and θ31 of the optical path changing means 407, 411 with the horizontal plane are also fixed, even if the mounting position P1 (-x1, -y1) of the light projecting unit 52 on the mounting surface 408 is further set to a predetermined fixed position, for cylindrical tubes 3 (1 b) whose outer diameter r2 and inner diameter r3 vary to various values, does a position P8 exist at which the light 145 refracted and transmitted inside the cylindrical tube 3 (1 b) can be stably received as the main luminous flux of the transmitted light, even at the light receiving unit mounting position P8 that is set fixed in advance?

[0073] 14 to 27 show an example in which the refracted / transmitted light 145 (or the straight line P4-P5) inside the cylindrical tube 3 (1b) is transmitted obliquely, not parallel to, the straight line P1-P8 connecting the optical centers of the light-emitting unit 52 and the light-receiving unit 54. However, to simplify the analysis, Condition 2) When the position / angle of the light-projecting unit 52 is set so that the refracted / transmitted light 145 (or the straight line P4-P5) inside the cylindrical tube 3 (1b) passes through approximately parallel to the straight line P1-P8 connecting the optical centers of the light-projecting unit 52 and the light-receiving unit 54 (and therefore approximately parallel to the x-axis), as shown in Figure 28, in such a case, due to the symmetry of light, the light travels approximately symmetrically with respect to the optical axis of symmetry sj1 (the y-axis in Figure 28). Therefore, angles θ1 and θ31 are each symmetric with respect to the y-axis sj1 and therefore are approximately equal. Similarly, the relationships of angle θ7 ≒ θ8, angle θ6 ≒ θ9, angle θ5 ≒ θ10, angle θ4 ≒ θ11, angle θ3 ≒ θ12, angle θ2 ≒ θ13, and angle θ1 ≒ θ31 each hold due to the symmetry with respect to the y-axis. Furthermore, in this case, due to the symmetry of light, the positions of the light-projecting unit 52 and the light-receiving unit 54 are also arranged approximately symmetrically with respect to the y-axis, and among the above-mentioned light paths P1-P2-P3-P4-P5-P6-P7-P8, the optical path from P1-P2-P3-P4 can be analyzed, and it can be seen that if the optical path P4-P5 is approximately parallel to the x-axis, the above-mentioned condition 1 is satisfied. Furthermore, if the transmitted light 145 inside the cylindrical tube 3 (1 b) passes approximately parallel to the line P1-P8 connecting the optical centers of the light-projecting unit 52 and the light-receiving unit 54, the optical path from the light-projecting unit 52 to the light-receiving unit 54 is the shortest, and is shorter than if the light-projecting unit 52 and the light-receiving unit 54 are not arranged symmetrically, as will be described later. As a result, there is an advantage in that a sufficient S / N ratio can be ensured even if the intensity of the light-emitting element of the light-projecting unit 52 is reduced.

[0074] In addition, the cylindrical pipe 3 (1b) whose diameter varies is fastened / clamped by the radius of curvature of the cylindrical curved surface 520 formed on the underside of the saddle band 44, and the axial position of the cylindrical pipe 3 at the cylindrical inner pressure contact surface between the case main body 41, 42 and the saddle band 44 is always fixed in a constant spatial positional relationship even if the outer diameter varies (in Figure 28, the symmetrical center line sj1 of the case main body 41, 42, the symmetrical center line sj1 of the saddle band 44, and the axial center O3 of the cylindrical pipe 3 are on the same plane coinciding with the optical symmetrical axis sj1 = y axis for any outer diameter of the cylindrical pipe 3 (1b)), so it is preferable to use the saddle band 44 according to the outer diameter of the cylindrical pipe 3 (1b). In order to physically arrange a cylindrical tube 3(1b) having an outer diameter of a certain size symmetrically about the optical symmetry axis sj1 shown in Figure 28, it is preferable to use a saddle band 44 having an inner joining cylindrical surface 520 with an inner diameter of D44 as shown in Figure 4, to physically arrange a cylindrical tube 3a having a large outer diameter including the maximum diameter symmetrically about the optical symmetry axis sj2 shown in Figure 25, it is preferable to use a saddle band 44a having an inner joining cylindrical surface 520a with an inner diameter of D44a as shown in Figure 27, and to physically arrange a cylindrical tube 3b having a small outer diameter including the minimum diameter symmetrically about the optical symmetry axis sj3 shown in Figure 26, it is preferable to use a saddle band 44b having an inner joining cylindrical surface with a large inner diameter.

[0075] So, Condition 31) As shown in Figure 25, in the case of a cylindrical tube 3a with a maximum outer diameter of r2 = r1, in order to be able to position the light-emitting unit 52 and the light-receiving unit 54 at positions that are approximately symmetrical with respect to the y-axis, the position of the inner bending point P4a of the cylindrical tube 3a must be set at a position below the center O3 (= O0) of the tube. From this condition and Figure 17, TIFF2026009443000026.tif8150 and TIFF2026009443000027.tif7150Also, Condition 32) As shown in Figure 26, in the case of a cylindrical tube 3b with a minimum outer diameter of r2b, in order to enable the light-emitting unit 52 and the light-receiving unit 54 to be positioned approximately symmetrically with respect to the y-axis, the position of the inner bending point P4b of the cylindrical tube 3b must be set below the center O3b of the tube. Furthermore, if the position of the inner bending point P4b of the cylindrical tube 3b with a minimum outer diameter is set to an appropriate position below the center O3b of the tube, the effect of the tube thickness (= r2 - r3) of the cylindrical tube 3b with a minimum outer diameter can be minimized. Here, if the ratio of the maximum outer diameter r1 to the minimum outer diameter r2b is m, then TIFF2026009443000028.tif6150

[0076] Organizing the above conditions 2 to 32, f0) As an initial setting, for example, if the maximum outer diameter of the cylindrical tube is set to r1 = 25.4 mm and the minimum outer diameter is set to r2b = 6 mm, TIFF2026009443000029.tif7150. Furthermore, the refractive index n1 of the case body 41 including the optical path changing means 407, 411 is generally in the range of 1.2 to 2.2 for synthetic resin materials and glass, so that TIFF2026009443000030.tif7150, but if you make the case body out of synthetic resin material such as polycarbonate, TIFF2026009443000031.tif10150. Next, the following approximate formula is obtained from FIG. 26 and formula 4. tan(θ20) = x2 / y2 ≒ x1 / y1 ≒ x1 / r1 ···(45) Furthermore, by transforming Equation 1, tan(θ1) = x1 / (y0-y1) ≒ tan(θ20) / (y0 / r1-1) ···(46) Furthermore, from Figure 26, tan(θ1 / m) ≒ r2b / (y0-r1+r2b) Since it is TIFF2026009443000032.tif9150, Assuming TIFF2026009443000033.tif7150, equations 46 and 47 can be substituted as follows: TIFF2026009443000034.tif8150TIFF2026009443000035.tif9150Furthermore, in Figure 26, if the intersection of the line P0-P2 and the x-axis is point Q0, and the intersection of the line passing through point P2 and parallel to the x-axis and the y-axis is point Q2, then triangle P0O0Q0 and triangle P0Q2P2 are similar, so TIFF2026009443000036.tif7150If you transform this, x2 ≒ (y0-y2) / k1 = r1·k1 / (k1+1 / tan(θ20)) ···(52) Furthermore, from Equation 45 and Equation 1, TIFF2026009443000037.tif7150y1 = y0-x1 / tan(θ1) = r1·(k1-tan(θ20) / tan(θ1)) ···(54) for example, If TIFF2026009443000038.tif8150, then from equation 50 tan(θ1 / m) ≒ 1 / (m·(k1-1)+1)=1 / 5.2=0.1923 ···(56) Therefore, θ1 can be calculated as follows: TIFF2026009443000039.tif6150= m·arctan(0.1923) =4.2*10.89 = 45.72 degrees ···(58) Also, θ20 is given by Equation 49. TIFF2026009443000040.tif7150Therefore, TIFF2026009443000041.tif7150TIFF2026009443000042.tif7150Next, from Equation 5 TIFF2026009443000043.tif7150TIFF2026009443000044.tif8150, so change the setting of formula 55, If we use TIFF2026009443000045.tif8150 and perform the same calculation as above, we get the following from equations 57, 60, and 62: TIFF2026009443000046.tif131504.2*7.80 = 32.76 degrees (66) TIFF2026009443000047.tif8150TIFF2026009443000048.tif7150TIFF2026009443000049.tif7150Thus, appropriate initial values ​​θ1, θ20, and θ2 could be calculated from the appropriately initialized magnifications m and k1.

[0077] f1) Next, when the outer diameter of the cylindrical pipe to which the liquid-detection device 4 is attached is the largest (r2 = r1), the fixed positions (-x1, -y1) and (x8, -y8) = (x1(rmax), -y1(rmax)) of the light-emitting unit and the light-receiving unit are calculated by simultaneously setting up geometric equations and optical equations so that the transmitted light for detection 145 passes through the side where the liquid-detection device is attached below the center of the cylinder. This condition is always met if θ2 in equation 62 is greater than 0. In other words, TIFF2026009443000050.tif7150 Combining the above equations 53 and 54 with equations 65, 67, and 69, we obtain the following equation. TIFF2026009443000051.tif8150y1(rmax) = r1 · (k1-tan(θ20) / tan(θ1)) ≒ r1 ···(72) Furthermore, in the case of a large outer diameter pipe 3a (for example, a pipe with an outer diameter D44a ≈ 2·r1 to 1.6·r1) including a cylindrical pipe with the largest outer diameter (r2 = r1) to which the liquid-detection device is attached, it is preferable that the inner joint surface 520a of the saddle band 44a that fixes / holds the cylindrical pipe 3a in a predetermined spatial positional relationship (for example, a relationship in which the respective axes of symmetry of the case bodies 41, 42, the cylindrical pipe 3a, and the saddle band 44a are all on the same plane) be formed into a cylindrical shape with an outer diameter D44a from a flexible material.

[0078] f2) Furthermore, when the outer diameter of the cylindrical pipe to which the liquid-detection device is attached is the smallest (r2=r2b), in FIG. 26, the fixed positions (-x1, -y1) and (x8, -y8) = (x1(rmin), -y1(rmin)) of the light-emitting unit and the light-receiving unit are calculated by solving simultaneous geometric equations and optical equations so that the transmitted light for detection 145 passes through the portion on the side where the liquid-detection device is attached below the center O3 of the cylinder. From Equation 6, TIFF2026009443000052.tif7150= arcsin(1.5·sin(13.56))=20.59 degrees ···(74) Also, from Equation 7 TIFF2026009443000053.tif6150TIFF2026009443000054.tif6150From Figure 19, TIFF2026009443000055.tif6150TIFF2026009443000056.tif6150Therefore, from Equation 10 tan(θ22) = x3 / (y3-r1+r2) TIFF2026009443000057.tif7150From now on, TIFF2026009443000058.tif7150 Furthermore, from equation 11, TIFF2026009443000059.tif7150TIFF2026009443000060.tif7161, and the refractive index n2 of the cylindrical tube 3 can be calculated as Assuming TIFF2026009443000061.tif6150, angles θ5 and θ23 can be calculated as follows from equations 12 and 13: TIFF2026009443000062.tif7150TIFF2026009443000063.tif7150Also, TIFF2026009443000064.tif7150TIFF2026009443000065.tif6150

[0079] Next, referring to FIG. 21, if the above condition 2 is satisfied, the angle θ25 will have the following value. TIFF2026009443000066.tif6150Also, Since it is TIFF2026009443000067.tif6150, TIFF2026009443000068.tif7150Substituting this into equation 18, we get TIFF2026009443000069.tif6150 Transforming this formula, we get Substituting the value of formula 87 from TIFF2026009443000070.tif7150, TIFF2026009443000071.tif6150TIFF2026009443000072.tif7150 are obtained, and substituting this into equation 90, TIFF2026009443000073.tif7150 Furthermore, from Equation 19, The resulting files are TIFF2026009443000074.tif6150 and TIFF2026009443000075.tif7150.

[0080] In the analysis of the above equations 88 to 97, the coordinates x3, y3, x4, and y4 are not used at all. Therefore, from equation 81, TIFF2026009443000076.tif8150, it is possible to calculate the fixed positions (-x1, -y1) and (x8, -y8) of the light-emitting and light-receiving units so that the detection transmitted light 145 passes through the portion of the side where the liquid-detection device is attached below the center O3 of the cylinder. In other words, if the condition of equation 98 is satisfied, the refraction / transmission conditions within the cylindrical tube 3 (1b) are met regardless of the coordinates of points P3 and P4.

[0081] For example, if Figure 21 is applied to a cylindrical tube 3b with a minimum outer diameter r2b = r1 / m, and equations 96 and 97 are first substituted into equations 15 and 16, the coordinates of point P4 can be calculated using the following equations. TIFF2026009443000077.tif7150TIFF2026009443000078.tif6150Next, the coordinates of point P3 can be calculated using the following equations from equations 9, 10, and 14. TIFF2026009443000079.tif7150TIFF2026009443000080.tif8150Furthermore, the coordinates of point P2 can be calculated using the following formula from formulas 3 and 4. TIFF2026009443000081.tif7150TIFF2026009443000082.tif6150Furthermore, the coordinates (x1, y1) of point P1 can be calculated from the intersection of the two lines in the following equation. TIFF2026009443000083.tif7150TIFF2026009443000084.tif6150 TIFF2026009443000085.tif13150TIFF2026009443000086.tif8150 TIFF2026009443000087.tif13150TIFF2026009443000088.tif7150Thus, when the outer diameter of the cylindrical tube is the smallest (r2 = r2b), the fixed positions of the light-emitting unit and the light-receiving unit when the transmitted light for detection l45 that satisfies condition 2 is transmitted are (-x1, -y1), (x8, -y8) = (x1(rm in), -y1(rmin)) can be calculated using equations 107 and 108, respectively. Furthermore, in the case of a small outer diameter pipe 3b (for example, a pipe with an outer diameter D44b ≈ 2.6·r2b to 2·r2b) including a cylindrical pipe with the smallest outer diameter (r2 = r2b) to which the liquid-detecting device is attached, when liquid 2 is poured into cylindrical pipe 3b, in Figure 26, the transmitted detection light 145b from point P4 is not refracted, or is refracted at a very small refraction angle, traveling straight through and transmitting through liquid 2. As a result, the distance over which the light reflected off the outer wall of cylindrical pipe 3b enters the fixed position of the light-receiving unit is relatively short and is not sufficiently attenuated, which could cause the light-receiving unit 54 to malfunction. In order to reliably prevent such malfunctions, it is preferable that the inner joint surface 520b of the saddle band 44b, which fixes / holds the small outer diameter cylindrical tube 3b in a predetermined spatial positional relationship (for example, a relationship in which the symmetry axes of the case main body 41, 42, the cylindrical tube 3b, and the saddle band 44b are all on the same plane), be formed into a cylindrical shape with an outer diameter D44b using a flexible material, and furthermore, a groove-shaped notch may be formed in the inner joint surface 520b.In this case, the light transmitted through the liquid that has traveled approximately in a straight line is guided / diffusedly reflected inside the groove-shaped notch, making it possible to significantly reduce the amount of light incident on the light receiving unit 54.

[0082] f3) Furthermore, an error is calculated between the fixed positions of the light-projecting unit and the light-receiving unit calculated when the cylindrical tube has the largest outer diameter in f1) above and the fixed positions of the light-projecting unit and the light-receiving unit calculated when the cylindrical tube has the smallest outer diameter in f2) above, and the fixed positions of the light-projecting unit and the light-receiving unit when the cylindrical tube has the largest outer diameter and / or the fixed positions of the light-projecting unit and the light-receiving unit when the cylindrical tube has the smallest outer diameter are changed so as to reduce the fixed position error.

[0083] Furthermore, when calculating the fixed positions of the light-projecting unit and the light-receiving unit, it is preferable to also calculate the fixed positions of the light-projecting unit and the light-receiving unit for a cylindrical tube whose outer diameter is half the outer diameter (r2=(r1+r2b) / 2) between the largest outer diameter tube (r2=r1) and the smallest outer diameter tube (r2=r2b), as this allows for a more detailed understanding of the tendency of fluctuations in the fixed positions of the light-projecting unit and the light-receiving unit. Furthermore, in the case where the outer diameter of the cylindrical tube to which the liquid-detecting device 4 of f1) is attached is the largest (r2=r1), when the analytical results of the above equations 88 to 97 are applied to the calculation of the fixed positions (-x1, -y1) of the light-emitting unit and the light-receiving unit in the liquid-detecting device, (x8, -y8)=(x1(rmax), -y1(rmax)), first, in Figure 29 shown corresponding to Figure 17, the refraction condition from the optical path changing means 407 to the cylindrical tube 3a at the position of point P2 is that the refractive index n1 of the optical path changing means 407 and the refractive index n2 of the cylindrical tube 3a are equal for the incident angle θ2 and the refraction angle θ32, so the following equation holds: TIFF2026009443000089.tif5150 Also, in Figure 29, which is shown corresponding to Figure 21, at the position of point P4, the angle θ23 = θ1 that the optical path P2-P4 makes with the x-axis, and the angle θ24 = θ20 that the radius P4-O0 makes with the y-axis, and the following equation holds instead of equation 17 between the incident angle θ61, the refraction angle θ71, and the angle θ25 that the refracted light P4-P5 into the air inside the cylindrical tube 3a makes with the x-axis. TIFF2026009443000090.tif6150Furthermore, the following equation holds between the incident angle θ61 and the refraction angle θ71 using the refractive index n2 of the cylindrical tube 3. TIFF2026009443000091.tif6150 Similarly, in Figure 29, which is shown corresponding to Figure 22, at the position of point P5, the following equation holds between the incident angle θ81 and the refraction angle θ91 using the refractive index n2 of the cylindrical tube 3. TIFF2026009443000092.tif6150And, from Equation 66 and Equation 17, If you set it to TIFF2026009443000093.tif7150, θ61 = arctan(sin(θ23) / (n2-cos(θ23))) = arctan(0.54112 / 0.65906) = 39.39 degrees ···(116) is obtained, and substituting this into equation 90, TIFF2026009443000094.tif7150Furthermore, from Equation 19, TIFF2026009443000095.tif7150TIFF2026009443000096.tif7150 are obtained. Also, in FIG. 25, the angle P2O0P0=θ20 is TIFF2026009443000097.tif6140TIFF2026009443000098.tif7150, the coordinates of point P2 can be calculated using equations 103 and 104, and further, the coordinates (x1, y1) of point P1 can be calculated using equations 107 and 109, -x1(rmax)=sin(θ1)(cos(θ1)·(y0-y2)-sin(θ1)·x2) ···(122) =sin(θ1)(cos(θ1)·(2.5·r1-r1·cos(θ20))-sin(θ1)·r1·sin(θ20)) TIFF2026009443000099.tif7150 -y1(rmax)=sin(θ1)**2·y0+cos(θ1)**2·y2-sin(θ1)·cos(θ1)·x2 ···(124) TIFF2026009443000100.tif7150 Therefore, rearranging the above, from equations 71 and 72, TIFF2026009443000101.tif8150TIFF2026009443000102.tif8150 are obtained, and from equations 108, 110, 123, and 125, TIFF2026009443000103.tif12150 is obtained, so in the above example, the fixed positions x1(rmax), y1(rmax) of the light-emitting unit (and light-receiving unit) when the cylindrical tube has the largest outer diameter, and the fixed positions x1(rmin), y1(rmin) of the light-emitting unit (and light-receiving unit) when the cylindrical tube has the smallest outer diameter can be moved in the direction that increases the absolute values ​​of both the x and y coordinates, and the above calculation can be repeated again.

[0084] f4) The fixing position changing process of f3) is repeated until the error between the fixing positions of the largest outer diameter tube and the smallest outer diameter tube falls within a predetermined error ε range (for example, if the outer diameter r1 of the largest outer diameter tube is around 1 m, it falls within the range of a circle with a radius of several mm, or if the outer diameter of the largest outer diameter tube is around 25 mm, it falls within the range of a circle with a radius of 1.0 mm, preferably within the range of a circle with a radius of 0.5 mm).

[0085] Furthermore, if the error between the fixed positions of the maximum and minimum outer diameter tubes does not fall within the range of the specified error ε even after changing the x and y coordinates of the fixed positions x1, y1 of the light-emitting unit (and light-receiving unit) of the cylindrical tubes with the largest and smallest outer diameters and repeating the calculations f1) to f3), it is advisable to change the inclination angles θ1 and / or θ31 of the mounting surfaces 408, 412 of the optical path changing means, or change the coordinate y0 of the intersection point P0 of the mounting surfaces, and repeat the calculations f1) to f3).

[0086] Thus, by appropriately setting the inclination angle θ1 and the coordinate y0 of the intersection point P0 of the mounting surface, when m = 4.2 and the outer diameter of the maximum outer diameter pipe is around 25 mm, it is possible to repeatedly and precisely adjust the range of the specified error ε until it falls within the range of a circle with a radius of 0.1 mm.

[0087] The range of the predetermined error ε depends on the directional sensitivity characteristics and the size of the light-receiving area of ​​the light-projecting unit 52 and the light-receiving unit 54. For example, when a silicon photodiode TPS704 manufactured by Toshiba Corporation is used for the light-receiving unit 54, the light-receiving unit is composed of a square light-receiving unit with a side length of 2.66 mm, and its half-value angle θ1 / 2 is ±65 degrees. Therefore, when measuring a tube with a relatively large diameter, it is preferable to arrange a condenser lens system in front of the light-receiving unit.

[0088] Furthermore, when a GaAs infrared light-emitting diode LN155 manufactured by Matsushita Electric Industrial Co., Ltd. is used for light-projecting unit 52, the half-value angle θ1 / 2 of the directional sensitivity characteristic is ±80 degrees, and when a GaAs infrared light-emitting diode TLN107A manufactured by Toshiba Corporation is used for light-projecting unit 52, the half-value angle θ1 / 2 of the directional sensitivity characteristic is ±15 degrees. Therefore, when performing measurements that reduce the influence of air bubbles, it is preferable to use a light-emitting element whose half-value angle θ1 / 2 of the directional sensitivity characteristic is large.

[0089] Next, FIG. 30 shown corresponding to FIG. 28 is another example of the configuration of liquid-detection device 4b of the present invention, and devices with the same numbers respectively perform the same functions. In liquid-detection device 4b, the inner cross-sectional shape of case bodies 41b, 42b is formed by a cylindrical surface 406, as in liquid-detection device 4, but this is an example in which light-projecting unit 52 and light-receiving unit 54 are arranged asymmetrically with respect to the y-axis. In the arrangement example of FIG. 30 as well, as in the above, it is necessary to interpose light-shielding material 450b in the optical path midway so that the light beam projected from light-projecting unit 52 does not directly enter light-receiving unit 54.

[0090] Even in the case of such an asymmetrically arranged optical path from the light-emitting unit 52 to the light-receiving unit 54, the tube 3, whose diameter varies, is fastened / clamped by the radius of curvature portion of the cylindrical curved surface 520 formed on the underside of the saddle band 44, and the axis position of the cylindrical tube 3 at the cylindrical inner pressure-welding / jointing surface between the case main body 41b, 42b and the saddle band 44 is always fixed in a constant spatial positional relationship even if its outer diameter varies (in Figure 30, the center line aj5 of the case main body 41b, the center line aj5 of the saddle band 44, and the axis O3 of the cylindrical tube 3 are all on the same plane coincident with the y-axis, regardless of the outer diameter of the tube 3), so it is preferable to change the saddle band 44 in the same manner as described above depending on the outer diameter of the tube 3.

[0091] In the case of an optical path in which the light-projecting unit 52 and the light-receiving unit 54 are asymmetrically arranged as shown in FIG. 30, the analysis steps f0) to f4) above can be performed by directly solving, by numerical analysis, the nonlinear equations of Equations 1 to 38, which are simultaneous geometric equations and optical equations, and by comparing the fixed positions of the light-projecting unit and the light-receiving unit calculated for the cylindrical tube having the largest outer diameter in f1) above, the fixed positions of the light-projecting unit and the light-receiving unit calculated for the cylindrical tube having the smallest outer diameter in f2) above, and the fixed positions of the light-projecting unit and the light-receiving unit calculated for a cylindrical tube having an outer diameter halfway between the largest outer diameter tube (r2=r1) and the smallest outer diameter tube (r2=r2b) in f2-2) Furthermore, in the same manner as in f3), the error between the fixed positions of the light-projecting unit and the light-receiving unit calculated when the cylindrical tube has the largest outer diameter in f1) above and the fixed positions of the light-projecting unit and the light-receiving unit calculated when the cylindrical tube has the smallest outer diameter in f2) above is calculated, and the fixed positions of the light-projecting unit and the light-receiving unit when the cylindrical tube has the largest outer diameter and / or the fixed positions of the light-projecting unit and the light-receiving unit when the cylindrical tube has the smallest outer diameter are changed so as to reduce the fixed position error.

[0092] Furthermore, similarly to f4), the fixing position changing process of f3) is repeated until the error between the fixing positions of the largest outer diameter pipe and the smallest outer diameter pipe is within a predetermined error ε range (for example, if the outer diameter r1 of the largest outer diameter pipe is around 1 m, it is within the range of a circle with a radius of several mm, and if the outer diameter of the largest outer diameter pipe is around 25 mm, it is within the range of a circle with a radius of 1.0 mm, preferably within the range of a circle with a radius of 0.5 mm). Furthermore, if the error between the fixed positions of the maximum and minimum outer diameter tubes does not fall within the range of the specified error ε even after changing the x and y coordinates of the fixed positions x1, y1 of the light-emitting unit (and light-receiving unit) of the cylindrical tubes with the largest and smallest outer diameters and repeating the calculations f1) to f3), it is advisable to change the inclination angles θ1 and / or θ31 of the mounting surfaces 408, 412 of the optical path changing means, or change the coordinate y0 of the intersection point P0 of the mounting surfaces, and repeat the calculations f1) to f3).

[0093] However, in the case of an asymmetrical arrangement of the light-projecting unit 52 and the light-receiving unit 54 as shown in Figure 30, if an optical path can be calculated in which the error between the fixed positions of the largest outer diameter tube and the smallest outer diameter tube is within a predetermined error ε, the length of the optical path from the light-projecting unit 52 to the light-receiving unit 54 will generally be longer than the optical path calculated in the case of a symmetrical arrangement, and therefore a decrease in the amount of received light will be observed, and generally the S / N ratio of the device will tend to decrease. However, if the inclination angle θ1 and the coordinate y0 of the intersection point P0 of the mounting surface are appropriately set, it will take some calculation time, but even if the arrangement of the light-emitting unit / light-receiving unit is asymmetric, if the ratio of the maximum outer diameter to the minimum outer diameter is m = 4.2 and the outer diameter of the maximum outer diameter tube is around 25 mm, it is possible to repeatedly and precisely adjust the range of the above-mentioned specified error ε until it falls within the range of a circle with an error radius of 0.5 mm.

[0094] Next, Figures 31 and 32 shown corresponding to Figures 14 and 28 show another example of the configuration of the liquid-detecting device 4c of the present invention, and devices with the same numbers respectively perform the same functions. In addition, in the liquid-detecting device 4c, the configuration in which the presence or absence of the liquid 2 is determined by utilizing one set (one pair) of liquid detection optical systems using one light-emitting means and one light-receiving means in the above-mentioned liquid-detecting device 4 has been changed to a configuration in which multiple sets of light-emitting means (52a, 52b, 52c, etc.) and light-receiving means (54a, 54b, 54c, etc.) are prepared, and the light-emitting unit and the light-receiving unit are arranged along the outer periphery of the cylindrical tube 1b / 3. By arranging multiple liquid detection optical systems (52a-54a, 52b-54b, 52c-54c, etc.) on the outer periphery of the cylindrical tube 1b / 3 to be detected, the presence or absence of liquid 2 in the cylindrical tube 1b / 3 can be checked at multiple points, even if bubbles / liquid drips / droplets occur on part of the tube surface, without being affected by the bubbles / liquid drips / droplets, making it possible to stably detect the presence or absence of liquid 2.

[0095] In the configuration of Figure 31, it is preferable to set the fixed position change process f4) when liquid 2 is not present in the tube by changing the projection angle of the light-emitting means and the light-receiving angle of the light-receiving means for each liquid detection optical system (52a-54a, 52b-54b, 52c-54c, etc.), and it is also preferable to repeatedly calculate and determine the setting allowable error ε of each optical system until it falls within the range of the desired error εi (i = a, b, c).For example, in the example of Figure 31, it is preferable to set the allowable error εa of the liquid detection optical system (52a-54a) located closest to the outer periphery of cylindrical tube 1b / 3 so that the error range is narrower than the allowable error εc of the liquid detection optical system (52c-54c) located closest to the inner periphery of cylindrical tube 1b / 3.

[0096] Furthermore, the mutual spaces between the multiple liquid detection optical systems (52a-54a, 52b-54b, 52c-54c, etc.) can be optically separated / blocked by light-shielding material 450b, so that the liquid detection optical systems do not interfere with each other.It is also possible to configure the liquid detection optical systems so that the peripheral portions of the liquid detection optical systems optically overlap and interfere with each other without using the light-shielding material 450b.

[0097] Furthermore, the configuration in which the above-mentioned multiple liquid detection optical systems are arranged on the outer periphery of the tube 1b / 3 to be detected can be configured in various variations, such as an example of a liquid detection optical system in which the light-emitting section is composed of one light-emitting means (any one of 52a, 52b, or 52c) and the corresponding light-receiving section is composed of multiple light-receiving means (54a, 54b, 54c, etc.), or an example of a liquid detection optical system in which the light-emitting section is composed of multiple light-emitting means (52a, 52b, 52c, etc.) and the corresponding light-receiving section is composed of one light-receiving means (any one of 54a, 54b, or 54c).

[0098] Furthermore, a liquid presence / absence determination means 55 (for example, a means composed of analog circuits such as operational amplifiers and inverting amplifiers, or a digital circuit configuration such as an MPU (microprocessor)) that electrically controls the above-mentioned multiple light-emitting means 52i (i=a, b, c) and light-receiving means 54i (i=a, b, c) and performs arithmetic processing of the inputs and outputs of the multiple light-emitting / light-receiving means to detect the presence or absence of liquid in the tube is mounted on the circuit board 50, and it is easy to appropriately control the inputs and outputs of the above-mentioned multiple light-emitting / light-receiving means using publicly known selectors or multiplexer technology, not shown.

[0099] With this configuration, and with reference to Figures 31 and 32, the operation of detecting the presence or absence of liquid 2 in cylindrical tube 1b / 3 using multiple liquid detection optical systems (52a-54a, 52b-54b, 52c-54c, etc.) will be described. First, Figure 31 illustrates each liquid detection optical path 52a-54a, 52b-54b, 52c-54c, etc. when there is no liquid 2 inside cylindrical tube 1b / 3. In the example of Figure 31, light-emitting means 52i (i = a, b, c) can each be independently turned on at all times, and in order to reduce power consumption, the operation of controlling the lighting by sequentially turning on and off the lights in a predetermined order in a time-division manner so that the lighting periods of each light-emitting means are staggered so that they do not overlap, and this lighting control operation can be repeated at a predetermined cycle.

[0100] On the other hand, it is preferable that the output of each light receiving means 54i (i=a, b, c) is inputted to a common liquid presence determining means 55 via a multiplexer, and time-division lighting is repeated at the above-mentioned predetermined period. In this case, it is preferable to synchronize the light emitting means 52i and the corresponding light receiving means 54i that are turned on by the multiplexer. In Figure 31, since there is no liquid 2 in the tube, it is usually possible to set the refraction detection light for liquid detection from the light emitting means 52i so that the light receiving means 54i can receive the maximum amount of light.

[0101] However, when the cylindrical tube 1b / 3 to be detected is filled with liquid 2, as shown in Figure 32, once each liquid detection transmitted light is refracted inside the cylindrical tube 1b / 3 and enters, it continues to travel almost straight and is significantly deflected from the liquid detection optical paths 52a-54a, 52b-54b, 52c-54c as shown in Figure 31, so that almost no projected detection light from the light emitting means 52i reaches the light receiving means 54i, and the liquid presence / absence determining process with an extremely excellent S / N ratio can be performed by the liquid presence / absence determining means 55.

[0102] Furthermore, when a liquid dripping phenomenon occurs on a part of the side wall surface of the cylindrical tube 1b / 3, it is preferable to determine that the liquid dripping does not indicate the presence of liquid 2. Therefore, after determining whether the output of each light receiving means 54i is on or off using a predetermined threshold value, these multiple logical outputs are subjected to, for example, a logical OR operation. When the transmitted light of at least one optical path for liquid detection reaches the light receiving means 54i via a path as shown in Figure 31, liquid 2 is present in the other optical paths for liquid detection, and even if sufficient detection light cannot be received, stable detection of the liquid in the tube is possible without being affected by the liquid dripping phenomenon.

[0103] Furthermore, when air bubbles adhere to a portion of the side wall surface of the cylindrical tube 1b / 3, it is usually preferable to determine that the adhesion of air bubbles indicates the presence of liquid 2. Therefore, after determining whether the output of each light receiving means 54i is on or off using a predetermined threshold value, these multiple logical outputs are subjected to, for example, a logical AND operation. If the transmitted light of at least one optical path for liquid detection does not reach the light receiving means 54i via the path shown in Figure 32, it is determined that liquid 2 is present in the cylindrical tube 1b / 3, and if at least one light receiving means does not receive a predetermined amount of detection light, the liquid presence / absence determining means 55 can be operated so as to enable stable detection of the liquid in the tube without being affected by air bubbles.

[0104] Furthermore, when droplets adhere to a portion of the side wall surface of cylindrical tube 1b / 3, it is preferable to determine that the adhesion of droplets normally means that no liquid 2 is present. Therefore, after determining whether the output of each light receiving means 54i is on or off using a predetermined threshold, these multiple logical outputs are, for example, subjected to a logical OR operation. Therefore, when the transmitted light of at least one optical path for liquid detection reaches the light receiving means 54i via a path such as shown in Figure 31, liquid 2 is present in that optical path for liquid detection, and even if sufficient detection light cannot be received, when the transmitted light of another optical path for liquid detection that does not have droplets adhered reaches the light receiving means 54i via a path such as shown in Figure 31, the output result of the light receiving means of the optical path for liquid detection to which droplets adhere can be ignored, and stable detection of the liquid in the tube is possible without being affected by the adhesion of droplets.

[0105] Next, Figure 33, which is shown corresponding to Figure 31, is an example of another configuration of liquid-detection device 4d of the present invention, and devices with similar numbers each perform similar functions. In liquid-detection device 4d, multiple sets of the above-mentioned liquid-detection device 4c are prepared, and multiple sets of multiple liquid-detection devices 4c1, 4c2 are arranged along the outer periphery of cylindrical tube 1b / 3 in a cross-sectional direction perpendicular to the axial direction of cylindrical tube 1b / 3. This further increases the number / locations of multiple liquid detection optical systems (52a-54a, 52b-54b, 52c-54c, etc.) that check for the presence or absence of liquid 2 in cylindrical tube 1b / 3. Even if air bubbles / liquid drips / droplets occur on part of the surface of cylindrical tube 1b / 3 that is the detection target, the liquid 2 flowing inside cylindrical tube 1b / 3 can be checked more reliably at multiple locations without being affected by the air bubbles / liquid drips / droplets.

[0106] In the configuration of Figure 33, the fixed positional relationship of the multiple liquid detection optical systems (52a-54a, 52b-54b, 52c-54c, etc.) arranged on the case main bodies 41 and 42 side can be determined by repeated calculations in the same manner as the fixed position change process when liquid 2 is not present in the pipe in f4) above.However, the fixed positional relationship of the multiple liquid detection optical systems (52d-54d, 52e-54e, 52f-54f, etc.) arranged on the saddle band 44 side is determined by performing the calculation of the fixed position change process when liquid 2 is not present in the pipe in f4) above for each of the limited ranges of outer diameters, since the outer diameter of the cylindrical pipe 1b / 3 to which the saddle-shaped fastener 44 can be applied is much narrower than that of the case main bodies 41 and 42.

[0107] Furthermore, the liquid detection optical systems (52a-54a, 52b-54b, 52c-54c, etc.) and the liquid detection optical systems (52d-54d, 52e-54e, 52f-54f, etc.) are optically arranged such that the light projected from the light-emitting means 52a, 52b, 52c is directly incident on the light-receiving means 54d, 54e, 54f, and the light projected from the light-emitting means 52d, 52e, 52f is directly incident on the light-receiving means 54a, 54b, 54c. Therefore, it is preferable to repeat the operation of controlling the lighting by sequentially turning on and off the lights in a predetermined order in a time-division manner, staggering the lighting periods of the light-emitting means so that they do not overlap, at a predetermined cycle.

[0108] Therefore, based on the above-described configuration, the present invention makes it possible to detect the presence or absence of liquid in cylindrical pipes of different diameters within a specific range using the same detection device, without having to adjust the projection angle of the light-emitting part of the detection device or replace the device itself. [Explanation of symbols]

[0109] 2 liquid 3 Cylindrical tube 4. Liquid detection device in pipes 41 Upper shell 41UBG Upper band guide 42 Lower shell 42DBG Bottom (lower) band guide 43 Cable ties 43b Cable tie fastener 44 Saddle Band 407, 411 Optical path changing means (prism) 407F Prism engagement means 52 Light projector 52H Light-emitting side opening 52a Light emitting means 54 Light receiving part 54H Light receiving side opening 54a Light receiving means RT Band Guide Locking Device

Claims

1. A liquid detection device for detecting the presence or absence of liquid in a cylindrical tube, the device comprising one or more pairs of light-emitting units and light-receiving units disposed along the outer periphery of the cylindrical tube in a cross-sectional direction perpendicular to the axial direction of the cylindrical tube, the device comprising: The shape of the measurement surface of the housing of the in-pipe liquid detection device is formed into a cylindrical curved surface having a radius that matches the maximum outer diameter of the cylindrical pipe to be measured, Between the light-emitting unit and the cylindrical tube, and between the light-receiving unit and the cylindrical tube, one or more sets of light-changing means are provided, each of which has an inner surface facing the cylindrical tube formed in a surface shape different from the outer diameter of the cylindrical tube, so that light is emitted at a predetermined angle toward the cylindrical tube; a plurality of sets of the light projecting unit and the light receiving unit are arranged so that the transmitted light for detecting the presence or absence of the liquid is refracted and projected via the light projecting unit and the light path changing means from the outside of the cylindrical tube into the air inside the hollow cylindrical tube at a substantially constant detection angle, and the refracted light is directly received by the light path changing means and the light receiving unit when the liquid is not present in the air inside the hollow cylindrical tube; a plurality of sets of the light projecting unit and the light receiving unit are arranged in the same cross-sectional direction so that, when the liquid is present in the optical path of the transmitted light inside the cylindrical tube, the refracted light passes through the liquid and does not directly reach the light receiving unit; and a liquid presence / absence determining means is further provided for processing the outputs of the plurality of light receiving units to detect the presence or absence of liquid in the tube; When the cylindrical tube has the largest outer diameter and there is no liquid inside the hollow cylindrical tube, the optical path changing means causes the detection transmitted light to pass through the air inside the hollow cylindrical tube, and the liquid detection device is attached from the cylindrical center of the cylindrical tube. calculating fixed positions of the light-emitting unit and the light-receiving unit by simultaneously solving geometric equations and optical equations so that the transmitted light for detection is transmitted to the side; and when the cylindrical tube has a smallest outer diameter and there is no liquid inside the hollow cylindrical tube, the transmitted light for detection passes through the air via the optical path changing means and is then incident on the cylindrical tube, and the transmitted light for detection passes through the air inside the hollow cylindrical tube, the transmitted light for detection that has passed through the air from the cylindrical tube is then propagated to the light receiving unit via the optical path changing means, and when the transmitted light for detection passes through the air inside the hollow cylindrical tube, the fixed positions of the light emitting unit and the light receiving unit are calculated by simultaneously solving geometric equations and optical equations so that the transmitted light for detection passes from the center of the cylindrical tube to the side where the liquid detecting device is attached, calculating fixed positions of the light-projecting unit and the light-receiving unit calculated when the outer diameter of the cylindrical tube is the maximum tube diameter and fixed positions of the light-projecting unit and the light-receiving unit calculated when the outer diameter of the cylindrical tube is the minimum tube diameter, respectively, relative to the attachment positions of the light-projecting unit and the light-receiving unit at preset spatial fixed positions; For outer diameter tubes whose outer diameters vary, when there is no liquid inside the hollow of the tube, the fixed positions of the light projecting unit and / or the light receiving unit are varied to find positions where the light projecting unit and the light receiving unit at the predetermined spatial fixed positions can stably receive the main beam of refracted and transmitted light, and the geometric equations and optical equations are simultaneously calculated until the varying difference in the fixed position of the light projecting unit for outer diameter tubes whose outer diameters vary from the maximum tube diameter to the minimum tube diameter and the varying difference in the fixed position of the light receiving unit for outer diameter tubes whose outer diameters vary from the maximum tube diameter to the minimum tube diameter fall within predetermined ranges, the fixing positions of the light-emitting unit and / or the light-receiving unit are repeatedly changed for the plurality of sets of light-emitting unit and light-receiving unit, and a fastener is provided for fixing the spatial arrangement relationship between the cylindrical tube and the light-emitting unit and the light-receiving unit so that the axis of the cylindrical tube maintains a predetermined positional relationship with the light-emitting unit and the light-receiving unit even if the outer diameter of the cylindrical tube changes; A liquid detection device in a pipe characterized in that the multiple sets of light-emitting units and light-receiving units enable the detection of the presence or absence of liquid in the pipe without being affected by bubbles / liquid drips / droplets even if they occur on part of the pipe surface.

2. 2. The device for detecting a liquid in a pipe according to claim 1, wherein the predetermined angle is a substantially constant angle of emission that is neither divergent nor convergent, and the surface shape different from the outer diameter of the cylindrical pipe is a flat surface.

3. the light changing means has convex surfaces on the upper and lower surfaces of the housing of the light changing means that fit into the housing of the liquid-detecting device, The liquid detection device in a tube as described in claim 2, wherein the housing is provided with an opaque / light-blocking material pre-formed between the light-emitting unit and the light-receiving unit on the inside of the housing of the light-changing means, which prevents transmitted light from the light-emitting unit from being directly received by the light-receiving unit.

4. A gripping structure for gripping the in-pipe liquid detection device according to any one of claims 1 to 3 on a side surface of the cylindrical pipe, the housing of the in-pipe liquid detection device comprises an upper shell body and a lower shell body, the upper shell body is provided with an upper band guide, and the lower shell body is provided with a lower band guide; a saddle band is disposed on a side surface of the cylindrical tube opposite to the housing of the liquid detection device along an axial direction of the cylindrical tube; a binding band is wound around the upper band guide and the lower band guide so as to surround the outside of the saddle band disposed on the side surface of the cylindrical tube; A gripping structure for a liquid detection device in a pipe, in which the liquid detection device in a pipe is gripped to the side surface of the cylindrical pipe by binding the binding band.

5. 5. The gripping structure for a device for detecting a liquid in a pipe according to claim 4, wherein the saddle band has a band-passing shape through which the binding band passes.

6. 5. The gripping structure for a device for detecting a liquid in a pipe according to claim 4, wherein the binding with the binding band is performed on a side surface of the cylindrical pipe by a saddle band engaging portion.

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