JP2009133747A - Channel sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To constitute a channel sensor 1 inexpensively by using a light transmission type photointerrupter 2, and to detect simply and surely the existence of liquid in a tube T. <P>SOLUTION: This sensor is equipped with a U-shaped light transmission type photointerrupter 2; a fixed plate 3 provided in the facing state to U-shaped both ends of the photointerrupter 2; and a tube holding body 4 provided in the interposed state between the photointerrupter 2 and the fixed plate 3, for holding a part of the tube T between itself and the fixed plate 3 without deforming it, and arranging the tube T into a gap G by fitting it into the gap G. The tube holding body 4 has a light guide structure 4A for guiding light from a light emitting part 21 to a position shifted from the center of the tube T in the fitted state into the gap G, and a shielding structure 4B for allowing a light receiving part 22 to receive only either of refracted light generated when the liquid exists in the tube T and refracted light generated when the liquid does not exist in the tube T in the fitted state into the gap G. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a flow path sensor capable of detecting the presence or absence of a liquid in a tube using a difference in refractive index between a gas and a liquid, and a tube holder used therefor.

  Conventionally, in order to identify the presence or absence of a liquid flowing in a tube such as a tube, a method of detecting the flow of the liquid, a method of detecting a change in the color of the liquid, a method of detecting the conductivity between electrodes immersed in the liquid, etc. There is.

  Among these, a device that detects the physical energy by the flow of the liquid and identifies the presence or absence of the liquid in the tube such as a tube requires a mechanism such as rotating a propeller, so that the device becomes large and a small amount of liquid flows. Not suitable for flow paths. In addition, a device that detects a change in the color of a liquid and discriminates the presence or absence of liquid in a tube such as a tube cannot be used for a transparent liquid, and the detection result is also affected by dirt in the tube such as a tube.

  On the other hand, in a method in which electrodes are provided in a tube such as a tube and the conductivity between the electrodes is detected, a current flows through the liquid, so that the properties of the flowing liquid may change or a chemical reaction may occur. In addition, it is necessary to install a sensor in a tube such as a tube.

  On the other hand, although a liquid breakage sensor using the refractive index of light has already been devised (Patent Document 1), the sensor requires a plurality of light emitting elements and light receiving elements, and an expensive photo sensor such as a CCD. A sensor is also required.

  In addition, there is a method of performing optical analysis by separately piping a plastic cell with high transparency and refractive index in the middle of the flow path. However, this method complicates the internal structure of the cell and makes it difficult to mold. There is also a problem. In addition, there is a possibility that the plastic cell may come off from the tube constituting the flow path.

Further, when the above-described flow path sensors are used in a thin tube having a diameter of about 3 mm, for example, there is a problem that stable detection is difficult because the obtained signal is weak.
JP 2006-10597 A

  Accordingly, the present invention has been made to solve the above-mentioned problems all at once, and it is possible to easily and reliably detect the presence or absence of liquid in the tube by configuring a flow path sensor at low cost using a light transmission type photo interrupter. Doing it is the main desired task.

  That is, the flow path sensor according to the present invention is a flow path sensor that detects the presence or absence of liquid in a light-transmitting tube, and has a U-shape having a light-emitting portion and a light-receiving portion facing each other with a gap therebetween. A light transmissive photo interrupter, a fixed plate provided facing both ends of the U-shape of the photo interrupter, provided between the photo interrupter and the fixed plate, and deforms a part of the tube And a tube holder that places the tube in the gap by fitting in the gap, and the tube holder is displaced from the center of the tube in the state of being fitted in the gap. A light guide structure that guides the light of the light emitting portion, and refracted light generated when there is liquid in the tube in a state of being fitted in the gap, or liquid in the tube. And having a light shielding structure for receiving the receiving unit only one of the refracted light produced when have.

  If it is such, a flow-path sensor can be comprised cheaply using a light transmission type photo interrupter, and the presence or absence of the liquid in a tube can be detected easily and reliably.

  In order to simplify the configuration of the tube holder, to reduce the manufacturing cost, and to further reduce the flow rate sensor, the fitting portion in which the tube holder is fitted to the bottom side of the U-shape in the gap And a fitting protrusion having a substantially L-shaped cross section that is formed from the fitting portion and a protruding portion erected on the U-shaped opening side of the gap, and the light guide structure is provided on the protruding portion. It is desirable that the through hole be formed.

  Further, in this case, the light shielding structure is such that the light shielding structure is constituted by the fitting portion, and only the refracted light generated when there is no liquid in the tube is received by the light receiving portion. It is desirable that the position where the light receiving unit can receive light is defined by the thickness of the joint portion.

  In order to make it possible to easily change the mounting position of the flow path sensor and to flexibly cope with the structure of the apparatus in which the flow path sensor is used, the fixing plate extends along the flow path direction of the tube. It has a long shape, and it is desirable that the attachment position of the photo interrupter and the tube holder to the fixing plate can be adjusted along the flow path direction.

  As described above, according to the present invention, it is possible to easily and reliably detect the presence or absence of the liquid in the tube by configuring the flow path sensor at low cost by using the light transmission type photo interrupter.

  Next, an embodiment of the flow path sensor 1 according to the present invention will be described with reference to the drawings. 1 is a cross-sectional view showing the configuration of the flow path sensor 1 according to the present embodiment, FIG. 2 is a perspective view of the flow path sensor 1 as viewed from below the tube holder 4, and FIG. FIG.

  <Device configuration>

  The flow path sensor 1 according to the present embodiment detects the presence or absence of liquid in the light-transmitting tube T using the difference in refractive index between gas and liquid. The tube is a transparent resin material (for example, polytetrafluoroethylene (PFA)) having a refractive index that is substantially the same as the refractive index of the liquid (for example, water) that flows through the inside.

  Specifically, as shown in FIGS. 1, 2, and 3, a photo interrupter 2, a fixing plate 3 to which the photo interrupter 2 is fixed, and a tube T between the photo interrupter 2 and the fixing plate 3 are provided. And a tube holder 4 to be arranged.

  Hereinafter, each part 2-4 is demonstrated.

  As shown in FIGS. 1 and 2, the photo interrupter 2 is of a light transmission type having a light emitting portion 21 and a light receiving portion 22 that face each other with a gap G interposed therebetween. The light emitting unit 21 of the present embodiment is an infrared light emitting diode, and the light receiving unit 22 is a phototransistor. In addition, the structure of the light emission part 21 and the light-receiving part 22 is not restricted above.

  The photo interrupter 2 includes a light emitting unit casing 201 that houses the light emitting unit 21, a light receiving unit casing 202 that houses the light receiving unit 22, and a connection unit 203 that connects the ends of the casings 201 and 202. It has a U-shape when viewed. A commercially available photo interrupter 2 of this embodiment is used.

  A light emitting portion slit 201 </ b> S for emitting light from the light emitting portion 21 is formed on the inner wall of the U shape of the light emitting portion casing 201. A light receiving portion slit 202 </ b> S for receiving light from the light emitting portion 21 is formed in the U-shaped inner wall of the light receiving portion casing 202. The slits 201S and 202S are linearly provided from the U-shaped bottom side to the U-shaped opening side. In addition, terminals 204 of the light emitting unit 21 and the light receiving unit 22 extend to the connecting unit 203.

  The photo interrupter 2 is attached to the fixed plate 3 so that both U-shaped end portions thereof face the fixed plate 3.

  As shown in FIGS. 1 and 3, the fixing plate 3 is provided so as to face both ends of the U-shape of the photointerrupter 2, and has a long shape extending along the tube T. The fixing plate 3 is provided with a plurality of fixing holes 31 in the extending direction for fixing the tube holding body 4 with screws. Thereby, the attachment position of the tube holder 4 and the photo interrupter 2 can be changed along the tube T. Also, a plurality of pairs of photo interrupters 2 and tube holders 4 can be attached to one fixed plate 3.

  As shown in FIGS. 1 to 3, the tube holder 4 is provided between the photo interrupter 2 and the fixed plate 3, is fixed to the fixed plate 3, and the tube T is connected to the fixed plate 3. The tube T is held without being deformed, and the tube T is disposed in the gap G by fitting in the gap G of the photo interrupter 2.

  The tube holder 4 is in a state of being fitted in the gap G, and the light guide structure 4A that guides the light of the light emitting unit 21 to a position shifted from the center of the tube T, and the refracted light generated when there is no liquid in the tube T. A light shielding structure 4 </ b> B that causes the light receiving unit 22 to receive only one of them.

  Specifically, the tube holder 4 of the present embodiment is separate from the photo interrupter 2 and holds the tube T without being deformed between the fixed plate 3 as shown in FIG. A holding main body portion 41 having a concave groove 411 and a fitting projecting in the groove direction of the concave groove 411 of the holding main body portion 41 and fitting into the gap G between the light emitting portion 21 and the light receiving portion 22 of the photo interrupter 2 And a mating protrusion 42.

  As shown in FIG. 2 in particular, the holding main body 41 has a substantially rectangular parallelepiped shape, and a concave surface 411 into which the tube T is fitted without deformation is formed on a contact surface (lower surface) 41a with the fixing plate 3. Is formed. The width and depth of the concave groove 411 are substantially the same as the outer diameter of the tube T. Further, a screw hole 41a1 for screw-fixing the tube holder 4 to the fixing plate 3 is formed on the lower surface 41a of the holding main body (see FIG. 2). A screw hole 41b1 for screwing the photo interrupter 2 is formed on the upper surface 41b of the holding main body 41 (see FIG. 3).

  As shown in FIGS. 1 and 2 in particular, the fitting protrusion 42 includes a fitting portion 421 that fits to the U-shaped bottom side of the gap G of the photo interrupter 2, and a gap G from the fitting portion 421. It has a substantially L-shaped cross section comprising a protrusion 422 erected facing the light emitting part 21 on the side of the letter-shaped opening.

  The L-shaped inner surface of the fitting protrusion 42 is continuous with one side surface of the concave groove 411 and the bottom surface of the concave groove 411 formed on the lower surface of the holding main body portion 41. That is, the width and depth of the L-shaped inner surface are substantially the same as the outer diameter of the tube T. And in the state where the tube T was hold | maintained between the fixing plate 3 and the ditch | groove 411 of the holding | maintenance main-body part 41, the tube T is arrange | positioned inside L-shape.

  The protruding portion 422 is in contact with the light emitting portion slit 201S of the light emitting portion casing 201 at the light emitting portion side surface in a state where the fitting protrusion 42 is fitted in the gap G of the photo interrupter 2. Moreover, the top surface (surface opposite to the fitting portion) of the protruding portion 422 is flush with the lower surface 41a of the holding main body portion.

  In the tube holder 4 configured as described above, the light guide structure 4A includes a through hole 422H provided in the protruding portion 422, as shown in FIGS.

  The through hole 422 </ b> H of the present embodiment guides part of light from the light emitting unit 21 to a position shifted vertically upward from a horizontal line passing through the center of the tube T. Other light is blocked by the light emitting portion side surfaces of the fitting portion 421 and the protruding portion 422.

  Further, the light shielding structure 4B includes a fitting portion 421 as shown in FIGS. That is, when the fitting part 421 is fitted to the U-shaped bottom side of the gap G of the photo interrupter 2, the light receiving part side surface of the fitting part 421 comes into contact with the light receiving part slit 202S, and the light receiving part slit 202S A part (the part from the U-shaped bottom side of the slit to the predetermined position) is closed to define the range of the slit 202S that can receive light. For this reason, the position where the light receiving unit 22 can receive light is limited by the thickness of the fitting unit 421. In the present embodiment, the thickness of the fitting portion 421 is set so that the light receiving portion 22 receives only the refracted light generated when there is no liquid in the tube T. In other words, the thickness of the fitting portion 421 is set so that the light receiving portion 22 does not exist on the optical path of the refracted light generated when there is liquid in the tube T.

  The detection principle of the presence or absence of liquid in the tube T of the flow path sensor 1 configured as described above is as follows.

  When there is no liquid in the tube T, incident light from the through hole 422H of the protrusion 422 is refracted through the side wall of the tube T and enters the tube T as shown in the partial enlarged view of FIG. Proceeds almost parallel to the light. Then, the light is refracted through the side wall of the tube T again and enters the light receiving unit 22 almost parallel to the incident light.

  On the other hand, when there is a liquid in the tube T, the incident light from the through hole 422H of the protrusion 422 has a substantially equal refractive index between the material of the tube T and the liquid. At the interface, it goes straight without refraction. Then, the light refracts again through the side wall of the tube T, but does not enter the light receiving unit 22 because the light receiving unit 22 is not provided on the optical path of the refracted light.

  From the above, the presence or absence of the liquid in the tube T can be detected by the presence or absence of light detection of the light receiving unit 22. That is, when there is a detection signal from the light receiving unit 22, it can be seen that there is no liquid in the tube T, and when there is no detection signal, it can be seen that there is liquid in the tube T.

  Next, the assembly of the flow path sensor 1 configured as described above will be described with reference to FIG.

  As shown in FIG. 3, the tube T is first arranged on the fixing plate 3, and the tube holding body 4 is fixed with screws 5 so as to sandwich the tube T with the fixing plate 3. At this time, a part of the tube T is disposed inside the L-shape of the fitting protrusion. Thereafter, the photo interrupter 2 is fitted so that the gap G fits into the fitting protrusion 42 of the tube holder 4. Then, the screw 6 is passed through the fixing hole 203 a provided in the connecting portion 203 and screwed into the screw hole 41 b 1 provided in the upper surface 41 b of the holding main body portion 4, so that the photo interrupter 2 is fixed to the tube holding body 4.

  <Effect of this embodiment>

  According to the flow path sensor 1 of the present embodiment configured as described above, the flow path sensor 1 can be configured at low cost by using the light transmission type photo interrupter 2, and the light from the light receiving unit 22 of the photo interrupter 2 can be configured. Since the signal can be used as it is, the presence or absence of liquid in the tube T can be detected easily and reliably.

  In addition, by appropriately designing the shape of the tube holder 4, the flow path sensor 1 corresponding to the tube T having various diameters can be configured. Even if the flow path sensor is compatible with the thin tube T, It can be manufactured at low cost using a commercially available light transmission type photo interrupter 2.

  <Other modified embodiments>

  The present invention is not limited to the above embodiment. In the following description, the same reference numerals are given to members corresponding to the above-described embodiment.

  For example, the fitting protrusion 42 of the above embodiment has a substantially L-shaped cross section, but may have a U-shaped cross section as shown in FIG. In this case, a through hole 424H is provided in the light receiving side wall 424, and the through hole 424H functions as the light shielding structure 4B. The through hole 424H in FIG. 4 guides only the refracted light to the light receiving unit 22 when there is no liquid in the tube T. Note that the through hole 424H may be provided at a position where only the refracted light when the liquid is in the tube T is guided to the light receiving unit 22. In FIG. 4, reference numeral 423 denotes a light emitting portion side wall, and reference numeral 423H denotes a through hole that functions as a light guide structure provided on the light emitting portion side wall.

  Furthermore, although the fixing plate 3 of the above embodiment has a long shape and is provided with a plurality of fixing holes 31, a part of the tube T is held with the tube holder 4. It may be large enough to be able to.

  In addition, the tube holding body 4 does not need to include the holding main body portion 41 and the fitting projection portion 42, and is only a fitting projection portion 42, that is, a structure having only an L-shaped cross section in the embodiment. There may be.

  In addition, some or all of the above-described embodiments and modified embodiments may be combined as appropriate, and the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. .

Sectional drawing of the flow-path sensor which concerns on one Embodiment of this invention. The lower perspective view of the tube holding body of the embodiment. The disassembled perspective view of the flow-path sensor of the embodiment. Sectional drawing of the flow-path sensor which concerns on the deformation | transformation embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Flow path sensor T ... Tube G ... Gap 21 ... Light emission part 22 ... Light receiving part 3 ... Fixing plate 4 ... Tube holder 4A ... Light guide structure 4B ... Shading structure 42 ... Fitting protrusion 421 ... Fitting part 422 ... Protrusion 422H ... Through hole

Claims (4)

A flow path sensor for detecting the presence or absence of liquid in a tube having light permeability,
A light-transmitting photo interrupter having a U-shape having a light emitting portion and a light receiving portion facing each other with a gap between them;
A fixing plate provided facing both U-shaped ends of the photo interrupter;
The tube is disposed between the photo interrupter and the fixed plate, holds a part of the tube without being deformed between the fixed plate and the tube is disposed in the gap by fitting into the gap. A tube holder, and
A light guide structure for guiding the light of the light emitting unit to a position shifted from the center of the tube in a state where the tube holder is fitted in the gap;
A light-blocking structure that allows the light-receiving portion to receive only one of refracted light generated when the tube has liquid or refracted light generated when there is no liquid in the tube in the state of being fitted in the gap. Flow path sensor. The tube holder has a substantially L-shaped cross section comprising a fitting portion that fits on the U-shaped bottom side of the gap, and a protruding portion that stands from the fitting portion on the U-shaped opening side of the gap. It has a fitting projection that makes a shape,
The flow path sensor according to claim 1, wherein the light guide structure is a through hole provided in the protrusion.   The light shielding structure is constituted by the fitting portion, and only the refracted light generated when there is no liquid in the tube is received by the light receiving portion, and the light receiving portion receives light depending on the thickness of the fitting portion. The flow path sensor according to claim 2, wherein possible positions are defined. The fixing plate has a long shape extending along the tube,
4. The flow path sensor according to claim 1, wherein attachment positions of the photo interrupter and the tube holder to the fixed plate can be changed along the tube.