JP5819627B2 - Method for detecting magnetic metallic foreign matter and apparatus therefor - Google Patents

Description

  The present invention relates to a method and an apparatus for detecting magnetic metal foreign substances contained in fluids such as beverages and liquid foods.

  2. Description of the Related Art Conventionally, an apparatus for detecting magnetic metal foreign matter mixed in a fluid such as a beverage is known.

  For example, the detection device disclosed in Patent Document 1 is provided with a pipe for flowing a fluid mixed with magnetic metal foreign matter from the upstream side toward the downstream side, and magnetized the magnetic metal foreign matter provided on the upstream side of the pipe. It has a magnetism device and a detection unit that is provided on the downstream side of the magnetism device and detects residual magnetism in the magnetic metal foreign matter.

  The detection unit includes a plurality of sensors whose crossing angle between the residual magnetism detection direction and the center line of the pipe is 90 degrees. These sensors are arranged in an annular shape so as to surround the piping when viewed from the upstream side toward the downstream side.

JP 2006-98117 A

  When a magnetic metal foreign object is detected using a plurality of magnetic sensors for a fluid flowing in a pipe, all the magnetic sensors must operate normally. For this purpose, it is necessary to confirm that the magnetic sensor operates normally prior to starting the flow of fluid through the piping. And as the number of magnetic sensors used increases, the operation for confirming the operation thereof becomes more time-consuming. However, the prior art does not disclose means for simplifying the confirmation work.

  Therefore, according to the present invention, it is possible to easily confirm whether or not these sensors operate normally with respect to a method and apparatus for detecting a magnetic metal foreign object using a plurality of magnetic sensors. The challenge is to make improvements.

  In order to solve the above-mentioned problems, there are a first invention related to a method for detecting a magnetic metal foreign object and a second invention related to an apparatus.

  The first aspect of the invention is a method of detecting the metal foreign matter by measuring magnetic lines of force from the magnetic metal foreign matter contained in the fluid flowing inside the pipe with a magnetic sensor.

  The features of the first invention are as follows. That is, the magnetic foreign matter is detected by measuring the lines of magnetic force by a plurality of magnetic sensors arranged intermittently in the circumferential direction of the pipe outside the pipe. On the outside of the pipe, on either the upstream side or the downstream side of the magnetic sensor, a coil is wound a plurality of times to generate magnetic lines of force by temporarily passing a current through the coil, while each of the magnetic sensors The magnetic field lines are detected. It is determined that the operation of the magnetic sensor that detects the lines of magnetic force is normal, and the operation of the magnetic sensor that does not detect the lines of magnetic force is determined to be abnormal.

In the first invention , the pipe is formed of a nonmagnetic material, and a cladding tube formed of a nonmagnetic material is provided outside the pipe, and the coil is wound around the cladding tube so that the lines of magnetic force are generated. generate.

  In one embodiment of the first invention, a heat insulating material is filled between the pipe and the cladding.

The object of the second invention is an apparatus for carrying out the method according to the first invention, and the second invention is characterized in that the apparatus has the following configuration.
A. Piping that allows fluid to flow continuously in one direction,
B. A plurality of magnetic sensors arranged intermittently in the circumferential direction of the pipe outside the pipe;
C. A coil that is wound a plurality of times on the outside of the pipe on either the upstream side or the downstream side of the magnetic sensor, and is capable of temporarily generating a line of magnetic force by temporarily passing a current;
D. Display means for indicating whether or not the magnetic field lines are detected by the magnetic sensor ; and
E. The pipe is formed of a nonmagnetic material, a cladding tube formed of a nonmagnetic material is provided outside the pipe, and the coil is wound around the cladding tube.

  In one embodiment of the second invention, a heat insulating material is filled between the pipe and the cladding tube.

  In the method and apparatus according to the present invention, when a current is temporarily passed through a coil wound around the outside of a pipe, a magnetic field line is generated. Therefore, it is confirmed whether each magnetic sensor detects the magnetic field line. By doing so, it is possible to easily know whether or not the operation of the magnetic sensor is normal. Prior to starting the flow of fluid through the pipe, the magnetic metal foreign matter can be reliably detected by performing the operation of checking each of the magnetic sensors in this way.

The partial view of piping containing a detection apparatus. The elements on larger scale of FIG. III-III sectional view taken on the line of FIG. The figure similar to FIG. 3 which shows an example of an embodiment. VV sectional view taken on the line of FIG. The figure similar to FIG. 2 which shows an example of an embodiment. The figure similar to FIG. 6 which shows an example of an embodiment.

  The details of the present invention relating to a magnetic metal foreign object detection method and an apparatus therefor will be described with reference to the accompanying drawings as follows.

  FIG. 1 is a partial view of a pipe including an example of a magnetic metal foreign object detection device suitable for carrying out the method according to the present invention, and is partially broken. The detection device 1 in the illustrated example is a cylindrical pipe in which a fluid (not shown) such as soft drink, juice, yogurt, mayonnaise flows continuously or intermittently in one direction indicated by an arrow A. 2, a magnetizing device 3 installed outside the piping 2 on the upstream side of the piping 2, a detection unit 4 installed on the downstream side of the magnetizing device 3 so as to surround the piping 2 from the outside, and a downstream of the detection unit 4 On the side, a three-way valve 5 incorporated in the pipe 2 and a control unit 6 electrically connected to the detection unit 4 and the three-way valve 5 are included.

  The pipe 2 is made of a non-magnetic material such as synthetic resin. When the fluid to be inspected is food, PPSU resin (polyphenylsulfone resin), PVDF resin (vinylidene fluoride resin), etc. It is preferable to use a synthetic resin. The pipe 2 is also covered with a cladding tube 71 in the length direction of the pipe 2 through the detection unit 4. A spacer 72 is interposed between the pipe 2 and the cladding tube 71. The cladding tube 71 is formed of a nonmagnetic material such as synthetic resin or aluminum, and the spacer 72 is also formed of a nonmagnetic material such as rubber, synthetic resin, or glass fiber. When a material having a heat insulating effect such as a synthetic resin foam or glass fiber is used as the spacer 72, the material also serves as a packing or a heat insulating material.

  The magnetism device 3 is capable of magnetizing metal particles contained in the fluid as metal foreign matters, for example, fine magnetic metal particles (not shown) having a diameter of about 0.3 to 2 mm. Made with magnets.

  The detection unit 4 includes a plurality of sensor units 10 (see FIG. 3) each including a magnetic sensor 11 and a shield 12 that shields the sensor unit 10 from magnetism in the external environment. As the magnetic sensor 11, a small sensor that can capture magnetic lines of force from a metal foreign substance in the fluid and that can be easily arranged in the circumferential direction with respect to the pipe 2 is used. An example of such a magnetic sensor 11 includes an MI sensor, a fluxgate sensor, and the like. Among them, a room temperature and high sensitivity fluxgate sensor is one of the particularly preferable ones for carrying out the present invention. Examples of elements used in these sensors include an MI (magnetic impedance) effect element, a Hall element, a magnetoresistive effect element, a coil (including a static magnetic field detection coil), and the like. The sensor unit 10 also includes a sensor circuit (not shown) for converting magnetic force lines captured by the magnetic sensor 11 into an electric signal to the control unit 6.

  The shield 12 can be made of, for example, PC permalloy. However, in order to have a broad shielding effect against the magnetism of the external environment, the shield 12 is preferably made of a PC permalloy having a double structure as shown in the drawing. The shield 12a and the aluminum high-frequency shield 12b set inside thereof are used in combination. The double-structured magnetic shield 12a is directed to the upstream side from each of the cylindrical housing parts 13a and 13b and the housing parts 13a and 13b, which are made so as to accommodate the sensor unit 10 and the shield 12b. And cylindrical rear sleeve portions 15a and 15b extending downstream from the housing portions 13a and 13b (see FIG. 2). The front sleeve portions 14a and 14b and the rear sleeve portions 15a and 15b are formed so as to surround the cladding tube 71 and to make the gap between the outer circumferential surface 73 of the cladding tube 71 as small as possible, and The magnetism of the environment is prevented from entering the housing portions 13a and 13b along the outer peripheral surface 73.

  A coil 81 is wound around the cladding tube 71 inside the magnetic shield 12a. The coil 81 is obtained by applying an insulating coating (not shown) to an electric wire 82 having a diameter of about 0.1 to 1 mm and winding the electric wire 82 around the cladding tube 71 several times to several tens of times. It extends to the operation panel 6 to be described later through a small through hole (not shown) formed in. A 5 to 15 ohm resistor 83 is connected in series with the wire 82. The coil 81 is arranged close to the magnetic sensor 11 so that the separation distance L from the magnetic sensor 11 along the cladding tube 71 is as small as possible. The separation distance L here means the shortest distance between the magnetic sensor 11 and the coil 81. In the preferred device 1, the separation distance L is in the range of 10-50 mm.

  The three-way valve 5 is configured to switch the opening direction by a signal issued by the control unit 6 that has detected the presence of metal foreign matter based on signals from the plurality of magnetic sensors 11 for a required time. Is used to remove metal foreign matter from the fluid.

  The controller 6 performs processing such as an algorithm on the electrical signal from the magnetic sensor 11 during operation of the device 1 in which the fluid is flowing in the pipe 2, removes noise from the external environment included in the electrical signal, and magnetically When the signal from the sensor 11 is enlarged and the signal is outside a predetermined threshold, an electronic circuit that can determine that a metal foreign object is present is provided. The control unit 6 can also switch the opening of the three-way valve 5 based on the result of the determination, and discharge the portion of the fluid containing the metallic foreign matter from the pipe 2. Furthermore, the control unit 6 can record and store a signal from the magnetic sensor 11 and can issue an alarm on the display unit 80 described later when it is determined that a metal foreign object exists. The personal computer 87 connected to the control unit 6 can show how the signal from the magnetic sensor 11 changes with time.

  The control unit 6 also causes a weak current, for example, a current of 0.5 to 10 mA, to flow through the coil 81 when the inspection switch 88 is temporarily turned on in a start-up inspection or the like prior to starting the flow of fluid through the pipe 2. As a result, a magnetic field is generated in the coil 81. When the inspection switch 88 is turned on, the magnetic sensor 11 is also turned on by the control unit 6 so that the magnetic sensor 11 detects the magnetic field and outputs a signal. The signal is amplified and sent to the control unit 6. . The control unit 6 determines that the operation of the magnetic sensor 11 that has output the signal is normal if the signal is within a preset threshold, and indicates that the display unit 80 of the control unit 6 is normal. 86 is turned on. If the signal is outside the threshold value, it is determined that the operation of the magnetic sensor 11 that has output the signal is abnormal, and the control unit 6 turns on the lamp 84 indicating that it is abnormal or sounds the buzzer 85. can do.

  The control unit 6 detects the magnetic field of each of the magnetic sensors 11 by manual operation or automatic operation while the magnetic field is generated in the coil 81. Whether or not there is an abnormality in the operation of the magnetic sensor 11 can be easily known from the detection result, and the start-up inspection for the apparatus 1 can be completed in a short time.

  FIG. 2 is an enlarged view of the detection unit 4 of FIG. The housing portions 13a and 13b in the outer shield 12a and the inner shield 12b of the detection unit 4 are respectively formed by front halves 17a and 17b and rear halves 18a and 18b. Each is fitted to each of the rear halves 18a, 18b from the inside. In the radial direction of the pipe 2, a spacer 22 fixed by a bolt 21 is interposed between the magnetic shields 12 a and 12 a. The magnetic sensor 11 is attached to a disk 24, and the disk 24 is fixed to the upstream wall 26 of the housing portion 13b via bolts 27 and nuts 28. A through hole 29 (see FIG. 3) for allowing the pipe 2 and the cladding tube 71 to pass therethrough is formed at the center of the disk 24. A connector 31 (see FIG. 3) for connecting a cord plug (not shown) extending from the control unit 6 is also attached to the disk 24. The connector 31 is electrically connected to each of the magnetic sensors 11. Has been.

  3 is a cross-sectional view taken along line III-III in FIG. The pipe 2 and the cladding tube 71 are passed through the through hole 29 of the disk 24, and a plurality of sensor units 10 are arranged outside the cladding tube 71 so as to surround the cladding tube 71. Each of the sensor units 10 includes a magnetic sensor 11, and in the illustrated example, twelve magnetic sensors 11 are arranged at a constant pitch in the circumferential direction. The magnetic sensor 11 is attached to a substrate 32 made of FRP in the sensor unit 10 so as to be as close as possible to the outer peripheral surface of the cladding tube 71.

  In the detection apparatus 1 formed in this way, each of the plurality of magnetic sensors 11 can capture magnetic lines of force from a fluid containing a metallic foreign object at a distance smaller than one half of the inner diameter D of the pipe 2. Further, the control unit 6 can extract a difference between signals from adjacent magnetic sensors 11 among the plurality of magnetic sensors 11 and determine the difference as the strength of the magnetic lines of force from the metal foreign object. Therefore, the detection device 1 can catch the magnetic lines of force from the metal foreign object in a state where the magnetic field in the external environment that has entered the housing portion 13b and cannot be prevented by the magnetic shield 12 is erased. The invention of the illustrated example in which the magnetic sensor 11 captures the lines of magnetic force from the fluid containing the metal foreign matter. Also, even if the fluid contains salt or bubbles, it does not affect the detection accuracy of the magnetic sensor 11. It is possible to target various kinds of fluids and fluids flowing under various conditions. For example, target fluids such as mayonnaise and yogurt that have high viscosity and bubbles are difficult to disappear, or fluids that are likely to contain many bubbles just after the fluid has just started to flow through pipe 2. When this is done, it is possible to detect metallic foreign objects with high accuracy. It is also possible to test a liquid food containing solid matter.

  In addition to preventing the outer peripheral surface of the pipe from condensing when the low temperature fluid flows through the pipe 2, the cladding 71 is wound around the cladding 71 when the high temperature fluid flows through the pipe 2. It is also possible to prevent the covering (not shown) of the electric wire 82 from being damaged. In order to ensure such effects by the coated tube 71, the spacer 72 is made of a heat-insulating material such as a synthetic resin foam or glass fiber, and these materials are used as a packing material for piping. 2 and the cladding tube 71 can be filled. However, the spacer 72 is not necessarily required to have substantially the same length as the length of the cladding tube 71 as in the illustrated example. For example, the spacer 72 may exist only at both ends of the cladding tube 71. It is.

  FIG. 4 is a view similar to FIG. 3 showing an example of the embodiment. The sensor unit 10 in FIG. 4 includes a first sensor unit 10a disposed in a horizontal direction and a vertical direction in the drawing, and a second sensor unit 10b disposed in a state inclined by 45 ° with respect to the first sensor unit 10a. And are included. Each of the first and second sensor units 10 a and 10 b includes a magnetic sensor 11. The other configuration inside the magnetic shield 12a is the same as the configuration in FIG.

  FIG. 5 is a diagram showing a VV line cut surface in FIG. 4. In FIG. 5, the second sensor unit 10 b is inclined by an angle α with respect to a horizontal line H parallel to the pipe 2. The angle α is preferably in the range of 45 ± 10 °. The first sensor unit 10a not appearing in FIG. 5 is attached to a vertical disk 24 orthogonal to the pipe 2 in the same manner as the sensor unit 10 in FIGS. The coil 81 is wound around the cladding tube 71, and the distance between the first sensor unit 10a and the magnetic sensor 11 and the distance between the second sensor unit 10b and the magnetic sensor 11 are both in the range of 10 to 50 mm. It is in. The magnetic field generated in the coil 81 can be used to determine whether or not the operation of the magnetic sensor 11 in the first and second sensor units 10a and 10b is normal.

  FIG. 6 is also a view similar to FIG. 2 showing an example of the embodiment. However, in FIG. 6, the coil 81 is wound around the inner surface 77 of the peripheral wall 76 in the high-frequency shield 12b. By using the coil 81 in such a state, the coil 81 and the magnetic sensor 11 can be brought close to each other, and the separation distance L can be reduced.

  FIG. 7 is also similar to FIG. 6 showing an example of the embodiment. In the present invention, the coil 81 can be wound around the outer peripheral surface 2a of the pipe 2 (see FIG. 1). However, in order to be able to use the pipe 2 under a wide range of temperature conditions, it is preferable that the pipe 2 be in the mode illustrated in FIGS.

  In addition, although the coil 81 in the illustrated example is provided on the upstream side of the magnetic sensor 11, it may be provided on the downstream side of the magnetic sensor 11.

  According to the present invention in which the coil 81 is wound around the outside of the pipe 2, the operation of the magnetic sensor 11 is confirmed even if the pipe 2 is for flowing a fluid in which hygiene management is important, such as food. Therefore, it is not necessary to open a part of the pipe 2 or insert devices inside the pipe 2, so that the operation of the magnetic sensor 11 can be confirmed in a hygienic state. In the illustrated control unit 6, the operations of the plurality of magnetic sensors 11 are sequentially confirmed. However, the control unit 6 can be formed so that the operations of the plurality of magnetic sensors 11 can be confirmed simultaneously. Furthermore, the control unit 6 can be made so that only the magnetic sensor 11 having an abnormal operation can be displayed.

DESCRIPTION OF SYMBOLS 1 Detection apparatus 2 Piping 11 Magnetic sensor 71 Coated tube 80 Display means (display part)
81 coils

Claims (4)

A method of detecting magnetic metal foreign matter contained in a fluid flowing inside a pipe by using a magnetic sensor to detect the metal foreign matter,
Measuring the lines of magnetic force by a plurality of magnetic sensors arranged intermittently in the circumferential direction of the pipe outside the pipe to detect the metal foreign matter,
On the outside of the pipe, on either the upstream side or the downstream side of the magnetic sensor, a coil is wound a plurality of times to generate magnetic lines of force by temporarily passing a current through the coil, while each of the magnetic sensors to detect the magnetic field lines in the operation for the magnetic sensor for detecting magnetic force lines are determined to be normal, it is determined that the said magnetic sensors do not detect the magnetic field lines is abnormal in operation, the pipe non The method according to claim 1, wherein the cladding is formed of a magnetic material, a cladding tube formed of a nonmagnetic material is provided outside the pipe, and the magnetic lines of force are generated by winding the coil around the cladding tube . The method according to claim 1 , wherein a heat insulating material is filled between the pipe and the cladding tube. An apparatus for detecting metallic foreign matter, characterized in that it has the following configuration for carrying out the method according to claim 1;
A. Piping that allows fluid to flow continuously in one direction,
B. A plurality of magnetic sensors arranged intermittently in the circumferential direction of the pipe outside the pipe;
C. A coil that is wound a plurality of times on the outside of the pipe on either the upstream side or the downstream side of the magnetic sensor, and is capable of temporarily generating a line of magnetic force by temporarily passing a current;
D. Display means for indicating whether or not the magnetic field lines are detected by the magnetic sensor ; and
E. The pipe is formed of a nonmagnetic material, a cladding tube formed of a nonmagnetic material is provided outside the pipe, and the coil is wound around the cladding tube. The apparatus according to claim 3 , wherein a heat insulating material is filled between the pipe and the cladding tube.

Images