JP4799086B2 - Electronic flow meter for high temperature - Google Patents

Description

  The present invention relates to a high-temperature electronic flow meter.

No. 8-4572 JP-A-10-54742

  Conventionally, an electronic flow meter that measures the flow rate of high-temperature water is known. This will be described with reference to the conventional example of FIG. 6. A magnet 105 is attached to an impeller 104 that rotates by passage of high-temperature water, the rotation speed of the magnet is detected by a magnetic sensor 106, and high-temperature water is detected from the rotation speed. The flow rate is calculated by the electronic unit 110 and the flow rate is displayed on a display unit (not shown). In such a high-temperature electronic flow meter, since the water shielding plate 107 is heated by high-temperature water, the temperature of the magnetic sensor 106 is likely to rise due to this influence. However, when the magnetic sensor 106 becomes high temperature, there is a problem that the magnetic detection sensitivity is lowered. Therefore, conventionally, one of the problems has been to prevent the temperature of the magnetic sensor 106 from increasing. In order to solve this problem, the magnetic sensor 106 may be disposed at a position away from the water shielding plate 107 as a heat source. However, if the magnetic sensor 106 is separated too much, the magnetic sensor 106 cannot detect magnetism. Therefore, for example, a method of preventing the heating of the magnetic sensor 106 by forming a vacuum part between the heat source and the magnetic sensor (Patent Document 1) or providing a heat insulating material or a radiation fin (Patent Document 2) is adopted. It had been.

  However, in the conventional high-temperature electronic flow meter, there has been a problem that the manufacturing cost is increased by forming a vacuum part or providing a heat insulating material or the like. In particular, copper having a high thermal conductivity is often used as the heat insulating material, which causes an increase in material cost and manufacturing cost. On the other hand, as shown in FIG. 6, when a cylindrical heat sink 100 is used, heat is easily trapped, and the magnetic sensor 106 cannot be sufficiently protected from high temperatures. Therefore, there has been a demand for a high-temperature electronic flow meter that can effectively prevent the temperature increase of the magnetic sensor and that is inexpensive to manufacture.

  The present invention has been made in the background as described above. In particular, it is an object of the present invention to provide a high-temperature electronic flow meter that can effectively prevent a temperature increase of a magnetic sensor and that is inexpensive to manufacture. .

Means for Solving the Problems and Effects of the Invention

This invention
A high-temperature water distribution case comprising an inlet and an outlet for high-temperature water, and a measuring chamber that is a space communicating with the inlet and the outlet and that is open at one end;
A water shielding plate that fits into the opening of the measuring chamber and blocks the hot water in the measuring chamber from leaking outside;
An impeller that is rotatably held in the measurement chamber and rotates according to the flow rate of the high-temperature water flowing through the high-temperature water distribution case;
A magnet which is provided at a position close to the water shielding plate in the impeller, and rotates with the rotation of the impeller;
A magnetic sensor disposed above the water shielding plate at a predetermined interval and detecting a change in a magnetic field due to rotation of the magnet;
An electronic circuit for calculating a flow rate of the high-temperature water flowing through the high-temperature water distribution case according to a change in the magnetic field detected by the magnetic sensor;
Blocking radiant heat from the water shielding plate heated by the high-temperature water, and convection of heated air heated between the water shielding plate and the air interposed between itself and the water shielding plate, said barrier so as to be directed to the outer peripheral portion from the central portion along the outer surface shape that is convex toward the water plate, disposed between the magnetic sensor and the water shield plates, the water shield plate lower convex toward the heat insulating case its convex at least a portion of the side surface is expanded upward, said magnetic sensor above the convex bottom formed so that to position,
A high-temperature electronic flow meter comprising:

  According to the present invention, the downward heat-projecting case is disposed between the water shielding plate heated by the high temperature water and the magnetic sensor. With such a structure, the air heated by the water shielding plate moves from the central portion toward the outer peripheral edge along the outer surface shape, and is easily discharged. As a result, the heated air is less likely to be trapped, and the temperature increase of the magnetic sensor can be effectively prevented.

Further, the present invention may be as follows.
The main surface of the heat shielding case on the side of the water shielding plate is formed on at least a part thereof with a cone-shaped portion or a truncated cone-shaped portion having a slope of 5 to 60 ° with respect to the water shielding plate. Electronic flow meter for high temperature.
With the above configuration, the heated air can be smoothly moved to the outer peripheral edge, and is easily released to the outside. Also, the design and manufacture of the heat shield case is relatively easy. By setting the angle to 5 to 60 °, the effect of releasing heated air is optimized. If this angle deviates from 5 to 60 °, the heated air becomes difficult to move, and the temperature of the magnetic sensor easily rises. A more preferable angle is 10 to 50 °, and further preferably 20 to 40 °.

further,
The heat shielding case may be a high-temperature electronic flow meter formed of a material having a thermal conductivity of 3 × 10 ⁻² W / (m · K) or less. Thereby, even when the air heated by the water shielding plate rises and hits the heat shielding case, the heat shielding case is hardly heated. That is, before the heat of the heated air moves to the heat shield case, the heated air is discharged toward the outer peripheral edge of the heat shield case. As long as it is a design possible value and is suitable for cost, the smaller the thermal conductivity, the better. As the material of the heat shielding case, for example, a resin can be used. In this case, the heat shield case can be manufactured by injection molding. Manufacturing using a synthetic resin makes it possible to keep manufacturing costs low.

on the other hand,
As a high-temperature electronic flow meter in which a metal thin film layer for reflecting infrared rays radiated from the water shielding plate is formed on at least a part of the main surface of the heat shielding case on the water shielding plate side. Good. That is, since the water shielding plate is at a high temperature, heat transfer is also caused by electromagnetic waves (infrared rays) generated therefrom. In order to prevent heat transfer due to the radiation, a temperature increase can be further suppressed by attaching a metal thin film layer to the main surface of the heat shielding case on the side of the water shielding plate and reflecting electromagnetic waves. Specifically, an aluminum foil can be suitably used as the metal thin film layer. Nickel plating may be applied. As a method for forming a thin film, there is a method of attaching with an adhesive or a heat-resistant substance interposed.

The present invention may employ the following configuration.
The heat shielding case is
A bottom portion parallel to the water shielding plate, which is disposed at a position facing the magnet with the water shielding plate sandwiched therebetween, and is connected to the bottom portion to expand upward, and is 5-60 with respect to the water shielding plate. A lower conical cylinder having a side with an angle of °,
An upper side having a larger cross-sectional shape than the lower conical cylinder part and opening upward, with a side surface expanding in diameter upward, and the side surface forming an angle of 5 to 60 ° with respect to the water shielding plate A conical cylinder,
A shoulder portion having a step shape connecting the upper conical tube portion and the lower conical tube portion;
A high-temperature electronic flow meter in which the magnetic sensor is disposed inside the lower conical cylinder.

  With the above structure, when the magnetic sensor is arranged inside the lower conical cylinder portion, the magnetic sensor can be positioned immediately above the bottom of the lower conical cylinder portion, and as a result, the distance between the magnet and the magnetic sensor Can be narrowed. Therefore, the sensing efficiency of the magnetic sensor can be increased. Furthermore, it becomes possible to effectively discharge the heated air to the outside using the slopes of the lower cone portion and the upper cone portion.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing an embodiment of a high-temperature electronic flow meter according to the present invention, and FIG. 2 is an external view. As described above, the high-temperature electronic flow meter 1 includes a high-temperature water distribution case 2 in which the measuring chamber 3 is formed, an impeller that rotates when the high-temperature water passes, a water shielding plate 7 that blocks high-temperature water, and an impeller 4. It is configured to include a provided magnet 5, a magnetic sensor 6 for detecting a change in magnetic field, and a heat shielding case 8 disposed between the water shielding plate 7 and the magnetic sensor 6.

  Each component will be described in more detail. The hot water distribution case 2 includes an inlet 2a and an outlet 2b for hot water, and the hot water flows in the direction of the arrow in FIG. The measuring chamber 3 has a structure in which the upper end is opened in communication with the inlet 2a and the outlet 2b. A water shielding plate 7 is fitted into the opening of the measuring chamber 3 so that high-temperature water in the measuring chamber 3 does not leak to the outside. The water shielding plate 7 is heated to a high temperature by being affected by the temperature of the high temperature water. The impeller 4 includes a blade 4a and a rotary shaft 4b, and is rotatably supported by bearings 19 and 20 provided on the bottom 2d of the high-temperature water circulation case 2 and the water shielding plate 7, respectively. Furthermore, a magnet 5 is attached to the impeller 4 at a position close to the water shielding plate 7. By passing the high-temperature water, the impeller 4 and the magnet 5 rotate, and the magnetic field around the magnet 5 changes periodically. On the other hand, a magnetic sensor 6 is provided above the magnet 5 at a predetermined distance from the water shielding plate 7, and this magnetic sensor 6 detects a periodic change of the magnetic field accompanying the rotation of the impeller 4. . The thickness of the water shielding plate 7 is made thin immediately above the magnet 5 so that the magnetic sensor 6 can easily detect the magnetism from the magnet 5. An electronic unit 10 having an electronic circuit is disposed above the magnetic sensor 6, and the electronic circuit calculates the flow rate of high-temperature water based on the change in the magnetic field detected by the magnetic sensor 6.

  On the other hand, a heat shielding case 8 for blocking heat from the water shielding plate 7 is disposed between the water shielding plate 7 and the magnetic sensor 6 to prevent the temperature of the magnetic sensor 6 from rising. As shown in FIGS. 1 and 3, the heat shielding case 8 is convex toward the water shielding plate 7 (downward). Therefore, even if the air in the vicinity of the heat shield case 8 is heated and moves toward the heat shield case 8 by convection, the heated air moves along the outer surface shape of the heat shield case that is convex downward. To come. That is, the heated air moves from the center of the heat shield case 8 toward the outer peripheral edge, and is discharged to the outside through the gap S between the heat shield case 8 and the water shield plate 7. As a result, heated air is not trapped between the heat shielding case 8 and the water shielding plate 7, and the temperature increase of the magnetic sensor 6 can be effectively prevented.

  FIG. 4A shows a perspective view of the heat shield case 8, and FIG. 4B shows a side view. Moreover, the principal part enlarged view of FIG. 1 is shown in FIG. As described above, at least a part of the heat shielding case 8 has a truncated cone shape. Angles θ1 and θ2 (FIG. 3) formed by the inclined surface of the truncated cone and the water shielding plate (horizontal plane) are 5 to 60 °. When the angles θ1 and θ2 deviate from 5 ° to 60 °, the heated air becomes difficult to move. Although not shown, the shape of the heat shield case 8 may be a cone instead of a truncated cone.

On the other hand, the heat shielding case 8 is preferably made of a material having a low thermal conductivity. Specifically, a material having a thermal conductivity of 3 × 10 ⁻² W / (m · K) or less may be used. By using a material with low thermal conductivity in this way, when the air heated by the water shielding plate 7 rises and hits the heat shielding case 7, it becomes difficult for heat to move to the heat shielding case 7. That is, since the heated air is discharged from the gap S before the heat moves, the temperature increase of the magnetic sensor 6 can be efficiently suppressed.

  Moreover, it is good to form metal thin film layers, such as aluminum foil, in the main surface at the side of the water-insulating board 7 of the heat-insulating case 8. That is, since the water shielding plate 7 is heated by high-temperature water, heat transfer by electromagnetic waves (infrared rays) occurs. If a metal thin film layer is formed on the surface of the heat shielding case 8, infrared rays can be reflected, so that the temperature rise can be further suppressed. As the metal thin film layer, nickel plating can be used in addition to the aluminum foil. In addition to the above method, the method for forming the metal thin film layer may employ a method of adhering the thin film with an adhesive, attaching a thin film with a heat-resistant substance, or depositing it. In addition, it is effective to form a metal thin film layer on only a part of the main surface of the heat shielding case 8 on the water shielding plate 7 side (for example, only near the magnetic sensor 6). It is desirable to form the layer over the entire surface.

  Next, the shape of the heat shield case 8 will be described in more detail. As shown in the cross-sectional view of FIG. 3 and the side view of FIG. 4B, the heat shield case 8 includes a lower conical tube portion 23, an upper conical tube portion 25, and the lower conical tube portion 23 and the upper conical tube portion 25. And a shoulder portion 24 having a connecting step shape. In addition, the lower conical cylinder portion 23 is disposed at a position directly above the magnet 5, and has a bottom portion 21 parallel to the water shielding plate 7, and is connected to the bottom portion so as to increase in diameter upward, and an angle with the water shielding plate 7. and side portion 22 having θ1 of 5 to 60 °. Further, the upper conical tube portion 25 has a larger cross-sectional shape than the lower conical tube portion 23 and opens upward, and the side surface diameter increases upward, and the angle θ2 with the water shielding plate 7 is 5. It is set to ˜60 °. As shown in FIGS. 1 and 3, the magnetic sensor 6 is housed inside the lower conical cylinder portion 23. More specifically, as shown in FIG. 4A, a radial case fixing portion 19 is formed inside the upper conical cylinder portion 25, and the cylindrical magnetic sensor storage case 13 is disposed inside the case fixing portion 19. It is fitted (Fig. 3). Inside the magnetic sensor storage case 13, an inner wall part 17 having an opening at the bottom is provided, and a sensor placement plate 18 is attached so as to close the opening of the inner wall part 17. The magnetic sensor 6 is placed on the sensor storage plate 18.

  By adopting such a structure, it is possible to efficiently protect the magnetic sensor 6 from infrared rays or heated air radiated from the water shielding plate 7 while keeping the gap between the magnet 5 and the magnetic sensor 6 narrow. That is, since the bottom part 21 and the water shielding board 7 are parallel, the space | interval of the bottom part 21 and the water shielding board 7 can be made very narrow. Further, since the inner wall portion 17 of the magnetic sensor storage case 13 is slightly reduced in diameter than the side portion 22 of the lower conical cylinder portion 23, the tip of the inner wall portion 17 is located just inside the lower conical cylinder portion 23. And the sensor storage plate 18 can be positioned. Accordingly, the front end portion of the inner wall portion 17 and the sensor storage plate 18 and the heat shield case 8 can be arranged in a close proximity to each other in a non-contact state, whereby the magnetic sensor 6 is attached to the water shield plate 7. It becomes possible to arrange in the near position. Therefore, even when the magnetic force of the magnet 5 decreases due to high temperature, the magnetic sensor 6 can sufficiently detect the change in the magnetic field. On the other hand, since the side portion 22 is formed to face obliquely, as described above, there is an effect that the heated air moves from the vicinity of the center to the outer peripheral edge portion along the outer surface shape. Further, since the upper conical cylinder portion 25 is formed, a sufficient gap S can be secured between the water shielding plate fixing case 9 and the heat shielding case 8 which will be described later, and thus the heated air is easily discharged. Furthermore, since the case fixing | fixed part 19 formed inside the upper side cone cylinder part 25 is radial, it is easy to radiate heat.

  On the other hand, as shown in FIG. 1, the measuring chamber 3 of the high-temperature water distribution case 2 includes a bottom wall 16c, an inner wall portion 16a and an outer wall portion 16b that are erected from the bottom wall 16c, and an outer wall portion 16b. A partition member 16 including a flange portion 16d protruding outward in the radial direction is disposed. A step portion 2c is formed on the inner peripheral surface of the measuring chamber 3, and a flange portion 16d is engaged with the step portion 2c. Further, a slight gap (not shown) is formed between the outer peripheral surface of the outer wall portion 16b and the inner peripheral surface of the measuring chamber 3, and the gap and the hollow space M (the inner wall portion 16a and the outer wall portion). A notch (not shown) that communicates with the space between the outer wall portions 16b is formed in the outer wall portion 16b. The reason for this structure is as follows. That is, when the high-temperature electronic flow meter 1 is in operation, air accumulates in the space N between the rotating shaft 4b and the inner wall portion 16a (the space between the rotating shaft 4b and the inner wall portion 16a). 20 may be damaged by frictional heat. Therefore, with the above structure, when the impeller 4 is rotated, the high-temperature water is pushed upward and is sent to the hollow space M through the gap and the notch. Thereafter, high-temperature water is sent to the space N through the gap between the upper end of the inner wall portion 16a and the heat shield plate 7, thereby eliminating air.

  As shown in FIG. 1, the water shielding plate 7 includes an inlay portion 7 a that protrudes downward in the axial direction from the outer peripheral edge portion, and a flange portion 7 b that protrudes radially outward from the outer peripheral edge portion. ing. And the inlay part 7a fits into the opening part of the measurement chamber 3, and the flange part 7b contact | abuts the edge part of the high temperature water distribution | circulation case 2. FIG. Further, a ring-shaped water shielding plate fixing case 9 is fitted over the flange portion 7b so that the water shielding plate 7 is fixed. By doing in this way, the leakage of the high temperature water in a measurement chamber can fully be prevented. The water shielding plate fixing case 9 is formed with screw holes at a plurality of locations, and the heat shielding case 8 is attached to the water shielding plate fixing case 9 by screwing the screws 14 from the heat shielding case 8 side. Fixed. More specifically, as shown in FIG. 4, the heat shield case 8 is formed with three screw holes 8a, and the heat shield case 8 is fixed using only the three screw holes 8a. . In other words, there is almost nothing other than the screw hole 8a at the peripheral edge of the water shielding plate 7 to block the gap between the heat shielding case 8 and thereby the clearance S through which the air heated by the water shielding plate 7 escapes (FIG. 1). Can be secured sufficiently.

  In the embodiment described above, the heat shielding case 8 is configured to include the lower conical cylinder portion 23, the upper conical cylinder portion 25, and the shoulder portion 25. However, as shown in FIG. Or you may. Even in such a shape, the effect of the present invention in which the heated air is allowed to escape to the outside along the shape of the outer surface of the heat shield case 8 is also exhibited.

  An electronic circuit for calculating the flow rate of the high-temperature water is housed in the electronic unit 10. The electronic unit 10 is externally fitted to the upper end portion of the magnetic sensor storage case 13, and is fixed by further fitting the ring-shaped member 11. In addition, a plurality of support columns 12 are formed in the heat shielding case 8, and the ring-shaped member 11 is fixed to the support columns 12 with screws 15.

  As described above, according to the present invention, it is not necessary to use a vacuum part or a heat insulating material as in the conventional example, so that the manufacturing cost can be reduced. Further, by protecting the magnetic sensor 6 from high heat, it is possible to prevent the sensing function of the magnetic sensor 6 from being lowered.

1 is a longitudinal sectional view of a high-temperature electronic flow meter 1 according to the present invention. 1 is an external view of a high-temperature electronic flow meter 1. The principal part enlarged view of FIG. (A) perspective view (B) side view of heat shield case 8 Another embodiment of the high-temperature electronic flow meter 1. Conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High temperature electronic flow meter 2 High temperature water distribution case 3 Weighing chamber 4 Impeller 5 Magnet 6 Magnetic sensor 7 Water shield plate 8 Heat shield case 9 Water shield plate fixing case 10 Electronic unit 11 Ring-shaped member 12 Strut 13 Magnetic sensor storage Case 14, 15 Screw

Claims (5)

A high-temperature water distribution case comprising an inlet and an outlet for high-temperature water, and a measuring chamber that is a space communicating with the inlet and the outlet and that is open at one end;
A water shielding plate that fits into the opening of the measuring chamber and blocks the hot water in the measuring chamber from leaking outside;
An impeller that is rotatably held in the measurement chamber and rotates according to the flow rate of the high-temperature water flowing through the high-temperature water distribution case;
A magnet which is provided at a position close to the water shielding plate in the impeller, and rotates with the rotation of the impeller;
A magnetic sensor disposed above the water shielding plate at a predetermined interval and detecting a change in a magnetic field due to rotation of the magnet;
An electronic circuit for calculating a flow rate of the high-temperature water flowing through the high-temperature water distribution case according to a change in the magnetic field detected by the magnetic sensor;
Blocking radiant heat from the water shielding plate heated by the high-temperature water, and convection of heated air heated between the water shielding plate and the air interposed between itself and the water shielding plate, said barrier so as to be directed to the outer peripheral portion from the central portion along the outer surface shape that is convex toward the water plate, disposed between the magnetic sensor and the water shield plates, the water shield plate lower convex toward the heat insulating case its convex at least a portion of the side surface is expanded upward, said magnetic sensor above the convex bottom formed so that to position,
A high-temperature electronic flow meter comprising: The main surface of the heat shield case on the water shield plate side is at least partially on the side surface whose diameter is increased upward so that the inclined surface forms an angle of 5 to 60 ° with respect to the water shield plate. The high-temperature electronic flow meter according to claim 1, wherein a cone-shaped portion or a truncated cone-shaped portion having a first side surface is formed. 3. The high-temperature electronic flow meter according to claim 1, wherein the heat shielding case is made of a material having a thermal conductivity of 3 × 10 ⁻² W / (m · K) or less.   The metal thin film layer for reflecting the infrared rays radiated | emitted from the said water shielding board is formed in the main surface at the side of the said water shielding board of the said heat shielding case at least in part. The electronic flow meter for high temperature according to item 1. The heat shielding case is
Across the water shield plate disposed at a position opposed to the magnet, and the shielding parallel bottom water plate, Ri Tsurana at its bottom, an angle of 5 to 60 ° with respect to the water shield plate A lower conical cylinder portion comprising a second side surface included in the side surface, the diameter of which is expanded upward as described above ,
With opening upward has a larger cross-sectional shape than the lower tapered tubular portion, included in the side that is enlarged upward at an angle of 5 to 60 ° to the front Kisaegi water plate An upper conical cylinder having a third side surface ;
A shoulder portion having a step shape connecting the upper conical tube portion and the lower conical tube portion;
The high-temperature electronic flow meter according to any one of claims 1 to 4, wherein the magnetic sensor is disposed inside the lower conical cylinder portion.

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