JP4950979B2 - Flow sensor - Google Patents

Description

  The present invention relates to a flow rate sensor including an impeller that is rotated by a fluid flow, which is mainly used in a water heater.

  In general, in a water heater, a flow sensor is installed in a water supply line connected to the heat exchanger, and when the water flow rate detected by the flow sensor exceeds a predetermined minimum flow rate, the burner that heats the heat exchanger is ignited. I try to let them.

  In the flow rate sensor used in such a water heater, generally, an impeller having a blade portion inclined with respect to the axial direction is used, and the sensor is detected by a pair of bearing members provided on the inlet side and the outlet side of the sensor case. An impeller is rotatably held in the case. In this case, the impeller rotates in the forward direction when water (fluid) flows in the sensor case from the inlet side to the outlet side. Even when the water flows backward, the impeller rotates in the reverse direction, and the burner is ignited.

  Therefore, conventionally, a flow rate sensor provided with a rotation restraining member for preventing rotation of the impeller during reverse flow of water is known (see, for example, Patent Document 1). The rotation restraining member has a cylindrical shape and forms a slit that engages with a radial spoke portion provided on the bearing member on the outlet side so as to be movable in the axial direction. A protrusion that engages with the blade portion of the car and inhibits the rotation of the impeller projects. In this case, with the axial direction from the inlet side to the outlet side of the sensor case as the forward direction, when water (fluid) flows in the forward direction in the sensor case, the rotation suppression member is pushed forward and the blade The rotation suppression of the car is released and the impeller rotates. On the other hand, when water flows backward from the outlet side to the inlet side in the sensor case due to drainage or the like, the rotation suppression member is pushed in the direction opposite to the forward direction, that is, the direction approaching the impeller, The rotation of the impeller is suppressed. Thereby, it can prevent that a burner is ignited at the time of backflow of water.

  Conventionally, the blade portion of the impeller is parallel to the axial direction, and the inlet-side bearing member is provided with an oblique guide vane inclined with respect to the axial direction. When the fluid flows in the forward direction in the sensor case, There is also known a flow rate sensor in which a fluid flow is turned into a swirl flow by a guide blade and a rotational force is applied to the impeller (see, for example, Patent Document 2). In this case, since the swirling motion is not given to the fluid flowing in from the outlet side during the reverse flow, the impeller is not rotated. However, in reality, the influence of the swirling of the fluid on the oblique guide vane extends to the arrangement part of the impeller, and the impeller may rotate in the forward rotation direction or the reverse rotation direction. Therefore, it is necessary to prevent the rotation of the impeller at the time of backflow by providing a rotation inhibiting member as in the above-described conventional example.

  By the way, even if the anti-rotation member is fixed at a position where the spokes of the outlet side bearing member and the slit side edge of the anti-rotation member engage with the impeller and fluid flows in the forward direction, only the fluid pressure is sufficient. The rotation suppression member may not move in the forward direction, and the rotation suppression of the impeller by the protrusion may not be released. Therefore, in the rotation suppression member of the above-described conventional example, the protrusion is formed to have a cam portion that inclines in the forward direction from the tip toward the reverse direction. According to this, when the fluid flows in the forward direction and the rotational force in the forward rotation direction is applied to the impeller, the cam is caused by the rotational force in the forward rotation direction when the blade portion of the impeller contacts the cam portion. A forward thrust acts on the rotation suppression member via the portion. Then, the thrust of the rotation inhibiting member is released by this thrust, the rotation inhibiting member moves in the forward direction, and the impeller rotates.

Here, when the inlet-side bearing member is provided with the oblique guide vanes and the vane portion of the impeller is parallel to the axial direction, it is unknown whether the impeller rotates in the forward or reverse direction when the fluid flows backward. If the above-described conventional rotation suppression member is attached to this, when the impeller tries to rotate in the forward rotation direction when the fluid flows backward, the cam portion moves the rotation suppression member in the forward direction against the fluid pressure. Thus, the impeller cannot be prevented from rotating.
JP 2000-283804 A JP-A-64-23118

  In view of the above, the present invention is a flow rate sensor in which a blade portion of an impeller is parallel to an axial direction, an oblique guide blade is provided on an inlet-side bearing member, and a rotation suppression member is attached. To prevent rotation of the impeller by the rotation suppressing member when flowing in the direction, and to prevent rotation of the impeller in either the forward or reverse direction when the fluid flows backward It is an issue.

  In order to solve the above-described problems, the present invention is a flow rate sensor including an impeller that rotates with the flow of a fluid, the sensor case housing the impeller, the sensor case provided on the inlet side and the outlet side, A pair of bearing members that rotatably hold the impeller in the case and a slit that is cylindrical and engages radially with spokes provided on the outlet side bearing member so as to be axially movable. And an anti-rotation member formed on the end surface facing the impeller, which is provided with a protrusion that engages with the impeller blade portion to inhibit the impeller rotation, and the impeller blade portion is parallel to the axial direction. The inlet-side bearing member is provided with an oblique guide blade inclined with respect to the axial direction, and the fluid flows in the forward direction in the sensor case with the axial direction from the inlet side to the outlet side of the sensor case as the forward direction. Occasionally, the slanted guide vanes The rotation flow is applied to the impeller as a swirling flow, and the rotation suppression member is pushed forward by the fluid pressure so that the rotation suppression of the impeller is released. The restraining member is provided with a first projection and a second projection separated in the circumferential direction as the projection, and the direction of the rotational force applied to the impeller when the fluid flows in the forward direction in the sensor case is the forward rotation direction, With the opposite direction as the reverse direction, the first protrusion has a cam portion extending in the forward direction from the tip of the first protrusion toward the reverse direction, and the circumferential direction of the first protrusion and the second protrusion. The interval is such that when the impeller rotates in the forward rotation direction and any blade portion of the impeller abuts against the side edge of the second protrusion in the reverse rotation direction and rotation is suppressed, The front part is in contact with the cam part of the first protrusion and the latter blade part is in contact with the cam part. Wherein the blade portion of the is configured to abut the side edge of the reverse rotation direction side of the second protrusion.

  According to the present invention, even if the rotation restraining member is fixed at a position where it engages with the impeller, if a fluid flows in the forward direction and a rotational force in the normal rotation direction is applied to the impeller, When the blade portion contacts the cam portion of the first protrusion, a forward thrust acts on the rotation suppression member via the cam portion due to the rotational force in the forward rotation direction. Then, the sticking of the rotation restraining member is released by this thrust, and thereafter, the rotation restraining member moves in the forward direction by the fluid pressure, and the rotation restraining of the impeller by the rotation restraining member is surely released. On the other hand, when the fluid flows backward, a rotational force in the forward rotation direction is applied to the impeller, and any blade portion of the impeller comes into contact with the cam portion of the first protrusion, and a forward thrust is applied to the rotation suppression member. Even if it acts, before the rotation suppression of the impeller is released, the other impeller portion of the impeller abuts on the side edge of the second protrusion on the reverse rotation direction side, and the impeller further moves forward. Is prevented from rotating. Further, the rotation of the impeller in the reverse rotation direction is prevented by contacting each blade portion with the side edge on the forward rotation direction side of each of the first and second protrusions. Therefore, it is possible to prevent the impeller from rotating in either the forward or reverse direction when the fluid flows backward.

  By the way, when the fluid flows in the forward direction, a swirl flow is generated by the oblique guide vanes, and the rotational force in the normal rotation direction acts not only on the impeller but also on the rotation restraining member. And the side edge by the side of the reverse direction of the slit of a rotation suppression member is pressed against a spoke part by this rotational force, and a rotation suppression member may become difficult to move to a forward direction by the frictional resistance between a spoke part. Therefore, in the present invention, it is desirable that the slit is inclined in the forward direction toward the forward direction. According to this, when the side edge on the reverse rotation direction side of the slit is pressed against the spoke portion by the rotational force in the normal rotation direction, the axial component of the pressing reaction force acts on the rotation suppression member as a forward thrust. Thus, the rotation restraining member is easy to move in the forward direction.

  FIG. 1 shows a flow sensor according to an embodiment of the present invention. This flow sensor is provided in a water supply channel connected to the heat exchanger of the water heater, and heats the heat exchanger when the water flow rate detected by the flow sensor exceeds a predetermined minimum flow rate. The burner is ignited.

  The flow rate sensor is provided on the cylindrical sensor case 1, the impeller 2 accommodated in the sensor case 1, and the inlet side and the outlet side of the sensor case 1, so that the impeller 2 can rotate freely in the sensor case 1. A pair of bearing members 3 and 4 to be held and a rotation restraining member 5 mounted on the outlet side bearing member 4 are configured as main members. The flow rate sensor is installed in such a posture that the inlet side of the sensor case 1 is downward and the outlet side is upward. In the following description, the axial direction from the inlet side to the outlet side of the sensor case 1 is a forward direction.

  The impeller 2 is magnetized with a cylindrical body portion 21 that is long in the axial direction (vertical direction), a rotating shaft 22 that penetrates the body portion 21, and a radially disposed outer peripheral surface of the body portion 21. And a plurality of blade portions 23. In the present embodiment, as shown in FIG. 2, four blade portions 23 are provided at 90 ° intervals in the circumferential direction. Moreover, each blade | wing part 23 is parallel to an axial direction.

  Although not shown, a magnetic sensor composed of a Hall element or the like is installed on the outer surface of the sensor case 1, and a pulse is output from the magnetic sensor each time each blade 23 passes a position facing the magnetic sensor. . Then, the number of output pulses per unit time is counted to detect the water flow rate.

  The inlet-side bearing member 3 is formed integrally with the sensor case 1, and includes a cylindrical bearing portion 31 for inserting and holding the lower end portion of the rotating shaft 22 of the impeller 2, and a bearing portion 31 as shown in FIG. A plurality of oblique guide vanes 32 extending radially outward and inclined with respect to the axial direction are provided. By the inclined guide vanes 32, the flow of water (fluid) flowing into the sensor case 1 from the inlet side becomes a swirling flow. Then, rotational force is applied to the impeller 2 by the swirl flow. In the following description, the direction of the rotational force applied to the impeller 2 when water flows in the sensor case 1 in the forward direction is the forward direction, and the opposite direction is the reverse direction. The forward rotation direction is clockwise when viewed from the inlet side (downward) of the sensor case 1.

  The outlet side bearing member 4 includes a cylindrical bearing portion 41 that inserts and holds the upper end portion of the rotating shaft 22 of the impeller 2, an annular rim portion 42 that is fitted and fixed to the upper end portion of the sensor case 1, and a bearing portion. There are four spoke parts 43 arranged radially between 41 and the rim part 42.

  The rotation suppression member 5 has a cylindrical shape, and four slits 51 are formed in the upper half of the rotation suppression member 5 so as to engage with the four spoke portions 43 of the outlet side bearing member 4 so as to be movable in the axial direction. . As shown in FIG. 2, each slit 51 is inclined in the forward direction (upward) in the forward direction (clockwise).

  Further, a first protrusion 52 separated in the circumferential direction as a protrusion that engages with the blade portion 23 of the impeller 2 to suppress the rotation of the impeller 2 on the lower end surface of the rotation suppressing member 5 that faces the impeller 2. And the 2nd protrusion 53 is protrudingly provided. The first protrusions 52 are provided in pairs in the circumferential direction at intervals of 180 °, and the second protrusions 53 are also provided in pairs in the circumferential direction at intervals of 180 °.

  Referring to FIG. 3, the first protrusion 52 has a cam portion 52 a extending from the tip (lower end) in the forward direction (upward) in the reverse direction. The side edge of the first protrusion 52 on the forward rotation direction side is parallel to the axial direction. Further, the side edge of the second protrusion 53 on the forward rotation direction side is also parallel to the axial direction. The side edge on the reverse direction side of the second protrusion 53 is parallel to the axial direction except for the reinforcing inclined portion 53a formed at the base end thereof.

  The circumferential interval between the first protrusion 52 and the second protrusion 53 is such that any one of the blade portions 23 of the impeller 2 moves to the side edge on the reverse direction side of the second protrusion 53 by rotating the impeller 2 in the forward rotation direction. Before the rotation of the blade portion 23 is suppressed, the other blade portion 23 adjacent to the blade portion 23 in the reverse rotation direction comes into contact with the cam portion 52a of the first protrusion 52, and as indicated by a virtual line in FIG. While the latter blade portion 23 is in contact with the cam portion 52 a, the former blade portion 23 is set so as to contact the side edge of the second protrusion 53 on the reverse rotation direction side.

  Here, since the specific gravity of the rotation suppression member 5 is greater than that of water, the rotation suppression member 5 is lowered to a position where it abuts on the impeller 2 when the water stops. When water flows in the sensor case 1 in the forward direction, as shown in FIG. 1, the rotation restraining member 5 is pushed forward, that is, upward by the water pressure acting on the lower end surface thereof, The rotation suppression of the impeller 2 is released. And the impeller 2 rotates in the normal rotation direction by the swirl flow by the oblique guide vanes 32.

  By the way, even if the rotation inhibiting member 5 is fixed to the lowered position and water flows in the forward direction, the rotation inhibiting member 5 may not move upward only with water pressure. In this case, when any blade portion 23 of the impeller 2 comes into contact with the cam portion 52a of the first protrusion 52, the rotation inhibiting member is rotated via the cam portion 52a by the rotational force in the forward rotation direction of the impeller 2. An upward thrust acts on 5. Then, the sticking of the rotation inhibiting member 5 is released by this thrust, and thereafter, the rotation inhibiting member 5 moves upward by the water pressure, and the rotation inhibition of the impeller 2 by the rotation inhibiting member 5 is reliably released.

  Further, when water flows in the forward direction, a swirl flow is generated by the oblique guide vanes 32, and a rotational force in the normal rotation direction acts not only on the impeller 2 but also on the rotation suppression member 5. Then, the rotational force causes the side edge of the slit 51 of the rotation suppression member 5 on the reverse direction side to be pressed against the spoke portion 43, and the rotation suppression member 5 may be difficult to move upward due to frictional resistance with the spoke portion 43. is there. However, in this embodiment, since the slit 51 is inclined in the forward direction toward the upper side, when the side edge on the reverse direction side of the slit 51 is pressed against the spoke part 43 by the rotational force in the forward direction, As shown in FIG. 4, the axial component Fa of the pressing reaction force F acts on the rotation suppression member 5 as an upward thrust. Accordingly, the rotation restraining member 5 can easily move upward.

  When water flows backward from the outlet side to the inlet side in the sensor case 1 due to drainage or the like, the rotation suppression member 5 is pushed downward by the water pressure acting on the upper end surface. Here, during the reverse flow of water, when a rotational force in the reverse direction is applied to the impeller 2, each blade portion 23 comes into contact with the side edge on the forward rotation direction side of each of the first and second protrusions 52 and 53. Thus, the rotation of the impeller 2 in the reverse direction is prevented.

  Further, when a rotational force in the forward rotation direction is applied to the impeller 2 during the reverse flow of water, any one of the blade portions 23 of the impeller 2 comes into contact with the cam portion 52a of the first protrusion 52, and the rotation suppression member The upward thrust acts on 5. However, at the time of reverse flow of water, the rotation restraining member 5 is pushed downward by the hydraulic force, and while the blade portion 23 is in contact with the cam portion 52 a, the other blade portion 23 has the second protrusion 53. Since it abuts on the side edge on the reverse direction side, the impeller 2 is prevented from further rotation in the forward direction. Therefore, it is possible to prevent the impeller 2 from rotating in either the forward or reverse direction during reverse flow of water.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to this. For example, in the above embodiment, two first protrusions 52 and two second protrusions 53 are provided, but the number of the first protrusions 52 and the second protrusions 53 may be one each. In this case, while one of the blade portions 23 of the impeller 2 is in contact with the cam portion 52 a of the first protrusion 52, the other blade portion 23 that is 180 ° away from the blade portion 23 is rotated in reverse of the second protrusion 53. The circumferential interval between the first protrusion 52 and the second protrusion 53 may be set so as to contact the side edge on the direction side.

  Moreover, although the said embodiment applies this invention to the flow sensor for the hot water heater which flows water as a fluid, this invention is applicable similarly to the flow sensor used with apparatuses other than a water heater.

The cut | disconnection side view of the flow sensor of embodiment of this invention. The disassembled perspective view of the flow sensor of an embodiment. The expanded view of the lower end part of the rotation suppression member of the flow sensor of the embodiment. The expanded view of the part which formed the slit of the rotation suppression member of the flow sensor of embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Sensor case, 2 ... Impeller, 23 ... Blade | wing part, 3 ... Entrance side bearing member, 32 ... Oblique guide blade, 4 ... Outlet side bearing member, 43 ... Spoke part, 5 ... Rotation suppression member, 51 ... Slit 52 ... 1st protrusion, 52a ... Cam part, 53 ... 2nd protrusion.

Claims (2)

A flow sensor comprising an impeller rotating with a fluid flow,
A sensor case that houses the impeller, a pair of bearing members that are provided on the inlet side and the outlet side of the sensor case and rotatably hold the impeller in the sensor case, and are cylindrical, and are provided on the outlet side bearing member. A slit that engages with the radial spoke portion so as to be movable in the axial direction is formed, and a projection that engages with the blade portion of the impeller to suppress rotation of the impeller is formed on the end surface facing the impeller. A rotation restraining member formed by projecting,
The blade portion of the impeller is parallel to the axial direction, and the inlet-side bearing member is provided with an oblique guide blade inclined with respect to the axial direction, with the axial direction from the inlet side to the outlet side of the sensor case as the forward direction, When the fluid flows in the sensor case in the forward direction, the flow of the fluid is swirled by the oblique guide vanes to apply a rotational force to the impeller, and the rotation suppression member is pushed forward by the fluid pressure. In the one that the rotation suppression of the impeller is released,
A first protrusion and a second protrusion, which are separated in the circumferential direction, are provided as the protrusions on the rotation suppression member, and the direction of the rotational force applied to the impeller when a fluid flows in the forward direction in the sensor case is the forward rotation direction. The first protrusion has a cam portion that inclines in the forward direction from the tip of the first protrusion in the reverse direction, with the opposite direction as the reverse direction.
The circumferential interval between the first protrusion and the second protrusion is prevented from rotating by rotating the impeller in the forward rotation direction so that any blade portion of the impeller contacts the side edge of the second protrusion in the reverse rotation direction. The other blade portion of the impeller is in contact with the cam portion of the first protrusion and the former blade portion is on the reverse direction side of the second protrusion while the latter blade portion is in contact with the cam portion. A flow sensor characterized in that it is set to abut against a side edge.   The flow rate sensor according to claim 1, wherein the slit is inclined in the forward rotation direction toward the forward direction.

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