JP3516027B2 - Water heater water flow sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is arranged on the inflow side of a heat exchanger of a water heater and detects the presence / absence of water flow and the increase / decrease in flow rate to blink the burner and determine the fuel combustion amount of the burner. A water flow sensor for transmitting a signal indicating a water flow state necessary for control, which is rotatably arranged in a cylindrical housing concentrically with the housing, and its rotational speed changes with the flow rate of the water flow. Regarding those equipped with a wing wheel.

[0002]

2. Description of the Related Art In a water flow sensor having the above structure for detecting the presence / absence of a water flow and the increase / decrease in the flow rate by the rotation of an impeller, even when water is not being supplied to a heat exchanger of a water heater,
For example, when draining water from the water heater to prevent freezing, a reverse flow may occur, the impeller may rotate, and the burner may be ignited as if water was being supplied to the heat exchanger, causing an accident. Therefore, various configurations have been proposed in which the impeller is prevented from rotating due to backflow.

The proposal for preventing the rotation of the impeller due to the reverse flow occurs when the water is drained from the drain port provided between the water flow sensor and the on-off valve after closing the on-off valve of the water supply pipe on the inflow side to stop the water supply. To prevent the impeller from rotating due to reverse flow, a check valve is provided on the inflow side, and a valve body of the check valve is provided with a water passage that allows drainage at a small flow rate that does not cause rotation of the impeller. Formed configuration (Japanese Utility Model Publication No. 5-823); the blades of the impeller and the flow straightening vanes on the downstream side of the impeller are both parallel and radial with respect to the center line of the rotating shaft of the impeller or an extension of the center line. And a guide vane formed of a radial diagonal flow plate that can reliably rotate the impeller even at a small amount of feed water on the upstream side of the impeller (Japanese Patent Publication No. 7-37906);
On the upstream side of the impeller, a guide vane made of a mixed flow plate in which a swirl flow in the direction of rotating the impeller having the blades inclined with respect to the axis of rotation of the rotating shaft is generated is arranged on the downstream side of the impeller. A configuration in which guide vanes made of a diagonal flow plate are arranged to make a swirl flow in a direction in which the backflow does not rotate even if a backflow occurs (Japanese Utility Model Laid-Open No. 4-55513); A configuration provided with a stopping means (Japanese Utility Model Laid-Open No. 2-79423, Japanese Patent Laid-Open No. 5-149765) is disclosed.

The construction disclosed in Japanese Utility Model Laid-Open No. 5-823 has a large loss of water supply pressure and causes an increase in cost due to the formation of the check valve portion. In the construction disclosed in Japanese Examined Patent Publication No. 7-37906, an impeller is used. A guide vane, which is a mixed flow plate, is required between the vane wheel and the flow straightening vanes on the upstream side, and the overall length of the casing in the axial direction of the rotary shaft of the vane becomes long, making it difficult to make it compact. In the configuration disclosed in Japanese Patent Laid-Open No. 4-55513, a swirl flow that does not cause the impeller to rotate when the reverse flow occurs is not provided by the mixed flow portion including the mixed flow vanes arranged on the downstream side of the impeller. It is practically difficult and
In the configurations disclosed in Japanese Patent No. 79423 and Japanese Patent Laid-Open No. 5-149765, there is a possibility that the function of preventing rotation due to backflow does not work depending on the mounting posture.

[0005]

It is possible to reliably prevent the rotation of the impeller when a backflow occurs without increasing the pressure loss of the water supply, increasing the cost, complicating the structure, and increasing the length of the casing in the impeller rotation axis direction. It is an object of the present invention to obtain a water flow sensor for a hot water supply device.

[0006]

The objects of the present invention have been solved by the following constitution. That is, a water flow sensor of a water heater connected to the inflow side of the heat exchanger of the water heater to detect the presence or absence of water flow and increase / decrease in the flow rate, in a cylindrical housing, concentric with the cylindrical housing. In a case in which a vane wheel is arranged and the rotation speed of which changes with changes in the flow rate of the water stream, the normal water flow at the time of hot water supply is parallel to the center line of the casing on the upstream side of the impeller in the casing. To make a parallel flow, a straightening vane made of a flat plate parallel to the center line, a water flow in a direction opposite to the normal direction on the downstream side of the impeller, and a parallel flow parallel to the center line of the casing. In order to do so, the vane wheel in which a plurality of vanes are formed substantially radially from the rotating shaft by arranging the straightening vanes parallel to the center line, the rotational force is generated by the parallel flow in the normal direction. In order to generate, the surface on the upstream side of each blade is inclined in the same direction with respect to the rotation axis, Configuration downstream face of which it is a surface shape which does not generate rotational force by the reverse parallel flow.

If the downstream surface of each blade of the impeller is a plane perpendicular to the reverse parallel flow, the impeller will not rotate due to the occurrence of the reverse flow (claim 2), but In order that the impeller does not rotate due to generation, the downstream surface is not necessarily limited to the plane perpendicular to the parallel flow in the opposite direction, and the downstream surface shape of each blade is the surface shape. If the shape is such that the total sum of the rotational forces generated between the respective parts constituting the above and the parallel flow in the opposite direction is zero, the impeller does not rotate due to the generation of the reverse flow (claim 3).

[0008]

1 is a longitudinal sectional view of an embodiment of a water flow sensor of a water heater according to the present invention. Reference numeral 1 is a cylindrical casing, 2 is an impeller, and the impeller 2 is the casing. A support shaft 3 fixed to the body 1 is rotatably supported concentrically with the inner peripheral surface of the housing 1. 2-1 is the impeller 2 due to the water flow described later.
A plurality of blades formed substantially integrally with the rotary shaft 2-2 so as to generate a rotational force on the rotary shaft 2-2.
-3 is a plurality of rotating shafts 2 radially from the rotating shaft 2-2.
-2 and the magnet holding arm formed integrally hold the annular permanent magnet 4. The ring-shaped permanent magnet 4 has N-poles and S-poles alternately magnetized on the outer periphery, and when the impeller 2 is rotated by a water flow, an element 5 for sensing the magnetic field embedded in the casing 1,
For example, an electric pulse is generated in the hall element to detect the presence / absence of water flow and the increase / decrease in flow rate. Arrow 6 indicates the normal water flow direction when water is being supplied to the water heater. When the water flow is generated in the normal direction, the water flow in the housing 1 is rectified into a parallel flow parallel to the axis of the rotating shaft 2-2 (the center line of the housing). An end member 7 having a straightening vane formed of a plane parallel to the axis is arranged at the end, and the end member 7 is fixed to the housing 1 by an annular locking member 8. 1-1 is a downstream side end portion of the casing 1 formed integrally with the casing 1, and is a backflow generated when water is not supplied to the fixing portion of the support shaft 3 and the heat exchanger of the water heater. Straightening vanes for straightening the flow into a parallel flow parallel to the axis.

FIG. 2 is a side view of the impeller 2, FIG. 3 is a view taken in the direction of arrow A in FIG. 2, that is, a view of the impeller 2 seen from the downstream side, and FIG.
-B sectional arrow view, ie, the figure which looked at the blade | wing 2-1 of the impeller 2 from the upstream side. 2, 3 or 4, 2-1a is a surface on the upstream side of each blade 2-1 and is inclined with respect to the axis of the rotating shaft 2-2, so that water is supplied to the water heater. The rotational force of the impeller 2 is generated by the parallel flow in the normal direction when the impeller 2 is running. 2-1b is a surface on the downstream side of each blade 2-1, and in the embodiment shown in FIG. 2, it is formed in a plane perpendicular to the axis of the rotating shaft 2-2 (claim 2), but the present invention is not limited to this. Rotation axis 2-
The present invention is not limited to a plane perpendicular to the axis of 2 and the total of the rotational force generated between the respective parts constituting the surface shape and the generated backward flow is zero (claim Item 3) will do. 3 and 4, reference numeral 2-4 is a hole into which the support shaft 3 is loosely fitted. Other reference numerals in FIG. 2 indicate the same parts as the same reference numerals in FIG.

FIG. 5 is a view of the casing 1 as seen from the downstream end 1-1 from the downstream side. The flow straightening vanes 1-2 are planes parallel to the axis of the rotary shaft 2-2 and the support shaft 3 is shown. And a portion 1-3 provided with a hole for inserting and fixing. In FIG. 5, straightening vanes 1-
2 is formed radially with respect to the axis.

FIG. 6 is a view of the end member 7 arranged at the upstream end of the housing 1 as seen from the upstream side, FIG. 7 is a sectional view taken along the line CC in FIG. 6, and FIG. 8 is a view of the end member 7. It is a perspective view for making an understanding of a shape easy. In FIGS. 6 and 8, 7-1 is a straightening vane made of a flat plate parallel to the axis of the rotary shaft 2-2, and in the embodiment shown in FIGS. 6, 7, and 8 is formed radially with respect to the axis. Has been done. 7-2 is a columnar portion formed in the center of the end member 7, and when the water supply to the water heater is stopped, the impeller 2 comes into contact with the lower end surface of the rotating shaft 2-2 of the impeller 2 and It prevents the support shaft 3 from falling off and supports the thrust received by the blade due to the backflow when the backflow occurs.

FIG. 9 is a perspective view showing the shape of the magnet holding arm 2-3 portion of the impeller 2, showing the process of mounting the annular permanent magnet 4. The magnet holding arm 2-3 includes a radial portion 2-3a formed radially from the rotary shaft 2-2 and a parallel portion 2 extending from the radial portion 2-3a in parallel with the rotary shaft 2-2.
-3b. When the permanent magnet 4 is pushed in the direction of arrow 9 along the slope formed at the tip of the parallel portion 2-3b,
The magnet holding arm 2-3 is elastically deformed once, and when the inner peripheral surface of the permanent magnet 4 crosses the slope, the magnet holding arm 2-3 is restored to the shape before the deformation, and in the state shown in FIG. The permanent magnet 4 of is fixed to the impeller 2. Four grooves 4-1, which are parallel to the center line of the permanent magnet 4, are provided in the inner periphery of the annular permanent magnet 4 at equal intervals, and at least one of the four magnet holding arms 2-3 is parallel. By engaging with the convex portion 2-3c formed on the portion 2-3b, the permanent magnet 4 is prevented from rotating relative to the magnet holding arm 2-3.

FIG. 10 is an enlarged view showing an example of the fitting relationship between the impeller 2 and the support shaft 3. The hole 2-4, which is rotatably fitted into the support shaft 3 of the impeller 2, has a large diameter on the opening end side and a small diameter at the deepest part, and is tapered like a gap between the large diameter portion and the small diameter portion. Is formed in. The small diameter portion of the hole 2-4 is loosely fitted to the small diameter portion 3-1 at the tip of the support shaft 3, and the large diameter portion of the hole 2-4 is loosely fitted to the large diameter portion 3-2 of the support shaft 3. ing. Support shaft 3
The portion between the small diameter portion 3-1 and the large diameter portion 3-2 is the small diameter portion 3
The diameter is smaller than the diameter of -1. The tip end surface of the support shaft 3 that receives the thrust received by the impeller 2 by the water flow while being supplied to the water heater by contacting the inner end surface of the hole 2-4 has a small resistance when the impeller rotates. In order to do so, it is formed in a substantially spherical surface 3-3 and makes point contact with the inner end surface of the hole 2-4.

The other end of the support shaft 3 has a collar 3-4 provided on the support shaft 3 and a support shaft at the center of the downstream end 1-1 of the housing 1 by caulking the shaft end. It is attached by holding the attachment portions 1-3 in a fixed manner. 10 is a mounting portion 1 of the support shaft 3.
-3 is a washer interposed between the outer end surface and the crimped portion. FIG. 11 shows the shape of the support shaft 3 before being crimped.

FIG. 12 is a view showing a shape before the annular locking member 8 for preventing the end member 7 arranged at the upstream end of the housing 1 from falling off is locked to the housing 1. Has a locking angle 8-1 formed radially. 13 is a sectional view taken along the line DD in FIG. 12, and FIG. 14 is a view showing a process of attaching the locking member 8 to the housing 1. The end member 7 is provided at the upstream opening end of the housing 1.
14, the locking member 8 is placed on the open end of the housing 1 as shown in FIG. 14, and the locking angle 8-1 is elastically bent in the direction of arrow 11 while being pushed in until it comes into contact with the end member 7. .

In order to prevent a rotational force from being generated in the impeller 2 when a reverse flow occurs, the downstream surface 2-1b of the blade 2-1 is not necessarily a plane perpendicular to the water flow direction, as shown in FIGS. It does not have to be provided, and as described above, any shape may be used as long as the total sum of the rotational forces generated between the respective parts forming the surface shape and the parallel flow in the opposite direction is zero. FIG. 15 shows a downstream surface 2 which is not a plane.
The cross-sectional shape of two shape examples of 1b is shown. One is a mountain-shaped surface having the same inclination in the opposite directions, and the other is a valley-shaped surface having the same inclination in the opposite directions. FIG. 16 is a view of the downstream surface of the blade having the cross-sectional shape of FIG. 15, seen from the downstream side.
FIG. 15 is a sectional view taken along the line EE of FIG. In FIGS. 15 and 16, 2-1b is a downstream surface, 2-1c is a boundary line between mutually inclined surfaces, and arrow 12 is an arrow indicating the direction of backflow. 2-1a shows the surface on the upstream side. In FIG. 16, a portion 2-1d around the hole 2-4 other than the inclined surface is a plane perpendicular to the backflow direction. In the embodiment of FIGS. 15 and 16, each blade is provided with a pair of slopes in opposite directions so that the total of the rotational force of the blades generated by parallel flow in the opposite direction, that is, reverse flow, becomes zero. However, as another embodiment, the total number of blades is an even number, each blade is formed with a slope in only one direction, and the number of blades having mutually different slope inclination directions is equal to each other, thereby causing backflow. The total sum of the rotational force of the impeller generated by the above may be set to zero.

The support shaft 3 is made of SUS material, and the locking member 8 is made of stainless steel strip for springs, except that it is formed by injection molding of synthetic resin material.

[0018]

The action and effect of the water flow sensor of the present invention is as follows:
1 only by changing the surface shapes of the upstream surface 2-1a and the downstream surface 2-1b, the impeller is rotated by the start of water supply to the water heater and the water heater is not complicated. The bar
The burner does not ignite the burner by rotating the impeller by the reverse flow generated when the water supply is stopped, while igniting the burner and increasing or decreasing the fuel combustion amount of the burner according to the change in the feed water flow rate.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of an embodiment of a water flow sensor for a water heater according to the present invention.

FIG. 2 is a side view of the impeller of the embodiment.

FIG. 3 is a view on arrow A of FIG.

FIG. 4 is a sectional view taken along the line BB of FIG.

FIG. 5 is a diagram of the casing of the embodiment as viewed from the downstream side.

FIG. 6 is a view of an end member arranged at an upstream end portion of a casing of the embodiment, viewed from the upstream side.

7 is a cross-sectional view taken along the line CC of FIG.

8 is a perspective view of the end member shown in FIGS. 6 and 7. FIG.

FIG. 9 is a perspective view showing a process of attaching an annular permanent magnet to the impeller of the embodiment.

FIG. 10 is a view showing a fitting relationship between the impeller and the support shaft of the embodiment.

FIG. 11 is a view showing the shape of the crimping side end portion of the support shaft of the embodiment before crimping.

FIG. 12 is a view showing a locking member that is locked to the inner peripheral surface of the upstream end of the casing of the embodiment.

13 is a cross-sectional view taken along the line DD of FIG.

FIG. 14 is a diagram showing a process of locking the locking member on the inner peripheral surface of the upstream end of the casing of the embodiment.

FIG. 15 is a diagram showing an example of the cross-sectional shape of the surface on the downstream side of the blade of the impeller of the example.

16 is a view of the blade having the cross-sectional shape of FIG. 15 as seen from the downstream side.

[Explanation of symbols]

1 case 2 wing wheels 2-1 wings 3 support shaft 4 annular permanent magnet 5 Magnetic field sensing element 6 Arrows showing the flow direction during water supply 7 Upstream end member 8 locking member 9 Arrows indicating the direction to push in the annular permanent magnet 10 washers 11 Arrows that indicate the direction of elastic bending 12 Diagram showing backflow direction

Continuation of the front page (56) References Japanese Unexamined Patent Publication No. 1-23118 (JP, A) Actual Kaihei 1-171319 (JP, U) Actual Kaihei 1-77920 (JP, U) Japanese Patent Publication 7-37906 (JP , B2) Japanese Patent Publication No. 39-19695 (JP, B1) J. Kohei 7-49385 (JP, Y2) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01F 1/10-1/12 G01P 13/00

Claims (3)

(57) [Claims] 1. A water heater connected to an inflow side of a heat exchanger,
A water flow sensor for a water heater that detects the presence or absence of a water flow and an increase / decrease in the flow rate. The water flow sensor is arranged in the cylindrical housing (1) concentrically with the cylindrical housing and rotates in accordance with the change in the water flow rate. In a case where a vane wheel (2) with a variable speed is provided; a normal water flow during hot water supply is provided in the casing (1) upstream of the impeller (2), and the center line of the casing (1). In order to create a parallel flow parallel to the center line, a straightening vane (7-
1) is parallel to the center line of the casing (1) in order to make the water flow in the direction opposite to the normal direction downstream of the impeller (2) parallel to the center line of the casing (1). The vane wheel (2) in which a plurality of blades are formed substantially radially from the rotating shaft (2-2), in which the straightening vanes (1-2) made of a flat plate are arranged,
In order to generate the rotational force by the parallel flow in the normal direction, the upstream surface of each blade is inclined in the same direction with respect to the rotation axis (2-2), and the downstream surface of each blade is A water flow sensor for a water heater having a surface shape that does not generate a rotational force due to the parallel flow in the opposite direction. 2. The downstream surface of each blade of the impeller (2) comprises:
2. A plane perpendicular to the parallel flow of the reverse phrase.
Water heater water heater sensor. 3. The surface shape on the downstream side of each blade of the impeller (2) has a sum of rotational forces generated between respective parts constituting the surface shape and the parallel flow in the opposite direction as zero. The water flow sensor for a water heater according to claim 1, which has a shape of a circle.