JP2019027745A - Premixing device - Google Patents

Abstract

To interlockingly vary the opening area of an air inflow opening and the opening area of a gas inflow opening of a premixing device while maintaining the opening area ratio and enable adjustment of the air-fuel ratio of a mixed gas.SOLUTION: An outer peripheral wall 101 is joined to the suction side of a fan, and the opening area of an air inflow opening 102 of the outer peripheral wall is varied by an air control part 120. Besides, an inner peripheral wall 111b is introduced inside the outer peripheral wall to guide a fuel gas, and the opening area of a gas inflow opening 113 of the inner peripheral wall is varied by a gas control part 115 interlocking with the air control part. Further, partition cylinders 105, 106 are installed between the outer peripheral wall and the inner peripheral wall to separate combustion air and the fuel gas. In the partition cylinders, an end (merge end) for merging the combustion air and the fuel gas is provided in a movable manner in the direction of the center line of the outer peripheral wall, and the outer peripheral wall and the inner peripheral wall are formed in shapes for increasing or reducing a gap at the position of the merge end with movement of the partition cylinders.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a premixing device that is connected to a suction side of a fan that sends a mixed gas of fuel gas and combustion air to the combustion device and previously mixes the fuel gas supplied to the fan and the combustion air.

  Some hot water heaters equipped with a combustion device that burns a mixed gas of fuel gas and combustion air are equipped with a fan for sending the mixed gas to the combustion device. A premixing device for previously mixing the fuel gas supplied to the fan and the combustion air is connected. When the fan is rotated, the fuel gas and the combustion air are sucked into the fan from the premixing device at a predetermined ratio, and the mixed gas is sent to the combustion device connected to the discharge side of the fan.

  Such a premixing device includes a mixing passage joined to the suction side of the fan. The mixing passage includes an air inlet through which combustion air flows and a gas inlet through which fuel gas flows. It is open. When the pressure in the mixing passage becomes negative due to suction by the rotation of the fan, combustion air flows from the air inlet and fuel gas flows from the gas inlet and is supplied to the fan through the mixing passage. At this time, since the ratio (air-fuel ratio) between the combustion air flowing into the mixing passage and the fuel gas is determined by the opening area ratio between the opening area of the air inlet and the opening area of the gas inlet, The opening area ratio is set in accordance with an appropriate air-fuel ratio of the mixed gas to be made.

  Further, in such a premixing device, a mechanism has been proposed in which the opening area of the air inlet and the opening area of the gas inlet are changed in conjunction with each other while maintaining the opening area ratio (for example, Patent Document 1). It is possible to adjust the flow rate of the mixed gas sent to the combustion device while keeping the fuel ratio constant.

Special table 2014-502337 gazette

  However, in the premixing device that employs a mechanism such as that of Patent Document 1, it is possible to change the opening area of the air inlet and the opening area of the gas inlet in conjunction with each other while maintaining the opening area ratio. However, the opening area ratio may fluctuate from the target value due to manufacturing variations, and even in this case, the opening area ratio is maintained, so there is a problem that the mixed gas may not have an appropriate air-fuel ratio. .

  The present invention has been made in response to the above-mentioned problems of the prior art, and interlocks the opening area of the air inlet of the premixing device and the opening area of the gas inlet while maintaining the opening area ratio. It is an object of the present invention to provide a technique capable of adjusting the air-fuel ratio of the mixed gas while allowing the air-fuel ratio to be changed.

In order to solve the above-described problems, the premixing device of the present invention employs the following configuration. That is,
In a premixing device that is connected to a suction side of a fan that sends a mixed gas of fuel gas and combustion air to the combustion device and mixes the fuel gas supplied to the fan and the combustion air in advance.
An outer peripheral wall joined to the suction side of the fan;
An air inlet for allowing the combustion air to flow into the outer peripheral wall;
An air control unit capable of changing an opening area of the air inlet;
An inner peripheral wall that is introduced into the outer peripheral wall and extends parallel to the center line of the outer peripheral wall to guide the fuel gas;
A gas inlet for allowing the fuel gas to flow between the inner peripheral wall and the outer peripheral wall from the inner peripheral wall;
In conjunction with the air control unit, a gas control unit capable of changing an opening area of the gas inlet while maintaining an opening area ratio with the opening area of the air inlet;
An outlet that opens to an end of the outer peripheral wall on the joint side with the fan and allows the mixed gas to flow out to the fan;
A partition cylinder installed between the outer peripheral wall and the inner peripheral wall and separating the combustion air flowing in from the air inlet and the fuel gas flowing in from the gas inlet;
The partition cylinder has a merging end for merging the combustion air and the fuel gas at an end on the outlet side, and the position of the merging end is provided to be movable in the direction of the center line of the outer peripheral wall. And
The outer peripheral wall and the inner peripheral wall are formed in a shape that increases or decreases the distance between the outer peripheral wall and the inner peripheral wall at the position of the merging end as the partition tube moves.

  In such a premixing device of the present invention, the fuel gas sucked from the inside of the inner peripheral wall by the rotation of the fan passes through the gas inlet and is first surrounded by a partition cylinder and the inner peripheral wall (gas chamber). And merges with the combustion air at the downstream merging end position. The flow rate of the fuel gas varies depending on the difference between the pressure inside the inner peripheral wall (approximately atmospheric pressure) and the pressure in the gas chamber (negative pressure). Since this gas chamber is connected to the merging end, the pressure in the gas chamber is interlocked with the pressure at the merging end, and as a result, the flow rate of the fuel gas changes according to the degree of the negative pressure at the merging end. And, for example, if the merging end moves to the side where the distance between the outer peripheral wall and the inner peripheral wall is wide (the side where the gap between the outer peripheral wall and the inner peripheral wall is large) as the partition tube moves, the negative pressure at the merging end Therefore, the flow rate of the fuel gas is relatively reduced. As a result, the adjustment to the air rich side in which the ratio of the combustion air in the mixed gas is increased is possible, and the air-fuel ratio of the mixed gas is increased.

  On the contrary, if the merging end moves to the side where the distance between the outer peripheral wall and the inner peripheral wall is narrow (the side where the gap between the outer peripheral wall and the inner peripheral wall is small) with the movement of the partition tube, Since the degree of negative pressure increases, the flow rate of fuel gas increases relatively. As a result, adjustment to the gas rich side that increases the ratio of the fuel gas in the mixed gas becomes possible, and the air-fuel ratio of the mixed gas becomes small.

  As described above, in the premixing device of the present invention, the air-fuel ratio of the mixed gas can be changed by moving the partition tube. Therefore, the opening area ratio between the air inlet and the gas inlet is targeted even if there is a manufacturing variation. Even if it deviates from the value, change the configuration (air control unit, gas control unit, etc.) that changes the opening area of the air inlet and the opening area of the gas inlet while maintaining the opening area ratio. Instead, the air-fuel ratio of the mixed gas can be adjusted by moving the partition tube.

  In the premixing device of the present invention described above, the inner peripheral wall is formed in a shape that maintains a distance from the merging end with the movement of the partition tube, and the outer peripheral wall is formed with the merging end with the movement of the partition tube. You may form in the shape which increases / decreases an interval.

  In this way, for example, by moving the partition tube to the side where the distance between the outer peripheral wall and the merging end becomes wider, the merging end moves to the side where the area of the gap between the outer peripheral wall and the inner peripheral wall becomes larger. Thus, the degree of negative pressure at the merging end is weakened and the flow rate of the fuel gas is relatively reduced, so that adjustment to the air rich side is possible. On the contrary, by moving the partition tube to the side where the distance between the outer peripheral wall and the merging end becomes narrow, the merging end moves to the side where the area of the gap between the outer peripheral wall and the inner peripheral wall becomes smaller. Since the degree of negative pressure at the merging end increases and the flow rate of the fuel gas relatively increases, adjustment to the gas rich side becomes possible.

It is explanatory drawing which showed the structure of the water heater 1 as an example of the combustion apparatus using the fan 20 which connected the premixing apparatus 100 of a present Example. It is the perspective view which showed the state which decomposed | disassembled the fan 20 of a present Example. It is the perspective view which showed the state which decomposed | disassembled the premixing apparatus 100 of a present Example. It is a perspective view which shows the state by which the air control part 120 and the gas control part 115 of the present Example were connected via the cam 117. FIG. It is explanatory drawing which shows a motion of the air control part 120 and the gas control part 115 which interlock | cooperated with the rotating shaft 122 in the premixing apparatus 100 of a present Example. It is sectional drawing which showed the case where the movable cylinder 106 is not provided with the premixing apparatus 100 of a present Example. It is explanatory drawing which showed a mode that the air-fuel ratio of mixed gas was adjusted with the movable cylinder 106 in the premixing apparatus 100 of a present Example. It is sectional drawing which showed the structure of the premixing apparatus 100 of the modification. It is sectional drawing which showed the structure of the other example premixing apparatus 100 which rotates and moves the gas control part.

  FIG. 1 is an explanatory diagram showing a configuration of a water heater 1 as an example of a combustion apparatus using a fan 20 connected to a premixing device 100 of the present embodiment. As shown in the drawing, inside the housing 2 of the water heater 1, a combustion unit 3 having a built-in burner for burning a mixed gas of fuel gas and combustion air, and a heat exchanger installed below the combustion unit 3. 4 and a fan 20 for sending a mixed gas to the combustion unit 3 are provided.

  A premixing device 100 that premixes fuel gas supplied to the fan 20 and combustion air is connected to the suction side of the fan 20, and a combustion unit 3 is connected to the discharge side of the fan 20. Yes. A gas supply passage 11 for supplying a fuel gas is connected to the premixing device 100. The gas supply passage 11 has a zero governor 12 for reducing the pressure of the fuel gas pumped from the upstream side to atmospheric pressure, a gas An open / close valve (not shown) for opening and closing the supply passage 11 is provided. When the fan 20 is driven, the combustion air existing in the housing 2 and the fuel gas downstream of the zero governor 12 in the gas supply passage 11 are mixed at a predetermined ratio by the premixing device 100 and sucked into the fan 20. Then, the mixed gas is fed into the combustion unit 3. In addition, the structure of the fan 20 and the structure of the premixing apparatus 100 of a present Example are demonstrated later using another figure.

  In the combustion unit 3, the mixed gas is burned by a built-in burner (not shown). In the illustrated example, the mixed gas is ejected downward from the burner, a flame is formed downward, and the combustion exhaust is sent to the lower heat exchanger 4. A water supply passage 5 is connected to one end of the heat exchanger 4, and a hot water supply passage 6 is connected to the other end of the heat exchanger 4. The clean water supplied through the water supply passage 5 is heated by heat exchange with the combustion exhaust of the burner in the heat exchanger 4 and then flows into the hot water supply passage 6 as hot water.

  The combustion exhaust gas that has passed through the heat exchanger 4 passes through the exhaust duct 7 and is discharged to the outside through an exhaust port 8 that projects to the top of the housing 2. Further, a double-pipe structure in which an air supply port 9 is provided on the outer periphery of the exhaust port 8, and combustion air taken into the housing 2 from the air supply port 9 is supplied to the fan via the premixing device 100. 20 sucked in.

  FIG. 2 is a perspective view showing a state in which the fan 20 of the present embodiment is disassembled. In FIG. 2, the upper and lower arrangements of the fans 20 are reversed with respect to FIG. 1. The illustrated fan 20 is a centrifugal type, and includes an impeller 30 that generates wind by rotating, a drive motor 40 that rotates the impeller 30, a casing 50 that houses the impeller 30, and the like.

  The impeller 30 has a cylindrical shape in which a plurality of blade pieces 31 are radially arranged with respect to the shaft 41 of the drive motor 40 at predetermined intervals. One end of the shaft 41 in the axial direction (lower end in the figure) is attached to the substantially circular rotating disk 32, and the other end (upper end in the figure) is attached to the annular support plate 33. It has been. The rotary disc 32 is fixed to the shaft 41 of the drive motor 40 at the center, and the impeller 30 rotates around the shaft 41 by the drive of the drive motor 40.

  The casing 50 is formed by joining a concave main body 51 to which the drive motor 40 is fixed to the outside (the lower surface in the drawing) and a concave lid body 52 facing the main body 51 at an outer edge portion. The main body 51 and the lid 52 are kept airtight by interposing a packing (not shown) between them, and are fixed with screws (not shown).

  Further, the casing 50 has a peripheral surface in a shape in which the radius with respect to the shaft 41 is increased in the rotation direction of the impeller 30 (counterclockwise in the drawing). An air passage 54 is formed extending in a tangential direction from the side with the larger radius of the peripheral surface, and the combustion unit 3 is connected to the discharge port 55 at the end of the air passage 54. Further, the lid 52 is provided with a suction port 53 that opens toward the inside of the impeller 30, and the premixing device 100 is connected to the suction port 53. The premixing device 100 is fixed to the lid body 52 with screws or the like (not shown), and airtightness is maintained by interposing a packing (not shown) therebetween.

  As is well known, in the centrifugal fan 20, when the impeller 30 is rotated by driving the drive motor 40, a flow of gas (combustion air or fuel gas) is generated from the inside to the outside of the impeller 30 by centrifugal force. The gas blown to the outside of the impeller 30 travels along the inner peripheral surface of the casing 50, and is sent to the combustion unit 3 from the discharge port 55 through the air passage 54. Further, as the gas blows out of the impeller 30, the gas is sucked into the impeller 30 from the premixing device 100 through the suction port 53.

  FIG. 2 shows the external appearance of the premixing device 100 before being fixed to the lid body 52 together with the fan 20. As will be described in detail later, the premixing device 100 of the present embodiment includes a cylindrical outer peripheral wall 101 joined to the suction port 53 of the lid body 52, and the center line of the outer peripheral wall 101 indicates the drive motor 40. Are located on the same straight line as the shaft 41 and the center of the suction port 53. The outer peripheral wall 101 is provided with a connection port 110 to which the gas supply passage 11 is connected. The center of the connection port 110 is located on a straight line orthogonal to the center line of the outer peripheral wall 101.

  The outer peripheral wall 101 of this embodiment has an air inlet 102 through which combustion air flows into the outer peripheral wall 101. Furthermore, the premixing apparatus 100 includes an air control unit 120 that can open and close (change the opening area) by rotating and moving along the surface where the air inlet 102 is opened. Yes. The air control unit 120 rotates in both forward and reverse directions by driving of a rotating motor 130 attached to the premixing device 100 via a bracket 131.

  FIG. 3 is a perspective view showing a state in which the premixing device 100 of the present embodiment is disassembled. In FIG. 3, the rotation motor 130 and the bracket 131 are not shown. As shown in the drawing, the outer peripheral wall 101 of the premixing device 100 of the present embodiment is upstream of the downstream outer peripheral wall 101a joined to the suction port 53 (see FIG. 2) of the fan 20 from the side opposite to the suction port 53. The outer peripheral walls 101b are joined together and fixed with screws (not shown). A rectangular air inlet 102 is opened in the cylindrical upstream outer peripheral wall 101b, and the side in the circumferential direction of the air inlet 102 of this embodiment is an arc of 160 degrees.

  Further, the upstream outer peripheral wall 101b is closed by a substantially circular lid plate 103 whose end (upper end in the figure) opposite to the downstream outer peripheral wall 101a is perpendicular to the center line. The lid plate 103 is provided with an insertion hole 104 penetrating the center, and a cylindrical fixed cylinder 105 is provided so as to protrude from the surface on the downstream outer peripheral wall 101a side (the lower surface in the drawing) surrounding the insertion hole 104. A male screw is formed on the outer peripheral surface of the fixed cylinder 105. The premixing apparatus 100 according to the present embodiment is provided with a substantially cylindrical movable cylinder 106 in which an internal thread that fits an external thread of the fixed cylinder 105 is formed on the inner peripheral surface. As will be described in detail later, the movable cylinder 106 is screwed into the fixed cylinder 105 and rotated in the direction of the center line of the outer peripheral wall 101 by rotating around the center line of the outer peripheral wall 101.

  The air control unit 120 formed in a cylindrical shape that covers the outer periphery of the upstream outer peripheral wall 101b is located on the same straight line as the upper surface plate 121 facing the cover plate 103 and the center line of the outer peripheral wall 101, and rotates. It is provided integrally with a rotating shaft 122 that rotates by driving of the motor 130. In addition, a cutout portion 120 a cut into a rectangular shape is provided on the peripheral surface of the air control unit 120. The notch 120a of the present embodiment corresponds to 160 degrees of the peripheral surface of the air control unit 120, and can overlap with the air inlet 102 of the upstream outer peripheral wall 101b. The notch 120a and the air inlet 102 Combustion air passes through the overlapping part. When the rotary shaft 122 rotates within a predetermined rotation range (in the present embodiment, within a range of 160 degrees), when the air control unit 120 rotates and moves along the upstream outer peripheral wall 101b, the notch 120a moves. Therefore, the opening area of the air inlet 102 (the area of the overlapping portion between the notch 120a and the air inlet 102) changes.

  On the other hand, in the downstream outer peripheral wall 101a of the present embodiment, an outlet 107 for allowing the mixed gas to flow out to the fan 20 is opened at the end (lower side in the figure) joined to the suction port 53 of the fan 20. In addition, it is formed in a tapered shape whose diameter increases toward the outflow port 107. The downstream outer peripheral wall 101 a is provided with a connection port 110, and the connection port 110 communicates with the introduction passage wall 111 introduced into the outer peripheral wall 101. The introduction passage wall 111 of the present embodiment is bent in an L shape, a cylindrical orthogonal passage wall 111a whose center line is orthogonal to the outer peripheral wall 101, and a cylindrical shape whose center line coincides with the outer peripheral wall 101. And an inner peripheral wall 111b. The inner peripheral wall 111b is arranged inside the movable cylinder 106, and the fitting member 112 is fitted inside the end portion (upper end in the drawing) of the inner peripheral wall 111b. In the center of the fitting member 112, a gas inlet 113 is formed to allow fuel gas to flow into the space between the inner peripheral wall 111 b and the outer peripheral wall 101 (mixing passage) from the inside (introduction passage) of the inner peripheral wall 111 b.

  Further, inside the inner peripheral wall 111b, a gas control unit 115 capable of opening and closing the gas inlet 113 (changing the opening area), and the gas controller 115 as the gas inlet 113 (fitting member 112). An urging spring 116 that urges toward the end is installed. The gas control unit 115 includes a tapered portion 115a that decreases in diameter toward the gas inflow port 113 side, and a plurality (in parallel to the center line of the inner peripheral wall 111b that protrudes radially outward from the outer peripheral surface of the gas control unit 115. In the present embodiment, four ridges 115b are provided.

  In the gas control unit 115 urged by the urging spring 116, a tapered portion 115a is inserted into the gas inlet 113, and a small-diameter pointed portion 115c protrudes from the gas inlet 113 into the upstream outer peripheral wall 101b. To position. Further, the protrusion 115b is in contact with the inner peripheral surface of the cylindrical fitting member 112, so that the linear movement of the gas control unit 115 along the center line of the inner peripheral wall 111b is guided. When the gas control unit 115 moves to the outlet 107 side (lower side in the figure) against the biasing force of the biasing spring 116, the amount of insertion of the tapered portion 115a into the gas inlet 113 is reduced. The opening area of the inlet 113 (the area of the gap between the gas inlet 113 and the tapered portion 115a) increases, and the fuel gas passes through the gap between the gas inlet 113 and the tapered portion 115a.

  The premixing apparatus 100 of the present embodiment is provided with a cylindrical cam 117 that converts the rotational motion of the air control unit 120 (rotating shaft 122) into a linear motion and transmits the linear motion to the gas control unit 115. The cam 117 according to the present embodiment includes a cam surface 117 a inclined with respect to the upper surface plate 121 (a plane perpendicular to the rotation shaft 122) and a protruding portion 117 b protruding outward in the radial direction. Even if it is rotated 180 degrees, it has a 2-fold rotational symmetry that matches the original shape. The cam 117 is inserted into the insertion hole 104 of the cover plate 103, and the protrusion 117 b moves along the guide groove 104 a formed on the inner peripheral surface of the insertion hole 104. The linear movement of the rotating shaft 122 in the axial direction is guided so as not to rotate around.

  FIG. 4 is a perspective view showing a state in which the air control unit 120 and the gas control unit 115 of the present embodiment are connected via the cam 117. In the drawing, the inside of the air control unit 120 is viewed from the gas control unit 115 side, and the upstream outer peripheral wall 101b, the cover plate 103, the fixed cylinder 105, the movable cylinder 106, the inner peripheral wall 111b, the fitting member 112, and the like. Is omitted. As shown in the figure, the upper surface plate 121 integral with the air control unit 120 has a pair of contact portions 121b that protrude from a surface opposite to the rotation shaft 122 (the lower surface in the drawing) and can contact the cam surface 117a. The position is shifted by 180 degrees around the axis of the rotating shaft 122.

  The cam 117 is formed with a recess 117c at the center of the surface facing the gas control unit 115 (the lower surface in the figure), and the pointed portion 115c of the gas control unit 115 is inserted into the recess 117c. As described above, the gas control unit 115 is biased toward the cam 117 by the biasing spring 116, and the biasing force is transmitted to the cam 117 so that the contact between the cam surface 117a and the contact portion 121b is maintained.

  In the illustrated example, the contact portion 121b is in contact with the higher inclined side of the cam surface 117a, and the contact is made by rotating the rotating shaft 122 counterclockwise (rotation direction indicated by a white arrow in the figure). The part 121b moves along the cam surface 117a toward the low slope side. Then, since the space between the upper surface plate 121 and the cam 117 is narrowed, the gas control unit 115 biased by the biasing spring 116 moves along the axial direction of the rotation shaft 122 (center line of the inner peripheral wall 111b). It moves in the direction approaching (upward in the figure).

  Thereafter, when the rotating shaft 122 is rotated in the reverse direction (clockwise), the distance between the upper surface plate 121 and the cam 117 increases as the contact portion 121b moves along the cam surface 117a toward the higher inclined side. Since it spreads, the gas control unit 115 moves in the direction away from the upper surface plate 121 along the axial direction of the rotating shaft 122 (downward in the drawing) against the biasing force of the biasing spring 116.

  FIG. 5 is an explanatory diagram showing the movement of the air control unit 120 and the gas control unit 115 in conjunction with the rotary shaft 122 in the premixing device 100 of the present embodiment. In the drawing, a cross section of the premixing device 100 including a center line of the outer peripheral wall 101 and cut along a plane perpendicular to the center line of the orthogonal passage wall 111a is shown. First, FIG. 5A shows a state where the air inlet 102 and the gas inlet 113 are closed. As described above, the air inlet 102 of the present embodiment is formed in a rectangular shape on the upstream outer peripheral wall 101b, and the side in the circumferential direction is an arc of 160 degrees. And the rectangular notch part 120a is formed in the surrounding surface of the air control part 120 which covers the outer periphery of the upstream outer peripheral wall 101b, and the edge of the circumferential direction of this notch part 120a is also a circular arc for 160 degrees. However, since the notch 120a and the air inlet 102 do not overlap, the air inlet 102 is closed by covering the entire air inlet 102 with the air control unit 120.

  In addition, the gas inlet 113 of the present embodiment opens at the end of the inner peripheral wall 111b introduced into the outer peripheral wall 101, and the tapered portion 115a of the gas control unit 115 is inserted into the gas inlet 113. Yes. When the air inlet 102 is closed by the air control unit 120, the contact portion 121b of the upper surface plate 121 is in contact with the lower inclined side of the cam surface 117a (see FIG. 4), and the cam 117 is the upper surface plate. 121, the large diameter side of the tapered portion 115 a of the gas control unit 115 biased by the biasing spring 116 is pressed against the inner periphery of the gas inlet 113, thereby closing the gas inlet 113. ing.

  Note that the air control unit 120 and the gas control unit 115 do not necessarily need to be fully closed if the opening areas of the corresponding air inlet 102 and gas inlet 113 can be changed. Even when the gas inlet 113 is not fully closed, the supply of fuel gas can be shut off by an on-off valve (not shown) provided in the gas supply passage 11.

  Then, when the rotating shaft 122 is rotated clockwise toward the upper surface plate 121 from the state of FIG. 5A, the air control unit 120 rotates and moves along the upstream outer peripheral wall 101b, so that the notch 120a and The area of the overlapping portion with the air inlet 102 (the opening area of the air inlet 102) increases, and combustion air flows into the outer peripheral wall 101 through the overlapping portion. FIG. 5B shows a state in which the entire air inlet 102 overlaps with the notch 120a and the opening area of the air inlet 102 is maximized by rotating the rotary shaft 122 by 160 degrees. ing. In addition, the arrow of the thick line in a figure represents the flow of the combustion air.

  Further, as the rotating shaft 122 rotates clockwise, the contact portion 121b of the upper surface plate 121 moves toward the higher inclined side along the cam surface 117a (see FIG. 4), and the cam 117 is moved to the upper surface plate 121. Since the gas control unit 115 is pushed back against the urging force of the urging spring 116, the amount of insertion of the tapered portion 115 a into the gas inlet 113 is reduced. Thereby, the area of the gap between the gas inlet 113 and the tapered portion 115a (the opening area of the gas inlet 113) increases, and the fuel gas passes through the gap from the inside of the inner peripheral wall 111b to the inner peripheral wall 111b and the outer peripheral wall. 101 flows in between. In addition, the arrow of the broken line in a figure represents the flow of fuel gas.

  As described above, the cover plate 103 is provided with the cylindrical fixed tube 105 protruding from the surface on the downstream outer peripheral wall 101 a side (the lower surface in the drawing), and the movable tube 106 is a male on the outer periphery of the fixed tube 105. A screw structure of a screw and an internal female screw on the inner periphery of the movable cylinder 106 is screwed into the fixed cylinder 105 so as to be rotatable around the center line of the outer peripheral wall 101. FIG. 5 shows a state in which the movable cylinder 106 is close to the cover plate 103 by fitting the movable cylinder 106 to the fixed cylinder 105 to the maximum extent of the screw structure. The movable cylinder 106 is disposed between the outer peripheral wall 101 (the downstream outer peripheral wall 101a and the upstream outer peripheral wall 101b) and the inner peripheral wall 111b. The combustion air flowing in from the air inlet 102 and the fuel gas flowing in from the gas inlet 113 are once separated by the fixed cylinder 105 and the movable cylinder 106, and the outlet 107 side of the movable cylinder 106 (the lower side in the figure). Side) end portion (hereinafter referred to as a merging end) 106a to be merged.

  In the premixing apparatus 100 of the present embodiment, the maximum opening area of the air inlet 102 is set smaller than the area of the gap between the fixed cylinder 105 and the movable cylinder 106 and the outer peripheral wall 101. In the path, the air inlet 102 is the most narrowed portion (the portion with the largest pressure loss). Further, since the maximum opening area of the gas inlet 113 is set smaller than the area of the gap between the fixed cylinder 105 and the movable cylinder 106 and the inner peripheral wall 111b, the gas inlet 113 is formed in the fuel gas flow path. It is the most narrowed part. The fixed cylinder 105 and the movable cylinder 106 of this embodiment correspond to the “partition cylinder” of the present invention.

  As described above, in the premixing device 100 of the present embodiment, by rotating the rotating shaft 122, the opening area of the air inlet 102 (air opening area) and the opening area of the gas inlet 113 (gas opening area) are linked. Can be changed. And the ratio (air-fuel ratio) of the combustion air and fuel gas mixed through the space between the outer peripheral wall 101 and the inner peripheral wall 111b (mixing passage) by the suction of the fan 20 (air-fuel ratio) is the air opening area and the gas opening area. Therefore, it is necessary to set the opening area ratio in accordance with the appropriate air-fuel ratio of the mixed gas burned by the combustion unit 3. Therefore, in the cam 117 of this embodiment, the cam surface 117a is inclined so as to maintain the opening area ratio at a predetermined value while interlocking the rotational movement of the air control unit 120 and the linear movement of the gas control unit 115. ing.

  Moreover, in the water heater 1, it is necessary to adjust the flow rate of the mixed gas sent to the combustion unit 3 according to the output (hot water supply capacity) set by the user. Such adjustment of the flow rate of the mixed gas is possible by changing the rotation speed (suction force) of the fan 20 in proportion to the set output value. In addition to this, in the premixing apparatus 100 of the present embodiment, the air opening area and the gas opening area maintain the opening area ratio by rotating the rotating shaft 122 even when the rotation speed of the fan 20 is fixed. Since it changes in conjunction, the flow rate of the mixed gas sent to the combustion unit 3 can be adjusted while keeping the air-fuel ratio constant.

  However, in such a premixing device 100, the opening area ratio may fluctuate from the target value due to manufacturing variations caused by component accuracy and the like, and even in this case, the air opening area and the gas are maintained while maintaining the opening area ratio. Since the opening area changes in conjunction with each other, the mixed gas may not have an appropriate air-fuel ratio. Therefore, in the premixing apparatus 100 of the present embodiment, the movable cylinder 106 is provided and the downstream outer peripheral wall 101a is formed in a taper shape, thereby adjusting the air-fuel ratio of the mixed gas as follows. Can do.

  First, FIG. 6 is a cross-sectional view showing a case where the movable cylinder 106 is not provided in the premixing apparatus 100 of the present embodiment. In the illustrated example, the opening area of the air inlet 102 and the opening area of the gas inlet 113 are maximized as in FIG. Here, in order to simplify the model, the supply of fuel gas is shut off by an on-off valve (not shown) provided in the gas supply passage 11, and the fan 20 is rotated at a constant rotational speed and sucked. Let Q be the flow rate of the combustion air flowing from the air inlet 102.

  The area of the clearance between the downstream outer peripheral wall 101a and the inner peripheral wall 111b at the position L1 of the end portion on the small diameter side (upper end portion in the figure) of the downstream outer peripheral wall 101a formed in a tapered shape is S1, and the flow velocity of the combustion air Is V1 and the pressure is P1. Further, the area of the gap between the downstream outer peripheral wall 101a and the inner peripheral wall 111b at the position L2 on the larger diameter side (lower side in the figure) of the downstream outer peripheral wall 101a from the position L1 is S2, the flow velocity of combustion air is V2, and the pressure Is P2.

Then, from the equation of continuity in incompressible fluid,
Q = S1V1 = S2V2 Formula (1)
It can be expressed as. In addition, assuming that the combustion air density ρ is constant, from Bernoulli's theorem,
^{V1 2/2 + P1 / ρ} = V2 2/2 + P2 / ρ ... formula (2)
When the equations (1) and (2) are transformed,
P2 = P1 + ρQ ² (1 / S1 ² −1 / S2 ² ) / 2 Formula (3)
It becomes.

  As described above, in the premixing device 100 of the present embodiment, the downstream outer peripheral wall 101a has a tapered shape whose diameter increases toward the outlet 107, whereas the inner peripheral wall 111b has a cylindrical shape, and the downstream outer peripheral wall Since the area of the gap between 101a and the inner peripheral wall 111b is S2> S1, the pressure is P2> P1 from Equation (3). Further, since the air is sucked by the fan 20, the atmospheric pressure> P2> P1. That is, the degree of negative pressure is stronger at the position L1 than at the position L2.

  Such a tendency is not limited to the case where the supply of the fuel gas is interrupted, and the fuel gas is supplied by opening the on-off valve of the gas supply passage 11 (the fuel gas flows in from the gas inlet 113). Even in this case, the degree of negative pressure at the position L1 on the large diameter side of the downstream outer peripheral wall 101a tends to be higher than that at the position L2.

  FIG. 7 is an explanatory diagram showing how the air-fuel ratio of the mixed gas is adjusted by the movable cylinder 106 in the premixing device 100 of the present embodiment. FIG. 7 shows a cross section of the premixing device 100 as in FIGS. 5 and 6, and the opening area of the air inlet 102 and the opening area of the gas inlet 113 are maximized. First, in FIG. 7A, the movable cylinder 106 is brought close to the cover plate 103 by fitting the movable cylinder 106 to the fixed cylinder 105 to the maximum extent of the screw structure, and the merging end 106a is located at the position shown in FIG. The state at L1 is shown.

  When the movable cylinder 106 is rotated counterclockwise from the state of FIG. 7A toward the lid plate 103, the movable cylinder 106 is separated from the lid plate 103 along the center line of the outer peripheral wall 101 by the screw structure ( (Downward in the figure). As a result, the insertion amount of the movable cylinder 106 between the downstream outer peripheral wall 101a and the inner peripheral wall 111b is increased, and FIG. 7B shows a state in which the merging end 106a is at the position L2 in FIG. Yes. In the premixing device 100 of the present embodiment, the movable cylinder 106 can be operated and rotated from the air inlet 102, and by rotating the movable cylinder 106 in the reverse direction (clockwise), The insertion amount of the movable cylinder 106 between the downstream outer peripheral wall 101a and the inner peripheral wall 111b is reduced, and the state shown in FIG. 7B can be returned to the state shown in FIG.

  The fuel gas sucked from the inside (introduction passage) of the inner peripheral wall 111b by the rotation of the fan 20 passes through the gas inlet 113 and is first a space surrounded by the fixed cylinder 105 and the movable cylinder 106 and the inner peripheral wall 111b (hereinafter referred to as the inner peripheral wall 111b). Gas chamber) G, and merges with the combustion air at the downstream merge end 106a. The flow rate of the fuel gas is the pressure difference before and after passing through the gas inlet 113, which is the narrowest in the flow path, that is, the pressure inside the inner peripheral wall 111b (approximately atmospheric pressure) and the pressure in the gas chamber G (negative pressure). It changes with the difference. Since the gas chamber G is connected to the merging end 106a, the pressure in the gas chamber G is linked with the pressure at the merging end 106a, and the pressure loss from the gas inlet 113 to the merging end 106a can be ignored. The pressure at 106a can be regarded as the pressure of the gas chamber G. Accordingly, the flow rate of the fuel gas changes according to the degree of negative pressure at the merging end 106a.

  Then, by increasing the amount of insertion of the movable cylinder 106 between the downstream outer peripheral wall 101a and the inner peripheral wall 111b, the merging end 106a moves from the position of FIG. 7A to the position of FIG. 7B ( Since the degree of negative pressure at the merging end 106a is weakened, the flow rate of the fuel gas is relatively reduced. Although the flow rate of the combustion air may change with the movement of the merge end 106a, the flow rate of the combustion air is much larger than the flow rate of the fuel gas (the air inlet 102 is larger than the gas inlet 113). Therefore, the rate of change in the flow rate of combustion air is very small compared to the rate of change in the flow rate of fuel gas. Therefore, by reducing the flow rate of the fuel gas, adjustment to the air rich side that increases the ratio of combustion air in the mixed gas becomes possible, and the air-fuel ratio of the mixed gas increases.

  On the contrary, by reducing the amount of insertion of the movable cylinder 106 between the downstream outer peripheral wall 101a and the inner peripheral wall 111b, the merging end 106a is moved from the position of FIG. 7B to FIG. 7A. When moving to the position (moving toward the small diameter side of the tapered downstream outer peripheral wall 101a), the degree of negative pressure at the merging end 106a increases, and the flow rate of the fuel gas relatively increases. As a result, adjustment to the gas rich side that increases the ratio of the fuel gas in the mixed gas becomes possible, and the air-fuel ratio of the mixed gas becomes small.

  As described above, in the premixing device 100 of the present embodiment, the movable cylinder 106 is provided between the outer peripheral wall 101 and the inner peripheral wall 111b, and the downstream outer peripheral wall 101a is formed in a tapered shape. By moving 106 in the direction of the center line of the outer peripheral wall 101, the air-fuel ratio of the mixed gas can be changed. Therefore, even when the opening area ratio between the air inlet 102 and the gas inlet 113 deviates from the target value due to manufacturing variations, the air opening area and the gas opening area are changed in conjunction with each other while maintaining the opening area ratio. The air-fuel ratio of the mixed gas can be adjusted by moving the movable cylinder 106 without changing the configuration (the air control unit 120, the gas control unit 115, the cam 117, etc.).

  In the premixing device 100 of the above-described embodiment, the downstream outer peripheral wall 101a is formed in a tapered shape whose diameter increases toward the outlet 107, but the taper is reversed and the downstream outer peripheral wall 101a is changed to the outlet. It may be formed in a taper shape with a diameter decreasing toward the 107 side. In this case, the action (change in the air-fuel ratio of the mixed gas) accompanying the movement of the movable cylinder 106 is reversed. That is, when the movable cylinder 106 is moved in a direction that increases the amount of insertion of the movable cylinder 106 between the downstream outer peripheral wall 101a and the inner peripheral wall 111b, the degree of negative pressure at the merging end 106a increases and the flow rate of the fuel gas Is relatively increased, adjustment to the gas rich side becomes possible, and the air-fuel ratio of the mixed gas becomes small. On the other hand, if the movable cylinder 106 is moved in a direction that reduces the amount of insertion of the movable cylinder 106 between the downstream outer peripheral wall 101a and the inner peripheral wall 111b, the degree of negative pressure at the merging end 106a becomes weaker and the flow rate of the fuel gas Is relatively reduced, adjustment to the air rich side becomes possible, and the air-fuel ratio of the mixed gas increases.

  The following modification is also present in the premixing apparatus 100 of the present embodiment described above. In the following, modifications will be described focusing on differences from the above-described embodiment. In the description of the modified example, the same components as those in the above-described embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 8 is a cross-sectional view illustrating the structure of a premixing device 100 according to a modification. In the drawing, a cross section of the premixing device 100 including a center line of the outer peripheral wall 101 and cut along a plane perpendicular to the center line of the orthogonal passage wall 111a is shown. In the premixing device 100 of the embodiment described above, the downstream outer peripheral wall 101a is formed in a tapered shape, whereas in the premixing device 100 in the modified example, the downstream outer peripheral wall 101a is formed in a cylindrical shape, Instead, the inner peripheral wall 111b is formed in a tapered shape whose diameter decreases toward the outlet 107 side (lower side in the figure). In the illustrated example, the movable cylinder 106 is in close proximity to the cover plate 103 by fitting the movable cylinder 106 to the fixed cylinder 105 to the maximum extent of the screw structure, and the merging end 106a of the movable cylinder 106 is connected to the inner peripheral wall 111b. Is located at the end of the larger diameter side of the taper.

  By moving the movable cylinder 106 from the state shown in FIG. 8 in the direction in which the insertion amount of the movable cylinder 106 between the downstream outer peripheral wall 101a and the inner peripheral wall 111b is increased (downward in the figure), the merging end 106a Is moved to the smaller diameter side of the taper of the inner peripheral wall 111b (the side where the gap between the downstream outer peripheral wall 101a and the inner peripheral wall 111b is larger), the degree of negative pressure at the merging end 106a becomes weaker, so the flow rate of the fuel gas It decreases relatively. As a result, adjustment to the air rich side becomes possible, and the air-fuel ratio of the mixed gas increases.

  On the contrary, by moving the movable cylinder 106 in a direction (upward in the figure) to reduce the amount of insertion of the movable cylinder 106 between the downstream outer peripheral wall 101a and the inner peripheral wall 111b, the merging end 106a Is moved to the large diameter side of the taper of the inner peripheral wall 111b (the side where the clearance between the downstream outer peripheral wall 101a and the inner peripheral wall 111b is small), the degree of negative pressure at the merging end 106a increases, so the flow rate of the fuel gas Increases relatively. As a result, adjustment to the gas rich side becomes possible, and the air-fuel ratio of the mixed gas becomes small.

  As described above, in the premixing device 100 of the modified example, the downstream outer peripheral wall 101a has a cylindrical shape, whereas the inner peripheral wall 111b is formed in a tapered shape, and the outer peripheral wall 101 and the inner peripheral wall 111b By moving the movable cylinder 106 provided therebetween in the direction of the center line of the outer peripheral wall 101, the air-fuel ratio of the mixed gas can be changed as in the above-described embodiment. Therefore, the movable cylinder can be changed without changing the configuration (the air control unit 120, the gas control unit 115, the cam 117, etc.) that changes the air opening area and the gas opening area in conjunction with each other while maintaining the opening area ratio. The movement of 106 makes it possible to adjust the air-fuel ratio of the mixed gas.

  In the premixing device 100 of the above-described modified example, the inner peripheral wall 111b is formed in a tapered shape with a diameter decreasing toward the outlet 107, but the inner peripheral wall 111b is disposed on the outlet 107 side opposite to the taper. In this case, the action accompanying the movement of the movable cylinder 106 (change in the air-fuel ratio of the mixed gas) is reversed. That is, when the movable cylinder 106 is moved in a direction that increases the amount of insertion of the movable cylinder 106 between the downstream outer peripheral wall 101a and the inner peripheral wall 111b, the degree of negative pressure at the merging end 106a increases and the flow rate of the fuel gas Is relatively increased, adjustment to the gas rich side becomes possible, and the air-fuel ratio of the mixed gas becomes small. On the other hand, if the movable cylinder 106 is moved in a direction that reduces the amount of insertion of the movable cylinder 106 between the downstream outer peripheral wall 101a and the inner peripheral wall 111b, the degree of negative pressure at the merging end 106a becomes weaker and the flow rate of the fuel gas Is relatively reduced, adjustment to the air rich side becomes possible, and the air-fuel ratio of the mixed gas increases.

  As mentioned above, although the premixing apparatus 100 of a present Example and the modification was demonstrated, this invention is not restricted to said Example and a modification, It can implement in a various aspect in the range which does not deviate from the summary. Is possible.

  For example, in the embodiment and the modification described above, the air opening area and the gas opening area are linked by the rotation movement of the air control unit 120 and the linear movement of the gas control unit 115 via the cam 117, so that It was supposed to change while maintaining. However, the mechanism for changing the air opening area and the gas opening area in conjunction with each other is not limited to this as long as the opening area ratio can be maintained. For example, as shown in FIG. 9, a rectangular gas inlet 114 is provided in the inner peripheral wall 111b, and a cylindrical gas control unit 140 can be rotationally moved along the inner peripheral wall 111b inside the inner peripheral wall 111b. May be installed. The gas control unit 140 is formed integrally with a circular lid 141 that closes the end of the inner peripheral wall 111 b, and a projection 142 that projects from the center of the lid 141 is connected to the rotary shaft 122. . Further, a rectangular gas passage port 140 a is opened on the peripheral surface of the gas control unit 140. In such a premixing apparatus 100, the gas control unit 140 rotates in conjunction with the rotation of the air control unit 120 as the rotation shaft 122 rotates, so that the gas passage port 140 a and the gas inflow port 114 are rotated. The area of the overlapping portion (the opening area of the gas inlet 114) changes, and the fuel gas flows from the inside of the inner peripheral wall 111b through the overlapping portion between the inner peripheral wall 111b and the outer peripheral wall 101.

  In the premixing device 100 of FIG. 9 as well, the movable cylinder 106 is provided between the outer peripheral wall 101 and the inner peripheral wall 111b, and the downstream outer peripheral wall 101a is formed in a taper shape so as to be movable. By moving the cylinder 106 in the direction of the center line of the outer peripheral wall 101, the air-fuel ratio of the mixed gas can be changed. Therefore, mixing is performed by moving the movable cylinder 106 without changing the configuration in which the air opening area and the gas opening area are changed in conjunction with each other while maintaining the opening area ratio (such as the air control unit 120 and the gas control unit 140). It becomes possible to adjust the air-fuel ratio of the gas.

  Further, in the above-described embodiment, the downstream outer peripheral wall 101a is formed in a tapered shape over the entire length in the direction of the center line. However, the downstream outer peripheral wall 101a does not necessarily need to be the entire length, and at least the joining end 106a of the movable cylinder 106 is movable. It suffices if the taper is formed in such a range.

  In the embodiment described above, the downstream outer peripheral wall 101a is tapered, whereas the inner peripheral wall 111b is cylindrical, and the distance between the merging end 106a and the downstream outer peripheral wall 101a as the movable cylinder 106 moves. The distance between the merging end 106a and the inner peripheral wall 111b is maintained. However, the shape of the downstream outer peripheral wall 101a and the inner peripheral wall 111b may be any shape that increases or decreases the distance between the downstream outer peripheral wall 101a and the inner peripheral wall 111b at the position of the merging end 106a as the movable cylinder 106 moves. Both the wall 101a and the inner peripheral wall 111b may be tapered. In this case, if the downstream outer peripheral wall 101a and the inner peripheral wall 111b have a tapered shape in which the inclination of the taper is reversed and the downstream outer peripheral wall 101a expands toward the outflow port 107, the taper reduces the inner peripheral wall 111b. If the diameter of the downstream outer peripheral wall 101a is tapered, the inner peripheral wall 111b may be tapered. In this way, the amount of change in the direction of the center line of the outer peripheral wall 101 becomes larger in the area of the gap between the downstream outer peripheral wall 101a and the inner peripheral wall 111b than in the embodiment described above. As a result, the amount of fluctuation in the degree of negative pressure at the merging end 106a accompanying the movement of the movable cylinder 106 also increases, so that a width in which the air-fuel ratio of the mixed gas can be adjusted can be secured.

1 ... Hot water heater, 2 ... Housing, 3 ... Combustion unit,
4 ... heat exchanger, 5 ... water supply passage, 6 ... hot water supply passage,
7 ... Exhaust duct, 8 ... Exhaust port, 9 ... Air supply port,
11 ... Gas supply passage, 12 ... Zero governor, 20 ... Fan,
30 ... Impeller, 31 ... Wings, 32 ... Rotating disc,
33 ... support plate, 40 ... drive motor, 41 ... shaft,
50 ... casing, 51 ... main body, 52 ... lid,
53 ... Suction port, 54 ... Air passage, 55 ... Discharge port,
100: Premixing device, 101: Outer peripheral wall, 101a: Downstream outer peripheral wall,
101b: upstream outer peripheral wall, 102: air inlet, 103: lid plate,
104 ... Insertion hole, 104a ... Guide groove, 105 ... Fixed cylinder (partition cylinder),
106 ... movable cylinder (partition cylinder), 106a ... merging end, 107 ... outlet,
110 ... Connection port, 111 ... Introduction passage wall, 111a ... Orthogonal passage wall,
111b ... inner peripheral wall, 112 ... fitting member, 113 ... gas inlet,
114 ... gas inlet, 115 ... gas control part, 115a ... taper part,
115b ... ridge, 115c ... pointed end, 116 ... biasing spring,
117 ... Cam, 117a ... Cam surface, 117b ... Projection,
117c ... recess, 120 ... air control unit, 120a ... notch,
121 ... Upper surface plate, 121b ... Contact part, 122 ... Rotating shaft,
130 ... Rotating motor, 131 ... Bracket, 140 ... Gas control unit,
140a ... Gas passage port, 141 ... Lid, 142 ... Projection.

Claims (2)

In a premixing device that is connected to a suction side of a fan that sends a mixed gas of fuel gas and combustion air to the combustion device and mixes the fuel gas supplied to the fan and the combustion air in advance.
An outer peripheral wall joined to the suction side of the fan;
An air inlet for allowing the combustion air to flow into the outer peripheral wall;
An air control unit capable of changing an opening area of the air inlet;
An inner peripheral wall that is introduced into the outer peripheral wall and extends parallel to the center line of the outer peripheral wall to guide the fuel gas;
A gas inlet for allowing the fuel gas to flow between the inner peripheral wall and the outer peripheral wall from the inner peripheral wall;
In conjunction with the air control unit, a gas control unit capable of changing an opening area of the gas inlet while maintaining an opening area ratio with the opening area of the air inlet;
An outlet that opens to an end of the outer peripheral wall on the joint side with the fan and allows the mixed gas to flow out to the fan;
A partition cylinder installed between the outer peripheral wall and the inner peripheral wall and separating the combustion air flowing in from the air inlet and the fuel gas flowing in from the gas inlet;
The partition cylinder has a merging end for merging the combustion air and the fuel gas at an end on the outlet side, and the position of the merging end is provided to be movable in the direction of the center line of the outer peripheral wall. And
The said outer peripheral wall and the said inner peripheral wall are formed in the shape which increases / decreases the space | interval of this outer peripheral wall and this inner peripheral wall in the position of the said confluence | merging end with the movement of the said partition cylinder. . The premixing device according to claim 1,
The inner peripheral wall is formed in a shape that maintains an interval with the merging end as the partition tube moves.
The said outer peripheral wall is formed in the shape which increases / decreases the space | interval with the said merging end with the movement of the said partition cylinder. The premixing apparatus characterized by the above-mentioned.

Images