JP6912288B2 - Premixer - Google Patents

Description

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

It is known that a water heater equipped with a combustion device that burns a mixed gas of fuel gas and combustion air is equipped with a fan for sending the mixed gas to the combustion device, and the suction side of this fan is equipped with a fan. , A premixer that premixes the fuel gas supplied to the fan with the combustion air is connected. When the fan is rotated, the fuel gas and the combustion air are mixed in a predetermined ratio by the premixer and sucked into the fan, and the mixed gas is sent to the combustion device connected to the discharge side of the fan.

As a structure of such a premixing device, the premixing device described in Patent Document 1 is provided with a mixing passage joined to the suction side of the fan, and an air inlet is provided at the end of the mixing passage on the opposite side of the fan. It is open. Further, the gas supply passage is introduced from the side surface of the mixing passage to the inside, and the gas inlet opening at the end of the gas supply passage in the mixing passage faces the air inlet side. Both the air valve that opens and closes the air inlet and the gas valve that opens and closes the gas inlet are attached to a moving shaft that can reciprocate along the center line of the mixing passage. By inserting these air valve and gas valve into the corresponding air inlet and gas inlet as a tapered so-called needle valve, the opening area of the air inlet (gap between the air inlet and the air valve) and the gas It is possible to accurately adjust the opening area of the inflow port (the gap between the gas inflow port and the gas valve).

In such a premixer, when the pressure in the mixing passage becomes negative due to suction by the rotation of the fan, combustion air flows in from the air inlet and fuel gas flows in from the gas inlet to mix in the mixing passage. The ratio of combustion air to fuel gas (air fuel ratio) is determined by the area ratio between the opening area of the air inlet and the opening area of the gas inlet. Then, by changing the rotation speed of the fan according to the output of the combustion device, it is possible to adjust the flow rate of the mixed gas sent to the combustion device. In addition, even if the rotation speed of the fan is fixed, by moving the moving shaft to which the air valve and the gas valve are attached, the opening area of the air inlet and the opening area of the gas inlet maintain the area ratio. Since it changes in conjunction with it, the flow rate of the mixed gas sent to the combustion apparatus can be adjusted while keeping the air-fuel ratio constant.

Japanese Patent Application Laid-Open No. 2014-502337

However, the premixing device having the structure described in Patent Document 1 has a problem that it is difficult to make the device compact for the following reasons. First, in order to change the opening area of the air inlet and the opening area of the gas inlet in conjunction with each other, it is necessary to linearly move the moving shaft to which the air valve and the gas valve are attached. The movement range is set according to the inner diameter of the air inlet, the inner diameter of the gas inlet, and the like. In particular, in order to adjust the flow rate of combustion air, which is required more than fuel gas, it tends to be necessary to secure the movement range of the movement axis, and as a result, the movement direction of the movement axis (center of the mixing passage). It was difficult to make the device compact in the direction of the line).

The present invention has been made in response to the above-mentioned problems of the prior art, and it is necessary to accurately adjust the opening area of the air inlet of the premixer and the opening area of the gas inlet in conjunction with each other. The purpose is to provide a technology that makes it possible to make the device compact.

In order to solve the above-mentioned problems, the first premixing device of the present invention adopts the following configuration. That is,
In a premixing device that is connected to the suction side of a fan that sends a mixed gas of fuel gas and combustion air to a combustion device and premixes the fuel gas supplied to the fan with the combustion air.
A mixing passage joined to the suction side of the fan,
An air inlet that opens into the mixing passage and allows the combustion air to flow into the mixing passage.
An air control unit that is provided so as to cover the air inlet and that changes the area of the air opening that the air inlet opens into the mixing passage by rotating and moving along the surface on which the air inlet opens.
A gas inlet that opens into the mixing passage and allows the fuel gas to flow into the mixing passage,
A gas control unit that changes the gas opening area where the gas inlet opens into the mixing passage by forming a portion to be inserted into the gas inlet in a tapered shape and linearly moving in a direction for changing the insertion amount. ,
A cam that links the rotational movement of the air control unit with the linear movement of the gas control unit by converting the rotational movement of the air control unit into a linear motion and transmitting it to the gas control unit .
With the air inlet blocked by the air control unit, the minimum air hole for allowing the combustion air to flow into the mixing passage,
The gas inflow port is closed by the gas control unit, and the gas inlet is provided with a minimum gas hole for allowing the fuel gas to flow into the mixing passage.

Since the premixing device of the present invention has a configuration in which the air opening area is changed by the rotational movement of the air control unit along the surface where the air inlet is opened, the air control unit in the direction of the center line of the mixing passage. It is not necessary to secure the movable range of the premixer, and the premixer can be made compact. In addition, when adjusting the flow rate of fuel gas, which requires a smaller flow rate than combustion air, the gas inlet moves linearly to change the insertion amount of the tapered portion inserted into the gas inlet. Since the opening area is changed and such a so-called needle valve configuration enables fine control of the flow rate, the flow rate of the fuel gas is accurately adjusted to supply a mixed gas having an appropriate air-combustion ratio. it is possible. Interlocking the adjusting precisely the flow rate of the fuel gas as this, compatibility between be made compact premixing device, a linear movement of the rotational movement and the gas control unit of the air control unit via the cam It becomes possible only by letting it. The air-fuel ratio of the mixed gas at the minimum flow rate at which the air inlet and the gas inlet are closed is determined by the area ratio of the opening area of the minimum air hole to the opening area of the minimum gas hole. Therefore, by providing the minimum air hole and the minimum gas hole so that the area ratio becomes the target value, the minimum flow rate is not affected by the assembly error or operation error of the air control unit and the gas control unit. It is possible to control the mixed gas at the time to an appropriate air-fuel ratio.

Further, in order to solve the above-mentioned problems, the second premixing device of the present invention adopts the following configuration. That is,
In a premixing device that is connected to the suction side of a fan that sends a mixed gas of fuel gas and combustion air to a combustion device and premixes the fuel gas supplied to the fan with the combustion air.
A mixing passage joined to the suction side of the fan,
An air inlet that opens into the mixing passage and allows the combustion air to flow into the mixing passage.
An air control unit that is provided so as to cover the air inlet and that changes the area of the air opening that the air inlet opens into the mixing passage by rotating and moving along the surface on which the air inlet opens.
A gas inlet that opens into the mixing passage and allows the fuel gas to flow into the mixing passage,
A gas control unit that changes the gas opening area where the gas inlet opens into the mixing passage by forming a portion to be inserted into the gas inlet in a tapered shape and linearly moving in a direction for changing the insertion amount. ,
A cam that links the rotational movement of the air control unit with the linear movement of the gas control unit by converting the rotational movement of the air control unit into a linear motion and transmitting it to the gas control unit.
With
The cam has a cam surface inclined with respect to a plane perpendicular to the rotation axis of the air control unit.
By moving the air control unit or the contact portion provided on the gas control unit along the inclination of the cam surface, the opening area ratio obtained by dividing the air opening area by the gas opening area is maintained at a predetermined value. However, the rotational movement of the air control unit and the linear movement of the gas control unit are interlocked with each other.
The cam surface is provided with a step for changing the opening area ratio from the predetermined value.
It is characterized by that.

In this way, when the contact portion moves along the inclination of the cam surface and crosses the step, the opening area can be made different from the predetermined value. Therefore, the opening area of the air inlet and the gas inlet In order to change the opening area in conjunction with it, it is possible not only to keep the air-fuel ratio of the mixed gas constant, but also to change it to an arbitrary air-fuel ratio as needed.

Further, in the premixing device of the present invention described above, a step may be provided on the cam surface where the contact portion contacts when the combustion device is ignited so that the opening area ratio is smaller than a predetermined value.

In this way, as the opening area ratio becomes smaller than the predetermined value, the air-fuel ratio also becomes smaller and the ratio of the fuel gas in the mixed gas becomes higher (the gas-rich state), so that the ignition operation of the combustion device is performed. By performing the above in a gas-rich state, ignition is stabilized and ignition failure can be suppressed.

Further, in the premixer of the present invention, the minimum air hole for allowing combustion air to flow into the mixing passage while the air inlet is blocked by the air control unit, and the gas inlet are blocked by the gas control unit. It is also possible to provide a minimum gas hole for allowing the fuel gas to flow into the mixing passage.

In this way, the air-fuel ratio of the mixed gas at the minimum flow rate when the air inlet and the gas inlet are closed is determined by the area ratio of the opening area of the minimum air hole to the opening area of the minimum gas hole. Therefore, by providing the minimum air hole and the minimum gas hole so that the area ratio becomes the target value, the minimum flow rate is not affected by the assembly error or operation error of the air control unit and the gas control unit. It is possible to control the mixed gas at the time to an appropriate air-fuel ratio.

It is explanatory drawing which showed the structure of the water heater 1 as an example of the combustion apparatus which uses the fan 20 which connected the premixing apparatus 100 of this Example. It is a perspective view which showed the disassembled state of the fan 20 of this Example. It is a perspective view which showed the disassembled state of the premixing apparatus 100 of this Example. FIG. 5 is a perspective view showing a state in which the air control unit 120 and the gas control unit 115 of this embodiment are connected via a cam 117. It is explanatory drawing which showed the reason which the excess ratio λ of combustion air can be stabilized by the premixing apparatus 100 of this Example. It is sectional drawing which showed the structure of the premixing apparatus 100 of the comparative example which rotationally moves a gas control unit 140. It is a perspective view which shows the shape of the cam 117 installed in the premixing apparatus 100 of the 1st modification. 6 is a graph showing the relationship between the rotation angle of the rotation shaft 122 in the premixing device 100 of the first modification, and the air opening area and the gas opening area. It is sectional drawing which showed the structure of the premixing apparatus 100 of the 2nd modification. It is a perspective view which shows the example of the premixing apparatus 100 which provided the air inlet 102 in the lid plate 103.

FIG. 1 is an explanatory diagram showing the configuration of a water heater 1 as an example of a combustion device in which a fan 20 to which the premixing device 100 of this embodiment is connected is used. As shown in the figure, 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 the fuel gas supplied to the fan 20 with the combustion air is connected to the intake side of the fan 20, and a combustion unit 3 is connected to the discharge side of the fan 20. There is. A gas supply passage 11 for supplying fuel gas is connected to the premixing device 100, and the gas supply passage 11 includes a zero governor 12 for reducing the pressure of fuel gas pumped from the upstream side to atmospheric pressure, and a gas. An on-off valve (not shown) that opens and closes the supply passage 11 is provided. When the fan 20 is driven, the combustion air existing in the housing 2 and the fuel gas on the downstream side of the zero governor 12 of the gas supply passage 11 are mixed in a predetermined ratio by the premixer 100 and sucked into the fan 20. Then, the mixed gas is sent to the combustion unit 3. The structure of the fan 20 and the structure of the premixing device 100 of this embodiment will be described later with reference to 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 gas 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 becomes hot water and flows out to the hot water supply passage 6.

The combustion exhaust that has passed through the heat exchanger 4 passes through the exhaust duct 7 and is discharged to the outside from the exhaust port 8 that protrudes from the upper part of the housing 2. Further, it has 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 fanned through the premixer 100. It is sucked into 20.

FIG. 2 is a perspective view showing a state in which the fan 20 of this embodiment is disassembled. In FIG. 2, the vertical arrangement of the fan 20 is reversed with respect to FIG. 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 at predetermined intervals with respect to the shaft 41 of the drive motor 40. One end (lower end in the drawing) of these blade pieces 31 in the axial direction is attached to a substantially circular rotating disk 32, and the other end (upper end in the drawing) is attached to an annular support plate 33. Has been done. The rotary disk 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 (lower surface in the drawing) and a concave lid 52 facing the main body 51 at an outer edge portion. Airtightness is maintained by interposing a packing (not shown) between the main body 51 and the lid 52, and the main body 51 and the lid 52 are fixed by screws (not shown) or the like.

Further, the casing 50 is formed with a peripheral surface having a shape in which the radius with respect to the shaft 41 increases in the rotation direction (counterclockwise in the drawing) of the impeller 30. The air passage 54 is formed by extending in the tangential direction from the side having a large 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 52 with screws (not shown) or the like, and airtightness is maintained by interposing a packing (not shown) between them.

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

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

Further, on the peripheral surface of the mixing passage 101 of this embodiment, an air inflow port 102 for allowing combustion air to flow into the mixing passage 101 is opened. Further, the premixing device 100 includes an air control unit 120 capable of opening and closing (changing the opening area) the air inlet 102 by rotating and moving along the surface on which the air inlet 102 is opened. There is. The air control unit 120 rotates in both forward and reverse directions by driving a rotation 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 this embodiment is disassembled. In FIG. 3, the rotation motor 130 and the bracket 131 are not shown. As shown, the mixing passage 101 of the premixing device 100 of this embodiment is a cylindrical downstream passage 101a joined to the suction port 53 (see FIG. 2) of the fan 20 and is opposite to the suction port 53. It is formed by connecting the cylindrical upstream passages 101b from the side, and is fixed by screws (not shown) or the like. A rectangular air inlet 102 is opened on the peripheral surface of the upstream passage 101b, and the circumferential side of the air inlet 102 of this embodiment is an arc of 160 degrees.

Further, the upstream passage 101b is closed by a substantially circular lid plate 103 whose end surface (upper surface in the drawing) opposite to the suction port 53 is perpendicular to the center line, and the lid plate 103 has a center. In addition to the insertion hole 104 that penetrates the air inlet 102, the minimum air hole 105 that allows combustion air to flow into the mixing passage 101 is opened separately from the air inlet 102.

The cylindrical air control unit 120 that covers the outer circumference of the upstream passage 101b rotates so as to be located on the same straight line as the upper surface plate 121 facing the lid plate 103 and the center line of the mixing passage 101. It is provided integrally with a rotating shaft 122 that is rotated by driving a motor 130. Further, a notch portion 120a notched in a rectangular shape is provided on the peripheral surface of the air control unit 120. The notch 120a of this 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 passage 101b, and the notch 120a and the air inlet 102 Combustion air passes through the overlapping part with. When the air control unit 120 rotates along the outer peripheral surface of the upstream passage 101b as the rotation shaft 122 rotates within a predetermined rotation range (within a range of 160 degrees in this embodiment), the notch portion 120a As the air moves, the opening area of the air inlet 102 (the area of the overlapping portion between the notch 120a and the air inlet 102) changes.

Further, the upper surface plate 121 is opened with a passage port 121a formed in an arc shape centered on the rotation shaft 122. The passage port 121a is provided so as to partially overlap with the minimum air hole 105 of the lid plate 103 regardless of the rotation position of the rotation shaft 122 within the range in which the rotation shaft 122 can rotate. The combustion air passes through the overlapping portion between the air and the minimum air hole 105.

On the other hand, a connection port 110 is provided on the peripheral surface of the downstream side passage 101a, and the connection port 110 communicates with an introduction portion 111 introduced inside the downstream side passage 101a. The introduction portion 111 of this embodiment is bent in an L shape, and has a cylindrical shape in which the center line coincides with the mixing passage 101 and the orthogonal introduction portion 111a having a cylindrical shape parallel to the mixing passage 101. It is provided with a parallel introduction portion 111b. A gas inflow port 113 for flowing fuel gas into the mixing passage 101 is opened at the center of the fitting member 112 fitted inside the end portion (upper part in the drawing) of the parallel introduction portion 111b.

Further, inside the parallel introduction portion 111b, a gas control unit 115 capable of opening and closing the gas inflow port 113 (changing the opening area) and a gas control unit 115 are placed inside the gas inflow port 113 (fitting member 112). An urging spring 116 for urging toward is installed. The gas control unit 115 includes a taper portion 115a whose diameter is reduced toward the gas inflow port 113, and a plurality of gas control units 115 which project outward in the radial direction from the outer peripheral surface of the gas control unit 115 and extend in parallel with the center line of the parallel introduction unit 111b. It has (four in this embodiment) ridges 115b.

In the gas control unit 115 urged by the urging spring 116, the tapered portion 115a is inserted into the gas inflow port 113, and the small-diameter tip portion 115c protrudes from the gas inflow port 113 and enters the inside of the upstream passage 101b. To position. Further, when the ridge 115b comes into contact with the inner peripheral surface of the cylindrical fitting member 112, the linear movement of the gas control unit 115 along the center line of the parallel introduction unit 111b is guided. When the gas control unit 115 moves to the fan 20 side (lower side in the figure) against the urging force of the urging spring 116, the amount of the tapered portion 115a inserted into the gas inflow port 113 changes, so that the gas flow The opening area of the inlet 113 (the area of the gap between the gas inflow port 113 and the tapered portion 115a) changes, and the fuel gas passes through the gap between the gas inflow port 113 and the tapered portion 115a.

The premixing device 100 of this embodiment is provided with a cylindrical cam 117 that converts the rotational motion of the air control unit 120 (rotational shaft 122) into a linear motion and transmits it to the gas control unit 115. The cam 117 of this embodiment has a cam surface 117a inclined with respect to the upper surface plate 121 (a plane perpendicular to the rotating shaft 122) and a protruding portion 117b protruding outward in the radial direction, and is around the axis of the rotating shaft 122. Even if it is rotated 180 degrees, it is rotationally symmetric twice, which matches the original shape. The cam 117 is inserted into the insertion hole 104 of the lid plate 103, and the protrusion 117b moves along the guide groove 104a formed on the inner peripheral surface of the insertion hole 104, whereby the axis of the rotating shaft 122 is aligned. The linear movement of the rotating shaft 122 in the axial direction is guided around the rotation without rotation.

FIG. 4 is a perspective view showing a state in which the air control unit 120 and the gas control unit 115 of this embodiment are connected via a cam 117. In the figure, the inside of the air control unit 120 is viewed from the gas control unit 115 side, and the upstream side passage 101b, the parallel introduction unit 111b, and the fitting member 112 are not shown. As shown in the figure, the upper surface plate 121 integrated with the air control unit 120 has a pair of contact portions 121b protruding from the surface (lower surface in the drawing) opposite to the rotating shaft 122 and capable of contacting the cam surface 117a. It is provided so as to be offset by 180 degrees around the axis of the rotating shaft 122.

A recess 117c is formed in the center of the surface (lower surface in the drawing) of the cam 117 facing the gas control unit 115, and the tip 115c of the gas control unit 115 is inserted into the recess 117c. As described above, the gas control unit 115 is urged to the cam 117 side by the urging spring 116, and the urging force is transmitted to the cam 117 to maintain the contact between the cam surface 117a and the contact portion 121b.

In the illustrated example, the contact portion 121b is in contact with the side of the cam surface 117a having a high inclination, and the rotation shaft 122 is rotated counterclockwise (the rotation direction indicated by the white arrow in the figure) to make contact. The portion 121b moves toward the lower side along the cam surface 117a. Then, since the distance between the top plate 121 and the cam 117 is narrowed, the gas control unit 115 approaches the top plate 121 along the center line (axial direction of the rotating shaft 122) of the parallel introduction unit 111b (upper in the drawing). ).

After that, when the rotation shaft 122 is rotated in the reverse direction (clockwise), the distance between the top plate 121 and the cam 117 becomes larger as the contact portion 121b moves toward the side with a higher inclination along the cam surface 117a. Since it spreads, the gas control unit 115 moves in a direction away from the upper surface plate 121 (lower side in the drawing) along the center line of the parallel introduction unit 111b against the urging force of the urging spring 116.

Further, the gas control unit 115 of the present embodiment is provided with a minimum gas hole 115d communicating with the end surface on the side opposite to the cam 117 by opening on the peripheral surface on the tip portion 115c side of the taper portion 115a. .. The gas minimum hole 115d can allow fuel gas to flow into the mixing passage 101 regardless of the position of the gas control unit 115 along the axial direction of the rotating shaft 122.

FIG. 5 is an explanatory diagram showing the movements of the air control unit 120 and the gas control unit 115 interlocked with the rotating shaft 122 in the premixing device 100 of this embodiment. The figure shows a cross section of the premixing device 100 including the center line of the mixing passage 101 and cut in a plane perpendicular to the center line of the orthogonal introduction portion 111a. First, FIG. 5A shows a state in which 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 peripheral surface of the upstream passage 101b, and the side in the circumferential direction is an arc of 160 degrees. A rectangular notch 120a is formed on the peripheral surface of the air control unit 120 that covers the outer periphery of the upstream passage 101b, and the circumferential side of the notch 120a is also an arc of 160 degrees. However, since the notch 120a and the air inlet 102 do not overlap with each other, the air inlet 102 is blocked by covering the entire air inlet 102 with the air control unit 120.

However, even when the air inlet 102 is blocked, a part of the arc-shaped passage port 121a formed in the upper surface plate 121 overlaps with the minimum air hole 105 of the lid plate 103, and the suction of the fan 20 causes the air to flow. Combustion air flows into the mixing passage 101 through the overlapping portion. The thick arrow in the figure indicates the flow of combustion air.

Further, the gas inflow port 113 of this embodiment is open at the end of the parallel introduction portion 111b introduced into the mixing passage 101, and the tapered portion 115a of the gas control unit 115 is inserted into the gas inflow port 113. ing. When the air inlet 102 is blocked by the air control unit 120, the contact portion 121b of the upper surface plate 121 is in contact with the lower slope side of the cam surface 117a (see FIG. 4), and the cam 117 is the upper surface plate. Since it is close to 121, the large diameter side of the tapered portion 115a of the gas control unit 115 is pressed against the inner circumference of the gas inflow port 113 by the urging force of the urging spring 116, so that the gas inflow port 113 is blocked. There is.

However, even when the gas inflow port 113 is blocked by the gas control unit 115, the gas control unit 115 is provided with the minimum gas hole 115d that communicates the parallel introduction portion 111b side of the gas inflow port 113 with the mixing passage 101 side. By the suction of the fan 20, the fuel gas flows into the mixing passage 101 through the gas minimum hole 115d. The broken line arrow in the figure indicates the flow of fuel gas.

Then, when the rotation shaft 122 is rotated clockwise from the state of FIG. 5A, the air control unit 120 rotates and moves along the outer peripheral surface of the upstream passage 101b, so that the notch portion 120a and the air inlet The area of the overlapping portion with the 102 (opening area of the air inflow port 102) increases, and the combustion air flows into the mixing passage 101 through the overlapping portion. FIG. 5B shows a state in which the entire air inlet 102 overlaps with the notch 120a by rotating the rotation shaft 122 by 160 degrees, and the opening area of the air inlet 102 is maximized. ing.

Further, as the rotation shaft 122 rotates clockwise, when the contact portion 121b of the upper surface plate 121 moves toward the side having a higher inclination along the cam surface 117a, the cam 117 moves away from the upper surface plate 121 ( (See FIG. 4), since the gas control unit 115 is pushed back against the urging force of the urging spring 116, the amount of the tapered portion 115a inserted into the gas inflow port 113 is reduced. As a result, the area of the gap between the gas inflow port 113 and the tapered portion 115a (the opening area of the gas inflow port 113) increases, and the fuel gas flows into the mixing passage 101 through the gap.

In this way, in the premixing device 100 of the present embodiment, 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 by rotating the rotating shaft 122. Can be changed. The ratio of the combustion air flowing into the mixing passage 101 by the suction of the fan 20 to the fuel gas (air-fuel ratio) is determined by the area ratio of the air opening area to the gas opening area (opening area ratio). It is necessary to set the opening area ratio according to an appropriate air-fuel ratio of the mixed gas to be burned in the unit 3. Therefore, the cam 117 of the present embodiment maintains the opening area ratio at a predetermined value (maintains an appropriate air-fuel ratio) while interlocking the rotational movement of the air control unit 120 and the linear movement of the gas control unit 115. An inclination of the cam surface 117a is formed.

Further, 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. The flow rate adjustment of such a mixed gas is generally performed 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 device 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 while the rotation speed of the fan 20 is fixed. Since it changes in tandem, the flow rate of the mixed gas sent to the combustion unit 3 can be adjusted while maintaining an appropriate air-fuel ratio.

As described above, in the premixing device 100 of the present embodiment, as the rotating shaft 122 rotates, the air control unit 120 integrated with the rotating shaft 122 causes the outer peripheral surface of the upstream passage 101b in which the air inlet 102 opens. The rotary motion is converted into a linear motion by the cam 117 and transmitted to the gas control unit 115, and the gas control unit 115 in which the taper portion 115a is inserted into the gas inflow port 113 changes the insertion amount. It is designed to move linearly in the direction of By doing so, the premixing device 100 can be made compact for the following reasons.

First, unlike the present embodiment, the air inlet 102 is provided in a circular shape in the center of the lid plate 103 integrated with the upstream passage 101b, and the air control unit 120 is provided in the mixing passage like the gas control unit 115. It is assumed that a configuration is adopted in which the opening area of the gas inflow port 113 is changed by the linear movement of the air control unit 120 so that the linear movement is possible along the center line of the 101. In this case, in order to adjust the flow rate of combustion air, which requires a larger flow rate than the fuel gas, it is necessary to secure a large movable range of the air control unit 120 in the direction of the center line of the mixing passage 101. As a result, it is difficult to make the premixing device 100 compact in the direction of the center line of the mixing passage 101. On the other hand, in the premixing device 100 of the present embodiment, the opening area of the air inlet 102 is changed by the rotational movement of the air control unit 120 along the outer peripheral surface of the upstream passage 101b, so that the mixing passage is used. It is not necessary to secure the movable range of the air control unit 120 in the direction of the center line of 101, and the premixing device 100 can be made compact.

On the other hand, in order to adjust the flow rate of the fuel gas, which requires a smaller flow rate than the combustion air, accuracy is required to supply the mixed gas at an appropriate air-fuel ratio. Therefore, in the premixing device 100 of the present embodiment, the opening area of the gas inlet 113 is changed by the linear movement of the gas control unit 115 that changes the insertion amount of the tapered portion 115a into the gas inlet 113. Since such a so-called needle valve configuration enables fine control of the flow rate, it is possible to accurately adjust the flow rate of the fuel gas and supply a mixed gas having an appropriate air-fuel ratio. The balance between accurately adjusting the flow rate of the fuel gas and making the premixing device 100 compact is the rotational movement of the air control unit 120 and the gas control unit 115 via the cam 117. It is possible only by linking with linear movement.

In addition, the following effects can be obtained by adopting the needle valve configuration for adjusting the flow rate of the fuel gas. First, as a comparison, as shown in FIG. 6, the gas inflow port 114 is provided in a rectangular shape on the peripheral surface of the parallel introduction section 111b, and the cylindrical gas control section 140 is provided inside the parallel introduction section 111b in the parallel introduction section. It is assumed that the installation is capable of rotational movement along the inner peripheral surface of 111b. The gas control unit 140 is integrally formed with a circular lid portion 141 that closes the end portion of the parallel introduction portion 111b, and a protrusion 142 projecting from the center of the lid portion 141 is connected to the rotation shaft 122. ing. Further, a rectangular gas passage port 140a is opened on the peripheral surface of the gas control unit 140. In the premixing device 100 of such a comparative example, the gas control unit 140 rotates and moves in conjunction with the rotational movement of the air control unit 120 as the rotary shaft 122 rotates, so that the gas passage port 140a and the gas flow occur. The area of the overlapping portion with the inlet 114 (the opening area of the gas inflow port 114) changes, and the fuel gas flows into the mixing passage 101 through the overlapping portion. However, as shown in the figure, the inflow of fuel gas is biased around the parallel introduction portion 111b in the mixing passage 101, and particularly when the opening area of the gas inflow port 114 is narrowed, it is compared with the combustion air. As a result, the dispersion of the fuel gas with a small inflow amount becomes non-uniform, and the air-fuel ratio of the mixed gas may vary.

On the other hand, in the premixing device 100 of the present embodiment, as described above, the configuration of the needle valve is adopted for adjusting the flow rate of the fuel gas, and the mixing passage is not affected by the change in the opening area of the gas inflow port 113. Since the inflow of fuel gas is uniform around the parallel introduction portion 111b in 101 (see FIG. 5B), the air-fuel ratio of the mixed gas can be stabilized.

Further, when the opening area of the air inlet 102 and the opening area of the gas inlet 113 are changed in conjunction with each other, the opening area ratio becomes higher due to an assembly error or an operation error of the air control unit 120 and the gas control unit 115. By deviating from the target value, the air-fuel ratio of the mixed gas may not be properly controlled, and such an effect tends to be large especially at the minimum flow rate in which the opening areas of the air inlet 102 and the gas inlet 113 are narrowed. In this respect, the premixer 100 of the present embodiment has a minimum air hole 105 provided separately from the air inlet 102 and a minimum gas hole 115d provided separately from the gas inlet 113. At the minimum flow rate in which the air inlet 102 and the gas inlet 113 are closed, combustion air flows into the mixing passage 101 through the minimum air hole 105, and fuel gas flows into the mixing passage 101 through the minimum gas hole 115d. It is supposed to flow in. In this way, the air-fuel ratio of the mixed gas at the minimum flow rate is determined by the area ratio between the opening area of the minimum air hole 105 and the opening area of the minimum gas hole 115d. By providing the target value, it is possible to control the mixed gas at the minimum flow rate to an appropriate air-fuel ratio.

The premixer 100 of the present embodiment described above also has the following modifications. Hereinafter, a modified example will be described focusing on points different from the above-described embodiment. In the description of the modified example, the same reference numerals are given to the same configurations as those in the above-described embodiment, and the description thereof will be omitted.

FIG. 7 is a perspective view showing the shape of the cam 117 installed in the premixing device 100 of the first modification. As shown in the figure, the cam 117 of the first modification has a convex portion 117d projecting as a step on the cam surface 117a. Then, as the rotation shaft 122 rotates, the contact portion 121b of the upper surface plate 121 moves along the inclination of the cam surface 117a and gets over the convex portion 117d.

FIG. 8 is a graph showing the relationship between the rotation angle of the rotation shaft 122 in the premixing device 100 of the first modification, and the air opening area and the gas opening area. First, the graph of FIG. 8A shows the relationship between the rotation angle of the rotation axis 122 and the air opening area. When the rotation angle of the rotation shaft 122 in a state where the air inlet 102 is blocked by the air control unit 120 is set to 0 degrees and the rotation shaft 122 is rotated clockwise (the rotation angle is increased), the air control unit is accompanied by the rotation angle. As the 120 rotates along the outer peripheral surface of the upstream passage 101b, the degree of overlap between the notch 120a and the air inlet 102 increases, so that the air opening area increases in proportion to the rotation angle. go. When the rotation angle of the rotation shaft 122 reaches 160 degrees, the entire air inlet 102 overlaps with the notch 120a, and the air opening area becomes maximum.

Subsequently, the graph of FIG. 8B shows the relationship between the rotation angle of the rotation axis 122 and the gas opening area. When the rotation angle of the rotation shaft 122 is 0 degrees, the gas inflow port 113 is blocked by the gas control unit 115, and as the rotation angle is increased, the contact portion 121b of the top plate 121 is inclined along the cam surface 117a. Move from the low side to the high side. Along with this, the cam 117 away from the upper surface plate 121 pushes back the gas control unit 115 against the urging force of the urging spring 116, so that the amount of the tapered portion 115a inserted into the gas inflow port 113 is reduced. , The gas opening area increases in proportion to the rotation angle. However, at a rotation angle at which the contact portion 121b overcomes the convex portion 117d of the cam surface 117a (between 40 degrees and 80 degrees in the illustrated example), the cam 117 pushes back the gas control unit 115 by the height of the convex portion 117d. Since the amount increases and the gas opening area is added, the gas opening area increases more than the proportional straight line.

Further, the graph of FIG. 8C shows the relationship between the rotation angle of the rotation shaft 122 and the opening area ratio obtained by dividing the air opening area by the gas opening area. Similarly to the above-described embodiment, the cam 117 of the first modification also maintains the opening area ratio at a predetermined value by moving the contact portion 121b of the top plate 121 along the cam surface 117a (the air-fuel ratio is kept constant). The inclination of the cam surface 117a is formed so as to keep it). Then, at the rotation angle at which the contact portion 121b exceeds the convex portion 117d of the cam surface 117a, the gas opening area is added, so that the opening area ratio is smaller than the predetermined value.

As described above, in the premixing device 100 of the first modification, a step (convex portion 117d) is provided on the cam surface 117a, and when the contact portion 121b crosses the step, the opening area ratio is set to a predetermined value. Can be different from. As a result, in order to change the air opening area and the gas opening area in conjunction with each other, it is possible not only to keep the air-fuel ratio of the mixed gas constant, but also to change it to an arbitrary air-fuel ratio as needed.

Then, in the premixing device 100 of the first modification, the opening area ratio is larger than a predetermined value at the rotation angle (contact rotation angle) of the rotation shaft 122 in a state where the contact portion 121b is in contact with the convex portion 117d of the cam surface 117a. As it becomes smaller, the air-fuel ratio also becomes smaller and the ratio of fuel gas in the mixed gas increases (becomes a gas-rich state). Therefore, for example, by setting the rotation angle of the rotation shaft 122 at the time of ignition of the water heater 1 to the contact rotation angle and performing the ignition operation in the gas-rich state, the ignition can be stabilized and ignition failure can be suppressed. It becomes.

FIG. 9 is a cross-sectional view showing the structure of the premixing device 100 of the second modification. In the figure, the cross section of the premixing device 100 including the center line of the mixing passage 101 and cut in a plane perpendicular to the center line of the orthogonal introduction portion 111a is shown, and the urging spring 116 is not shown. As shown in the figure, the premixing device 100 of the second modification is provided with an upstream passage 101b, an air control unit 120, and a cover member 150 that airtightly covers the periphery of the upper surface plate 121. A guide passage 151 for guiding combustion air is connected to the member 150. An air maximum hole 152 for passing combustion air is provided in the guidance passage 151, and the opening area of the air maximum hole 152 is set to be smaller than the maximum opening area of the air inlet 102. There is.

Further, an insertion member 155 is inserted inside the connection port 110, and a gas maximum hole 156 through which fuel gas passes is opened in the center of the insertion member 155. The opening area of the gas maximum hole 156 is set to be smaller than the maximum opening area of the gas inflow port 113.

In the premixer 100 of the second modification, the flow of combustion air is rate-determining through the maximum air hole 152 at the maximum flow rate at which the opening areas of the air inlet 102 and the gas inlet 113 are maximized. At the same time, since the flow of fuel gas is rate-determining through the passage of the maximum gas hole 156, the air-fuel ratio of the mixed gas at the maximum flow rate is the area between the opening area of the maximum air hole 152 and the opening area of the maximum gas hole 156. It depends on the ratio. Therefore, by providing the maximum air hole 152 and the maximum gas hole 156 so that the area ratio becomes the target value, the air control unit 120 and the gas control unit 115 are affected by an assembly error or an operation error. It is possible to control the mixed gas at the maximum flow rate to an appropriate air-fuel ratio.

Although the premixing device 100 of the present embodiment and the modified example has been described above, the present invention is not limited to the above-mentioned embodiment and the modified example, and can be carried out in various embodiments without departing from the gist thereof. It is possible.

For example, in the above-described examples and modifications, the air inlet 102 is provided on the peripheral surface of the upstream passage 101b. However, the position where the air inlet 102 is provided is not limited to this, and as shown in FIG. 10, a fan-shaped air inlet 102 about the center line of the mixing passage 101 may be provided on the lid plate 103. .. In the example of FIG. 10, an air control unit 120 that covers the upstream passage 101b and the lid plate 103 is rotatably provided about the rotation shaft 122, and the air control unit 120 faces the lid plate 103. The surface (corresponding to the upper surface plate 121 of the embodiment) has a fan-shaped ventilation hole 120b which is open so as to overlap with the air inlet 102. When the air control unit 120 rotates with the rotation of the rotating shaft 122, the ventilation holes 120b move, so that the opening area of the air inlet 102 (the area of the overlapping portion between the ventilation holes 120b and the air inlet 102) changes. do. The minimum air hole 105 is opened on the peripheral surface of the downstream passage 101a. If the air inflow port 102 is provided on the lid plate 103 in this way, the height for providing the air inflow port 102 on the upstream side passage 101b becomes unnecessary, so that the height is predicted in the direction of the center line of the mixing passage 101. It is possible to further make the mixing device 100 more compact.

Further, in the above-described embodiment and modification, the cam 117 is provided so as to be non-rotatable around the axis of the rotating shaft 122 and linearly movable in the axial direction of the rotating shaft 122, and is formed toward the upper surface plate 121 side. The contact portion 121b of the upper surface plate 121 came into contact with the cam surface 117a (see FIG. 4). However, the configuration of the cam 117 is not limited to this as long as the rotational motion of the air control unit 120 (rotational shaft 122) can be converted into a linear motion and transmitted to the gas control unit 115. For example, the cam 117 is arranged upside down from FIG. 4, the cam surface 117a is directed toward the gas control unit 115, and the rotation shaft 122 is rotatably connected to the rotation shaft 122 around the axis of the rotation shaft 122. The rotation of the 122 and the rotation of the cam 117 may be linked so that the pair of contact portions provided on the tip portion 115c side of the gas control unit 115 come into contact with the cam surface 117a.

Further, in the first modification described above, by providing the convex portion 117d on the cam surface 117a, the opening area ratio of the rotating shaft 122 at a predetermined rotation angle is made smaller than the predetermined value, but the opposite is true. The opening area ratio may be made larger than a predetermined value by providing a recess as a step on the cam surface 117a. As the opening area ratio becomes larger than the predetermined value, the air-fuel ratio also becomes large and the ratio of the fuel gas in the mixed gas becomes low (in an air-rich state), so that the concentration of carbon monoxide in the combustion exhaust is lowered. It becomes possible.

In addition, in the first modification described above, the cam surface 117a is such that the opening area ratio once decreases from the predetermined value and then returns to the predetermined value in the process of rotating the rotating shaft 122 from 0 degrees to 160 degrees. A convex portion 117d was provided on the surface. However, a step may be provided on the cam surface 117a so that the opening area ratio is switched with a predetermined rotation angle of the rotation shaft 122 as a boundary.

1 ... 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 ... wing piece, 32 ... rotating disk,
33 ... Support plate, 40 ... Drive motor, 41 ... Shaft,
50 ... casing, 51 ... body, 52 ... lid,
53 ... Intake port, 54 ... Blower, 55 ... Discharge port,
100 ... premixer, 101 ... mixing passage, 101a ... downstream passage,
101b ... upstream passage, 102 ... air inlet, 103 ... lid plate,
104 ... Insertion hole, 104a ... Guide groove, 105 ... Minimum air hole,
110 ... Connection port, 111 ... Introduction part, 111a ... Orthogonal introduction part,
111b ... Parallel introduction part, 112 ... Fitting member, 113 ... Gas inlet,
114 ... gas inlet, 115 ... gas control unit, 115a ... taper unit,
115b ... ridge, 115c ... tip, 115d ... minimum gas hole,
116 ... urging spring, 117 ... cam, 117a ... cam surface,
117b ... Protruding part, 117c ... Concave part, 117d ... Convex part,
120 ... Air control unit, 120a ... Notch, 120b ... Vent,
121 ... Top plate, 121a ... Passage port, 121b ... Contact part,
122 ... Rotating shaft, 130 ... Rotating motor, 131 ... Bracket,
140 ... gas control unit, 140a ... gas passage port, 141 ... lid part,
142 ... protrusion, 150 ... cover member, 151 ... guide passage,
152 ... Air maximum hole, 155 ... Insert member, 156 ... Gas maximum hole.

Claims (4)

In a premixing device that is connected to the suction side of a fan that sends a mixed gas of fuel gas and combustion air to a combustion device and premixes the fuel gas supplied to the fan with the combustion air.
A mixing passage joined to the suction side of the fan,
An air inlet that opens into the mixing passage and allows the combustion air to flow into the mixing passage.
An air control unit that is provided so as to cover the air inlet and that changes the area of the air opening that the air inlet opens into the mixing passage by rotating and moving along the surface on which the air inlet opens.
A gas inlet that opens into the mixing passage and allows the fuel gas to flow into the mixing passage,
A gas control unit that changes the gas opening area where the gas inlet opens into the mixing passage by forming a portion to be inserted into the gas inlet in a tapered shape and linearly moving in a direction for changing the insertion amount. ,
A cam that links the rotational movement of the air control unit with the linear movement of the gas control unit by converting the rotational movement of the air control unit into a linear motion and transmitting it to the gas control unit .
With the air inlet blocked by the air control unit, the minimum air hole for allowing the combustion air to flow into the mixing passage,
A premixing device comprising a gas minimum hole for allowing the fuel gas to flow into the mixing passage in a state where the gas inlet is closed by the gas control unit. In a premixing device that is connected to the suction side of a fan that sends a mixed gas of fuel gas and combustion air to a combustion device and premixes the fuel gas supplied to the fan with the combustion air.
A mixing passage joined to the suction side of the fan,
An air inlet that opens into the mixing passage and allows the combustion air to flow into the mixing passage.
An air control unit that is provided so as to cover the air inlet and that changes the area of the air opening that the air inlet opens into the mixing passage by rotating and moving along the surface on which the air inlet opens.
A gas inlet that opens into the mixing passage and allows the fuel gas to flow into the mixing passage,
A gas control unit that changes the gas opening area where the gas inlet opens into the mixing passage by forming a portion to be inserted into the gas inlet in a tapered shape and linearly moving in a direction for changing the insertion amount. ,
A cam that links the rotational movement of the air control unit with the linear movement of the gas control unit by converting the rotational movement of the air control unit into a linear motion and transmitting it to the gas control unit.
With
The cam has a cam surface inclined with respect to a plane perpendicular to the rotation axis of the air control unit.
By moving the air control unit or the contact portion provided on the gas control unit along the inclination of the cam surface, the opening area ratio obtained by dividing the air opening area by the gas opening area is maintained at a predetermined value. However, the rotational movement of the air control unit and the linear movement of the gas control unit are interlocked with each other.
A premixing device characterized in that the cam surface is provided with a step for changing the opening area ratio from the predetermined value. In the premixing device according to claim 2,
The premixing device is characterized in that the cam surface is provided with the step that makes the opening area ratio smaller than the predetermined value at a position where the contact portion contacts when the combustion device is ignited. In the premixing device according to claim 2 or 3.
With the air inlet blocked by the air control unit, the minimum air hole for allowing the combustion air to flow into the mixing passage,
A premixing device comprising a gas minimum hole for allowing the fuel gas to flow into the mixing passage in a state where the gas inlet is closed by the gas control unit.

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