Fluid mixing device

Abstract

To provide a fluid mixing device capable of closing a gas supply passage by using a flow regulating valve to suppress discharge of fuel gas to an air supply passage when electric conduction of an actuator is stopped due to power failure, etc.SOLUTION: In a fluid mixing device 1 having a venturi part 27 in which an inflow port 3c into which fuel gas flows is provided in a low pressure region generated by increase in flow speed when air passes through a restriction part, the inflow port 3c includes a flow regulating valve 6 comprising a valve element 8 for opening / closing a valve port 28 leading to the inflow port 3c, a valve seat 20 provided on an upper end peripheral surface of the valve port 28, a motor 4 for controlling the movement of the valve element 8 through electric conduction and a coil spring 10 for energizing the valve element 8 to the valve seat 20. A first O-ring 12 formed of an elastic member is mounted to a portion around an upper part of the valve element 8. When the motor 4 is not energized, the coil spring 10 causes the first O-ring 12 of the valve element 8 to be seated on the valve seat 20 so as to enable full closing of the valve port 28.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed in this application relates to a fluid mixing device equipped with a Venturi tube having an inlet formed therein through which a second fluid flows into a low-pressure region generated by an increase in flow velocity of a first fluid when the first fluid passes through a throttle section. [Background technology]

[0002] Conventionally, a fluid mixing device equipped with a venturi tube in which a gas resistance switching means for switching the flow resistance of fuel gas between large and small and a butterfly valve for adjusting the flow resistance of air are linked is disclosed in Patent Document 1 and the like.

[0003] Patent Document 1 discloses a premixing device in which the downstream end of a gas supply passage, which has a flow control valve for supplying fuel gas, is connected to a gas suction section provided in an air supply passage upstream of a fan, and which is equipped with an air resistance switching means for switching between high and low air resistance in the part of the air supply passage upstream of the gas suction section, and a gas resistance switching means for switching between high and low air resistance in the part of the gas supply passage downstream of the flow control valve, the air resistance switching means being composed of a butterfly valve rotatably provided in the part of the air supply passage upstream of the gas suction section, and the gas resistance switching means being composed of a switching valve provided in the gas supply passage so as to be able to open and close, and the switching valve is opened and closed in conjunction with the rotation of the butterfly valve between the open position and the closed position, thereby mixing fuel gas into air and supplying the mixture to a burner via a fan. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6608749 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0005] The premixing device disclosed in Patent Document 1 connects a cam to the valve stem of a butterfly valve, and an actuator such as a stepping motor rotates the cam in conjunction with the rotation of the butterfly valve. A rod connected to a switching valve of the gas resistance switching means is brought into contact with the cam, and as the cam rotates, the rod moves up and down, opening and closing the switching valve of the gas resistance switching means in conjunction with the rotation of the butterfly valve between the open and closed positions. Therefore, if the actuator such as a stepping motor is de-energized due to a power outage or other reason, the switching valve of the gas resistance switching means is maintained in a position corresponding to the position of the stopped cam. Therefore, if an on-off valve (equivalent to a "shut-off valve") located upstream of the switching valve fails for some reason, the switching valve of the gas resistance switching means does not close the gas supply path, and gas shut-off may become impossible.

[0006] The technology disclosed in this application has been proposed in view of the above-mentioned problems, and aims to provide a fluid mixing device in which the flow control valve has a closing function for closing the gas supply path, so that when power to the actuator is cut off due to a power outage or the like, the flow control valve can close the gas supply path and prevent fuel gas from being discharged into the air supply path. [Means for solving the problem]

[0007] In order to achieve the above object, the fluid mixing apparatus according to claim 1 is a fluid mixing apparatus having a throttle section which narrows the flow path area, and comprising a Venturi tube which forms an inlet through which a second fluid flows into a low-pressure region which is generated when the flow velocity of a first fluid increases as the first fluid passes through the throttle section, and the inlet through which the second fluid flows is provided with a second fluid flow rate adjustment means which adjusts the inflow rate of the second fluid flowing in from the inlet, and the second fluid flow rate adjustment means is composed of a valve element which opens and closes the inlet, a valve seat on which the valve element sits, a drive unit which controls the movement of the valve element when energized, and a second biasing unit which biases the valve element towards the valve seat, and is characterized in that when the drive unit is not energized, the second biasing unit causes the valve element to sit on the valve seat, thereby providing a closing function which can completely close the inlet.

[0008] The fluid mixing apparatus according to claim 2 is the fluid mixing apparatus according to claim 1, wherein a first fluid resistance adjusting means for adjusting the airflow resistance of the first fluid is provided in the venturi tube, and the first fluid resistance adjusting means is composed of a butterfly valve rotatably provided in the venturi tube at approximately the same position as the valve body of the second fluid flow rate adjusting means, a first biasing part for biasing the butterfly valve in the valve opening direction (horizontal to the flow direction of the first fluid), and a shaft extending in the direction of the valve body of the second fluid flow rate adjusting means, one end of which abuts on an end portion of the valve body and the other end of which is connected to a connecting part provided on the butterfly valve, and the shaft is biased by the first biasing part. The first fluid resistance adjustment means is characterized in that it is biased toward the valve element of the second fluid flow rate adjustment means via the connecting part of the butterfly valve, and when the drive part is energized and the valve element of the second fluid flow rate adjustment means moves in the valve opening direction against the biasing force of the second biasing part, the shaft moves toward the valve element of the second fluid flow rate adjustment means, and conversely, when the valve element of the second fluid flow rate adjustment means moves in the valve closing direction, the shaft moves toward the butterfly valve against the biasing force of the first biasing part, and the shaft acts on the connecting part of the butterfly valve, and is provided with a linkage mechanism that rotates the butterfly valve of the first fluid resistance adjustment means between the open position and the closed position in conjunction with the opening and closing movement of the valve element of the second fluid flow rate adjustment means.

[0009] A fluid mixing apparatus according to claim 3 is the fluid mixing apparatus according to claim 2, wherein the biasing force of the first biasing part is set smaller than the biasing force of the second biasing part, and as a result, when the drive part is not energized, the biasing force of the second biasing part of the second fluid flow rate adjustment means moves the valve element in the valve closing direction and seats on the valve seat to close the inlet, and the shaft abutting the valve element moves toward the butterfly valve against the biasing force of the first biasing part and acts on a connecting part of the butterfly valve to rotate the butterfly valve in the valve closing direction and close the valve. [Effects of the Invention]

[0010] In the fluid mixing apparatus according to claim 1, the second fluid (mainly fuel gas) flow rate adjustment means has a valve element urged in a valve closing direction by a second urging unit, and the opening and closing of the valve element of the second fluid flow rate adjustment means is controlled by energizing a drive unit (such as a stepping motor), and when the drive unit is not energized, the second urging unit causes the valve element to seat on the valve seat, maintaining the closed state. Therefore, if energization to the drive unit is stopped for some reason, the valve element in the flow rate adjustment means will seat on the valve seat, making it possible to completely close the inlet for the second fluid (mainly fuel gas), and even if the shut-off valve provided upstream fails for some reason, the supply path for the second fluid can be closed.

[0011] In the fluid mixing apparatus according to claim 2, when the valve element of the second fluid flow control means opens from a closed state against the biasing force of the second biasing unit by energizing the drive unit (e.g., a stepping motor), the shaft, one end of which abuts the valve element, is released and can move toward the valve element. Because the butterfly valve is biased in the valve opening direction by the first biasing unit, the shaft moves toward the valve element of the second fluid flow control means, causing the butterfly valve to rotate in the valve opening direction. Conversely, when the valve element of the second fluid flow control means moves in the valve closing direction, the shaft moves toward the butterfly valve against the biasing force of the first biasing unit, causing the butterfly valve to rotate in the valve closing direction. In other words, the butterfly valve of the first fluid resistance control means is rotated between the open and closed positions in conjunction with the opening and closing operation of the valve element of the second fluid flow control means by the drive unit. Therefore, a single drive unit can adjust the flow rate of the second fluid flowing in from the inlet and the airflow resistance of the first fluid, thereby reducing costs. Furthermore, by controlling the drive unit, it is also possible to adjust the magnitude of the airflow resistance of the first fluid according to the flow rate of the second fluid flowing in from the inlet.

[0012] In the fluid mixing apparatus according to claim 3, by setting the biasing force of the first biasing unit smaller than the biasing force of the second biasing unit, when the drive unit is not energized, the inlet through which the second fluid flows is closed and the butterfly valve is rotated in the valve closing direction to close the valve, maximizing the airflow resistance of the first fluid. As a result, if the drive unit is de-energized for some reason, the flow of the second fluid into the Venturi tube (mixing unit) is prevented and the amount of air is also reduced, making it possible to effectively prevent unintended combustion. [Brief explanation of the drawings]

[0013] [Figure 1] 1A is a front view of a fluid mixing device according to one embodiment of the present invention, FIG. 1B is a view of the front view from the left, and FIG. 1C is a view of the front view from the left. [Figure 2] FIG. 2 is a cross-sectional view taken along line AA in FIG. 1(B). [Figure 3] 1A is a top view, FIG. 1B is a front view, FIG. 1C is a bottom view, and FIG. 1D is a cross-sectional view taken along the line BB in FIG. 1B of a second body that constitutes the body of the fluid mixing device. [Figure 4] (A) is a top view, (B) is a front view, (C) is a bottom view, and (D) is a side view of the front view seen from the right, of the main part of the flow control valve. [Figure 5] (A) Front view, (B) bottom view, and (C) side view of a butterfly valve. [Figure 6] (A) A side view and (B) a front view of the shaft. [Figure 7] FIG. 10 is a diagram showing an assembled flow rate adjustment valve and a butterfly valve. [Figure 8] 1A to 1C are diagrams illustrating the operation of the fluid mixing device. DETAILED DESCRIPTION OF THE INVENTION

[0014] First, a fluid mixing apparatus 1 according to one embodiment of the present invention will be described with reference to the drawings.

[0015] Fig. 1 is an external view of a fluid mixing device 1 according to one embodiment of the present invention. In Fig. 1, (A) is a front view, (B) is a view of the front view from the left, and (C) is a view of the front view from the left.

[0016] The fluid mixing device 1 is primarily composed of a first body 2 and a second body 3, each equipped with a mixing section that uses the Venturi effect to mix a first fluid (air) and a second fluid (fuel gas). A fuel gas supply unit 7 is connected to a supply path for the second fluid (fuel gas) and is equipped with a fuel gas flow rate control valve. A motor cover 5 houses a motor that drives the fuel gas flow rate control valve. The motor cover 5 and the fuel gas supply unit 7 are assembled via a first plate 26. The fuel gas supply unit 7 is provided with a fuel gas supply port 7a, which is connected to the fuel gas supply path. A main shutoff valve (not shown) that closes the fuel gas supply path is provided upstream of the fuel gas supply path. The Venturi tube is composed of a first body 2 and a second body 3 incorporated inside the first body 2. A butterfly valve 18 is rotatably incorporated into the Venturi tube to adjust the airflow resistance of the first fluid (air). The air-fuel mixture mixed in the Venturi tube is supplied to a burner (not shown) via an air-fuel mixture fan (not shown) provided above the first body 2 in the drawing in FIG. 1(A).

[0017] Figure 2 is a cross-sectional view taken along the line AA in Figure 1B. A motor 4 is installed inside the motor cover 5. The fuel gas flow control valve 6 is composed of the motor 4, valve element shaft 9, coil spring 10, valve element 8, first O-ring 12, and a valve seat 20 on the upper surface of a valve port 28 provided in the fuel gas supply unit 7. A motor body such as a stepping motor and a thrust mechanism are installed inside the motor 4, and the motor body and thrust mechanism enable the valve element shaft 9 to be moved left and right (within the drawing). The valve element 8 is connected to the right end (within the drawing) of the valve element shaft 9, and a coil spring 10, which penetrates the valve element shaft 9 and is attached between the motor 4 and the valve element 8, biases the valve element 8 toward the valve seat 20. As a result, when the motor 4 is not energized, the biasing force of the coil spring 10 moves the valve element shaft 9 toward the valve seat 20, and the first O-ring 12 attached around the left end of the valve element 8 seats on the valve seat 20, completely closing the valve port 28 provided in the fuel gas supply part 7. Therefore, when the motor 4 is de-energized due to a power outage or the like, the flow control valve 6 can completely shut off the fuel gas supplied from the fuel gas supply path.

[0018] The lower end surface (right end in the drawing) of the fuel gas supply unit 7 and the upper end surface (left end in the drawing) of the first body 2 are assembled via a second O-ring 21, which maintains a sealed state between the fuel gas supply unit 7 and the first body 2. The second body 3 is assembled inside the first body 2 from above in the drawing, and a third O-ring 22 maintains a sealed state between the first body 2 and the second body 3. Both the first body 2 and the second body 3 have a hollow that penetrates the center in the vertical direction in the drawing, forming an air flow passage. The second hollow portion 16 of the second body 3 has a throttled portion whose flow path area narrows toward the bottom in the drawing. The first body 3 is provided with a first hollow portion 17, which is continuous with the throttled portion of the second body 3 and has a gradually expanding flow path area toward the bottom in the drawing, continuing from the second hollow portion 16. In other words, the hollow portion 17 of the first body 2 and the hollow portion 16 of the second body 3 form a Venturi tube (hereinafter referred to as the "Venturi portion 27").

[0019] A butterfly valve 18, which adjusts the airflow resistance of the air, is mounted in the venturi section 27 and is rotatable about a rotation axis 25. A torsion spring 23, which biases the butterfly valve 18 to an open position (horizontal to the flow direction), is attached between the underside of the butterfly valve 18 in the drawing and the inner surface (right side in the drawing) of the first body 2. The spring constant of the torsion spring 23 is set smaller than the spring constant of the coil spring 10 of the flow control valve 6. Therefore, when the motor 4 is de-energized, the biasing force of the coil spring 10 causes the butterfly valve 18 to rotate to a closed position (perpendicular to the flow direction) against the biasing force of the torsion spring 23, thereby achieving a closed valve state (maximum airflow resistance).

[0020] The butterfly valve 18 has a connecting portion 19 on its upper side in the drawing, which has an opening in the center that opens upward in the drawing. A shaft 11 is attached to the connecting portion 19, extending toward the lower end surface (right end of the drawing) of the valve element 8 of the flow control valve 6. As shown in FIG. 2 , the shaft 11 passes through through holes provided coaxially in the first body 2 and the second body 3, with one end (left end of the drawing) abutting the lower end surface (right end of the drawing) of the valve element 8 and the other end (right end of the drawing) fitting into the opening of the connecting portion 19 of the butterfly valve 18 to connect to the butterfly valve 18. The shaft 11, butterfly valve 18, connecting portion 19, and torsion spring 23 constitute an air resistance control valve 31. The through holes provided coaxially in the first body 2 and the second body 3 also function to prevent lateral movement of the shaft 11. When the motor 4 is energized and the valve element 8 of the flow control valve 6 moves in the valve opening direction (to the left in the drawing) against the biasing force of the coil spring 10, the upper end of the shaft 11 that abuts the lower end face of the valve element 8 is released and is free to move leftward to the lower end face of the valve element 8. As a result, the biasing force of the torsion spring 23 causes the shaft 11 to move leftward with its upper end abutting the lower end face of the valve element 8, thereby rotating the butterfly valve 18 to an open position and adjusting the air flow resistance of the venturi section 27.

[0021] Next, we will explain the supply of fuel gas in the fluid mixing apparatus 1. The fuel gas flows from the inlet 15 inside the fuel gas supply port 7a of the fuel gas supply unit 7 through the valve port 28, the fuel gas supply chamber 14, the communication port 30 opening in the first body 2, the fuel gas inlet chamber 24 formed in the gap between the first body 2 and the second body 3, and the fuel gas inlets 3c, 3c opening on the side of the second body 3 (shown in FIGS. 3B and 3C), into the venturi portion 27, where it mixes with air and is supplied to a burner (not shown). At this time, the flow velocity of the air increases as it passes through the venturi portion 27, creating a low-pressure region, which causes the fuel gas to be supplied to the venturi portion 27 through the fuel gas inlets 3c, 3c.

[0022] Next, the second body 3 constituting the body of the fluid mixing apparatus 1 will be described. Fig. 3A is a top view, Fig. 3B is a front view, Fig. 3C is a bottom view, and Fig. 3D is a cross-sectional view taken along the line B-B of Fig. 3B. As shown in Fig. 3B, the second body 3 is configured with an annular groove 3b for attaching a third O-ring 22 around the side surface at the top of the drawing, and a second body main body 3a. As shown in Figs. 3A, 3B, and 3D, the side surface of the second body main body 3a is provided with fuel gas inlets 3c, 3c, 3c, 3c, which are through-holes through which fuel gas flows into the venturi section 27, a shaft support hole 3d through which the shaft 11 passes, and a shaft support hole 3e for supporting the rotating shaft 25 of the butterfly valve 18, at approximately equal intervals.

[0023] Next, the details of the flow control valve 6 of the fluid mixing system 1 will be described using FIG. 4. FIG. 4A is a top view, FIG. 4B is a front view, FIG. 4C is a bottom view, and FIG. 4D is a side view of the front view viewed from the right. From the top of FIG. 4B, the flow control valve 6 includes the motor 4, which is composed of the motor section 4a and the connector section 4b; the valve body 8, which is composed of the valve body shaft 9, the spring retainer 8a, the O-ring groove 8b, and the valve body 8c; and, as described above, the coil spring 10, which biases the valve body 8 downward in the drawing, the first O-ring 12 fitted into the O-ring groove 8b, and the valve seat 20, which are not shown in FIG. 4 but are attached as described above. As described above, the motor section 4a houses the motor body, thrust mechanism, and other components. When the motor body is energized, the motor body, thrust mechanism, and other components move the valve body shaft 9 linearly in the vertical direction in the drawing. This allows the valve element 8 to move within the valve port 28 to adjust the flow rate of fuel gas flowing into the venturi portion 27 through the valve port 28, and when the motor body is de-energized due to a power outage or the like, the biasing force of the coil spring 10 causes the valve element 8 to move toward the valve seat 20, and the first O-ring 12 seats on the valve seat 20 of the valve port 28, completely closing it and preventing the flow of fuel gas into the venturi portion 27.

[0024] Next, we will explain the butterfly valve 18 of the air resistance adjustment valve 31, which adjusts the air flow resistance. Figure 5 shows the appearance of the butterfly valve 18, with Figure 5(A) being a front view, Figure 5(B) being a bottom view, and Figure 5(C) being a side view. As shown in Figure 5(A), the butterfly valve 18 is composed of a butterfly valve main body 18a, rotation bearing portions 18b, 18b, and a rotation restriction portion 18c. The butterfly valve main body 18a is in the shape of a circular disk with an outer diameter slightly smaller than the inner diameter of the cylindrical cavity at the position of the venturi portion 27 where the butterfly valve 18 rotates. The butterfly valve main body 18a rotates within the venturi portion 27, adjusting the angle at which it is tilted relative to the air flow direction to adjust the air flow resistance within the venturi portion 27. When the butterfly valve 18 is rotated to a position perpendicular to the airflow direction, the airflow resistance is maximized (this state is called the closed valve state), and when the butterfly valve 18 is rotated to a position horizontal to the airflow direction, the airflow resistance is minimized (this state is called the open valve state). In the closed valve state, the rotation restricting portion 18c of the butterfly valve 18 abuts against the first body 2, restricting the rotation of the butterfly valve 18. The right side of the butterfly valve main body 18a in the drawing is integrally attached with the connecting portions 19, 19, which have an opening groove on the right side of the drawing. The opening width of the opening of the connecting portion 19 is sized to fit the outer diameter of the connecting portion 11b of the shaft 11 (see FIG. 6). As described above, the butterfly valve 18 rotates when the shaft 11 moves left or right in FIG. 2.

[0025] Figure 6 shows the appearance of the shaft 11, with (A) being a side view and (B) being a front view. The shaft 11 comprises a shaft body 11a and, at the lower end in the figure, a connecting part 11b which is inserted into the open groove of the connecting part 19 to connect the shaft 11 to the butterfly valve 18.

[0026] 7 is a diagram illustrating the assembled state of the flow control valve 6 and the air resistance adjustment valve 31. As described above, in the flow control valve 6, a coil spring 10 that urges the valve disc 8 downward in the drawing is attached to the valve disc shaft 9 between the motor 4 and the valve disc 8, with the valve disc shaft 9 passing through the coil spring 10. A first O-ring 12 is attached to the top of the valve disc 8, and when the flow control valve 6 is closed, the first O-ring 12 seats on the valve seat 20 of the valve port 28 to close the valve port 28. Because the first O-ring 12 is made of an elastic material, when the motor 4 is not energized, the urging force of the coil spring 10 causes the first O-ring 12 to seat on the valve seat 20 of the valve port 28, thereby completely closing the valve port 28.

[0027] An air resistance adjustment valve 31, which adjusts the air resistance of the air in the venturi section 27, is attached below the flow control valve 6 in the drawing. One end of the shaft 11 of the air resistance adjustment valve 31 abuts the lower end surface of the valve disc 8, and the other end is connected to a connecting portion 19 attached to the right side of the butterfly valve 18 in the drawing. A torsion spring 23 is attached between the left side of the butterfly valve 18 in the drawing and the first body 2, biasing the butterfly valve 18 to an open position (horizontal to the air flow direction). That is, the shaft 11 is biased upward in the drawing by the torsion spring 23 via the butterfly valve 18, and the valve disc 8 of the flow control valve 6 restricts the shaft 11 from moving upward in the drawing. Therefore, as described above, when the valve disc 8 of the flow control valve 6 opens and moves upward in the drawing, the shaft 11 moves upward in the drawing while abutting the lower end surface of the valve disc 8, rotating the butterfly valve 18 to an open position. Conversely, when the valve element 8 of the flow rate control valve 6 moves downward in the drawing (in the valve closing direction), the shaft 11 moves downward in the drawing while abutting against the lower end surface of the valve element 8 against the biasing force of the torsion spring 23, and the butterfly valve 18 can be rotated to the closed position. In this way, the fluid mixing apparatus 1 is able to adjust the air flow resistance of the venturi portion 27 by the air resistance adjustment valve 31 in conjunction with the adjustment of the flow rate of the fuel gas by the flow rate adjustment valve 6.

[0028] Next, the operation of the fluid mixing apparatus 1 will be described with reference to Fig. 8. Fig. 8(A) is a diagram showing the state in which the flow rate control valve 6 is closed and the butterfly valve 18 of the air resistance control valve 31 is closed, (B) is a diagram showing the state in which the flow rate control valve 6 is half open and the butterfly valve 18 of the air resistance control valve 31 is open 45°, and (C) is a diagram showing the state in which the flow rate control valve 6 is fully open and the butterfly valve 18 of the air resistance control valve 31 is fully open.

[0029] (A) When the flow control valve 6 is closed and the butterfly valve 18 of the air resistance control valve 31 is closed, the inflow of fuel gas into the venturi section 27 is suppressed, and the air resistance in the venturi section 27 is maximized, suppressing the amount of air flowing. (B) When the flow rate control valve 6 is half open and the butterfly valve 18 of the air resistance control valve 31 is open at 45 degrees, the valve element 8 moves in the valve opening direction as shown by arrow (1) in Fig. 8, and in conjunction with this, the shaft 11 moves toward the valve element 8, rotating the butterfly valve 18 as shown by arrow (4) to open at 45 degrees. Therefore, with the butterfly valve 18 in the 45 degree open state, air flows as shown by arrow (2), and the flow rate of the air increases in the venturi section 27, creating a low-pressure region. As shown by arrow (3), fuel gas is supplied from the valve port 28 through the fuel gas inlets 3c, 3c to the venturi section 27, and the mixture of fuel gas and air is supplied to the burner (not shown) via a mixture fan (not shown). (C) When the flow control valve 6 is fully open and the butterfly valve 18 of the air resistance control valve 31 is fully open, the valve disc 8 moves further in the valve opening direction as shown by arrow (1') in Figure 8, and in conjunction with this, the shaft 11 moves toward the valve disc 8, rotating the butterfly valve 18 as shown by arrow (4') and opening by 90 degrees. As a result, the butterfly valve 18 is fully open in the horizontal direction relative to the air flow direction, and an even larger amount of air flows as shown by arrow (2'), and the air flow rate increases in the venturi section 27, creating an even lower-pressure region. As shown by arrow (3'), an even larger amount of fuel gas is supplied to the venturi section 27 from the valve port 28 through the fuel gas inlets 3c, 3c, and the fuel gas and air mixture is supplied to the burner (not shown) via a mixture fan (not shown).

[0030] As described above, in the fluid mixing apparatus 1, when the motor body in the motor 4 is de-energized due to a power outage or the like, the biasing force of the coil spring 10 in the flow control valve 6 closes the valve element 8, and the first O-ring 12, formed of an elastic material, seats on the valve seat 20 of the valve port 28, completely closing the valve port 28. This prevents fuel gas remaining in the fuel gas supply path from flowing into the venturi section 27, which is the mixing section. As a result, even if the main shut-off valve (not shown) provided upstream fails for some reason, the fuel gas supply path can be closed. Furthermore, as described above, the valve element 6 is moved by the motor 4, which is the drive unit of the flow control valve 6 that adjusts the inflow amount of fuel gas into the venturi section 27. As a result, the butterfly valve 18 of the air resistance control valve 31 rotates via the shaft 11, thereby adjusting the air flow resistance in the venturi section 27. Therefore, the flow control valve 6 and the air resistance control valve 31 can be driven and controlled by only a single motor 4, thereby reducing costs. Furthermore, the spring constant of the torsion spring 23 that urges the butterfly valve 18 of the air resistance control valve 31 to the open position is set to be smaller than the spring constant of the coil spring 10 that urges the valve body 8 of the flow rate control valve 6 in the valve closing direction. Therefore, if the power supply to the motor 4, which is the drive unit, is stopped for some reason, the valve body 8 of the flow rate control valve 6 will close and the butterfly valve 18 of the air resistance control valve 31 will also rotate to the closed position, thereby preventing the inflow of fuel gas into the venturi section 27, which is the mixing section, and also maximizing the air flow resistance, thereby suppressing the amount of air flowing, thereby effectively preventing unintended combustion.

[0031] Here, the fluid mixing device 1 is an example of a fluid mixing device, air is an example of a first fluid, fuel gas is an example of a second fluid, fuel gas inlet 3c (including communication port 30) is an example of an inlet, venturi portion 27 is an example of a venturi tube, flow control valve 6 is an example of a second fluid flow control means, valve body 8 is an example of a valve body, valve seat 20 is an example of a valve seat, motor 4 is an example of a drive unit, coil spring 10 is an example of a second biasing unit, air resistance control valve 31 is an example of a first fluid resistance control means, butterfly valve 18 is an example of a butterfly valve, torsion spring 23 is an example of a first biasing unit, shaft 11 is an example of a shaft, and connecting portion 19 is an example of a connecting unit.

[0032] Although the embodiments of the present invention have been described in detail above, these are merely examples, and the present invention should not be construed in any way as being limited by the specific descriptions in such embodiments. It should be understood that the present invention can be implemented in various forms with various changes, modifications, improvements, etc. made based on the knowledge of those skilled in the art, and that all such embodiments are included within the scope of the present invention as long as they do not deviate from the spirit of the present invention. [Explanation of symbols]

[0033] 1...Fluid mixing device 2. First body 3. Second body 3c Fuel gas inlet 4. Motor 6. Flow control valve 7. Fuel gas supply unit 8. Valve body 10. Coil spring 11. Shaft 12. First O-ring 18. Butterfly valve 19...Connection part 20 Valve seat 23 Torsion spring 27. Venturi section 31. Air resistance adjustment valve

Claims

1. A fluid mixing device including a Venturi tube having a throttle section with a narrowed flow path area, and an inlet formed therein through which a second fluid flows into a low-pressure region generated by an increase in flow velocity of a first fluid when the first fluid passes through the throttle section, the inlet through which the second fluid flows is provided with a second fluid flow rate adjusting means that adjusts the inflow rate of the second fluid flowing in from the inlet, the second fluid flow rate adjustment means comprises a valve element that opens and closes the inlet, a valve seat on which the valve element is seated, a drive unit that controls movement of the valve element by energization, and a second biasing unit that biases the valve element toward the valve seat, a closing function in which, when the drive unit is not energized, the second biasing unit causes the valve element to seat on the valve seat, thereby completely closing the inlet.

2. a first fluid resistance adjusting means for adjusting the air flow resistance of the first fluid to a large or small value is provided in the Venturi pipe; the first fluid resistance adjustment means comprises a butterfly valve rotatably provided in the Venturi tube at approximately the same position as the valve element of the second fluid flow rate adjustment means, a first biasing portion that biases the butterfly valve in a valve opening direction (a direction horizontal to the flow direction of the first fluid), and a shaft that extends toward the valve element of the second fluid flow rate adjustment means, one end of which abuts on an end portion of the valve element and the other end of which is connected to a connecting portion provided on the butterfly valve, the shaft is biased by the first biasing portion toward the valve body of the second fluid flow rate adjusting means via the connecting portion of the butterfly valve, 2. The fluid mixing apparatus according to claim 1, further comprising an interlocking mechanism wherein, when the drive unit is energized and the valve disc of the second fluid flow rate control means moves in a valve opening direction against the biasing force of the second biasing unit, the shaft moves toward the valve disc of the second fluid flow rate control means, and conversely, when the valve disc of the second fluid flow rate control means moves in a valve closing direction, the shaft moves toward the butterfly valve against the biasing force of the first biasing unit, and the shaft acts on a connecting portion of the butterfly valve, thereby rotating the butterfly valve of the first fluid resistance adjustment means between an open position and a closed position in conjunction with the opening and closing movement of the valve disc of the second fluid flow rate control means.

3. 3. The fluid mixing apparatus according to claim 2, wherein the biasing force of the first biasing portion is set to be smaller than the biasing force of the second biasing portion, such that when the drive portion is not energized, the biasing force of the second biasing portion of the second fluid flow rate control means moves the valve disc in the valve closing direction and seats on the valve seat to close the inlet, and the shaft abutting the valve disc moves toward the butterfly valve against the biasing force of the first biasing portion and acts on a connecting portion of the butterfly valve to rotate the butterfly valve in the valve closing direction to close the valve.

Images