Fluid mixing device

Abstract

To provide a fluid mixing device that employs an integral structure for a cam and a butterfly valve, which rotates the butterfly valve so as to open and close by rotating the cam by a shaft connected to a flow volume adjusting valve.SOLUTION: In an interlocking mechanism in which, when a shaft 11 moves toward a butterfly valve 18 together with the opening and closing operation of a valve body 8 of a flow volume adjusting valve 6 for a combustion gas, a cam 19 that abuts on the tip of the shaft 11 rotates, the butterfly valve 18 is rotated in accordance with the shape of the rotating cam 19, and the butterfly valve 18 is rotated in an open attitude and a close attitude in conjunction with the opening and closing operation of the valve body 8, the cam 19 is formed in integral structure with the butterfly valve 19.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 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 the fuel gas into the 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 stem of a butterfly valve. An actuator, such as a stepping motor, rotates the butterfly valve and the cam, which in turn raises and lowers a rod connected to a switching valve that contacts the cam. The switching valve opens and closes in conjunction with the butterfly valve's rotation between its open and closed positions. Therefore, the butterfly valve is located in the air supply passage, and the cam is located in the gas resistance switching device. Because the switching valve opens and closes by rotating according to the shape of the cam, the angle of the cam relative to the butterfly valve is important when connecting the cam to the stem of the butterfly valve. If the angle of the cam is not accurately set when attaching it to the stem of the butterfly valve, the intended opening and closing of the switching valve in conjunction with the butterfly valve's rotation between its open and closed positions cannot be achieved. Therefore, the positioning of the cam when assembling it to the stem of the butterfly valve is difficult, resulting in high manufacturing costs. Furthermore, since the butterfly valve and the cam must be manufactured separately, it is difficult to reduce the cost of the parts.

[0006] The technology disclosed in the present application has been proposed in view of the above-mentioned problems, and aims to provide a fluid mixing device in which a butterfly valve is opened and closed by rotating a cam with a shaft connected to a flow control valve, in which the cam and the butterfly valve are integrated into a single structure. [Means for solving the problem]

[0007] In order to achieve the above object, a fluid mixing apparatus according to claim 1 is a fluid mixing apparatus having a throttling section which narrows the flow path area and which is equipped with a Venturi tube having 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 when the first fluid passes through the throttling section, and which is equipped with a first fluid resistance adjusting means which is provided in the Venturi tube and adjusts the airflow resistance of the first fluid to a large or small value, and a second fluid flow rate adjusting means which is provided at the inlet through which the second fluid flows in and adjusts the inflow rate of the second fluid flowing in from the inlet, and the second fluid flow rate adjusting 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, a shaft which is connected to an end of the valve element and extends towards the first fluid resistance adjusting means, and a second biasing unit which biases the valve element towards the valve seat, and the first fluid resistance adjusting means is The device comprises a butterfly valve rotatably provided in a Venturi tube at approximately the same position as the valve disc, a first biasing section that biases the butterfly valve in a valve opening direction (horizontal to the flow direction of the first fluid), and a cam that is provided on the rotation axis of the butterfly valve, abuts against the tip of the shaft of the second fluid flow control means, and rotates along with the rotation of the butterfly valve, and when the shaft moves towards the butterfly valve as the valve disc of the second fluid flow control means opens and closes, the cam that the tip of the shaft abuts against rotates, rotating the butterfly valve according to the shape of the rotating cam, and comprising an interlocking mechanism that rotates the butterfly valve of the first fluid resistance adjustment means to an open position and a closed position in conjunction with the opening and closing movement of the valve disc of the second fluid flow control means, and is characterized in that the cam is disposed in the Venturi tube, and the cam and the butterfly valve are formed as an integral structure. [Effects of the Invention]

[0008] In the fluid mixing apparatus according to claim 1, when a drive unit (such as a stepping motor) is energized, the valve element of the second fluid (primarily fuel gas) flow rate control means opens and closes, and the shaft moves toward the butterfly valve of the first fluid (primarily air) resistance control means. The shaft abuts against a cam mounted on the rotation axis of the butterfly valve, rotating the cam, thereby rotating the butterfly valve of the first fluid resistance control means between an open position and a closed position in conjunction with the opening and closing of the valve element of the second fluid flow rate control means. This structure allows the cam, like the butterfly valve, to be disposed in the air supply passage, making it possible to form the cam and butterfly valve as a single unit by integral molding. This reduces component costs and eliminates the need for assembly and adjustment of the cam and butterfly valve, thereby reducing manufacturing costs. [Brief explanation of the drawings]

[0009] [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 line BB of FIG. 1B, of a second body that constitutes the body of the fluid mixing device. [Figure 4] 1A is a top view of the main part of a flow control valve, FIG. 1B is a front view, and FIG. 1C is a side view of the front view viewed from the right. [Figure 5] (A) Front view, (B) bottom view, and (C) side view of a butterfly valve. [Figure 6] FIG. 10 is a diagram showing an assembled flow rate adjusting valve and an air resistance adjusting valve. [Figure 7] 1A to 1C are diagrams illustrating the operation of the fluid mixing device. DETAILED DESCRIPTION OF THE INVENTION

[0010] First, a fluid mixing apparatus 1 according to one embodiment of the present invention will be described with reference to the drawings.

[0011] 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.

[0012] 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. The fuel gas supply path is equipped with a main shut-off valve (not shown) that closes 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).

[0013] FIG. 2 is a cross-sectional view taken along the line AA in FIG. 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, shaft 11, 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. One end of the shaft 11 is fixed to or abuts against the end (right end of the drawing) of the valve element 8, connecting it to the valve element 8. 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, attached between the motor 4 and the valve element 8 so that the valve element shaft 9 passes through, 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.

[0014] 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").

[0015] 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).

[0016] A cam 19 is molded integrally with the butterfly valve 18 on the upper side surface of the figure. The shaft 11 of the flow rate control valve 6 passes through a through hole provided coaxially in the first body 2 and the second body 3, and its lower end (the left end in the figure) abuts against the cam 19. As shown in FIG. 2, the surface of the cam 19 that abuts against the shaft 11 of the flow rate control valve 6 is arc-shaped. The butterfly valve 18, cam 19, and torsion spring 23 constitute an air resistance control valve 31. The through hole provided coaxially in the first body 2 and the second body 3 also functions 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 shaft 11 connected to the lower end of the valve element 8 also moves to the left in the drawing, and the cam 19 is released to rotate freely with the lower end face of the shaft 11 abutting against it, and the cam 19 rotates due to the biasing force of the torsion spring 23, and at the same time the butterfly valve 18 is also rotated in the direction of the open position, making it possible to adjust the air flow resistance of the venturi section 27.

[0017] 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 section 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 section 27, creating a low-pressure region, which causes the fuel gas to be supplied to the venturi section 27 through the fuel gas inlets 3c, 3c.

[0018] 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.

[0019] Next, 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, and FIG. 4C 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 element 8, which is composed of the valve element shaft 9, the spring retainer 8a, the O-ring groove 8b, and the valve body 8c; the shaft 11; and, in addition to these, the coil spring 10, which biases the valve element 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 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 element 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.

[0020] Next, we will explain the butterfly valve 18 of the air resistance adjustment valve 31, which adjusts the air flow resistance between high and low. 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 body 18a, rotation bearing portions 18b, 18b, a rotation restriction portion 18c, and a cam 19 provided in the center. The butterfly valve 18 and cam 19 are integrally molded into a single structure. Therefore, as described above in the "Effects of the Invention," it is possible to reduce parts costs and eliminate the need for adjustment of the attachment of the cam and butterfly valve, thereby reducing manufacturing costs.

[0021] The butterfly valve body 18a has a circular disk shape 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 venturi portion 27 is rotated to adjust the airflow resistance at the angle of inclination with respect to the airflow direction. When rotated to a position perpendicular to the airflow direction, the airflow resistance is maximized (this state is called the closed state). When rotated to a position horizontal to the airflow direction, the airflow resistance is minimized (this state is called the open state). In the closed state, the rotation restricting portion 18c of the butterfly valve 18 abuts against the first body 2 to restrict the rotation of the butterfly valve 18. The cam 19 integrally provided with the butterfly valve 18 has a first circular arc 19a, a recessed portion 19b, a second circular arc 19c, and a protruding portion 19d formed continuously, as shown in FIG. 5C. Recess 19b is formed to fit into the lower end of shaft 11, and when butterfly valve 18 is in a closed state (vertical position relative to the flow direction), the lower end of shaft 11 is positioned in recess 19b, maintaining the closed state of butterfly valve 18. When butterfly valve 18 is in an open state (horizontal position relative to the flow direction), shaft 11 abuts against protrusion 19d, preventing excessive rotation of butterfly valve 18.

[0022] 6 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.

[0023] An air resistance adjustment valve 31 that adjusts the air resistance to ventilation in the venturi portion 27 is attached below the flow rate adjustment valve 6 in the drawing. The lower end of the shaft 11 of the flow rate adjustment valve 6 abuts against the cam 19 of the butterfly valve 18 of the air resistance adjustment valve 31. A torsion spring 23 is attached between the left side of the butterfly valve 18 in the drawing and the first body 2, and urges the butterfly valve 18 into an open position (horizontal to the air flow direction). As mentioned above, the cam 19 is formed integrally with the butterfly valve 18, and therefore, like the butterfly valve 18, the cam 19 is also urged by the torsion spring 23 in the direction of the butterfly valve 18 toward the open position. Therefore, when the flow rate control valve 6 is controlled in the valve opening direction, the shaft 11 connected to the valve disc 8 moves toward the valve disc 8 (upward in the drawing), the cam 19 it abuts is released, and the butterfly valve 18 rotates together with the cam 19 in the direction of the open position according to the shape of the arc portion of the cam 19 against which the shaft 11 abuts, due to the biasing force of the torsion spring 23, and the butterfly valve 18 is controlled to rotate in the valve opening direction. Conversely, when the flow rate control valve 6 is controlled in the valve closing direction, the shaft 11 connected to the valve disc 8 moves toward the cam 19 (downward in the drawing), and the shaft 11 presses down on the cam 19 against which it abuts, and the cam 19 and the butterfly valve 18 rotate in the direction of the closed position according to the shape of the arc portion of the cam 19 against which the shaft 11 abuts, and the butterfly valve 18 is controlled to rotate in the valve closing direction. In this way, the fluid mixing device 1 is able to adjust the flow rate of the fuel gas by the flow rate control valve 6 and the air resistance of the air in the venturi section 27 by the air resistance control valve 31 according to the shape of the cam 19.

[0024] Next, the operation of the fluid mixing apparatus 1 will be described with reference to Fig. 8. In Fig. 8, (A) is a diagram showing the flow rate control valve 6 in a closed state and the butterfly valve 18 of the air resistance control valve 31 in a closed state, (B) is a diagram showing the flow rate control valve 6 in a half-open state and the butterfly valve 18 of the air resistance control valve 31 in a 45° open state, and (C) is a diagram showing the flow rate control valve 6 in a fully open state and the butterfly valve 18 of the air resistance control valve 31 in a fully open state.

[0025] (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 inhibited, and the air resistance in the venturi section 27 is maximized, thereby inhibiting 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, as shown by arrow (1) in Fig. 8, the valve element 8 moves in the valve opening direction, causing the shaft 11 to move toward the valve element 8 and the butterfly valve 18 to rotate as shown by arrow (4) and open at 45 degrees. Therefore, with the butterfly valve 18 open at 45 degrees, 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).

[0026] 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. Also, 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, 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 the single motor 4. Furthermore, because the spring constant of the torsion spring 23 that urges the butterfly valve 18 of the air resistance control valve 31 to an open position is set smaller than the spring constant of the coil spring 10 that urges the valve element 8 of the flow rate control valve 6 in a valve closing direction, if the power supply to the motor 4, which is the drive unit, is stopped for some reason, the valve element 8 of the flow rate control valve 6 closes and the butterfly valve 18 of the air resistance control valve 31 also rotates to a closed position, thereby preventing the inflow of fuel gas into the venturi portion 27, which is the mixing portion, and maximizing the air flow resistance, thereby suppressing the amount of air that flows. Furthermore, because the butterfly valve 18 and cam 19 can be formed as an integral structure by integral molding, it is possible to reduce parts costs and there is no need to adjust the attachment of the cam 19 to the butterfly valve 18, thereby reducing manufacturing costs.

[0027] 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 rate control valve 6 is an example of a second fluid flow rate 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 cam 19 is an example of a cam.

[0028] 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.

[0029] As in the above embodiment of the present invention, by employing the cam 19 integrally constructed with the butterfly valve 18, the relationship between the amount of fuel gas flowing into the venturi portion 27 by the flow control valve 6 and the magnitude of air resistance at the air resistance control valve 31 can be controlled according to the shape of the arc of the arc portion of the cam 19 with which the shaft 11 abuts. Therefore, by changing the shape of the arc portion of the cam and replacing this part, which is an integral structure of the modified cam and the butterfly valve, it is possible to easily set the relationship between the amount of fuel gas flowing in and the magnitude of air resistance as desired depending on the application. In other words, by employing cams integrally constructed with the butterfly valves having various arc shapes depending on the application, it is possible to provide a fluid mixing apparatus having a variety of relationships between the amount of fuel gas flowing in and the magnitude of air resistance. [Explanation of symbols]

[0030] 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··Cam 20 Valve seat 23 Torsion spring 27. Venturi section 31. Air resistance adjustment valve

Claims

[Claim 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, a first fluid resistance adjusting means provided in the Venturi tube for adjusting the air flow resistance of the first fluid; a second fluid flow rate adjusting means provided at the inlet through which the second fluid flows in, and adjusting the inflow rate of the second fluid flowing in from the inlet, the second fluid flow rate adjusting 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, a shaft that is connected to an end of the valve element and extends toward the first fluid resistance adjusting means, and a second biasing unit that biases the valve element toward the valve seat, the first fluid resistance adjustment means comprises a butterfly valve rotatably provided in the Venturi tube at approximately the same position as the valve body 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 cam that is provided on a rotation axis of the butterfly valve, abuts against a tip end of the shaft of the second fluid flow rate adjustment means, and rotates together with the rotation of the butterfly valve; When the shaft moves toward the butterfly valve together with the opening and closing operation of the valve element of the second fluid flow rate adjustment means, the cam abutting the tip of the shaft rotates, causing the butterfly valve to rotate according to the shape of the rotating cam, and the butterfly valve of the first fluid resistance adjustment means is rotated between an open position and a closed position in conjunction with the opening and closing operation of the valve element of the second fluid flow rate adjustment means, a cam disposed inside the venturi tube, and the cam and the butterfly valve are integrally formed into a fluid mixing device;

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