JP2015014431A - Premixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extinguish a burner with good responsiveness on the occurrence of abnormal conditions, in a premixing device with air resistance switching means for switching ventilation resistance of an air supply passage to the magnitude and gas resistance switching means for switching ventilation resistance of a gas feeding passage to the magnitude.SOLUTION: A resistance switching valve V constituting air resistance switching means and gas resistance switching means has a cylindrical valve body 6. When the valve body 6 is present in an open position, an air inlet path 61, a gas inlet path 62 and an outflow path 63 are brought into communication with an air supply path 3, a gas supply path 4 and a fuel/air mixture passage 5, respectively. By turning the valve body 6 in the open position, communication opening degrees to the air supply path 3 and the gas supply path 4 are changed to the magnitude, respectively. Also, when the valve body 6 is present in a closed position, the communication of the air inlet path 61, the gas inlet path 62 and the outflow path 63 with the air supply path 3, the gas supply path 4 and the fuel/air mixture passage 5 are cut, respectively.

Description

  The present invention relates to a premixing device that mixes fuel gas with air and supplies the air-fuel mixture to a burner via a fan.

  Conventionally, as a premixing device of this type, according to Patent Document 1, an air supply path for supplying air and a gas supply path for supplying fuel gas are connected to an air-fuel mixture path on the suction side of the fan, and open and close to the gas supply path A valve and a proportional valve as a flow control valve are interposed, air resistance switching means for switching the ventilation resistance of the air supply path between large and small, and the ventilation resistance of the portion of the gas supply path on the downstream side of the proportional valve. A gas resistance switching means for switching is known.

  The proportional valve supplies an amount of fuel gas proportional to the energization current (proportional valve current) to the proportional valve, and the proportional valve current is controlled so that an amount of fuel gas corresponding to the required combustion amount is supplied. Furthermore, the fan speed is controlled in accordance with the required combustion amount so that the air-fuel ratio of the air-fuel mixture supplied to the burner becomes constant. However, the required combustion amount becomes less than the predetermined value, the fan rotation speed becomes less than the lower limit rotation speed that can maintain the proportional characteristic of the blown air amount, or the proportional valve current becomes less than the lower limit current that can maintain the proportional characteristic of the gas supply amount. In such a case, it becomes impossible to supply air or fuel gas in an amount corresponding to the required combustion amount.

  Therefore, in the above conventional example, when the required combustion amount becomes a predetermined value or less, the air resistance switching means increases the air supply path ventilation resistance and the gas resistance switching means increases the gas supply path ventilation resistance. Yes. According to this, it is possible to supply an amount of air or fuel gas corresponding to the required combustion amount equal to or less than a predetermined value without setting the fan rotation speed or the proportional valve current below the lower limit rotation speed or the lower limit current.

  By the way, when an abnormality such as a power failure occurs, it is desired to extinguish the burner quickly. Here, in the above-mentioned conventional example, the resistance of the gas supply path is increased by branching the downstream side of the proportional valve of the gas supply path into two passages and closing the connection port to the mixture passage of one of the passages. The other passage is not blocked, and the supply of fuel gas cannot be stopped downstream of the on-off valve of the gas supply path. For this reason, even if the on / off valve is closed when an abnormality occurs, it takes time until the burner is extinguished because the fuel gas present in the gas supply passage downstream of the on / off valve is supplied to the burner. End up.

International Publication No. 2012/134033

  In view of the above points, the present invention can switch the ventilation resistance of the gas supply path portion downstream of the air supply path and the flow rate control valve between large and small, and can extinguish the burner with good responsiveness when an abnormality occurs. An object of the present invention is to provide a premixing device as described above.

  In order to solve the above-mentioned problems, the present invention is a premixing device that mixes fuel gas with air and supplies the air-fuel mixture to a burner via a fan, and supplies an air supply path for supplying air and fuel gas The gas supply path is connected to the air-fuel mixture passage on the suction side of the fan, the flow rate adjustment valve is interposed in the gas supply path, the air resistance switching means for switching the ventilation resistance of the air supply path to the large and small, and the flow rate control An air resistance switching means and a gas for connecting the air supply path and the gas supply path to the air-fuel mixture path, comprising a gas resistance switching means for switching the ventilation resistance of the portion of the gas supply path downstream of the valve between large and small A resistance switching valve that constitutes a resistance switching means is provided, and the resistance switching valve has a cylindrical valve body that is rotatable and movable in the axial direction, and an air supply path is provided on a peripheral wall portion of the valve body. Air inlet and gas supply that can communicate A gas inflow passage that can communicate with the gas passage and an outflow passage that can communicate with the mixture passage, and a confluence passage that connects the air inflow passage and the gas inflow passage to the outflow passage is formed inside the valve body. When the valve body is in one open position in the axial direction, the air inflow path, the gas inflow path, and the outflow path communicate with the air supply path, the gas supply path, and the gas mixture path, respectively, and the valve body is in the other axial direction. When in the closed position, at least the communication between the gas inflow path and the gas supply path is cut off, and the air inflow path and the gas inflow path are respectively rotated by rotating the valve body in the open position. It is formed so that the communication opening degree with respect to a gas supply path may change in magnitude.

  According to the present invention, the valve body is rotated in the open position, and the communication opening degree of the air inflow path and the gas inflow path with respect to the air supply path and the gas supply path is changed to a large or small size. The ventilation resistance in the portion of the gas supply path on the downstream side of the control valve can be switched between large and small. Further, when the valve body is moved to the closed position, the communication between the gas inflow path and the gas supply path is cut off, and the supply of fuel gas can be stopped at the downstream end of the gas supply path. Therefore, by moving the valve body to the closed position when an abnormality occurs, the supply of fuel gas to the burner is quickly stopped, and the burner can be extinguished with good response.

  In the present invention, it is desirable to include an urging means for urging the valve body toward the closed position and an electromagnetic actuator for moving the valve body to the open position against the urging force of the urging means. According to this, when energization to the electromagnetic actuator is stopped due to a power failure, the valve body is moved to the closed position by the urging force of the urging means, so that the burner can be extinguished without requiring any control, which is safe.

The cut side view which shows the premixing apparatus of embodiment of this invention. The figure which shows when the valve body of FIG. 1 exists in a closed position. (A) is sectional drawing cut | disconnected by the IIIa-IIIa line of the valve body of FIG. 1, (b) is sectional drawing cut | disconnected by the IIIb-IIIb line of the valve body of FIG. The graph which shows the relationship between combustion amount and fan rotation speed.

  Referring to FIG. 1, reference numeral 1 denotes a burner including an all-primary combustion burner having a combustion surface 1a on which an air-fuel mixture (a mixed gas of air and fuel gas) is jetted and burned. A fan 2 is connected to the burner 1, and a fuel gas is mixed with air by the premixing device A according to the embodiment of the present invention, and the mixture is supplied to the burner 1 through the fan 2. . The premixing device A includes an air supply path 3 for supplying air, a gas supply path 4 for supplying fuel gas, and an air-fuel mixture path 5 on the suction side of the fan 2. An on-off valve 4 a and a proportional valve 4 b serving as a flow rate adjusting valve are interposed in the upstream portion of the gas supply path 4. The premixing device A further includes an air resistance switching means for switching the ventilation resistance of the air supply path 3 between large and small, and a gas resistance switching means for switching the ventilation resistance of the portion of the gas supply path 4 on the downstream side of the proportional valve 4b. And.

  During combustion of the burner 1, the energization current (proportional valve current) to the proportional valve 4 b is controlled so that an amount of fuel gas corresponding to the required combustion amount is supplied, and the air-fuel mixture supplied to the burner 1 is empty. The rotation speed of the fan 2 (fan rotation speed) is controlled in accordance with the required combustion amount so that the fuel ratio becomes constant. However, the required combustion amount becomes a predetermined value or less, and the fan rotation speed has a proportional characteristic of the air flow rate. When the rotation speed becomes lower than the lower limit rotation speed that can be maintained or the proportional valve current becomes lower than the lower limit current that can maintain the proportional characteristic of the gas supply amount, it becomes impossible to supply air or fuel gas in an amount corresponding to the required combustion amount.

  Therefore, when the required combustion amount becomes a predetermined value or less, the ventilation resistance of the air supply path 3 is increased by the air resistance switching means, and the ventilation resistance of the gas supply path 4 is increased by the gas resistance switching means. According to this, it is possible to supply an amount of air or fuel gas corresponding to the required combustion amount equal to or less than a predetermined value without setting the fan rotation speed or the proportional valve current below the lower limit rotation speed or the lower limit current. FIG. 4 shows the relationship between the combustion amount and the number of fan rotations. In FIG. 4, a is a characteristic line when the ventilation resistance of the air supply path 3 is reduced, and b is the ventilation resistance of the air supply path 3. It is a characteristic line in the case of.

  Here, in the present embodiment, the premixing device A includes a resistance switching valve V that constitutes an air resistance switching unit and a gas resistance switching unit that connect the air supply path 3 and the gas supply path 4 to the mixture path 5. Provided.

  The resistance switching valve V has a cylindrical valve body 6 that is rotatable and movable in the axial direction. An air inflow path 61 that can communicate with the air supply path 3, a gas inflow path 62 that can communicate with the gas supply path 4, and an outflow path 63 that can communicate with the air-fuel mixture path 5 are formed in the peripheral wall portion of the valve body 6. It has been established. Further, a merging passage 64 including a shaft hole that connects the air inflow passage 61 and the gas inflow passage 62 to the outflow passage 63 is formed in the valve body 6. And when the valve body 6 exists in one open position (position shown in FIG. 1) of an axial direction, the air inflow path 61, the gas inflow path 62, and the outflow path 63 are respectively the air supply path 3, the gas supply path 4, and When the valve body 6 is in communication with the air-fuel mixture passage 5 and the valve body 6 is in the other axially closed position (position shown in FIG. 2), the air inflow passage 61, the gas inflow passage 62 and the outflow passage 63, and the air supply passage 3, The communication with the gas supply path 4 and the gas mixture path 5 is cut off.

  On one end side of the valve body 6, a spring 7 as an urging means for urging the valve body 6 toward the closed position and an electromagnetic actuator 8 are arranged. The electromagnetic actuator 8 includes a plunger 8a that is press-fitted into the merging passage 64 at one end of the valve body 6, and a fixed iron core 8b that faces the outer end of the plunger 8a. Then, when the electromagnetic actuator 8 is energized, the plunger 8a is magnetically attracted toward the fixed iron core 8b and moves in one axial direction, so that the valve element 6 moves to the open position against the biasing force of the spring 7. I have to.

  A motor 9 is disposed on the other end side of the valve body 6. A shaft member 9b having a non-circular cross-section that is press-fitted into the confluence passage 64 at the other end of the valve body 6 is fitted to the rotor 9a of the motor 9 so as to be slidable in the axial direction while preventing rotation. The valve body 6 rotates through the shaft member 9b by the operation of 9. Then, by rotating the valve body 6 in the open position, the communication opening degree of each of the air inflow path 61 and the gas inflow path 62 with respect to the air supply path 3 and the gas supply path 4 is changed to be large or small. .

  This point will be described in detail. As shown in FIG. 3A, the air inflow passage 61 is composed of a large-diameter first passage 61a and a small-diameter second passage 61b formed with an angular difference in the circumferential direction. As shown in FIG. 3B, the gas inflow passage 62 is also composed of a relatively large-diameter first passage 62a and a small-diameter second passage 62b formed with an angular difference in the circumferential direction. The valve body 6 has a low resistance position where the first passage 61a of the air inflow passage 61 and the first passage 62a of the gas inflow passage 62 communicate with the air supply passage 3 and the gas supply passage 4, respectively, and an air inflow passage. The second passage 61b of 61 and the second passage 62b of the gas inflow passage 62 can be rotated by the motor 9 to a high resistance position (position shown in FIG. 3) communicating with the air supply passage 3 and the gas supply passage 4, respectively. I am doing so. The outflow passage 63 is formed so as to communicate with the air-fuel mixture passage 5 at the same communication opening degree at both the low resistance position and the high resistance position.

  When the valve body 6 is in the low resistance position, the communication opening degree of the air inflow path 61 and the gas inflow path 62 with respect to the air supply path 3 and the gas supply path 4 becomes large, and the ventilation of the air supply path 3 As the resistance decreases, the ventilation resistance in the portion of the gas supply path 4 on the downstream side of the proportional valve 4b decreases. On the other hand, when the valve body 6 is in the high resistance position, the communication opening degree of the air inflow path 61 and the gas inflow path 62 with respect to the air supply path 3 and the gas supply path 4 becomes small, and the air supply path 3 Of the gas supply path 4 on the downstream side of the proportional valve 4b.

  When the valve body 6 is moved to the closed position, the communication between the gas inflow path 62 and the gas supply path 4 is cut off, and the supply of fuel gas can be stopped at the downstream end of the gas supply path 4. Therefore, by moving the valve body 6 to the closed position when an abnormality occurs, the supply of the fuel gas to the burner 1 is quickly stopped, and the burner 1 can be extinguished with good responsiveness. Furthermore, in this embodiment, when the energization to the electromagnetic actuator 8 is stopped due to a power failure, the valve body 6 is moved to the closed position by the urging force of the spring 7, so that the burner 1 can be extinguished without requiring any control. It is safe.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to this. For example, in the above embodiment, when the valve body 6 is in the closed position, the air inflow path 61, the gas inflow path 62 and the outflow path 63, the air supply path 3, the gas supply path 4, and the gas mixture path 5 are communicated with each other. However, since it is sufficient that the supply of the fuel gas can be stopped, at least the communication between the gas inflow path 62 and the gas supply path 4 may be interrupted.

  Moreover, in the said embodiment, although the air inflow path 61 and the gas inflow path 62 are comprised by the large diameter 1st channel | paths 61a and 62a and the small diameter 2nd channel | paths 61b and 62b, respectively, 2nd channel | paths 61b and 62b are comprised. Instead, a narrow slit-shaped passage extending in the circumferential direction from the first passages 61a and 62a may be formed.

  Moreover, in the said embodiment, although the proportional valve 4b is used as a flow control valve interposed in the gas supply path 4, you may use the zero governor which adjusts secondary gas pressure to atmospheric pressure as a flow control valve. When the zero governor is used, the supply amount of the fuel gas changes according to the differential pressure between the atmospheric pressure as the secondary gas pressure and the negative pressure in the air supply path 3. Since the negative pressure in the air supply path 3 changes according to the fan rotation speed, the fuel gas supply amount changes according to the fan rotation speed, that is, the air supply amount.

  A ... premixing device, 1 ... burner, 2 ... fan, 3 ... air supply path, 4 ... gas supply path, 4b ... proportional valve (flow rate control valve), 5 ... mixture passage, V ... resistance switching valve, 6 ... Valve body 61... Air inflow path 62. Gas inflow path 63 63 Outflow path 64. Junction path 7 Spring (biasing means) 8 Electromagnetic actuator

Claims (2)

A premixing device that mixes fuel gas with air and supplies the air-fuel mixture to a burner via a fan, wherein an air supply path for supplying air and a gas supply path for supplying fuel gas are mixed on the suction side of the fan An air resistance switching means for switching the ventilation resistance of the air supply path between large and small, and a part of the gas supply path on the downstream side of the flow rate control valve. In what comprises gas resistance switching means for switching the ventilation resistance to large or small,
A resistance switching valve that constitutes an air resistance switching means and a gas resistance switching means for connecting the air supply path and the gas supply path to the mixture passage is provided,
The resistance switching valve has a cylindrical valve body that can rotate and move in the axial direction. An air inflow path that can communicate with the air supply path and a gas supply path communicate with the peripheral wall of the valve body. A possible gas inflow path and an outflow path that can communicate with the mixture passage are opened, and a confluence path that connects the air inflow path and the gas inflow path to the outflow path is formed inside the valve body.
When the valve body is in one open position in the axial direction, the air inflow path, the gas inflow path, and the outflow path communicate with the air supply path, the gas supply path, and the gas mixture path, respectively, and the valve body is in the other axial direction. When in the closed position, at least the communication between the gas inflow path and the gas supply path is cut off,
The air inflow path and the gas inflow path are formed so that the opening degree of the communication with respect to the air supply path and the gas supply path is changed to be large or small by rotating the valve body in the open position. Mixing equipment.   2. An urging means for urging the valve body toward the closed position, and an electromagnetic actuator for moving the valve body to the open position against the urging force of the urging means. Premixing equipment.

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