WO2015146425A1 - Blower - Google Patents

Abstract

The present invention is equipped with: a first impeller (5) provided to the apical end of a drive axis (2); a second impeller (7) provided closer towards the axis-direction base end of the drive axis (2) than the first impeller (5); a first casing (4) that rotatably houses the first impeller (5); and a second casing (6) that rotatably houses the second impeller (7). The size and/or shape of the casings (4) (6) that respectively house each impeller (5)(7) are differentiated so as to make the inner pressure (P1) of the first casing (4) and the inner pressure (P2) of the second casing (6) different. When a mixed gas of air and a combustible gas are passed through the first casing (4) and only air is passed through the second casing (6), the inner pressure (P2) of the second casing (6) surpasses the inner pressure (P1) of the first casing (4).

Description

Blower

The present invention relates to a blower, and more particularly to a blower that can discharge two gases having different pressures.

Conventionally, as disclosed in FIG. 1 of Patent Document 1 below, a gas-fired boiler is known in which a premixed gas of combustion air and gas is supplied to a main burner (2) and burned. In this boiler, in the duct (6) from the blower (5) to the main burner (2), the combustion air from the blower (5) is jetted and mixed with the gas from the gas supply path (10), and the The air-fuel mixture is supplied to the main burner (2).

JP 2006-266534 A

Although not limited to boilers, there are cases in which it is desired to obtain two gases with different pressures (the same gas with different pressures or different gases) in various devices. For example, when a boiler includes a main burner and a pilot burner for igniting the main burner, it may be desired to supply air of different pressures to the main burner and the pilot burner.

In the boiler described in Patent Document 1, gas is mixed into the combustion air downstream from the blower. However, there are cases where it is desired to mix gas into the combustion air upstream from the blower. That is, air and gas are sucked into the suction port of the blower, and the mixture may be supplied to the main burner by the blower. On the other hand, only the combustion air may be supplied to the pilot burner. In such a case, conventionally, it has not been possible to cope with only one blower.

Furthermore, when a mixture of air and gas is sucked into the suction port of the blower, the mixture may flow out to the back of the impeller and leak outside from the periphery of the drive shaft.

Therefore, the problem to be solved by the present invention is to provide a blower capable of discharging two gases having different pressures. Also, in a blower that can handle two gases, even if one gas is a mixture of air and gas, the blower that can prevent the mixture from leaking to the outside, or can prevent ignition even if a leak occurs It is an issue to provide.

The present invention has been made to solve the above problems, and a first aspect of the present invention includes a drive shaft that is rotated by a motor, a first impeller provided at a tip portion of the drive shaft, and a first impeller. A second impeller provided closer to the axial base end side of the drive shaft than the one impeller; a first casing that rotatably accommodates the first impeller and provided with a suction port and a discharge port; The impeller is rotatably accommodated, and includes a second casing provided with a suction port and a discharge port, and the impellers and the impellers are arranged so that the internal pressure of the first casing and the internal pressure of the second casing are different. The blower is characterized in that the sizes and / or shapes of the casings are different from each other.

According to the first aspect of the present invention, two impellers having different pressures can be discharged by rotating an impeller having a different configuration with a single drive shaft. At this time, the two gases may be the same gas or different gases.

According to a second aspect of the present invention, the second impeller is configured such that a blade is provided on a base end side in the axial direction of the main plate of the first impeller, a space in which the blade of the first impeller rotates, and the first impeller The space in which the blades of the two impellers rotate is partitioned by a partition, and the partition is a part of the first casing and / or the second casing.

According to the second aspect of the present invention, the blades of the first impeller and the blades of the second impeller are provided on each surface of the common main plate back to back. And the space where the blade | wing of each impeller rotates is partitioned off with a partition. By making the main plate of each impeller common, it can be configured compactly.

According to a third aspect of the present invention, the main plate is provided with a boss part protruding toward the axial base end side, and the blades of the second impeller are provided on the axial base end side of the boss part. The boss portion is rotatably fitted in a through-hole formed in the partition wall, and the first casing is provided with a suction port in the central portion of the side wall on the tip side in the axial direction, while being discharged on the outer peripheral portion. An outlet is provided, and the second casing is a blower characterized in that a suction port is provided on the side wall on the axial base end side and a discharge port is provided on the outer peripheral portion.

According to the third aspect of the present invention, it is possible to easily partition the space in which the blades of each impeller rotate by providing the boss portion on the main plate and rotatably inserting the boss portion into the through hole of the partition wall. it can. In addition, the first casing is provided with a suction port at the central portion in the radial direction and is provided with a discharge port at the outer peripheral portion. Therefore, the first casing can be easily applied to a centrifugal blower such as a turbo fan or a sirocco fan. On the other hand, the second casing is provided with a suction port on the side wall on the proximal end side in the axial direction, while a discharge port is provided on the outer peripheral portion. In addition to being easily applicable to a centrifugal blower such as the above, it can also be easily applied to a cascade fan having the same configuration (operating principle) as a cascade pump by providing a suction port on the radially outer side. In any case, since the suction port is provided on the axial base end side of the second casing, fluid leakage to the axial base end side due to suction of fluid from the axial base end side of the second casing (casing Leakage of fluid from the inside) can be prevented.

According to a fourth aspect of the present invention, an air-fuel mixture of air and combustible gas is passed through the first casing, while only air is passed through the second casing, and the internal pressure ( P2) is a blower characterized by being higher than the internal pressure (P1) of the first casing.

According to the fourth aspect of the present invention, the air / gas mixture can be discharged from the first casing, while only the air can be discharged from the second casing. Moreover, gas leakage from the first casing to the second casing can be reliably prevented by setting the internal pressure (P2) of the second casing higher than the internal pressure (P1) of the first casing.

Further, according to a fifth aspect of the present invention, an air-fuel mixture of air and combustible gas is passed through the first casing, while only air is passed through the second casing. Although the internal pressure (P2) is lower than the internal pressure (P1) of the first casing, the leakage flow rate (q) of the air-fuel mixture from the first casing to the second casing and the flow rate of only air in the second casing The gap between the main plate and the partition, the gap between the boss portion and the through hole, and the internal pressures (P1, P2) are set so that the mixed gas concentration with (Q2) is less than the flammable concentration. It is a fan characterized by having.

According to the fifth aspect of the present invention, air / gas mixture can be discharged from the first casing, while only air can be discharged from the second casing. Moreover, even if the internal pressure (P2) of the second casing is lower than the internal pressure (P1) of the first casing and gas leaks from the first casing to the second casing, gas is flowing into the first casing (that is, the first casing). During the rotation of the one impeller, since the second impeller is always rotating and ventilating, gas leakage to other than the discharge port of the second casing can be prevented. In addition, the leakage flow rate (q) from the first casing to the second casing is regulated by the relationship between the pressure loss due to the clearance of the leakage flow path from the first casing to the second casing and the internal pressure of each casing, After dilution with air in the two casings, it is less than the flammable concentration, so there is no risk of ignition.

According to the present invention, a blower capable of discharging two gases having different pressures can be realized. Also, in a blower that can handle two gases, even if one gas is a mixture of air and gas, the blower that can prevent the mixture from leaking to the outside, or can prevent ignition even if a leak occurs Can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS It is the schematic which shows Example 1 of the air blower of this invention, and has shown one part in cross section. It is the schematic which shows Example 2 of the air blower of this invention, and has shown one part in cross section.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic view showing Example 1 of the blower 1 of the present invention, and a part thereof is shown in cross section. In the illustrated example, the drive shaft 2 of the blower 1 extends from the motor 3 to the right side. Accordingly, in the following, the right side in FIG. 1 is referred to as the axial front end side, and the left side is referred to as the axial base end side. There is.

The blower 1 of this embodiment includes a first impeller 5 housed in a first casing 4, a second impeller 7 housed in a second casing 6, and a motor 3 that rotates these impellers 5, 7. The impellers 5 and 7 are fixed to a common drive shaft 2 and are rotated by the same motor 3. The drive shaft 2 is an output shaft of the motor 3 in this embodiment.

The first impeller 5 is provided at the front end of the drive shaft 2 in the axial direction, and the second impeller 7 is provided at the base end side in the axial direction of the drive shaft 2 relative to the first impeller 5. Although details will be described later, in the present embodiment, a second impeller 7 is provided on the back surface of the main plate 8 of the first impeller 5. In the present embodiment, the first casing 4 and the second casing 6 are integrally formed with the partition wall 9 as a boundary, but may be formed separately. Further, each casing 4, 6 may be composed of a plurality of members. In this case, the partition wall 9 can be configured as a part of the first casing 4 and / or the second casing 6.

The first impeller 5 has a configuration similar to that of a conventionally known centrifugal blower impeller. The first impeller 5 may be formed in an open type without the side plate 10, but in the present embodiment, it is formed in a closed type having the side plate 10. Specifically, the first impeller 5 is configured by providing a plurality of blades 11 at regular intervals in the circumferential direction between the main plate 8 and the side plate 10. The main plate 8 has a disc shape provided perpendicular to the drive shaft 2, and is disposed in close proximity to the left side wall 4 a (partition wall 9) of the first casing 4. A boss 12 is formed at the center of the main plate 8 so as to protrude toward the proximal end in the axial direction, and a bulge 13 is formed as protruding toward the distal end in the axial direction.

The main plate 8 is provided with a plurality of blades 11 at equal intervals in the circumferential direction on the outer peripheral side of the bulging portion 13. Each blade 11 is provided between the main plate 8 and the side plate 10. The blade 11 of the first impeller 5 is typically a rearward blade (a blade whose outer end portion is inclined in the direction opposite to the rotation direction), but in some cases, a forward blade (a blade whose outer end portion is inclined in the rotation direction). Alternatively, it may be a radial blade (a blade along the radial direction).

The side plate 10 is formed of an annular plate material, and is formed in an arc shape so as to go to the distal end side in the axial direction as it goes inward in the radial direction. A shaped portion 14 is formed. The outer peripheral portion on the front end side of the cylindrical portion 14 is formed to have a slightly small diameter, and the enlarged diameter hole of the suction port 15 of the first casing 4 is fitted into the small diameter portion. Thereby, the opening of the cylindrical portion 14 of the first impeller 5 is arranged continuously with the suction port 15 of the first casing 4.

The first casing 4 has generally the same configuration as a spiral casing of a conventionally known centrifugal blower. The first casing 4 has a hollow structure that accommodates the first impeller 5 and includes a fluid suction port 15 and a discharge port 16. The suction port 15 is provided in the center portion of the right side wall 4 b of the first casing 4, while the discharge port 16 is provided in the outer peripheral portion of the first casing 4.

The first casing 4 has a left side wall 4a and a right side wall 4b perpendicular to the drive shaft 2. On the outer peripheral portion of the left side wall 4a of the first casing 4, an inclined wall 4c that goes to the left as it goes outward is formed, and then a side wall 4d that is perpendicular to the drive shaft 2 is formed again. On the other hand, a cylindrical portion 4 e is formed at the center of the right side wall 4 b of the first casing 4 so as to extend to the right side, and the hollow hole serves as a suction port 15. As described above, a diameter-expanded hole is formed in the inner peripheral portion on the proximal end side of the cylindrical portion 4e so that the distal-side small diameter portion of the cylindrical portion 14 of the first impeller 5 is rotatably fitted.

On the other hand, the outer peripheral portion of the first casing 4 is formed in a single spiral curved portion in a side view when the blower 1 of FIG. 1 is viewed from the left or right, and a tangential direction is formed at the end of the curved portion. A cylindrical portion 4f is provided so as to extend to the top. In other words, the outer peripheral wall of the first casing 4 is formed such that the radius gradually increases from the center as it goes in the circumferential direction, and the cylindrical portion 4f is provided at a location where the radius is the largest. And the hollow hole of the cylindrical part 4f is made into the discharge outlet 16. FIG.

The second impeller 7 has a smaller outer diameter than the first impeller 5 in this embodiment, and is configured by providing blades 17 on the back surface (axially proximal end side) of the main plate 8 of the first impeller 5. Specifically, a boss portion 12 is formed at the center portion of the main plate 8 of the first impeller 5 so as to protrude toward the proximal end side in the axial direction. A blade 17 of the two impeller 7 is provided. Here, the blades 17 of the second impeller 7 are provided on the outer peripheral portion of the protruding tip portion of the boss portion 12 at equal intervals in the circumferential direction. As a result, the second impeller 7 is connected to the short cylindrical body portion 18 (the portion of the boss portion 12 excluding the blades 17) formed coaxially with the drive shaft 2 and the outer peripheral portion of the body portion 18. And blades 17 provided at equal intervals in the circumferential direction. The right end portion (end portion on the main plate 8 side) of the boss portion 12 is rotatably fitted in the through hole 22 formed in the center portion of the left side wall 4a of the first casing 4.

The second casing 6 has a hollow structure that accommodates the second impeller 7 and includes a fluid suction port 19 and a discharge port 20. Specifically, the second casing 6 has a left side wall 6 a and a right side wall 6 b that are perpendicular to the drive shaft 2. The left side wall 6a of the second casing 6 is disposed in close proximity to and facing the left end surface of the second impeller 7 (the left end surface of the main body 18). In addition, in the center part of the main-body part 18 of the 2nd impeller 7, the column-shaped slight convex part protrudes a little on the left side, The convex part can rotate in the slight recessed part of the left side wall of the 2nd casing 6. Inset.

On the other hand, the right side wall 6b of the second casing 6 is also a part of the left side wall 4a of the first casing 4 in this embodiment, and the blades 11 of the first impeller 5 rotate together with the left side wall 4a of the first casing 4. It functions as a partition wall 9 that partitions the space from the space where the blades 17 of the second impeller 7 rotate. In other words, the left side wall 4a of the first casing 4 serves as the partition wall 9 that also serves as the right side wall 6b of the second casing 6 on the radially inner side, and partitions the space in which the blades 11 and 17 of the impellers 5 and 7 rotate. The partition wall 9 is disposed so as to face and face the left end surface of the main plate 8 of the first impeller 5, and the boss portion 12 is rotatably fitted in a through hole 22 formed in the center portion. A fluid flow path 21 is formed in the outer periphery of the second casing 6.

In the present embodiment, the left side wall 6a of the second casing 6 is provided with a thick cylindrical portion 29 extending toward the axial base end side. The thick cylindrical portion 29 is disposed coaxially with the drive shaft 2 through the hollow shaft. The thick tube portion 29 has an outer peripheral portion of the axially distal end portion thereof airtightly fixed to an outer peripheral portion of the left side wall 6a of the second casing 6, while the right end portion of the casing of the motor 3 is abutted against the axial base end portion. Fixed.

The outer peripheral portion of the left side wall 6a of the second casing 6 is formed to bulge to the left side, and the outer peripheral portion of the right end surface of the thick tube portion 29 is airtightly fixed to the bulged portion 6a ′. Accordingly, a gap is opened between the left side wall 6a of the second casing 6 and the right end surface of the thick-walled cylindrical portion 29 on the radially inner side of the bulging portion 6a ′ of the second casing 6. This gap communicates with the suction portion 23 on the outer peripheral surface of the thick-walled cylinder portion 29 via the communication passage 30 formed in the thick-walled cylinder portion 29. In other words, the suction part 23 is provided on the outer peripheral surface of the thick-walled cylinder part 29, and the suction part 23 opens into the gap via the communication path 30. In addition, a suction port 19 is formed at a circumferential direction setting place in the bulging portion 6 a ′ of the second casing 6, and the clearance and the fluid flow path 21 in the second casing 6 are formed through the suction port 19. And communicate. On the other hand, a discharge port 20 is provided on the outer peripheral portion of the second casing 6 so as to be separated from the suction port 19 by a set distance in the circumferential direction.

In the case of the blower 1 of the present embodiment, the first casing 4 and the first impeller 5 constitute a centrifugal blower such as a turbofan. That is, when the motor 3 is rotated, the first impeller 5 is rotated, and the gas is sucked from the suction port 15 at the central portion in the radial direction and discharged to the discharge port 16 at the outer peripheral portion. On the other hand, the second casing 6 and the second impeller 7 constitute a cascade fan. That is, when the motor 3 is rotated, the second impeller 7 is rotated, and gas is sucked from the suction port 19 on the outer peripheral portion and discharged to the discharge port 20 on the outer peripheral portion.

The cascade fan is a blower having the same configuration as the cascade pump (in other words, the same operating principle). Specifically, the second impeller 7 is configured such that blades 17 are provided at equal intervals in the circumferential direction on the outer peripheral portion of the substantially short cylindrical main body portion 18, while the second casing 6 includes the second impeller 7. It is a substantially short cylindrical container that is covered, and is provided with a suction port 19 and a discharge port 20 that are spaced apart by a set distance in the circumferential direction. A gap (gap along the circumferential direction) between the second impeller 7 and the second casing 6 is a partition portion (not shown) on the side where the circumferential separation distance between the suction port 19 and the discharge port 20 is short. On the side where the circumferential separation distance is long, such a partition is not provided and the fluid flow path 21 is secured. Therefore, when the second impeller 7 is rotated in the second casing 6, gas can be sucked from the suction port 19 and discharged to the discharge port 20 by one-way. In such a configuration, the flow rate is small as compared with the centrifugal blower, but it is easy to adopt a configuration in which the fluid pressure is increased and discharged. In addition, in this embodiment, even if the motor 3 and the drive shaft 2 are on the proximal end side in the axial direction of the second casing 6, the air can be sucked from the outer peripheral portion via the thick cylindrical portion 29, and a filter (not shown) is attached. Is also easier.

In the blower 1 of the present embodiment, the impellers 5 and 7 are held on the same drive shaft 2 and rotated. However, the configurations of the impellers 5 and 7 and the casings 4 and 6 (in other words, the size and / or Since the shapes are made different from each other, the internal pressure P1 of the first casing 4 and the internal pressure P2 of the second casing 6 can be made different. In other words, the discharge pressure P1 from the first casing 4 and the discharge pressure P2 from the second casing 6 can be made different from each other to obtain two gases having different pressures. At this time, the two gases may be the same gas or different gases. For example, air may be passed through both casings 4 and 6, or, as described below, a mixture of air and combustible gas is passed through the first casing 4, while only air is passed through the second casing 6. Also good.

The blower 1 of the present embodiment is preferably applied to a gas-fired boiler provided with a premix burner. In this case, a mixture of air and gas is sucked into the suction port 15 of the first casing 4, mixed in the first casing 4, then sent to the burner and burned. In order to supply the air-fuel mixture to the first casing 4, for example, the suction port 15 of the first casing 4 sucks gas from the gas supply source as the air is sucked into the suction port 15, and goes to the suction port together with air. A gas suction mechanism (not shown) may be provided.

On the other hand, air is sucked into the suction port 19 of the second casing 6 through the filter and discharged from the discharge port 20 of the second casing 6. Although this air is not particularly limited in its use, for example, it is used as combustion air to a pilot burner for igniting a main burner to which an air-fuel mixture from the first casing 4 is supplied. Or it is set as air for cooling or air seal of the attachment part of a main burner. In other words, the air-fuel mixture from the first casing 4 is supplied from the wind box to the boiler can body, and the main burner is provided at the end of the wind box on the can body side, but the gap at the connection between the wind box and the boiler can body is sealed. The cooling air for the packing seal to be stopped and the air sealing air for preventing the combustion gas from leaking from such a connecting portion. Alternatively, when a viewing window that can visually recognize the state of the boiler can (particularly the burner portion) is provided, the ventilation air is used to prevent condensation on the viewing window.

Even when applied to a gas-fired boiler equipped with a premixing burner, only air is passed through the first casing 4 and the gas from the gas supply source is jetted into the combustion air from the first casing 4 downstream of the blower 1. And may be premixed. Alternatively, in the oil-fired boiler, air from the first casing 4 is supplied to the burner and used as combustion air for fuel sprayed from the burner, while air from the second casing 6 (from the first casing 4). The air for the spraying into the oil spray nozzle of the burner may be used in a smaller amount and a higher pressure than the air.

By the way, in the case of the blower 1 of the present embodiment, since the first impeller 5 and the second impeller 7 are interlocked, for example, air from the second casing 6 is necessary, but the air-fuel mixture from the first casing 4 is Even if it may be temporarily unnecessary, only the first impeller 5 cannot be stopped. In that case, for example, a damper may be provided on the suction side or the discharge side of the first casing 4 and the damper may be closed.

In the case where only the air is passed through the second casing 6 while the air-fuel mixture of air and combustible gas is passed through the first casing 4, the following (a) or (b ) Is preferable.

≪ (a) First configuration≫
The internal pressure P2 of the second casing 6 is set higher than the internal pressure P1 of the first casing 4. Specifically, the casings 4 and 6 and the impellers 5 and 7 are configured so as to always have such a pressure relationship. Thereby, even if air leaks from the second casing 6 to the first casing 4, gas does not leak from the first casing 4 to the second casing 6. As described above, when the first casing 4 and the first impeller 5 constitute a centrifugal blower, while the second casing 6 and the second impeller 7 constitute a cascade fan, the discharge pressure of the cascade fan can be easily increased.

≪ (b) Second configuration≫
Although the internal pressure P2 of the second casing 6 is lower than the internal pressure P1 of the first casing 4, it is suppressed to a flow rate that does not ignite even if gas leaks from the first casing 4 to the second casing 6. Specifically, the air-fuel mixture (gas concentration is usually 7 to 10%) leaks from the first casing 4 to the second casing 6 at the flow rate q, while the ventilation of only air in the second casing 6 is the flow rate Q2. In this case, after the air-fuel mixture leaked from the first casing 4 to the second casing 6 is mixed with the air in the second casing 6, the concentration of the mixed gas is less than the flammable concentration (for example, 4% or less for city gas 13A). Configured. That is, the gap between the main plate 8 and the partition wall 9 (the axial separation dimension), the gap between the boss portion 12 and the through hole 22 (the radial separation gap), and the internal pressures P1 and P2 (the differential pressure between them) are set. . In this case, even if a gas leak from the first casing 4 to the second casing 6 occurs, the second impeller 7 always rotates while the gas is flowing into the first casing 4 (that is, while the first impeller 5 is rotating). Since the air is ventilated, gas leakage to other than the discharge port 20 of the second casing 6 can be prevented. Moreover, the leakage flow rate q from the first casing 4 to the second casing 6 is determined by the relationship between the pressure loss due to the clearance of the leakage flow path from the first casing 4 to the second casing 6 and the internal pressure of each casing 4, 6. Regulating and lowering the flammable concentration after dilution with air in the second casing 6 (that is, lower than the lower limit of combustion), there is no risk of ignition.

FIG. 2 is a schematic view showing Example 2 of the blower 1 of the present invention, and a part thereof is shown in cross section. The blower 1 according to the second embodiment is basically the same as the blower 1 according to the first embodiment, including the configuration, usage, pressure relationship, and the like. Therefore, in the following description, differences between the two will be mainly described, and corresponding portions will be described with the same reference numerals. Descriptions of matters common to both embodiments are omitted.

In the first embodiment, the second casing 6 and the second impeller 7 constitute a cascade fan, but in the second embodiment, the second casing 6 and the second impeller 7 constitute a centrifugal blower. In this case, the second casing 6 is configured as a spiral casing similarly to the first casing 4. And as for the 2nd casing 6, while the suction inlet 19 is formed in a radial direction center part, the discharge outlet 20 is formed in an outer peripheral part.

More specifically, a cylindrical portion 24 is provided at the central portion of the left side wall 6a of the second casing 6 so as to extend toward the axial base end side. The cylindrical portion 24 is disposed coaxially with the drive shaft 2 and includes flanges 25 and 26 at both ends in the axial direction. The motor 3 is attached to the flange 25 at the proximal end portion in the axial direction, and the flange 26 at the distal end portion in the axial direction is overlapped and fixed to the left side wall 6 a of the second casing 6. Openings are formed in the circumferential side wall of the cylindrical portion 24 at a plurality of locations in the circumferential direction, and the openings serve as the suction portions 23. And the hollow hole of the cylinder part 24 is connected with the suction inlet 19 of the left side wall 6a of the 2nd casing 6. FIG.

The second impeller 7 is configured by providing a plurality of blades 17 at equal intervals in the circumferential direction between the main plate 18 and the side plate 27, similarly to the first impeller 5. Also in this case, the blade 17 of the second impeller 7 is typically a backward blade, but may be a forward blade or a radial blade depending on circumstances.

The blades 17 of the second impeller 7 are provided on the back surface of the main plate 8 of the first impeller 5. More specifically, the main body portion 18 of the second impeller 7 in the first embodiment is the main plate 18 of the second impeller 7 in the first embodiment. Further, in the second embodiment, the side plate 27 of the second impeller 7 is inclined toward the proximal side in the axial direction as it goes radially inward, and then a cylindrical portion 28 is formed at the center. And the cylindrical part 28 is rotatably fitted in the suction inlet 19 formed in the center part of the left side wall 6a of the second casing 6. With this configuration, when the motor 3 is driven, air is sucked from the opening (19) of the cylindrical portion 28, and is sucked into the hollow hole of the cylindrical portion 28 of the side plate 27 of the second impeller 7, and the second It discharges to the discharge outlet 20 formed in the outer peripheral part of the casing 6.

In the second embodiment, the first casing 4 is formed such that the left side wall 4a is only a surface perpendicular to the drive shaft 2, and the right side wall 4b is curved so as to be along the outside of the side plate 10 of the first impeller 5. In addition, an inclined wall 4c that goes to the right as it goes outward is formed on the outer peripheral portion, and then a side wall 4d that is perpendicular to the drive shaft 2 is formed again.

Also in the case of the second embodiment, since the configurations (in other words, size and / or shape) of the impellers 5 and 7 and the casings 4 and 6 are different from each other, the internal pressure P1 of the first casing 4 and the second casing The internal pressure P2 of 6 can be made different. In other words, the discharge pressure P1 from the first casing 4 and the discharge pressure P2 from the second casing 6 can be made different from each other to obtain two gases having different pressures. At this time, the two gases may be the same gas or different gases. For example, air may be passed through both casings 4 and 6, or a mixture of air and combustible gas may be passed through the first casing 4, while only air may be passed through the second casing 6. When applied to a gas-fired boiler equipped with a premix burner, a mixture of air and gas is supplied to the suction port 15 of the first casing 4, and only air is supplied to the suction port 19 of the second casing 6, Used in the same manner as in Example 1.

Also in the case of the second embodiment, it can be configured in any of the << (a) first configuration >> and << (b) second configuration >> described in the first embodiment. However, the second casing 6 and the second impeller 7 can be used. Considering that the centrifugal blower configured is smaller than the centrifugal blower including the first casing 4 and the first impeller 5, << (b) the second method >> can be suitably applied. That is, the internal pressure P2 of the second casing 6 is lower than the internal pressure P1 of the first casing 4, but only the leakage flow rate q of the air-fuel mixture from the first casing 4 to the second casing 6 and the air in the second casing 6. It is preferable that the gap between the main plate 8 and the partition wall 9, the gap between the boss portion 12 and the through hole 22, and the internal pressures P1 and P2 are set so that the mixed gas concentration with the flow rate Q2 is less than the flammable concentration. .

By the way, in the first embodiment, a relatively thick cylindrical portion 29 is disposed between the second casing 6 and the motor 3, and opens to the outer peripheral surface and the right end surface of the peripheral side wall of the cylindrical portion 29. The communication path 30 was provided, and the gap between the left side wall 6a of the second casing 6 and the right end surface of the cylindrical portion 29 was communicated with the outside. A suction port 19 is provided on the left side wall 6a of the second casing 6 outside the central hole through which the drive shaft 2 is passed. On the other hand, in the second embodiment, a relatively thin cylindrical portion 24 is disposed between the second casing 6 and the motor 3, and an opening 23 is provided in the peripheral side wall of the cylindrical portion 24, so that the left side of the second casing 6 is provided. The suction port 19 of the wall 6 a was communicated with the outside through the hollow hole and the opening 23 of the cylindrical portion 24. At this time, the left side wall 6a of the second casing 6 was provided with a suction port 19 at a central portion through which the drive shaft 2 passes. Therefore, in any embodiment, while the impellers 5 and 7 are rotating, on the left side of the left side wall 6a of the second casing 6, a flow of outside air sucked into the suction port 19 of the second casing 6 occurs. Fluid leakage to the motor 3 side is prevented.

The blower 1 of the present invention is not limited to the configuration of each of the embodiments described above, and can be changed as appropriate. In particular, the first impeller 5 provided at the distal end portion of the drive shaft 2, the second impeller 7 provided closer to the base end side in the axial direction of the drive shaft 2 than the first impeller 5, and the first impeller 5 are rotatable. Each impeller 5 is provided with a first casing 4 to be accommodated and a second casing 6 that accommodates the second impeller 7 in a rotatable manner so that the internal pressure P1 of the first casing 4 and the internal pressure P2 of the second casing 6 are different. 7 and the casings 4 and 6 can be changed as appropriate as long as the sizes and / or shapes of the casings 4 and 6 are different from each other.

In particular, in the embodiment, the type (type) of the blower constituted by the first casing 4 and the first impeller 5 and the type (type) of the blower constituted by the second casing 6 and the second impeller 7 are as described above. Not limited to each embodiment, it can be changed as appropriate. For example, the blower configured by the first casing 4 and the first impeller 5 may be a sirocco fan.

In each of the above embodiments, the blades 17 of the second impeller 7 are provided on the back surface of the main plate 8 of the first impeller 5 so that the impellers 5 and 7 are integrally formed. You may comprise. In that case, the first impeller 5 and the second impeller 7 may be provided separately in the axial direction of the drive shaft 2. Accordingly, the first casing 4 and the second casing 6 may be provided separately. However, when the air-fuel mixture of combustion air and fuel gas is passed through the first casing 4, the above-described << (a) first configuration is used from the viewpoint of gas leakage countermeasures to the back surface of the main plate 8 of the first impeller 5. >> or << (b) Second Configuration >> is preferably connected to the second casing 6 at the axially proximal end of the first casing 4. In other words, it is preferable to partition the space in which the blades 11 and 17 of the impellers 5 and 7 rotate as a structure in which one casing is partitioned by the partition wall 9.

In addition, although the first impeller 5 in each of the embodiments and the second impeller 7 in the embodiment 2 are closed types including the side plates 10 and 27, they may be open types without the side plates 10 and 27. Further, the first casing 4 in each of the embodiments and the second casing 6 in the embodiment 2 are spiral casings. The spiral casings include guide vanes outside the rotation region of the impellers 5 and 7. (Diffuser) may be provided. The internal pressure of each casing 4 and 6 can be changed also by the presence or absence and structure of a diffuser.

Further, the cylindrical portion 24 of the second embodiment is applied instead of the thick cylindrical portion 29 of the first embodiment, or conversely, the thick cylindrical portion 29 of the first embodiment is applied instead of the cylindrical portion 24 of the second embodiment. You may do it. In short, in each embodiment, it is only necessary that outside air can be sucked into the suction port 19 provided on the axially proximal end side of the second casing 6, and it is not essential to install the thick tube portion 29 and the tube portion 24. . For example, in the first embodiment, the thick tube portion 29 may be omitted, the motor 3 may be fixed to the left side wall 6 a of the second casing 6, and the communication path 30 may be provided in the casing of the motor 3.

The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiments or examples are merely examples in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the scope of claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Blower 2 Drive shaft 3 Motor 4 1st casing (4a: Left side wall, 4b: Right side wall, 4c: Inclined wall, 4d: Side wall, 4e: Cylindrical part, 4f: Cylindrical part)
5 1st impeller 6 2nd casing (6a: left side wall, 6a ': bulging part, 6b: right side wall)
7 Second impeller 8 Main plate (first impeller) 9 Bulkhead 10 Side plate (first impeller) Side plate 11 (First impeller) Blade 12 (First impeller) Boss portion 13 (First impeller) bulging portion 14 Cylindrical portion (of the first impeller) 15 Suction port of the first casing 16 Discharge port of the first casing 17 Blade of the second impeller 18 Main body of the second impeller (main plate)
19 Suction port (to the second casing) 20 Discharge port (of the second casing) 21 Fluid flow path 22 Through hole 23 Suction portion 24 Tube portion (24a: opening)
25 (Axial base end) flange 26 (Axial front end) flange 27 (Second impeller) side plate 28 (Second impeller) cylindrical part 29 Thick cylindrical part 30 Communication path

Claims (5)

A drive shaft rotated by a motor;
A first impeller provided at the tip of the drive shaft;
A second impeller provided on the axial base end side of the drive shaft from the first impeller;
A first casing that rotatably accommodates the first impeller and is provided with a suction port and a discharge port;
The second impeller is rotatably accommodated, and includes a second casing provided with a suction port and a discharge port,
The blower characterized in that the impellers and the casings have different sizes and / or shapes so that the internal pressure of the first casing and the internal pressure of the second casing are different. The second impeller is configured by providing a blade on the axial base end side of the main plate of the first impeller,
The space in which the blades of the first impeller rotate and the space in which the blades of the second impeller rotate are partitioned by a partition wall,
The blower according to claim 1, wherein the partition wall is a part of the first casing and / or the second casing. The main plate is provided with a boss portion protruding toward the axial base end side,
A blade of the second impeller is provided on the base end side in the axial direction of the boss portion,
The boss portion is rotatably fitted in a through hole formed in the partition wall,
The first casing is provided with a suction port in the central portion of the side wall on the axial front end side, and provided with a discharge port in the outer peripheral portion,
The blower according to claim 2, wherein the second casing is provided with a suction port on a side wall on an axially proximal end side, and provided with a discharge port on an outer peripheral portion. While the air-fuel mixture of air and combustible gas is passed through the first casing, only the air is passed through the second casing,
The blower according to any one of claims 1 to 3, wherein an internal pressure (P2) of the second casing is higher than an internal pressure (P1) of the first casing. While the air-fuel mixture of air and combustible gas is passed through the first casing, only the air is passed through the second casing,
Although the internal pressure (P2) of the second casing is lower than the internal pressure (P1) of the first casing, the leakage flow rate (q) of the air-fuel mixture from the first casing to the second casing and the second casing So that the mixed gas concentration with the air-only flow rate (Q2) is less than the flammable concentration, the gap between the main plate and the partition wall, the gap between the boss portion and the through hole, and the internal pressures (P1, The blower according to claim 2 or 3, wherein P2) is set.

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