JP7510897B2 - Blower - Google Patents

Description

The present invention relates to a blower for use in a combustion device. In particular, the present invention relates to a water drainage structure for a blower that draws in combustion exhaust gas after it has passed through a heat exchanger of the combustion device and discharges it outside the combustion device.

A blower used in a combustion device such as a water heater has an electric motor, a cylindrical impeller with multiple blades arranged radially around the rotating shaft of the electric motor, and a fan casing that houses the impeller. The main body of the electric motor is fixed to the outside of one side of the fan casing, and the rotating shaft extends from the main body toward the inside of the fan casing. The fan casing houses the impeller connected to the rotating shaft, and forms an air passage that guides the airflow generated by the rotation of the impeller.

The fan casing is formed in a scroll shape so that the radius of the impeller relative to the impeller's axis of rotation increases in the direction of rotation of the impeller. An intake port is provided on the other side of the fan casing. Furthermore, an air passage that extends tangentially around the periphery of the fan casing and connects to the exhaust port is provided.

A so-called tension-type combustion device has been proposed (see, for example, Patent Document 1), in which a blower is provided downstream of the heat exchanger in the flow path of the combustion exhaust, and the blower sucks in the combustion exhaust after passing through the heat exchanger and discharges it to the outside. In this tension-type combustion device, when the blower is operated, the combustion chamber and heat exchange chamber located upstream of the blower become negative pressure. Therefore, these housings do not require high sealing properties to prevent leakage of the combustion exhaust, and the structure can be simplified compared to a push-in type combustion device.

On the other hand, in a combustion device in which the blower is located downstream of the heat exchanger, the combustion exhaust gas may condense in the blower, generating drain water, or rainwater may enter the blower from the exhaust pipe connected downstream of the blower, causing water to accumulate inside the blower. For this reason, it is necessary to prevent such accumulated water from interfering with the impeller and corroding the blower. In Patent Document 1, the blower is placed horizontally above the heat exchanger, and drain holes are opened on the outermost periphery of the blower's fan casing, and the fan discharge pressure drains the accumulated water inside the blower from the drain holes through a drain pipe into a drain tank.

JP 2015-143602 A

However, in a tension-type combustion device, the exhaust gas is sucked into the blower during combustion operation. Therefore, when the impeller is rotated, the exhaust gas, together with the accumulated water, is discharged to the outside through the drain holes on the outermost periphery of the fan casing, causing the exhaust gas to leak through the drain tank connected to the drain pipe. In particular, if the exhaust pipe is clogged with dust or a backwind occurs in the exhaust pipe that communicates with the outside, the internal pressure inside the fan casing increases, making the exhaust gas more likely to leak.

The present invention was made to solve the above problems, and the object of the present invention is to drain the water stagnating inside the blower of a tension-type combustion device and to prevent the combustion exhaust gas from leaking outside the blower through the drain hole during combustion operation.

According to the present invention,
A vertically-mounted blower that sucks in combustion exhaust gas after passing through a heat exchanger and discharges it to the outside,
The fan has an impeller, a scroll-shaped fan casing that houses the impeller, and an electric motor that drives the impeller to rotate.
the fan casing has a first side surface on which an inlet port for drawing in exhaust gas from combustion opens laterally, a second side surface facing the first side surface and to which an electric motor is fixed, and a peripheral surface surrounding an outer periphery of an impeller and connected to an exhaust port for discharging exhaust gas from combustion,
The first side surface is below the lowest part of the impeller and is
A blower is provided having a drain hole above a joint between a first side surface and a peripheral surface .

According to this, the blower that draws in the combustion exhaust gas after passing through the heat exchanger is arranged vertically, so drain water and rainwater flow down to the lowest part of the blower, i.e., the lowest part of the circumferential surface of the fan casing. And, because the drain hole is provided below the lowest part of the impeller on the first side , even if water accumulates at the lowest part of the circumferential surface inside the fan casing, the accumulated water can be drained outside the blower before it interferes with the impeller.

On the other hand, the exhaust gas sucked into the inside of the impeller from the intake port is blown out towards the outside of the impeller, so the internal pressure inside the fan casing increases with distance from the outer periphery of the impeller, and the area inside the fan casing near the outermost periphery is under positive pressure. Therefore, when the blower is placed vertically, if a drain hole is provided at the bottom of the periphery of the fan casing where accumulated water accumulates, the exhaust gas will be discharged from the drain hole to the outside of the blower during combustion operation due to the fan discharge pressure.

However, according to the above-mentioned blower, the combustion exhaust gas is sucked into the inside of the impeller through the intake port opening on the first side surface of the fan casing, so that a large negative pressure state is formed inside the impeller, and the gap between the impeller and the opposing first side surface is in a negative pressure state. Therefore, a negative pressure state is also formed in a certain range radially outward from the outer periphery of the impeller, and a part of the combustion exhaust gas flowing outward from the outer periphery of the impeller is drawn back into the inside of the impeller through the gap between the impeller and the first side surface. Therefore, if a drain hole is formed radially outward from the outer periphery of the impeller, i.e., below the lowest part of the impeller and above the connecting part between the first side surface and the circumferential surface in the vertical direction of the lowest part of the impeller , it is possible to prevent the combustion exhaust gas from leaking out of the blower from the drain hole during combustion operation.

Preferably, in the above blower,
The suction port opens in a bell-mouth shape on the first side surface of the fan casing and has a suction passage extending from the outside to the inside of the first side surface of the fan casing .

As described above, according to the present invention, in a tension-type combustion device, it is possible to drain stagnant water inside the blower and prevent combustion exhaust from leaking outside the blower through the drain hole during combustion operation.

FIG. 1 is a schematic diagram showing an example of a combustion apparatus according to an embodiment of the present invention. FIG. 2 is a schematic partially exploded perspective view showing an example of a blower according to an embodiment of the present invention. FIG. 3 is a schematic vertical cross-sectional view showing an example of a blower according to an embodiment of the present invention. FIG. 4 is a distribution diagram showing the internal pressure in the blower according to the embodiment of the present invention.

The blower and combustion device according to the embodiment of the present invention will be specifically described below with reference to the attached drawings. As shown in FIG. 1, the combustion device according to the present embodiment is a water heater 1 that heats water supplied from a water supply pipe 71 into a heat exchanger 21 using the combustion exhaust of a burner 11, and supplies the water through a hot water outlet pipe 72 to a hot water supply terminal such as a shower or faucet (not shown).

The water heater 1 has an exterior casing, which includes a casing body 2 with an opening at the front, and an opening/closing door (not shown) for opening and closing the front opening of the casing body 2. In this specification, the front opening side of the casing body 2 is referred to as the front side, the side facing the front opening is referred to as the back side, the direction in which these face each other is referred to as the front-to-back direction, the direction that intersects the front-to-back direction and the horizontal direction is referred to as the left-to-right direction, and the direction that intersects the front-to-back direction and the height direction is referred to as the up-to-down direction.

Inside the casing body 2, from the bottom up, there are arranged a combustion chamber 10, a heat exchange chamber 20, and an exhaust chamber 30, and a blower 50 is attached to the left side of the exhaust chamber 30. An exhaust pipe 80 is connected to the upper wall of the casing body 2, which communicates with an exhaust port 55 of the blower 50 (described later) and discharges the combustion exhaust gas to the outside of the water heater 1.

A burner 11 is disposed below the combustion chamber 10. A gas supply pipe 70 that supplies fuel gas is connected to the burner 11. An ignition electrode 12 is disposed above the burner 11, and a distribution plate (not shown) is disposed below the burner 11. When the blower 50 is operated, air in the exterior casing is supplied to the burner 11 as combustion air through the distribution plate, and the ignition electrode 12 is operated to ignite the fuel gas, generating combustion exhaust. The combustion exhaust gas ejected from the burner 11 is supplied to the heat exchange chamber 20, and is discharged to the outside of the water heater 1 through the exhaust chamber 30 and the blower 50. Therefore, in this specification, the lower side where the combustion chamber 10 is provided corresponds to the upstream side of the flow path of the combustion exhaust gas, and the upper side opposite to the side where the combustion chamber 10 is provided corresponds to the downstream side of the flow path of the combustion exhaust gas.

The heat exchange chamber 20 has a generally rectangular box-shaped housing that is open at the top and bottom. The bottom end of the heat exchange chamber 20 is connected to the top end of the combustion chamber 10, and the top end of the heat exchange chamber 20 is connected to the bottom end of the exhaust chamber 30. The heat exchange chamber 20 incorporates a heat exchanger 21 that recovers heat from the combustion exhaust gas generated by the burner 11 and heats water supplied from the water supply pipe 71. The heat exchanger 21 has a plurality of heat transfer fins 211 and a heat transfer tube 212 that is inserted through each heat transfer fin 211. The heat transfer tube 212 is extended in a serpentine or spiral shape within the heat exchange chamber 20, with one end of the heat transfer tube 212 connected to the water supply pipe 71 and the other end of the heat transfer tube 212 connected to the hot water outlet pipe 72. Note that other heat transfer media may be used instead of water.

The exhaust chamber 30 has a housing that is generally inverted L-shaped when viewed from the front, in which a lower exhaust section 31 and an upper fan connection section 32 that is narrower in the left-right direction than the exhaust section 31 are integrally formed. The upper end of the fan connection section 32 is closed. An outlet 33 that opens to the left side is provided in the left wall of the fan connection section 32, and although not shown, a fastening section is provided on the periphery of the fan connection section 32 for connecting and fixing the blower 50.

2 and 3, the blower 50 has an impeller 51, a fan casing 53 that houses the impeller 51, and an electric motor 52 that drives the impeller 51 to rotate. The fan casing 53 has a flat fixed plate 530 with an intake port 54, and a fan casing body 531. The fan casing body 531 is integrally formed with a support plate 532 to which the body of the electric motor 52 is fixed on the outer side and from which the rotating shaft 521 extends toward the inside of the fan casing 53, and a belt-shaped peripheral wall plate 533 curved to surround the outer periphery of the impeller 51, and is open to the right and upward. The fixed plate 530 is joined to the fan casing body 531 at the periphery so as to cover the fan casing body 531 from the right side. Therefore, in this embodiment, the fixing plate 530 corresponds to the first side surface, the support plate 532 of the fan casing body 531 corresponds to the second side surface, and the peripheral wall plate 533 of the fan casing body 531 corresponds to the peripheral surface. The blower 50 is attached to the fan connection part 32 of the exhaust chamber 30 in a vertically placed state with the rotating shaft 521 extending horizontally. The fan casing body may be composed of two parts: a support plate that constitutes the second side surface, and a band-shaped peripheral wall plate that constitutes the peripheral surface. The fan casing may also be composed of a fan casing body in which the first side surface and the peripheral wall plate are integrally formed, and a support plate.

Although not shown, the fixing plate 530 has a fastening portion on the outer periphery. The blower 50 is connected and fixed to the fan connection portion 32 by screwing the fastening portion of the fixing plate 530 and the fastened portion of the fan connection portion 32 described above. The suction port 54 is opened in a bell-mouth shape at approximately the center of the fixing plate 530. When the blower 50 is attached to the fan connection portion 32 of the exhaust chamber 30, the suction port 54 communicates with the outlet port 33 that opens on the left wall of the fan connection portion 32. The suction port 54 is also provided so that its center is located on approximately the same line as the rotation shaft 521. When the blower 50 is attached to the fan connection portion 32 of the exhaust chamber 30, the fixing plate 530 has a small drain hole 7 opened vertically downward from the lowest part of the outer periphery of the impeller 51.

As shown in FIG. 3, the intake port 54 has an intake passage 540 that extends from the outside (right side in FIG. 3) of the fan casing 53 to the inside (left side in FIG. 3). The tip of the intake port 54 is located inside the impeller 51. When the blower 50 is operated, as shown by the dashed line, the combustion exhaust gas blown out from the outlet 33 of the exhaust chamber 30 is sucked into the inside of the impeller 51 from the tip of the intake port 54.

The impeller 51 is a cylindrical sirocco fan. The impeller 51 has a plurality of blades 511 formed elongated in the axial direction of the rotating shaft 521 of the electric motor 52, which are arranged radially at a predetermined interval from the rotating shaft 521. One end of each of the blades 511 is attached to the outer edge of the annular first rotating plate 512, and the other end of each blade is attached to the disk-shaped second rotating plate 513. The second rotating plate 513 is fixed at its center to the rotating shaft 521 of the electric motor 52, and the impeller 51 is driven to rotate around the rotating shaft 521 by the driving of the electric motor 52. Note that instead of a sirocco fan, a turbo fan may be used.

The multiple vanes 511 of the impeller 51 are curved on the outer periphery in the direction of rotation of the impeller 51. When the impeller 51 is driven to rotate by the driving of the electric motor 52, a flow of exhaust gas from the inside to the outside of the impeller 51 is generated by centrifugal force, and the exhaust gas sucked in from the suction port 54 is blown out from between the multiple vanes 511 toward the outside of the impeller 51.

The fan casing 53 is formed in a scroll shape so that the radius of the fan casing 53 increases in the direction of rotation of the impeller 51 (clockwise in FIG. 2) relative to the rotating shaft 521 of the motor 52. An air passage 534 extends upward in the tangential direction from the peripheral wall plate 533 on the side of the fan casing 53 with a larger radius, and an exhaust port 55 opens upward at the end of the air passage 534. The impeller 51 is housed in the fan casing 53 so that the gap between the peripheral wall plate 533 forming the exhaust port 55, which is the starting end of the spiral shape, and the outer periphery of the impeller 51 is minimized, and the gap between the peripheral wall plate 533 and the outer periphery of the impeller 51 increases according to the direction of rotation of the impeller 51. For this reason, the gap between the bottom of the outer periphery of the impeller 51 and the opposing peripheral wall plate 533 is larger than the gap between the top of the outer periphery of the impeller 51 and the opposing peripheral wall plate 533. The exhaust port 55 may open forward or backward.

As mentioned above, when the impeller 51 is driven to rotate, centrifugal force creates an airflow that blows the exhaust gas from inside the impeller 51 to the outside. Therefore, during combustion operation, the exhaust gas after passing through the heat exchanger 21 is sucked into the inside of the impeller 51 through the exhaust chamber 30 and the suction port 54. The exhaust gas blown out from the impeller 51 then travels along the peripheral wall plate 533, passes through the air passage 534, and is discharged from the exhaust port 55 to the outside of the water heater 1.

In this embodiment, the blower 50 is installed vertically, so that drain water generated during combustion operation and rainwater entering the blower 50 from the exhaust pipe 80 accumulate at the bottom of the peripheral wall plate 533 of the fan casing 53. In addition, when the exhaust port 55 is provided at the top as described above, a certain size gap is formed between the bottom of the outer periphery of the impeller 51 and the bottom of the peripheral wall plate 533 in the scroll-shaped fan casing 53. Therefore, by forming the drain hole 7 below the bottom of the outer periphery of the impeller 51, the accumulated water can be drained from the drain hole 7 to the outside of the blower 50 before it interferes with the impeller 51.

4 shows the internal pressure distribution in the fan casing 53 in a vertical cross section including the rotating shaft 521 when the blower 50 is operated alone without blockage. The evaluation conditions are set as follows: the opening diameter at the tip of the suction port 54 is 28 mm, the opening diameter of the exhaust port 55 is 59 mm, the outer diameter of the impeller 51 is 75 mm, the minimum diameter of the fan casing 53 is 97 mm, the maximum diameter of the fan casing 53 is 106 mm, the opening diameter of the drain hole is 3 mm, and the total flow rate is 0.84 ^m3 /min.

According to the above evaluation, a large negative pressure state of -300 Pa or less is formed inside the impeller 51. Also, in the lower region of the fan casing 53, the internal pressure increases with distance from the outer periphery of the impeller 51, and depending on the blockage state of the exhaust pipe 80, a positive pressure state of about 50 to 150 Pa is formed at the bottom of the fan casing 53. Therefore, if a drain hole 7 is provided at the bottom of the peripheral wall plate 533 of the fan casing 53, drainage is improved, but during combustion operation, the fan discharge pressure causes the combustion exhaust gas to leak from the drain hole 7 to the outside of the blower 50.

However, even outside the impeller 51, a negative pressure state of about -300 to -50 Pa is formed within a certain range from the outer periphery of the impeller 51. This is thought to be because the combustion exhaust gas is sucked into the inside of the impeller 51 through the suction port 54 opening in the fixed plate 530, creating a large negative pressure state inside the impeller 51, and the gap between the first rotating plate 512 of the impeller 51 and the opposing fixed plate 530 and the gap between the second rotating plate 513 of the impeller 51 and the opposing support plate 532 also become negative pressure, creating a negative pressure state within a certain range radially outward from the outer periphery of the impeller 51. Therefore, as shown by the dashed line in FIG. 3, part of the exhaust gas from the inside of the impeller 51 that flows from the outer periphery of the impeller 51 to the outside around the first and second rotating plates 512 and 513 on the left and right sides of the impeller 51 is drawn back to the inside of the impeller 51 through the gap between the impeller 51 and the fixed plate 530 and the support plate 532. Since the pressure outside the blower 50 is approximately atmospheric pressure, a positive pressure state higher than the internal pressure near the outer periphery of the impeller 51 in the fan casing 53 is formed outside the water drain hole 7. Therefore, if the water drain hole 7 is formed in an area where a negative pressure state is formed radially outward from the lowest part of the outer periphery of the impeller 51, that is, below the lowest part of the impeller 51 and above the lowest part of the peripheral wall plate 533 of the fan casing 53, the leakage of the exhaust gas from the water drain hole 7 to the outside of the blower 50 during combustion operation can be prevented.

In addition, if the drain hole 7 is provided on the fixed plate 530 on the suction port 54 side above the connection between the fixed plate 530 and the peripheral wall plate 533 vertically below the bottom of the impeller 51, a larger negative pressure state can be expected, so that it is possible to reliably prevent the combustion exhaust gas from leaking from the drain hole 7 to the outside of the blower 50 during combustion operation.

As described above, according to this embodiment, in a tension-type combustion device, it is possible to drain stagnant water in the blower 50 and prevent the combustion exhaust gas from leaking outside the blower 50 through the drain hole 7 during combustion operation.

Reference Signs List 1 water heater 7 drain hole 11 burner 21 heat exchanger 50 blower 51 impeller 52 motor 521 rotating shaft 530 fixed plate 53 fan casing 532 support plate 533 peripheral wall plate 54 suction port 55 exhaust port

Claims (2)

A vertically-mounted blower that draws in combustion exhaust gas after passing through a heat exchanger and discharges it to the outside,
The fan has an impeller, a scroll-shaped fan casing that houses the impeller, and an electric motor that drives the impeller to rotate.
the fan casing has a first side surface on which an inlet port for drawing in exhaust gas from combustion opens laterally, a second side surface facing the first side surface and to which an electric motor is fixed, and a peripheral surface surrounding an outer periphery of an impeller and connected to an exhaust port for discharging exhaust gas from combustion,
The first side surface is below the lowest part of the impeller and has a drain hole above a connecting portion between the first side surface and the peripheral surface in the vertical direction of the lowest part of the impeller . The blower according to claim 1,
The suction port opens into a bell-mouth shape on the first side surface of the fan casing, and has a suction passage extending from the outside to the inside of the first side surface of the fan casing .