Air blower

Abstract

To exactly determine a clogging degree of a passage 2 without any influence of atmospheric pressure and temperature, in a fan apparatus comprising the passage 2 in which a fan 6 is interposed and switching means 7 that switches an effective sectional area at a predetermined portion of the passage 2.SOLUTION: On a premise that at a state where the effective sectional area at the predetermined portion of the passage is switched to a small first area, an energizing current value to a fan 6 when a rotational speed of the fan 6 is made to a predetermined rotational speed is defined as a first fan current value, at a state where the effective sectional area of the predetermined portion of the passage is switched to a large second area, an energizing current value to the fan 6 when the rotational speed of the fan 6 is made to the predetermined rotational speed is defined as a second fan current value, and a ratio of the first fan current value to the second fan current value is defined as a detected current ratio, control means is configured to: memorize as a standard current ratio a detected current ratio that is detected when the fan apparatus is set up; and determine a clogging degree of the passage by comparison of a detected current ratio after detection of the standard current ratio with the standard current ratio.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a blower device including a ventilation path provided with a fan, a switching means for switching the effective cross-sectional area of a predetermined portion of the ventilation path, and a control means.

Background Art

[0002] Conventionally, as a combustion device including this type of blower device, there is known one including a burner, a supply air path upstream of the burner, a combustion chamber where the air-fuel mixture ejected from the burner burns, a ventilation path including an exhaust path downstream thereof, a fan provided in the supply air path, a gas supply path having a downstream end connected to a gas suction portion provided in a portion of the supply air path upstream of the fan, and a zero governor provided in the gas supply path for regulating the secondary gas pressure to atmospheric pressure (see, for example, Patent Document 1).

[0003] Here, the supply amount of the fuel gas from the gas supply path changes according to the differential pressure between the atmospheric pressure which is the secondary gas pressure and the negative pressure acting on the gas suction portion. And since the negative pressure acting on the gas suction portion changes according to the rotational speed of the fan, the supply amount of the fuel gas changes in proportion to the rotational speed of the fan, that is, the supply amount of air. Therefore, by controlling the rotational speed of the fan according to the required combustion amount, an amount of air-fuel mixture (mixed gas of fuel gas and primary air) corresponding to the required combustion amount is supplied to the burner through the supply air path, and the air excess ratio (primary air amount / theoretical air amount) of the air-fuel mixture becomes constant.

[0004] Further, in the above conventional example, a butterfly valve as switching means for switching the effective cross-sectional area of a predetermined portion of the air supply passage is provided, and control is performed to switch the combustion capacity to at least two levels of large and small by switching the effective cross-sectional area by the butterfly valve. That is, when the required combustion amount is relatively small, the butterfly valve is set to a closed position where the effective cross-sectional area of a predetermined portion of the air supply passage becomes small, thereby switching the combustion capacity to a small capacity so that an amount of air-fuel mixture corresponding to the relatively small required combustion amount is supplied to the burner. When the required combustion amount is relatively large, the butterfly valve is set to an open position where the effective cross-sectional area of a predetermined portion of the air supply passage becomes large, thereby switching the combustion capacity to a large capacity so that an amount of air-fuel mixture corresponding to the relatively large required combustion amount is supplied to the burner.

[0005] Conventionally, in a blower device having a ventilation passage provided with a fan, an energization current value (fan current value) to the fan (accurately, the drive motor of the fan) is detected, and the degree of blockage of the ventilation passage is determined by comparing the detected fan current value with a reference fan current value corresponding to the rotational speed of the fan (for example, see Patent Document 2).

[0006] However, when the air density changes due to changes in atmospheric pressure and temperature, the fan current value also changes. Therefore, in the above conventional example in which the degree of blockage of the ventilation passage is determined by comparing the reference fan current value with the detected fan current value, the degree of blockage may be erroneously determined due to the influence of atmospheric pressure and temperature.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] In view of the above points, an object of the present invention is to provide a blower device including a ventilation passage provided with a fan and a switching means for switching the effective cross-sectional area of a predetermined portion of the ventilation passage, and to accurately determine the degree of blockage of the ventilation passage without being affected by air pressure or temperature.

Means for Solving the Problem

[0009] In order to solve the above problems, the present invention provides a blower device including a ventilation passage provided with a fan, a switching means for switching the effective cross-sectional area of a predetermined portion of the ventilation passage, and a control means. In a state where the effective cross-sectional area of a predetermined portion of the ventilation passage is switched to a predetermined first area by the switching means, when the rotational speed of the fan is set to a predetermined rotational speed, the energization current value to the fan is defined as a first fan current value. In a state where the effective cross-sectional area of a predetermined portion of the ventilation passage is switched to a predetermined second area larger than the first area by the switching means, when the rotational speed of the fan is set to a predetermined rotational speed, the energization current value to the fan is defined as a second fan current value. The ratio between the first fan current value and the second fan current value is defined as a detected current ratio. The control means stores the detected current ratio detected at the time of installation of the blower device as a reference current ratio, and is configured to determine the degree of blockage of the ventilation passage by comparing the detected current ratio detected thereafter with the reference current ratio.

[0010] Here, each of the first and second fan current values is affected by air pressure and temperature. However, the detected current ratio becomes a value not affected by air pressure and temperature by dividing the first fan current value affected by air pressure and temperature by the second fan current value also affected by air pressure and temperature. According to the present invention, by comparing the reference current ratio, which is the detected current ratio detected at the time of installation of the blower device, i.e., in a state where the ventilation passage is not blocked, with the detected current ratio detected thereafter, the degree of blockage of the ventilation passage can be accurately determined without being affected by air pressure and temperature.

[0011] As will be described in detail later, when the above-described predetermined portion of the ventilation passage (the portion where the switching means is arranged) is blocked, the second fan current value hardly changes, but the first fan current value decreases, and the detected current ratio decreases. Also, when a blockage occurs in a portion other than the above-described predetermined portion of the ventilation passage, the first fan current value hardly changes, but the second fan current value decreases, and the detected current ratio increases. Therefore, when the detected current ratio is less than the reference current ratio, it can be determined that the degree of blockage in the above-described predetermined portion of the ventilation passage has increased, and when the detected current ratio is greater than the reference current ratio, it can be determined that the degree of blockage in a portion other than the above-described predetermined portion of the ventilation passage has increased.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0013] The combustion device equipped with the blower of the embodiment of the present invention shown in FIG. 1 includes a fully premixed burner 1, a ventilation passage 2 for supplying and exhausting air to and from the burner 1, a gas supply passage 3 for supplying fuel gas, and a controller 4 as control means. The ventilation passage 2 is composed of an air supply passage 21 on the upstream side of the burner 1, a combustion chamber 22 where the air-fuel mixture ejected from the combustion surface 1a of the burner 1 burns, and an exhaust passage 23 on the downstream side of the combustion chamber 22. A heat exchanger 5 for hot water supply is arranged in the combustion chamber 22. Further, a fan 6 controlled by the controller 4 is interposed in the air supply passage 21.

[0014] The downstream end of the gas supply passage 3 is connected to a gas suction portion 211 provided in a portion of the air supply passage 21 located upstream of the fan 6. Then, the fuel gas sucked from the gas suction portion 211 is mixed with the air supplied from a portion of the air supply passage 21 upstream of the gas suction portion 211 to generate an air-fuel mixture, and this air-fuel mixture is supplied to the burner 1 through a portion of the air supply passage 21 downstream of the gas suction portion 211.

[0015] A venturi portion 212 having a smaller diameter than the portion of the air supply passage 21 adjacent to the upstream side of the gas suction portion 211 where a butterfly valve 7 to be described later is arranged is provided. The portion of the air supply passage 21 adjacent to the downstream side of the venturi portion 212 is surrounded by a cylindrical portion 213 having a larger diameter than the venturi portion 212. Then, the downstream end of the venturi portion 212 is inserted into the upstream end of the cylindrical portion 213 with an annular gap, and this gap constitutes the gas suction portion 211. A gas chamber 31 communicating with the gas suction portion 211 is provided at the downstream end of the gas supply passage 3 so as to surround the cylindrical portion 213. Further, in the gas supply passage 3, a main valve 32 controlled by the controller 4, a zero governor 33 for regulating the secondary gas pressure to atmospheric pressure, and a variable throttle valve 34 controlled by the controller 4 are provided in order from the upstream side.

[0016] The amount of fuel gas supplied through the gas suction portion 211 changes according to the differential pressure between the secondary gas pressure and the negative pressure acting on the gas suction portion 211. Here, the negative pressure acting on the gas suction portion 211 changes according to the rotational speed of the fan 6 (hereinafter referred to as the fan rotational speed). Further, the ratio of the supply amount of fuel gas to the supply amount of air changes according to the opening degree of the variable throttle valve 34. By setting the opening degree of the variable throttle valve 34 to a predetermined reference opening degree according to the gas type to be used, the air excess ratio of the air-fuel mixture becomes a predetermined appropriate value (for example, 1.3). Then, by controlling the fan rotational speed according to the required combustion amount (the combustion amount required to discharge hot water at the set hot water temperature), an air-fuel mixture with an appropriate air excess ratio and an amount corresponding to the required combustion amount is supplied to the burner 1.

[0017] In addition, in order not to cause exhaust gas failure due to the intrusion of wind into the exhaust passage 23, that is, in order to ensure wind resistance performance, the lower limit rotational speed of the fan 6 cannot be set too low. And when the required combustion amount becomes less than a predetermined amount corresponding to the lower limit rotational speed of the fan 6, it becomes impossible to supply an amount of air corresponding to the required combustion amount. Therefore, in a predetermined portion of the air passage 2, in this embodiment, a butterfly valve 7 controlled by the controller 4 is arranged in a portion of the air supply passage 21 upstream of the gas suction portion 211 as switching means for switching the effective cross-sectional area of the portion. And when the required combustion amount becomes less than the above-mentioned predetermined amount, the butterfly valve 7 is set to a closed posture shown by a solid line in FIG. 1 where the effective cross-sectional area of the arrangement portion of the butterfly valve 7 is set to a predetermined first area, so that the fan rotational speed is not lowered below the lower limit rotational speed and an amount of air corresponding to a required combustion amount less than the predetermined amount can be supplied.

[0018] However, simply closing the butterfly valve 7 increases the negative pressure acting on the gas suction portion 211, causing the fuel gas supply amount to become excessive and the air excess ratio of the air-fuel mixture supplied to the burner 1 to fall below the appropriate value. Therefore, when the required combustion amount is relatively small, the butterfly valve 7 is closed, and the opening degree of the variable throttle valve 34 is decreased from the reference opening degree to a low-capacity state, so that an air-fuel mixture in an amount corresponding to a relatively small required combustion amount with an appropriate air excess ratio is supplied to the burner 1. Further, when the required combustion amount is relatively large, the butterfly valve 7 is set to an open position shown by a phantom line in FIG. 1 where the effective cross-sectional area of the portion where the butterfly valve 7 is disposed is set to be large, and the opening degree of the variable throttle valve 34 is returned to the reference opening degree to a high-capacity state, so that an air-fuel mixture in an amount corresponding to a relatively large required combustion amount with an appropriate air excess ratio is supplied to the burner 1.

[0019] By the way, if foreign matter accumulates at any location in the ventilation passage 2 and the degree of blockage at this location exceeds a certain limit, it is desirable to determine that it is abnormal and stop the combustion device (error stop). Here, generally, the energization current value (fan current value) to the fan 6 is detected, and the degree of blockage of the ventilation passage 2 can be determined by comparing the reference fan current value corresponding to the fan rotation speed with the detected fan current value. However, when the air density changes due to changes in atmospheric pressure and temperature, the fan current value also changes. Therefore, when the degree of blockage of the ventilation passage 2 is determined by comparing the reference fan current value with the detected fan current value, the degree of blockage may be misjudged due to the influence of atmospheric pressure and temperature.

[0020] Therefore, in the present embodiment, with the butterfly valve 7 in the closed position, when the fan rotation speed Nf is set to a predetermined rotation speed (for example, 4500 rpm) YNf, the fan current value is defined as the first fan current value If1, and with the butterfly valve 7 in the open position, when the fan rotation speed is set to the above-mentioned predetermined rotation speed, the fan current value is defined as the second fan current value If2. The ratio (= If1 / If2) of the first fan current value If1 to the second fan current value If2 is defined as the detected current ratio RI, and the controller 4 performs the blockage degree discrimination control shown in FIG. 2.

[0021] The blockage degree determination control is performed during post-purge after the main valve 32 is closed to stop combustion. That is, after starting the post-purge in STEP1, it proceeds to STEP2, closes the butterfly valve 7 to a closed position, sets the fan rotation speed Nf to a predetermined rotation speed YNf, and acquires the first fan current value If1. Next, it proceeds to STEP3, opens the butterfly valve 7 to an open position, sets the fan rotation speed Nf to the predetermined rotation speed YNf, and acquires the second fan current value If2. Then, in STEP4, the detection current ratio RI is calculated (detected) by dividing the first fan current value If1 acquired in STEP2 by the second fan current value If2 acquired in STEP3.

[0022] Next, it proceeds to STEP5 and determines whether or not a flag F whose initial value is set to "0" is set to "1". When the post-purge is first performed during the trial operation at the time of installation of the combustion device, since the flag F is "0", it is determined as "NO" in STEP5 and proceeds to STEP6, and stores the detection current ratio RI detected in STEP4 as the reference current ratio RIn. Next, after setting the flag F to "1" in STEP7, it proceeds to STEP10, stops the fan 6, and ends the post-purge.

[0023] When post-purge is performed during the operation after the trial operation of the combustion device, it is determined as "YES" when proceeding to STEP5 through STEP1 to STEP4. Then, proceed to STEP8 and below, and determine the degree of blockage of the ventilation passage 2 by comparing the detected current ratio RI detected in STEP4 this time with the reference current ratio RIn. Specifically, in STEP8, it is determined whether the detected current ratio RI detected in STEP4 this time is greater than 92% of the reference current ratio RIn. If RI > RIn × 0.92, proceed to STEP9 and determine whether the detected current ratio RI detected in STEP4 this time is less than 120% of the reference current ratio RIn. And if RI < RIn × 1.2, proceed to STEP10 to end the post-purge. On the other hand, if RI ≤ RIn × 0.92, proceed from STEP8 to STEP11, determine that the degree of blockage at the arrangement part of the butterfly valve 7 of the ventilation passage 2 has increased to the combustion deterioration level, display that fact, and perform an error stop that prohibits the subsequent operation of the combustion device. Also, if RI ≥ RIn × 1.2, proceed from STEP9 to STEP12, determine that the degree of blockage at a part other than the arrangement part of the butterfly valve 7 of the ventilation passage 2 has increased to the combustion deterioration level, display that fact, and perform an error stop that prohibits the subsequent operation of the combustion device.

[0024] Here, although the first and second fan current values If1 and If2 are affected by the atmospheric pressure and temperature, the detected current ratio RI becomes a value not affected by the atmospheric pressure and temperature by dividing the first fan current value If1 affected by the atmospheric pressure and temperature by the second fan current value If2 also affected by the atmospheric pressure and temperature. And in this embodiment, by comparing the reference current ratio RIn, which is the detected current ratio RI detected when the combustion device is installed, that is, when there is no blockage in the ventilation passage 2, with the detected current ratio RI detected thereafter, the degree of blockage of the ventilation passage 2 can be accurately determined without being affected by the atmospheric pressure and temperature.

[0025] In addition, when blockage occurs due to adhesion of foreign matter in parts other than the arrangement part of the butterfly valve 7 in the ventilation passage 2, as long as the blockage rate does not increase significantly, the effective cross-sectional area of the blocked part will be larger than the effective cross-sectional area of the arrangement part of the butterfly valve 7 in the state where the butterfly valve 7 is in the closed position. Therefore, as shown in Fig. 3(a), as the blockage rate in parts other than the arrangement part of the butterfly valve 7 increases, the second fan current value If2 decreases relatively greatly, but the first fan current value If1 hardly decreases, and the detection current ratio RI increases as the blockage rate increases. And the ratio of the detection current ratio RI to the reference current ratio RIn (=RI / RIn) changes as shown in Fig. 3(b) with the change in the blockage rate in parts other than the arrangement part of the butterfly valve 7. When the blockage rate in parts other than the arrangement part of the butterfly valve 7 reaches 80% or more, the combustibility deteriorates. Therefore, as described above, if RI≧RIn×1.2, it is determined that the degree of blockage in parts other than the arrangement part of the butterfly valve 7 has increased to the combustion deterioration level, and an error stop has occurred.

[0026] In addition, when blockage occurs due to adhesion of foreign matter in the arrangement part of the butterfly valve 7 in the ventilation passage 2, as shown in Fig. 4(a), the first fan current value If1 decreases as the blockage rate in the arrangement part of the butterfly valve 7 increases, but the second fan current value If2 remains almost constant without being affected by the blockage in the arrangement part of the butterfly valve 7, and the detection current ratio RI decreases as the blockage rate increases. And the ratio of the detection current ratio RI to the reference current ratio RIn (=RI / RIn) changes as shown in Fig. 4(b) with the change in the blockage rate in the arrangement part of the butterfly valve 7. When the blockage rate in the arrangement part of the butterfly valve 7 reaches 30% or more, the combustibility deteriorates. Therefore, as described above, if RI≦RIn×0.92, it is determined that the degree of blockage in the arrangement part of the butterfly valve 7 has increased to the combustion deterioration level, and an error stop has occurred. If the blockage location can be specified in this way, the maintenance work will become easier.

[0027] As described above, the embodiments of the present invention have been described with reference to the drawings, but the present invention is not limited thereto. For example, it is also possible to correct the fan rotation speed according to the closing rate obtained from the ratio of the detected current ratio RI to the reference current ratio RIn. Further, the switching means for switching the effective cross-sectional area of a predetermined portion of the ventilation passage 2 can be configured by means other than the butterfly valve 7 of the above embodiment. Furthermore, although the above embodiment applies the present invention to a blower for a combustion device, the present invention can be similarly applied to blowers for uses other than combustion devices.

Explanation of Reference Numerals

[0028] 2... Ventilation passage, 4... Controller (control means), 6... Fan, 7... Butterfly valve (switching means).

Claims

1. In a blower device comprising a ventilation passage provided with a fan, a switching means for switching the effective cross-sectional area of a predetermined portion of the ventilation passage, and a control means, when the effective cross-sectional area of a predetermined portion of the ventilation passage is switched to a predetermined first area by the switching means and the rotational speed of the fan is set to a predetermined rotational speed, the energization current value to the fan is defined as a first fan current value; when the effective cross-sectional area of a predetermined portion of the ventilation passage is switched to a predetermined second area larger than the first area by the switching means and the rotational speed of the fan is set to a predetermined rotational speed, the energization current value to the fan is defined as a second fan current value; and the ratio between the first fan current value and the second fan current value is defined as a detected current ratio. The control means is configured to store, as a reference current ratio, the detected current ratio detected at the time of installation of the blower device, and to determine the degree of blockage of the ventilation passage by comparing the detected current ratio detected thereafter with the reference current ratio. A blower device characterized by this.

2. The blower device according to claim 1, wherein the control means determines that the degree of blockage in the predetermined portion of the ventilation passage has increased when the detected current ratio has decreased from the reference current ratio, and determines that the degree of blockage in a portion other than the predetermined portion of the ventilation passage has increased when the detected current ratio has increased from the reference current ratio.

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