KR101466267B1 - Stall detecting device - Google Patents

Abstract

A stall sensing apparatus for an axial flow fan is disclosed. A stall detecting apparatus for an axial fan according to the present invention includes: a casing; A fan which rotates at a predetermined position in the casing so as to send an airflow through the casing; And a piezoelectric body installed in the casing and harvesting electric energy using a pressure difference between the front of the fan and the rear of the fan.

Description

[0001] Stall detecting device for an axial flow fan [

The present invention relates to an apparatus for stall detection of an axial flow fan.

An axial flow fan is widely used to supply air to the engine room of a ship. The conventional axial fan rotates at a high speed to supply air to the engine room and the like.

When an axial fan is installed in an engine room or the like, unexpected duct loss may occur at the front and rear ends of the fan, thereby reducing the efficiency of the axial fan, increasing noise, and damaging it due to vibration. These phenomena are known to be caused by a so-called "rotation stall" occurring in an axial fan.

Fig. 1 shows results of flow analysis of an axial flow fan widely used in an engine room, etc., by flow rate. FIG. 1 (a) shows a case where the flow rate is 2,450 m ³ / min. As designed, the tip leakage vortex at the blade end of the axial flow fan is not interfered with the adjacent blade And it shows a clean flow field.

However, even if an axial flow fan designed as shown in FIG. 1 (a) is actually installed in an engine room or the like and is affected by incidental pressure loss factors in the periphery, the flow rate is reduced as shown in FIG. 1 (d). When the flow rate is 2,000 m ³ / min as shown in FIG. 1 (b), the reverse flow region is not shown, A phenomenon of causing interference is beginning to appear.

Further, when the flow rate decreases as shown in FIG. 1 (c) (when the flow rate is 1,600 m ³ / min) or FIG. 1 (d) (when the flow rate is 1,200 m ³ / min), the influence of the tip ridge vortex , A reverse flow region is widely generated on a large scale, and a stall occurs in the hub portion of the fan.

When a stall occurs, all the blades are interfered with the reverse flow region as they rotate, and the fan blades may be damaged due to the turbulent noise and vibrations.

Conventionally, in order to prevent the stall phenomenon of the axial flow fan, a technique of adding a ring-shaped structure 3 to the periphery of the blade 1 of the casing is applied as shown in Fig. 2, There is a problem that the overall shape of the casing must be designed and manufactured again.

On the other hand, Figure 3, as the flow rate of the axial fan reduced ^{((a): 2,450m 3 /} min, (b): 2,000m 3 / min, (c): 1,600m 3 / min, (d): 1,200m ³ / min) and the pressure distribution in the casing surrounding the fan blade. 3 (c) and 3 (d), it can be determined that a stall phenomenon has occurred. In this case, it can be seen that a large pressure difference is formed between the front and rear of the fan blades.

The above-described background technology is technical information that the inventor holds for the derivation of the present invention or acquired in the process of deriving the present invention, and can not necessarily be a known technology disclosed to the general public prior to the filing of the present invention.

US 6,302,640 discloses a structure in which a ring is inserted into a casing around a blade to prevent stall of the axial flow fan. US Patent Application Publication No. US2012 / 0219398 discloses a structure in which an axial flow fan The method comprising the steps of: measuring a sound emanating from a flow adjacent to the pan; comparing with a library of fixed visual indicia derived from a plurality of test values representative of the performance of the fan within the operating variable; Selecting a fixed visual display closest to the visual display for the fixed visual display, and deriving a control signal from the selected fixed visual display.

Patent Document 1: United States Patent No. 6,302,640 Patent Document 2: U.S. Published Patent Application No. US2012 / 0219398

An object of the present invention is to provide a device capable of detecting the stall phenomenon of the axial flow fan by using the energy hobbed using the periodic pressure difference generated in the casing by the rotation of the fan blades.

Other objects of the present invention will become readily apparent from the following description.

According to an aspect of the present invention, there is provided an electronic device comprising: a casing; A fan which rotates at a predetermined position in the casing so that the airflow is delivered through the casing; A link structure having a rotation axis in a central region; A piezoelectric body mounted on the casing; A first pressing plate installed in a region through which one side of the casing penetrates at a position rearward of the fan in the air flow direction in the casing and connected to one end of the link structure and a second pressing plate connected to the other end of the link structure for pressing the piezoelectric body, A second pressure plate connected to the second pressure plate; And a monitoring unit for determining whether or not the fan is stalled based on whether an amount of electric energy produced by the piezoelectric body exceeds a predetermined reference value, wherein the first pressure plate, corresponding to a pressure change in the rear of the fan, And the link structure is rotated about the rotation axis so that the second pressing portion does not press or press the piezoelectric body corresponding to the movement of the first platen, A stall sensing device for an axial flow fan is provided.

The piezoelectric body may include a piezoelectric element made of a ceramic-polymer composite material.

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The fan may include a plurality of blades having a predetermined chord length, and the piezoelectric body may be installed over a predetermined area corresponding to a position of a leading edge of the blade.

The area where the piezoelectric body is installed may correspond to the distance from the position of the leading edge of the blade toward the front of the fan by the cord length of the blade.

The area where the piezoelectric body is installed may correspond to the distance of the cord length of the blade from the position of the leading edge of the blade toward the rear of the fan.

Other aspects, features, and advantages will become apparent from the following drawings, claims, and detailed description of the invention.

According to the embodiment of the present invention, electric energy is harvested using the periodic pressure difference generated in the casing during the rotation process of the fan blades, and the stall phenomenon of the axial fan can be detected using the accumulated energy value.

Further, according to the amount of stored energy, the operation of the fluid machine is stopped before the axial flow fan is damaged by the stall phenomenon, thereby improving the maintenance performance of the equipment.

In addition, since the pressure difference generated at the tip portion of the fan blade is converted into electric energy by using the piezoelectric element, the noise of the blade passing frequency occurring when the three- There is also an effect to absorb.

1 is a view showing a flow analysis result of an axial flow fan.
2 is a sectional view showing the structure of an axial flow fan according to the prior art;
3 is a view showing a change in the pressure distribution of the casing according to the flow rate of the axial flow fan.
4 is a cross-sectional view illustrating an apparatus for detecting a stall of an axial fan according to an embodiment of the present invention.
5 and 6 are views showing a mounting position of a piezoelectric member according to an embodiment of the present invention.
7 is a flowchart illustrating a stall detecting flow of an axial fan according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises" or "having" and the like refer to the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

Also, the terms " part, "" unit," " module, "and the like, which are described in the specification, refer to a unit for processing at least one function or operation and may be implemented by hardware or software or a combination of hardware and software .

It is to be understood that the components of the embodiments described with reference to the drawings are not limited to the embodiments and may be embodied in other embodiments without departing from the spirit of the invention. It is to be understood that although the description is omitted, multiple embodiments may be implemented again in one integrated embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

FIG. 4 is a cross-sectional view illustrating an apparatus for sensing a stall of an axial flow fan according to an embodiment of the present invention. FIG. 5 and FIG. 6 are views showing a mounting position of a piezoelectric body according to an embodiment of the present invention. Referring to FIG. 4, a casing 100, a fan 110, a blade 120, a piezoelectric body 130, a pressure plate 140, and a link structure 150 are shown.

The present embodiment is characterized by a stall detection system using a piezoelectric element.

In this embodiment, as shown in FIG. 3, energy is accumulated using the periodic pressure difference generated in the casing by loading of the fan blades, and the stall phenomenon of the axial flow fan is measured using the accumulated energy Thereby preventing vibration, noise, and damage caused by stalling of the axial flow fan in advance.

The piezoelectric body plays a role of converting the fluctuation power of the pressure into electricity. For example, the vibration plate of the piezoelectric body may be used to generate electricity from vibration generated when a person moves.

In the case of a piezoelectric power generation plate, when a person having a body weight of 60 kg (about 600 N) is walking while pressing the piezoelectric power generation plate while assuming that the width X length X thickness is respectively 0.2 m X 0.3 m X 0.03 m, (10,000Pa) class power generation.

Using this, there is a case where a piezoelectric power generation plate is installed on the passageway of a frequent human movement or the gate of a subway to produce about 6000Ws of power per day.

In this embodiment, as shown in Fig. 4, a piezoelectric body is attached to a casing wall at a position where the blades of the axial flow fan are installed, thereby harvesting energy from periodic pressure fluctuations in the axial flow fan.

For example, the size of the 'peeling area' (red box area in FIG. 5) where periodic pressure fluctuations occur in the axial flow fan may be about 4.8 m × 0.1 m. In this case, a piezoelectric diaphragm of 0.03 m thickness is installed Considering that the change in the pressure field in the casing by the blade is 500 Pa to 4,000 Pa, it is possible to obtain a power generation amount of about 0.1 to 1 W from the following equation (1).

Piezoelectric power generation rate (J) = 0.5 × shape factor per vibration mode × material performance index × piezoelectric bolt constant × Force ^ 2 (1)

However, instead of using the electric energy accumulated in the piezoelectric body as a power source, it can be utilized as a sensing value for judging whether a stall occurs or not.

In other words, it is possible to grasp in advance whether or not the stall of the axial fan is generated according to the amount of power harvested in the piezoelectric body, and to grasp and prevent the initial stall from developing to the rotating stall to reach the axial fan.

For example, in the case of a fluid machine interpreted in the above example, it is possible to monitor that the axial flow fan reaches the stall when a power generation amount of about 0.25 W or more is obtained.

The axial flow fan according to the present embodiment has a structure in which the fan 110 rotates at a predetermined position in a cylindrical casing 100 and an airflow is transmitted through the casing 100 in accordance with the rotation of the fan 110 do.

The stator of the axial fan according to the present embodiment is characterized in that a casing is provided with a piezoelectric body. The piezoelectric body is divided into a region passing through one side of the casing due to a pressure fluctuation in the rear of the fan 110 And the second pressing plate connected to the other end of the link structure presses the piezoelectric body in accordance with the movement of the first pressing plate connected to the one end of the link structure rotated around the rotation axis harvesting.

Various piezoelectric devices made of a ceramic-polymer composite material can be used as the piezoelectric substance according to the present embodiment.

FIG. 4 illustrates an example of a structure in which the piezoelectric body 130 is provided in the casing 100. FIG. As described above, in the axial flow fan, there is a pressure difference between the fan 110 and the fan 110 due to a low pressure in front of the fan 110 and a high pressure in the rear thereof.

In order to operate the piezoelectric body 130 using this pressure difference, in this embodiment, a pressure plate 140 (the pressure plate 140 in this specification) is attached to the rear of the casing 110 (the higher pressure side) The second pressing plate connected to the other end of the link structure 150 may press the piezoelectric body 130 when the pressure is increased during the rotation of the fan 110. [

4, a link structure 150 having a rotation axis in a center area may be installed in the casing 100. One end of the link structure 150 is connected to the pressure plate 140 (i.e., the first pressure plate) And a second pressure plate for pressing the piezoelectric body 130 may be coupled to the other end of the link structure 150. [

Accordingly, when the rear pressure of the fan 110 increases, the pressing plate 140 is pressed. As a result, the second pressing plate coupled to the other end of the link structure 150 operates to press the piezoelectric body 130 . Accordingly, power is generated in the piezoelectric body 130.

This process is repeated according to the rotation of the fan 110, so that predetermined electric energy is accumulated in the piezoelectric body 130. As described with reference to FIG. 3, when a cyclic pressure difference is formed between the front and rear of the blade 120, stall phenomenon occurs in the axial flow fan. Therefore, the electric energy accumulated in the piezoelectric body 130 If the amount exceeds the predetermined reference value, it is possible to determine that the stall phenomenon has occurred (or will occur) in the axial flow fan.

For this, the stall sensing apparatus according to the present embodiment may further include a monitoring unit (not shown). The monitoring unit receives a signal regarding the amount of electric energy stored in the piezoelectric body 130, It is possible to judge whether or not the stall phenomenon occurs in the axial flow fan.

Since electric energy is accumulated in the piezoelectric body 130 though it is small, it is possible to utilize the electric power accumulated in transmitting the signal regarding the amount of electric power harvested. For example, assuming that 0.25 W of electric power is accumulated in the piezoelectric body 130, information about the amount of electric energy accumulated using 1 mW of the electric power can be wirelessly transmitted.

The above-described monitoring unit may receive the radio signal transmitted from the piezoelectric body 130 and detect whether the axial fan is stalled (considering the amount of power used for wireless transmission).

As described above, the pressure plate 140, the link structure 150, and the piezoelectric body 130 are installed in the wall portion of the casing 100 at the front and / or rear of the fan 110, And can be operated by a pressure difference that occurs.

Here, it is explained how the piezoelectric body 130 or the like is provided over a region of the wall of the casing 100, which is more efficient in energy hubbing of the piezoelectric body 130. [

The plurality of blades 120 radially coupled to the fan 110 have a predetermined chord length and the piezoelectric bodies 130 and the like according to the present embodiment have a leading edge (2) and (3), when the position of the origin is the origin.

Xmin = 0 point - Chord length (2)

Xmax = 0 point + Chord length (3)

here,

Xmin: Starting point of the piezoelectric body installation (maximum distance in front of the fan in the piezoelectric mounting area)

Xmax: Piezoelectric mounting end point (maximum distance on the rear side of the fan in the piezoelectric mounting area)

0 point: point on the casing wall corresponding to the leading edge of the blade

Chord length: Chord length of the blade

Thus, the piezoelectric body 130 and the like according to the present embodiment are arranged in a region (see a red color box region in FIG. 6) having a distance of a code length forward and a code length rearward with respect to the position of the leading edge of the blade 120, As shown in FIG.

That is, since the region where the pressure difference between the front and the rear increases in accordance with the rotation of the fan 110 is a region with a distance of the code length in the forward and backward directions with respect to the position of the leading edge of the blade 120, ), It is possible to harvest electric energy more effectively.

On the other hand, in the circumferential direction of the casing 100, the piezoelectric structure as illustrated in Fig. 4 can be freely installed without being restricted by the number of piezoelectric structures.

As described above, the present embodiment is characterized in that the stall phenomenon occurring in the blade 120 of the axial fan, which is widely used in a machine room or the like, is sensed by the amount of electric power harvested using the piezoelectric element .

That is, there is a pressure difference between the front and rear of the axial flow fan. In this embodiment, the pressure difference is harvested as energy by using the piezoelectric element to detect whether the axial flow fan is stalled.

7 is a flowchart illustrating a stall detecting flow of an axial fan according to an embodiment of the present invention.

As shown in FIG. 7, a pressure difference is formed between the front and rear of the blade 120 by the rotation of the axial flow fan (S100).

The piezoelectric body 130 produces electricity using this pressure difference (S200). The piezoelectric body 130 produces electric power proportional to the square of the magnitude of the pressure difference, as can be seen from the above equation (1).

The produced electric power can be monitored by sending radio waves in a wireless state (S300). If the pressure difference is determined to have reached the stall state (S400), the axial fan is stopped and maintained (S500 ) Stall can be prevented, and noise and damage caused by the stall can be prevented in advance.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the following claims And changes may be made without departing from the spirit and scope of the invention.

100: casing 110: fan
120: blade 130:
140: pressure plate 150: link structure

Claims (5)

A casing;
A fan which rotates at a predetermined position in the casing so that the airflow is delivered through the casing;
A link structure having a rotation axis in a central region;
A piezoelectric body mounted on the casing;
A first pressing plate installed in a region through which one side of the casing penetrates at a position rearward of the fan in the air flow direction in the casing and connected to one end of the link structure and a second pressing plate connected to the other end of the link structure for pressing the piezoelectric body, A second pressing part connected to the second pressing part; And
And a monitoring unit for determining whether the fan is stalled based on whether an amount of electric energy produced by the piezoelectric body exceeds a predetermined reference value,
Wherein the first pressing plate is moved in a direction to close or open the penetrating area in correspondence with a pressure change in the rear of the fan, and the link structure moves the second pressing plate in a direction corresponding to the movement of the first pressing plate, And is rotated about the rotation axis so as not to press or press the piezoelectric body,
Wherein the monitoring unit uses electric energy produced from the piezoelectric body as a driving power source. delete delete The method according to claim 1,
Wherein the fan comprises a plurality of blades having a predetermined chord length,
Wherein the piezoelectric body is installed over a predetermined area corresponding to a position of a leading edge of the blade. 5. The method of claim 4,
Wherein the region where the piezoelectric body is installed corresponds to a distance of the cord length of the blade from the position of the leading edge of the blade toward the front of the fan and from the position of the leading edge of the blade toward the rear of the fan, Of the stator of the axial flow fan.

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