JP5177037B2 - Blower - Google Patents

Description

  The present invention relates to a blower suitable for use in cooling an automobile radiator.

  Conventionally, an axial flow type fan is often used for cooling an automobile radiator. In addition, in the axial flow type fan, a phenomenon is known in which a part of the air blown to the downstream side of the fan flows backward from the periphery of the fan blade to the upstream side of the fan. Therefore, a fan shroud is arranged so as to cover the outside of the fan blade. As a technique for reducing noise caused by the rotation of the fan, there is known a technique in which a plurality of protrusions are provided on a portion of the fan shroud surrounding the fan. (For example, Patent Document 1)

JP-A-2005-147018

  The invention described in Patent Document 1 is made by paying attention to the air flow in the part surrounding the fan. However, the inventors of the present invention, after earnest research, have made noise in the fan shroud. The problem was found that it was caused by pressure fluctuations due to the overall shape.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a blower that can reduce pressure fluctuation caused by the shape of a fan shroud and reduce generated noise. .

In order to solve the above-described object, an invention according to claim 1 is directed to an axial fan (3) having a plurality of blades (3b) for blowing air, and an outer periphery of the axial fan (3) with a predetermined interval therebetween. And a cylindrical portion (5a) arranged coaxially and a guide portion (5c) whose one end side edge is connected to the cylindrical portion (5a) to induce an air flow by the axial fan (3). In the blower (1) provided with the shroud (5), L is a value that can be taken by the length of the finite straight line from the center of the axial fan (3) to the edge on the other end side of the guide part (5c), When the maximum value of L is L1, the cylindrical portion (5a) of the axial fan (3) includes at least one of the intersections of the finite straight line having L satisfying the following formula 1 and the cylindrical portion (5a). cylindrical portion of the center is the inner wall surface of (5a) depressed toward the outside direction of), the axial flow fan ( ) Center, characterized in that it comprises a central and the fan which is formed in the pressure fluctuation suppressing space (5e) of.

  When the fan shroud (5) includes the pressure fluctuation suppression space (5e), the pressure fluctuation caused by the shape of the fan shroud (5) is alleviated, and the generated noise can be reduced.

The invention according to claim 2 is the pressure according to the invention according to claim 1 , wherein the outer edge of the guide portion (5c) is a polygonal shape formed by a plurality of straight lines, and the rotation axis (4a) is the center. The finite straight perpendicular bisector connecting the circumferential edges of the fluctuation suppressing space (5e) is orthogonal to the side constituting the outer edge of the guide portion (5c) or by a predetermined angle in the rotational direction of the blade (3b). It is characterized by deviation.

  Thereby, since the pressure fluctuation which generate | occur | produces toward the rotation direction of a braid | blade (3b) from the site | part which approaches the outer edge of a fan shroud (5) can be suppressed, the generated noise can be reduced.

The invention according to claim 3 is the invention according to claim 1 or 2 , wherein a plurality of pressure fluctuation suppression spaces (5e) are provided.

  By providing the pressure fluctuation suppression space (5e) at a plurality of locations, the pressure fluctuation can be suppressed at a plurality of locations, so that the space between the outer edge of the fan shroud (5) and the tubular portion (5a) is In the case where there are a plurality of narrow areas compared to other parts, the generated noise can be further reduced.

According to a fourth aspect of the present invention, in the invention according to at least one of the first to third aspects, the pressure fluctuation suppression space (5e) is a cylinder when viewed from the direction of the air flow of the axial fan (3). The inner wall surface of the shaped portion (5a), which is parallel or cylindrical with respect to a straight line passing through the point and the center located in the most distal portion in the rotational direction in the range where the pressure fluctuation space (5e) is formed The part (5a) is characterized by having a flat surface (5g) that inclines in the rotational direction toward the outer diameter direction.

  Since the pressure fluctuation suppression space (5e) has a flat surface (5g) that opposes the pressure fluctuation generated in the rotational direction of the axial fan (3), the blade ( The pressure fluctuation generated in the rotation direction 3b) can be suppressed. Therefore, the generated noise can be reduced.

  In addition, the code | symbol in the parenthesis attached | subjected to each said means is an example which shows a corresponding relationship with the specific means of embodiment description later mentioned.

It is a front view which shows the fan shroud in 1st Embodiment of this invention. It is sectional drawing of the radiator fan and radiator in 1st Embodiment. It is AA sectional drawing of the radiator fan in FIG. It is a figure which shows the positional relationship of the pressure fluctuation suppression space in 1st Embodiment. It is a figure which shows the pressure fluctuation generate | occur | produced inside the fan shroud for comparative examination which does not have the characteristic of this invention. It is a figure which shows the range which provides the pressure fluctuation suppression space at the time of measuring the reduction | decrease degree of the noise using the fan shroud in 1st Embodiment. It is a graph showing the reduction degree of the noise using the fan shroud in 1st Embodiment. It is a figure which shows the positional relationship of the pressure fluctuation suppression space in 2nd Embodiment of this invention.

(First embodiment)
Hereinafter, an embodiment in which the present invention is applied to a cooling fan of a vehicle radiator will be described with reference to FIGS. 1, 2, and 3. FIG. 1 is a front view of a radiator fan 1 according to this embodiment. FIG. 2 is a cross-sectional view of the radiator fan 1 and the radiator 2 in the present embodiment. FIG. 3 is a cross-sectional view of the radiator fan 1 taken along the line AA in FIG.

  The radiator 2 exchanges heat between cooling water that cools the driving source for driving the vehicle such as the engine and the ambient air where the radiator is installed, and the waste heat recovered from the heat source such as the engine by the cooling water into the atmosphere. It is a heat exchanger that dissipates heat.

  The radiator 2 includes a plurality of flat tubes (not shown) through which cooling water flows. And a radiator core (not shown) that is connected to the outer surface of the flat tube and promotes heat exchange between air and cooling water, and the longitudinal direction of the flat tube at the longitudinal end of the flat tube It has a header tank (not shown) that extends in an orthogonal direction and communicates with a plurality of flat tubes.

  The radiator fan 1 includes an axial fan 3. The axial fan 3 includes a boss portion 3a that serves as the center of rotation. The axial fan 3 is provided with fan blades 3b that generate an air flow in the axial direction of the axial fan 3 by rotation, radially from the boss portion 3a. The plurality of fan blades 3b have one end connected to the boss portion 3a and the other end connected to a circular ring portion 3c.

  The radiator fan 1 includes a motor 4 that is an electric motor that gives rotational power to the axial fan 3. The motor 4 has a motor shaft 4a that is a rotating shaft. Further, the motor shaft 4a and the boss portion 3a of the axial fan 3 are connected by a fixing member (not shown). Therefore, when the motor 4 rotates the motor shaft 4 a, the axial fan 3 rotates and an air flow is generated in the axial direction of the axial fan 3.

  The radiator fan 1 includes a fan shroud 5. The fan shroud 5 includes a cylindrical portion 5a disposed on the outer periphery of the axial flow fan 3 with a predetermined interval. Moreover, the opening part 5b which ensures the communication of the airflow with the radiator fan 1 exterior is provided in the fan side of the cylindrical part 5a. And the guide part 5c which guide | induces the airflow by the axial fan 3 is comprised by the side of the radiator 2 of the cylindrical part 5a. The motor 4 is supported at the center of the opening 5b by a plurality of motor stays 5d.

  Next, the pressure fluctuation suppression space in this embodiment of the present invention will be described with reference to FIGS. 1 and 3.

  The tubular portion 5a is provided with a pressure fluctuation suppressing space 5e that is a recess that extends outward from the center of the tubular portion 5a. Further, a finite straight vertical bisector connecting the circumferential edges of the cylindrical portion 5a of the pressure fluctuation suppressing space 5e is orthogonal to the side constituting the outer edge of the guide portion 5c or predetermined in the blade rotation direction. It is shifted by an angle. The pressure fluctuation suppression space 5e is formed by recessing the tubular portion 5a in a fan shape with the center point of the axial fan 3 as the center. Further, the fan shroud 5 in this embodiment includes a lip portion 5f that forms a bell mouth shape that spreads from the radiator 2 side toward the opening portion 5b. Therefore, in this embodiment, the pressure fluctuation suppression space 5e is a space surrounded by the radiator 2 facing surface of the lip portion 5f and the end surfaces 5g and 5h of the cylindrical portion 5a.

  Note that the end face 5g constituting the pressure fluctuation suppression space 5e is relative to a straight line passing through the point and the center located at the most distal portion in the rotational direction of the axial fan 3 within the range in which the pressure fluctuation suppression space 5e is formed. Thus, it becomes a plane that inclines in the rotational direction as it goes in the parallel or cylindrical portion 5a outer diameter direction.

  Next, the determination method of the place which provides the pressure fluctuation suppression space in this embodiment is demonstrated using FIG.

  First, the distance from the center of the axial fan 3 to the outer edge of the fan shroud 5 is represented as L. Further, the center of the axial fan 3 is a point O shown in FIG. A point having the longest distance from the point O on the outer edge of the fan shroud 5 is defined as a point Ln shown in FIG. In the present embodiment, since the fan shroud 5 is rectangular, Ln exists on the diagonal of the fan shroud 5. The distance from the point O to the point Ln is L1. That is, L1 is the maximum value of the distance from the center of the axial fan 3 to the outer edge of the fan shroud 5. Further, a point having the shortest distance from the point O on the outer edge of the fan shroud 5 is set as a point Ls shown in FIG. The distance from the point O to the point Ls is L2. Next, L1 = 400 in the present embodiment is substituted into Equation 1 of the present invention. And if the number 1 into which L1 is substituted is transformed, L ≦ (400) / (√2). Therefore, since 240 ≦ (400) / (√2), L2 satisfies the condition of L. Therefore, in the present embodiment, the pressure fluctuation suppression space 5e that spreads in the rotation direction of the axial fan 3 is provided from the straight line O-Ls that connects the point O and the point Ls. In addition, since the upper bottom of the fan shroud 5 as a pair of the points Ls also satisfies the above condition, in the present embodiment, a pressure fluctuation suppression space is similarly provided at the upper portion of the fan shroud 5.

  Next, a method for determining a range in which the pressure fluctuation suppression space 5e in this embodiment is provided will be described with reference to FIG.

  First, the angle of the tip width of the fan blade 3b around the point O is assumed to be A1 shown in FIG. And the angle of the range which provides the pressure fluctuation suppression space 5e centering on the point O is set to A2. These A1 and A2 are substituted into Equation 2. In the range of the angle A2 that satisfies this equation 2, a pressure fluctuation suppression space 5e that extends from the point Ls toward the rotational direction of the axial fan 3 is provided.

  Next, the reason for determining the position and range in which the pressure fluctuation suppression space 5e is provided according to the present invention will be described with reference to FIG. FIG. 5 is a view showing a sound pressure fluctuation generation region accompanying the rotation of the axial fan 3 in the comparative examination shroud 501 with the pressure fluctuation suppression space 5e removed from the fan shroud 5 of the present embodiment.

  The comparative examination shroud shown in FIG. 5 does not include the pressure fluctuation suppression space in the present embodiment. Further, in FIG. 5, the point where the distance between the outer edge of the fan shroud 501 and the cylindrical portion 501b is the shortest is the upper bottom closest portion 501a. At this time, in FIG. 5, the rear end portion 502b of the blade 502 is approaching the upper bottom closest portion 501a. Then, the air pushed by the blade 502 generates a high-pressure region 503 having a higher pressure fluctuation than the other parts around the upper-bottom nearest portion 501a. In addition, the pressure fluctuation in the peripheral region 504 of the farthest part 501c shown in FIG. . Since this pressure fluctuation is also the vibration of air, noise is generated by the pressure fluctuation accompanying the rotation of the axial fan.

  The inventors of the present invention, after intensive research, have determined that the difference in pressure fluctuation between the high pressure region 503 shown in FIG. 5 and the peripheral region 504 of the farthest part 501c is caused by the difference in volume of the region. It was. Therefore, by providing the pressure fluctuation suppression space 5e in a range that satisfies Equations 1 and 2 where pressure fluctuation is particularly high, the difference in volume between regions is reduced, and the difference in generated pressure fluctuation is alleviated. ing.

  Next, Formula 2 will be described based on the result of measuring the noise reduction using the fan shroud 5 in the present embodiment. FIG. 6 is a diagram showing angles of a range in which the pressure fluctuation suppression space 5e is provided when the measurement shown in FIG. 7 described later is performed. FIG. 7 shows a graph showing how the sound pressure level of noise generated by changing the angle A2 of the range in which the pressure fluctuation suppression space 5e is provided is changed using the fan shroud 5. It is. Note that the measurement shown in FIG. 7 was performed using an axial fan having five blades with an angle A1 of the tip width of the fan blade 3b being 30 degrees.

  First, according to FIG. 6, the axial flow fan 3 starts from the upper and lower bottoms, where L is the shortest distance from the center of the axial flow fan 3 to the outer edge of the fan shroud 5. It shows that the pressure fluctuation suppression space 5e is provided in a range of 6 steps of 5, 10, 15, 20, 25, and 30 degrees in the rotation direction.

  According to the graph shown in FIG. 7, the sound pressure level is reduced by 2.5 dB when A2 is 5 degrees. Moreover, when A2 is 10 degrees, it decreases by 4.8 dB. When A2 is 15, a decrease in sound pressure level by 15.2 dB is recognized.

  Therefore, from the measurement result shown in FIG. 7, the noise reduction effect is recognized when the range in which the pressure fluctuation suppression space 5e is provided is in the range of 5 to 30 degrees. Further, when the pressure fluctuation suppression space 5e is provided in a fan shape centered on the portion where L, which is the distance to the outer edge of the fan shroud 5, is the shortest, the above-described noise reduction effect of A2 has been recognized. A similar noise reduction effect was confirmed at the double angle. That is, when A1 is 30 degrees, a noise reduction effect is recognized when A2 is 5 degrees to 60 degrees. From this result, the following relational expression is derived.

5/30 ≦ A2 / A1 ≦ 60/30 (unit: degree)
The above relational expression is equal to the above formula 2. Therefore, noise can be reduced by providing the pressure fluctuation suppression space 5e in the range of the above formula 2.

  As described above, by providing the pressure fluctuation suppression space 5e, it is possible to alleviate the uneven pressure fluctuation generated around the axial fan 3 due to the shape of the fan shroud 5. Therefore, it is possible to reduce noise caused by pressure fluctuation due to rotation of the axial flow fan 3.

(Second Embodiment)
Next, features of the second embodiment of the present invention will be described with reference to FIG.

  In the first embodiment, the pressure that spreads in the rotational direction of the axial fan 3 from the line segment in which the distance from the center of the axial fan 3 to the outer edge of the fan shroud 5 in the pressure fluctuation suppression space satisfies Formula 1 of the present invention. Although the variation suppression space is provided, in the present embodiment, the axial flow fan 3 is centered on a line segment in which the distance from the center of the axial flow fan 3 to the outer edge of the fan shroud 5 satisfies the equation (1). The rotation direction and the reverse rotation direction are provided in equal ranges.

  FIG. 8 is a front view of the fan shroud 5 in the present embodiment. In addition, the same code | symbol was attached | subjected regarding the site | part common to FIG. 1 which shows 1st Embodiment of this invention.

  First, the distance from the center of the axial fan 3 to the outer edge of the fan shroud 5 is represented as L. Further, the center of the axial fan 3 is a point O shown in FIG. A point having the longest distance from the point O on the outer edge of the fan shroud 5 is defined as a point Ln shown in FIG. In the present embodiment, since the fan shroud 5 is rectangular, Ln exists on the diagonal of the fan shroud 5. The distance from the point O to the point Ln is L1. That is, L1 is the maximum value of the distance from the center of the axial fan 3 to the outer edge of the fan shroud 5. Further, a point having the shortest distance from the point O on the outer edge of the fan shroud 5 is set as a point Ls shown in FIG. The distance from the point O to the point Ls is L2. Next, L1 = 400 in the present embodiment is substituted into Equation 1. And if the number 1 into which L1 is substituted is transformed, L ≦ (400) / (√2). Therefore, since 240 ≦ (400) / (√2), L2 satisfies the condition of L. Therefore, in the present embodiment, the pressure fluctuation suppression space 5e is provided in a range equal to each other in the rotational direction and the reverse rotational direction of the axial fan 3 around the straight line O-Ls connecting the point O and the point Ls. .

  As described above, the pressure fluctuation suppression space 5e is provided in the rotation direction and the reverse rotation direction of the axial flow fan 3 in the equal range around the straight line O-Ls connecting the point O and the point Ls. Pressure fluctuations that occur in the reverse rotation direction relative to the straight line O-Ls due to requirements or the like can be suppressed, and noise generation can be reduced.

(Other embodiments)
In the above-described embodiment, the fan shroud 5 is rectangular. However, the present invention is not limited to this, and may be a square, a polygon, or a shape partially including a curved surface.

  Moreover, in the said 1st Embodiment, although the pressure fluctuation suppression space 5e was formed by denting the cylindrical part 5a in the fan shape centering on the center point of the axial fan 3, although this invention was formed. However, the present invention is not limited to this, and it may be formed only by a curved surface or a flat surface having a curvature different from that of the cylindrical portion.

  The present invention is not limited to the above-described embodiment, and may be implemented in any form as long as it does not depart from the invention described in the claims.

DESCRIPTION OF SYMBOLS 1 Radiator fan 2 Radiator 3 Axial fan 3a Boss part 3b Fan blade 3c Ring part 3d Fan blade front-end | tip 5 Fan shroud 5a Cylindrical part 5b Opening part 5c Guide part 5d Motor stay 5e Pressure fluctuation suppression space 5f Lip part

Claims (4)

An axial fan (3) having a plurality of blades (3b) for blowing air;
A cylindrical part (5a) disposed coaxially on the outer periphery of the axial fan (3) with a predetermined interval and an edge on one end side are connected to the cylindrical part (5a) to connect the axial fan ( 3) In the air blower (1) provided with a fan shroud (5) comprising a guide part (5c) for guiding the air flow according to 3), the guide part (5c) and the other parts from the center of the axial fan (3) When the value that can be taken by the length of the finite straight line to the edge on the end side is L, and the maximum value of L is L1, the finite straight line having the L satisfying the following formula 1 and the cylindrical portion (5a) ), The inner wall surface of the cylindrical portion (5a) is depressed outward from the center of the axial fan (3) including at least one of the intersections of the axial flow fan (3). and characterized in that it comprises a central and the fan which is formed in the pressure fluctuation suppressing space (5e) That blower.
The outer edge of the guide part (5c) is a polygonal shape formed by a plurality of straight lines,
A finite straight vertical bisector that connects the circumferential edge of the pressure fluctuation suppression space (5e) with the rotation axis (4a) as a center, and a side that forms the outer edge of the guide portion (5c) The blower according to claim 1 , wherein the blower is shifted orthogonally or by a predetermined angle in the rotation direction of the blade (3b). The blower according to claim 1 or 2 , wherein a plurality of the pressure fluctuation suppression spaces (5e) are provided. The pressure fluctuation suppression space (5e) is an inner wall surface of the cylindrical portion (5a) when viewed from the direction of the air flow of the axial fan (3), and the pressure fluctuation space (5e) is formed. Of the range, a plane (5g) that is parallel to the straight line passing through the center and the point located at the most distal portion in the rotation direction or inclined in the rotation direction toward the outer diameter direction of the cylindrical portion (5a). ) blower according to at least one of claims 1 to 3, characterized in that it has a.