JPH01397A - blower fan - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a blower fan, and can be used, for example, as a radiator cooling fan for blowing cooling air to a radiator that cools the cooling water of an automobile engine. Can be done.

[Conventional technology]

FIG. 3 is a diagram schematically showing the front internal structure of the automobile. A radiator 4 for cooling engine cooling water is arranged in front of the engine 5. The radiator 4 normally includes an upper tank 4a, a lower tank 4c, and a core portion 4b consisting of a tube and fins that connect the upper and lower tanks. A blower fan 12 is arranged between the radiator 4 and the engine 5 to send cooling air to the radiator 4. This blower fan consists of a boss part 2 which is rotated by an external driving force such as an electric motor, and blades 1 arranged around the outer periphery of this boss part 2. The cooling air generated by the blower fan is passed through the fan shroud 3.
It is well guided from the radiator 4 side.

Further, in an automobile equipped with an automobile air conditioner, a condenser 6 that forms a part of the automobile air conditioner is disposed in front of the radiator 4. Note that the above-mentioned capacitor 6 and radiator 4 are installed in the front part of the hood 10 of the automobile.
A front grille 8 is open to introduce blowing air toward the vehicle.

In the figure, reference numeral 7 indicates a bumper of the automobile, and 9 indicates a skirt portion of the automobile.

In such automobiles, it has become necessary to improve the cooling performance of the engine 5 in recent years as the engine displacement becomes airfoil-shaped or the engine output increases. Therefore, the radiator 4, which is an engine coolant cooling device, is also required to have greater heat dissipation performance. However, since there is a limit to the mounting space allowed for the radiator 4 in the engine room of an automobile, generally speaking, in order to improve the heat dissipation amount of the radiator 4, the pitch of the louvered fins of the core portion 4b is reduced, One possibility is to increase the heat dissipation area. However, if the pinch of the louvered fins is reduced, the ventilation resistance of the cold air passing through the core portion 4b of the radiator 4 naturally increases.

Further, as shown in FIG. 3, in an automobile equipped with an automobile air conditioner, a condenser 6 is disposed in front of the radiator 4 for cooling the refrigerant of the air conditioner. Like the radiator 4 described above, this condenser 6 is also in a situation where the fin pitch has to be reduced in order to improve cooling performance. That is, the ventilation resistance of the cooling air passing through the capacitor 6 also tends to increase.

Furthermore, as a trend in recent years, in order to reduce air resistance at the front of the vehicle, the front of the bonnet 10 is becoming lower, creating a slant nose. The opening area of No. 8 tends to decrease.

In this way, in recent automobiles, the blower fin 12
A phenomenon is occurring in which the ventilation resistance in front of the vehicle is becoming extremely high.

On the other hand, regarding the shape of the carpenter of the blower fan 12, various studies have been made in the past.
6 and Japanese Patent Laid-Open No. 59-173598 have been devised. Such blower fans are intended to reduce noise when the fan rotates, but as mentioned above, in recent automobiles where ventilation resistance in front of the fan is increasing, it is not always possible to use such a conventional fan. There are areas where noise has not been completely reduced.

[Problem to be solved by the invention]

Therefore, the inventors of the present application developed the ventilation resistance (
As the fan noise increases as the fan front resistance (hereinafter referred to as "fan front resistance") increases, various studies were conducted, and the authors hypothesized that the cause of this was that the air flow passing through the fan changed due to the front resistance.

Therefore, regarding the conventional fan mentioned above, the air flow on the fan blade surface when the fan rotates is calculated using the conventionally known Taft method.
Observations were made while gradually increasing the fan front resistance. As a result, in a region where the front resistance of the fan is relatively low, the air passing through the fan 12 flows almost parallel to the rotation axis of the fan 12 (hereinafter referred to as axial flow), as shown by arrow F in FIG. ), and it was also found that there was little movement of the tuft attached between the big brother of wing 1 and the tip of the wing, and that there was little disturbance on the surface of wing 1.

FIG. 5 is a view of one blade of a blower fan showing such an axial flow, viewed from the front direction. The arrow F in FIG. 5 indicates the flow direction of the air flowing on one surface of the blade.

As can be seen from this, in the blower fan exhibiting axial flow, air flows in concentric circles around the boss portion 2 on one surface of the blade. Note that the arrow R in FIGS. 4 and 5 indicates the rotation direction of the blade 1.

However, when the fin front resistance becomes large,
It has been found that the air passing through the fan 12 changes into a flow (referred to as a diagonal flow) that spreads outward from the center of the fan 12 after passing through the fan 12, as shown by arrow F in FIG. Ta.

In addition, in this mixed flow, the tufts at the leading edge of the fan in the large fan section floated upwards from the blade and became heavily wet, indicating that the air flow was separating from the top of the blade. Also,
The seventh view of one blade 1 of the blower fan 12 seen from the front.
As can be seen from the figure, in this mixed flow, there is a strong tendency for the air flowing on the surface of the blade 1 to flow away from the center of the fan 12, particularly from the mid-stomach region to the blade tip. Indicated. Furthermore, the movement of the tuft near the trailing edge of the blade l in the rotational direction was rapid, indicating that the turbulence on the blade 1 surface was large.

Furthermore, in a region where the fan front resistance is large, the angle of attack α of the fan is considered to be larger than in a region where the fan front resistance is small. This angle of attack is closely related to fan noise and air volume characteristics, and it is generally known that if the suppression angle becomes too large, the stall will occur.

Here, when the cross section of the blade l is taken as shown in Fig. 2, the angle β between the fan rotation direction R and the straight line connecting the blade leading edge 1a and the blade trailing edge 1b is attached. Furthermore, the angle formed by the straight line and the air flow direction F flowing into the fan is defined as the angle of attack α. Further, the distance connecting the leading edge 1a of the blade 1 and the rear edge 8i1b is referred to as the blade chord length.

From the above, the following may be considered as the cause of worsening fan noise in areas where front resistance is large. In other words, as shown in FIG. 9 (A), the conventional fan mounting angle β gradually decreases from the large upper part to the middle part of the stomach, and then decreases from the middle part of the blade to the tip of the blade. , the number of wing attachment parts is increased. This is because the air turbulence at the tip is improved and noise is reduced by increasing the blade attachment angle β at the tip of the blade and increasing the axial flow velocity at the tip. Furthermore, the reason why the blade attachment angle β at the large-breasted portion is increased is to increase the air volume. However, in a region where the fan front resistance is high, the suppression angle α becomes large as described above, so the suppression angle becomes too large at the blade tip and the large-breasted portion, reaching the stall region.
As a result, boundary layer separation occurs on the negative pressure surface of the fan, which is thought to worsen the noise.

Furthermore, as described above, in the region where the fan front resistance is high, the flow on the blade 1 surface changes from the axial flow direction to the diagonal flow direction.

Therefore, as shown in FIG. 8, when taking the center line l of the blade 1 and the vertical cross section X-x at the tip of Hl,
As shown in FIG. 10(a), a normal airfoil cross section is formed. However, when the cross section XI-XI in Figure 8 is taken, the warp direction is reversed at the center, as shown in b) in Figure 10, and a normal wing wall is not formed. do not have. That is, when the air exhibits a diagonal flow outward on one surface of the blade as shown in Fig. 7, the cross section along the air flow is as shown in (1) in Fig. 10 as described above. As a result, the air cannot flow well over the surface of the blade, and as a result, it is thought that boundary layer separation of the air occurs from the surface of the blade, causing noise.

[Means to solve the problem]

The present invention provides a low-noise system that does not cause boundary separation of the air passing through the fan from the blade surface of the blower fan and generates noise even when the front resistance of the fan increases as described above. The purpose is to obtain a blower fan.

Therefore, in order to achieve this object, the present invention has the following configuration. In other words, the blade mounting angle of the blade is set to a substantially constant value in the first region from the large part, which is the connection part with the boss part, to at least the middle part, which is the average fan radius position, and is continuous to this first region. In the second region extending to the tip of the blade, this blade attachment angle is increased. Further, the chord length of the wing is gradually increased from the large wing section to the wing tip section. In addition, a second center line from the middle part of the blade to the tip of the blade is inclined in the fan rotation direction with respect to the first center line from the middle part to the middle part of the blade, and the first center line and the second center line are aligned with each other. The wing walls were formed at right angles.

In addition, the pressure distribution in the chord direction is approximately constant along the blade axis direction in the first region from the large brother part to at least the intermediate position of the blade, and the pressure distribution in the chord direction is approximately constant along the blade axis direction, and the pressure distribution in the second region continuing from the first region to the blade tip part is
In the region of , the absolute value of this pressure distribution is gradually increased while maintaining approximately similar pressure distribution curves in the chord direction. Then, the chord length of the blade is gradually increased from the large side part to the blade tip part, and the second center line in the middle direction of the second area is inclined in the fan rotation direction with respect to the first center line in the width direction of the first area. Then, an airfoil was formed perpendicular to this center line.

〔Example〕

Next, an embodiment in which the present invention is used as a blower fan that sends cooling air to an automobile radiator will be described. FIG. 1 is a front view of this blower fan viewed from the axial direction. This blower fan 100 is placed between the engine and the radiator.

Boss portion 101 rotates by receiving driving force from an electric motor etc.
has a cylindrical outer shape.

Four blades 103 are arranged on the circumferential side surface of the boss portion 101 having a cylindrical shape. In this embodiment, the boss portion 101 and the four blades 103 are integrally formed from a resin material.

Here, the connecting part between the boss part 101 and the wing 103 is called a big brother part.
The tip of the wing 103 is called a wing tip. In addition, the boss part 10
When the diameter of the blade 1 is Dh and the diameter of the circle connecting the tips of the blades 1103 is Dt, the position on the circle having a diameter of Dh-4-(Dt-Dh)/2=Dm is called the blade intermediate position.

The blade attachment angle β of the blade 103 of this embodiment is as shown in (b) in FIG.
m/2) have the same blade attachment angle βm. In the second region from the intermediate portion to the tip of the blade, the blade attachment angle β gradually increases. Here, let βm be the blade attachment part β from the big brother part to the intermediate part, and let βt be the blade attachment angle at the big tip part.

By setting the installation angle β from the tip of the wing to the midpoint of the wing to a relatively small value, the suppression angle is set to a small value and set within a range that does not cause a stall even if the forward resistance becomes high, reducing noise. can be achieved.

However, if the suppression angle α is set to a small value, the lift force 2 shown by the arrow in FIG. 2 also becomes small. As a result, the air volume of the fan decreases. In order to maintain a sufficient air volume from the fan, this lifting force l must be kept at the same value as before. This lift force i is proportional to Rρv2s (ρ: air density, ■: mainstream velocity, S: blade area, R: lift coefficient), and the lift coefficient R is proportional to the suppression angle α within the range of not stalling. As shown in FIG.

On the other hand, the axial velocity Ca of the blower fan 100 of this embodiment is
As shown in Fig. 11, it is set to be relatively small in the first region from the large-side part to the middle part of the wing, and to increase sharply in the second region from the middle part of the wing to the tip of the wing. This is the part where not much airflow is produced.

For this reason, in areas where the fan front resistance is high, even if the blade chord length is set to a large value, the air volume will not increase much, and on the contrary, the drag will increase, which will promote the blade suction surface peeling phenomenon and worsen the noise. will come. Therefore, in the first area, the first
As shown in Figure 2, the blade chord length is set to a relatively small value that gradually increases.

On the other hand, from the middle of the blade to the tip of the blade, the chord length increases dramatically to generate a large amount of air. In order to increase the chord length from the middle part of the blade to the tip of the blade, in this embodiment, the width of the blade is extended in the fan rotation direction R as shown in FIG. It is increasing.

Here, if the center line is a line connecting the midpoints of the widthwise length of each cross section of the blade 103, that is, the chord length, then the center line in the first region is 1L (first In the second region, lines p, z (referred to as a second center line p2) are shown in the second region. As mentioned above, in the second region, the width direction is extended in the fan rotation direction to increase the chord length, so the second centerline 12 is different from the first centerline 11. It is formed at a position inclined by a predetermined angle θ toward the fan rotation direction R side. This angle θ is determined according to the blade chord length, which is determined by the fan output, fan diameter, etc. In this embodiment, the angle θ is set between 3° and 17°. There is.

Furthermore, from this large part to the middle part of the blade, the blade is at the 10th point in the cross section perpendicular to the first center line 11.
It is shaped to form an airfoil as shown in figure (a), and from the middle part of the blade to the tip of the blade,
It is shaped so that an airfoil is formed in a cross section perpendicular to the second centerline 12.

19 shows a cross section XIX-XIX, which is a cross section at right angles to the first center line l in FIG. 1, and FIG. 20 shows a cross section at right angles to the second center line 2 in FIG. XX-XXIJi
It shows a top view. In this way, in the blade 103 of this embodiment, even if the flow of air passing through the blade becomes a diagonal flow as shown in FIG. Since the cross section is formed, it is possible to suppress the phenomenon that the air separates from the surface of the blade, and as a result, the cause of fan noise can be prevented.

FIG. 13 shows the relationship between the amount of air blown by the fan, the noise level, and the static pressure.

In FIG. 13, (a) shows a conventional fan, and (b) shows the present embodiment. Note that static pressure indicates the difference in pressure between the front and back surfaces of the fan. The line marked m in Figure 13 is the resistance curve corresponding to the engine idling state when this blower fan is installed in a car, and the line marked n is the resistance curve when the car is driven from low to medium speed. This is a resistance curve corresponding to driving conditions. The fan noise becomes a problem when the engine is in an idling state, as shown in the first part of FIG. In this idle state, as can be seen from FIG. 13, in the blower fan of this embodiment, the noise level is reduced and the static pressure is increased compared to the conventional fan.

An increase in static pressure indicates that the amount of air blown is increasing. The blower fan used in the experiment shown in FIG. 13 has four blades, and the outer diameter of the blade tip is Dt.
is 300 mm, the diameter Dh of the boss part is 90 mm,
The electric motor that provides external driving force to this boss portion 101 is
It is an 80 watt motor and has a rotation speed of 2180 revolutions per minute.

In this example, the blade attachment angle has the same value from the large part to the blade middle part, and from the blade middle part to the blade tip part,
It is set to increase gradually.

Therefore, the 14th example shows another embodiment of the present invention, and the solid line A in FIG. 14 shows the blade attachment angle of a conventionally known fan. Also, the 14th
In the figure, the dotted chain line B indicates the blade attachment angle β at the blade tip.
t/βm has a value of 1.7, and C and D in FIG.
, and E are respectively β and 73m is 1.9. 1.
8. 1.5. Moreover, βm/βL shows values of 0.52, 0.55, 0.58, and 0.66, respectively.

Further, the chord lengths corresponding to the examples A to E are shown in FIG. 15. In conventional fan A, the ratio of the chord length at the middle part of the blade to the chord length at that position gradually increases from the middle part of the blade to the tip of the blade, and from the middle part to the tip part, the ratio remains the same. It shows. In addition, in the case corresponding to B in FIG. 14, the ratio of the chord length at the tip of the blade to the chord length at the middle of the blade, that is, L t /L m has a value of 1.7, Further, those indicated by C have a value of 1.2, those indicated by D have a value of 1.4, and those indicated by E have a value of 2.2.

FIG. 16 shows the noise reduction effect of each of the fans A to E.

As shown in FIG. 16, compared to the conventional fan shown in A, B-IE, which is an embodiment of the present invention, exhibits a noise reduction effect of 2.5 decibels to 4 decibels. It shows. In the examples shown in FIGS. 1 and 15, the values of βt to βm were in the range of 1.5 to 1.9, and L t /L m was in the range of 1.2 to 2.2. However, even when L t /L m is 2.2 or more, it is expected that the noise reduction effect will be exhibited. However, L
If t/L m is too large, the strength when the fan rotates at high speed will decrease, and in practical terms L t
/Lm is considered to be about 2.0 to 2.5 at its maximum.

Further, in the first region, since the mounting angles β of the blades 103 are approximately the same, the pressure distribution in the chord direction is approximately constant along the blade axis direction of the blades 103.

Furthermore, in the second region, as the mounting angle gradually increases, the absolute value of the pressure distribution gradually increases while maintaining substantially similar pressure distribution curves in the chord direction.

Next, other embodiments of the present invention will be described.

In the above-mentioned embodiment, the first region is the range from the big brother to the middle part of the blade, but the first region may be set to the range from the big brother to beyond the middle part of the blade.

FIG. 23 shows the distribution of the mounting angle β, and B in the figure is the fan B of the above-mentioned embodiment explained in FIG.
Fans F to I of this embodiment are indicated by F-[ in the figure. Fan B is the middle part of the wing KDm=%(Dh+0
．． 5 (Dt Dh)) (position ■ in the figure), and then gradually increases until the mounting angle at the blade tip becomes equal to the mounting angle in the first region! , 7 times more. Fans F~■ are for fan B with the same diameter and approximately the same output.
The mounting angle of the first region is made larger than the mounting angle of fan B, with the mounting angle of the blade tips being the same. If the mounting angle of fan B in the first region is β8, then the mounting angle of fan F-1 in the first region β, ˜β1 is β,=1.1×β8. βc=1
．． 3βm.

β,=1.4βB, β+=1.5×β8.

Also, the first area of Fan F is % (Dh + 0.7
1 (Dm-Dh)) (■ position in the figure), the first area of the fan G is %(Dh+0.79(Dt-Dh)l)
(Position ■ in the figure), the first area of fan H is at the base of the wing.
A (Dh+0.88 (Dt -Dhl [■ in the figure)
position], the first area of Fan I is from Oe to %(Dh+
0.95 (Dt-Dh)) [Position ■ in the figure].

Furthermore, the mounting angle in the first region of the fan F-1 is 0.64 times, 0.76 times, and 0.6 times the mounting angle at the blade tip, respectively.
82 times and 0.88 times.

FIG. 21 shows fans A, B, and
It shows the noise reduction effect and air volume ratio of F~■,
FIG. 22 shows the noise reduction effect and air flow rate ratio in the state indicated by m in FIG. 13, that is, when the engine is idling. From this figure, fan G has the greatest noise reduction effect and also has a large air volume ratio. When this fan G is represented in FIG. 13, it becomes a curve (c).

Although the above embodiment shows an example in which the number of blades 103 is four, the number is not limited to four, and the same effect can be obtained with five or more blades.

Further, in the above example, the blade 103 and the boss portion 101 were integrally molded using grease, but as shown in FIG.
may be formed from a plate material such as aluminum or iron, and may be connected to the boss portion by welding. In addition, the 18th
As shown in the figure, the blades 103 and the boss portion 101 may be formed separately and joined together by means such as a rehenot.

Furthermore, in this embodiment, as shown in FIG. 3, the fan is placed at the rear of the radiator and used as a so-called suction fan that sucks in air. Good too.

Further, the blower fan of the present invention is not limited to use for cooling radiators, but is also used for home use (such as fans for air fans,
It can also be used in household electric fans, etc.

The fan used in the above example has a fan diameter of 300 mm.
mm, when the input from the motor is 80W, the mounting angle β of the first region is 16 to 24°, and the mounting angle β of the blade tip is 16 to 24
The value is set as appropriate depending on conditions such as the fan diameter, the input from the motor, and the vehicle to which the fan is installed.

〔Effect of the invention〕

As described above, even if the blower fan of the present invention is used in a state where the ventilation resistance in front of the blower fan is high and the airflow passing through the fan becomes a diagonal flow, the air will separate from the blade surface. As a result, a fan with low noise can be realized.

[Brief explanation of the drawing]

Fig. 1 is a front view of a blower fan showing an embodiment of the present invention viewed from the axial direction, Fig. 2 is a cross-sectional view of the blade, Fig. 3 is a schematic diagram showing the inside of the front of an automobile, and Fig. 4 is a diagram of the fan. FIG. 5 is a side view schematically showing the side surface of the fan, FIG. 5 is a front view of the fan blade viewed from the front, FIG. 6 is a side view schematically showing the side surface of the fan, and FIG. 7 is a front view of the fan blade. Figure 8 is a front view of the fan, Figure 9 is a diagram showing the blade installation angle, Figure 10 is a diagram showing a cross-sectional view of the blade, and (a) is the XX cross-sectional view in Figure 8. ,
(b) is a cross-sectional view taken along line XI-XI in Fig. 8, Fig. 11 is a drawing showing the axial velocity passing through the fan, Fig. 12 is a drawing showing the chord length in this example, and Fig. 13 is a drawing in this example. Fig. 14 is a diagram showing another example of the blade mounting angle, and Fig. 15 is a diagram showing another example of the blade chord length. , FIG. 16 is a diagram showing the noise reduction effect corresponding to each example, and FIGS. 17 and 18 are,
A front view of a fan showing another modification, FIG. 19 is a cross-sectional view of XIX-X in FIG.
The X-sectional view, FIGS. 21 and 22 are diagrams showing the noise reduction effect and air flow rate ratio of the embodiment of the present invention, and FIG. 23 is a diagram showing the installation angle distribution of another embodiment. 100...Blower fan, 10th work...Boss part 1103
...wing, 11...first center line, 2□...second center line.

Claims (1)

[Claims] (1) A boss section for receiving rotational force from the outside, and a plurality of wings connected around the boss section, the wings being connected to the boss section. The blade attachment angle is approximately constant in the first region from the blade base, which is the connection part, to at least the middle part of the blade, which is the average fan radius position, and continues from this first region to the blade tip. In the second region, the blade attachment angle gradually increases from the predetermined value, the chord length of the blade gradually increases from the blade base to the blade tip, and the center point in the spanwise direction from the blade root to the blade intermediate part. and,
With respect to a first center line connecting the rotation center point of the boss portion,
A second center line connecting a center point in the span direction from the intermediate portion of the blade to the tip portion of the blade and a center point of rotation of the boss portion is inclined in the fan rotation direction, and the blade is Second
A blower fan characterized by having an airfoil formed in a direction perpendicular to the center line of the fan. (2) It is equipped with a boss part for receiving rotational force from the outside, and a plurality of wings connected around the boss part as a center, and the wings are connected to the boss part at the base of the wing. The pressure distribution in the chord direction is approximately constant along the blade axis direction in the first region from the center to at least the middle portion of the blade, which is the average fan radius position, and continues from this first region to the blade tip. In the second region up to, the absolute value of the pressure distribution gradually increases while maintaining substantially similar pressure distribution curves in the chord direction, and the chord length of the blade gradually increases from the blade base to the blade tip; a center point in the wing span direction from the wing base to the wing intermediate portion;
With respect to a first center line connecting the center point of the boss portion, a second center line connecting the center point in the blade span direction from the intermediate portion of the blade to the tip portion of the blade and the center point of the boss portion 1. A blower fan, characterized in that the blades are inclined in the direction, and the blades have airfoils formed in a direction perpendicular to the first and second center lines. (3) The blower fan according to claim 1, wherein the blade attachment angle in the first region of the blade is set in a range of 0.5 to 0.9 times the blade attachment angle at the tip of the blade. (4) The first region of the wing extends from the region from the root of the wing to the middle of the wing,
The blower fan according to claim 1 or 2, wherein the area extends from the base of the blade to a position 0.95 times the blade length. (5) The blower fan according to claim 1 or 2, wherein the chord length of the tip of the blade is within a range of 1.2 to 2.2 times the chord length of the intermediate portion of the blade. (6) The blower fan according to claim 1 or 2, wherein the second centerline of the blade is inclined in the fan rotation direction at an angle of 3° to 17° with respect to the first centerline.