JP3058786B2 - Mixed flow fan and refrigerator using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in performance of a mixed flow blower, such as noise reduction.

[0002]

2. Description of the Related Art In general, there are two types of blowers, an axial flow type and a centrifugal type. The former is a blower that blows air from the rear to the front along the axial direction by a rotating blade like a propeller fan. In addition, the latter is called a turbo fan or sirocco fan, etc., and is a blower that blows air taken in from the center in the radial direction by blades, and the blown air is guided in a certain direction by a spiral casing. is there.

Conventionally, as shown in FIG. 7, an axial-flow type propeller fan 1 has been generally used as a blower for a refrigerator or the like. The propeller fan 1 is mounted on the fan unit 3 on the back of the freezer 2 and is disposed above the cooler 4. Then, the cool air cooled by the cooler 4 moves upward on the back surface of the freezer 2, passes through the blower motor 5 from below the propeller fan 1, and changes its direction forward from below the rear side of the propeller fan 1 by its suction force. Is done. Then, by the rotation of the propeller fan 1, cool air is blown out from the cool air inlet 9 of the unit front wall 8 into the freezer 2 through the cool air inlet 7 of the unit rear wall 6, and the freezer 2 is cooled. In FIG. 7, reference numeral 10 denotes the rotation axis of the propeller fan, 1
1 is a motor cover, 12 is a refrigerator, and 13 and 14 are cool air ducts through which cool air circulates.

[0004] In rare cases, a blower may be provided below the freezer 2. In consideration of the positional relationship with the cooler 4, the blower is generally provided in the space behind the freezer 2. Therefore, since the cool air from the cooler 4 must flow upward from below, the air inflow side of the propeller fan 1 has an uneven flow in which cool air flows only from below, that is, an uneven flow.

[0005]

The function of the freezer refrigerator is to cool the inside of the refrigerator. The cooling capacity is not determined only by the cooler 4 but also the air volume of the propeller fan 1 is important. Since it is one of the factors, if the air volume set at the time of design cannot be secured, the propeller fan 1
It is necessary to take measures such as increasing the number of rotations. But,
Since the refrigerator is operated all day, the noise is becoming a serious problem, especially at night. Therefore, the reduction of the compressor noise and the noise of the propeller fan 1 (not shown) were the most important issues.

However, the characteristic of the propeller fan 1 is that the inflow radius and the outflow radius of the air are equal, and work is added to the air as a reaction of the fluid pressure applied to the blade 1a. 1a is designed. Therefore, when the noise of the propeller fan 1 is measured, compared with the noise of the propeller fan 1 when there is no drift shown in FIG.
The sound is louder only at the primary blade passing frequency, which is proportional to the product of the number of blades and the number of rotations shown in (Blade Passage Frequency).

[0007] Therefore, when there is a drift in the air inflow side structurally, such as in a refrigerator or the like, the propeller fan 1 performs a lot of work in the lower side where the amount of air is large.
Since there is almost no work where the upper air volume is small, the fluctuation of the fluid pressure applied to the surface of each blade 1a on the upper and lower sides of the propeller fan 1 becomes large,
The noise at the blade passing frequency becomes more remarkable than when there is no drift.

The mechanism of generating noise due to this drift is that pressure fluctuations occur due to fluctuations in the lift or drag fluid pressure on the surface of the blade 1a, or the blade 1a
This is considered to be because the boundary layer developed on the surface a was disturbed and the vortex was discharged to the wake. However, in order for the blade 1a to work on the air, that is, to obtain the pressure and the air volume, the difference between the pressure generated on the surface on the rotation direction side of the blade 1a and the pressure generated on the surface on the non-rotation side, that is, the fluid pressure is efficiently Is the root cause.

It is known that a propeller fan 1 generally used as a blower for cooling the inside of a refrigerator has low noise, but the situation is the same even when a sirocco fan or a turbo fan is used. Considering the functions of the above, its countermeasures were extremely difficult.

[0010] Then, usually, the generated noise is converted into other means,
For example, in a refrigerator using a sound absorbing material or in a refrigerator, JP-A-2-24065 discloses a method of absorbing and insulating sound by using a structure that does not emit noise forward.
These methods have limited noise reduction.

Therefore, it is conceivable to use a mixed flow fan having the characteristics of an axial fan and a centrifugal fan. This oblique blower blows air from the rear center and sucks out air to the front diagonally in the radial direction.It is located between the axial flow type and the centrifugal type in terms of performance. It is known and has already been used in large aircraft and air conditioning related fields. However, in the consumer and home electric appliances fields, it has been difficult to manufacture due to problems such as miniaturization and low cost, and practical application has not been achieved.In recent years, however, mixed flow blowers have been used as blowers such as outdoor units of home air conditioners. It became so. However, this mixed flow fan also has a noise problem, and has not been realized for use in a refrigerator or the like due to further downsizing.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a mixed flow blower which can reduce noise by reducing the fluid pressure applied to the blades even when the air flow is uneven. Then, a low-noise refrigerator-freezer is provided by using this mixed flow blower.

[0013]

Means for solving the problems according to the first aspect of the present invention are, as shown in FIG. 1, a conical inner plate 22 attached to a rotating shaft 21, a ring-shaped outer plate 23, and a plurality of blades 24 disposed along the inclination of the inner plate 22 between the plate 22 the outer plate 23, each vane 24 is straight
It consists of a linear flat plate, and when air passes through the blades 24
The inner plate 22 is mounted at a constant mounting angle α toward the upstream in the rotational direction with respect to the radial direction of the inner plate 22 so that the turning angle becomes zero, and between the inner plate 22 and the outer plate 23 from the center of rotation. It blows air toward the outer periphery.

According to a second aspect of the present invention, there is provided an inner plate
And the outer plate 41 are separated, and the inner plate 22 or the outer plate 41 is separated .
Only the one that can be rotated.

Then, it is attached to the back of the refrigerator-freezer.
The blower 29 for cooling the inside of the refrigerator blows cool air into the refrigerator.
A front wall 30 having a cool air port 9 formed therein;
Is formed, and the front wall 30 and the rear wall 31 are provided.
And the above-mentioned mixed flow type blower is arranged .

[0016]

In the above means for solving the problems, the inner plate 22 and the outer plate 2
The air sucked from the gap on the center side with the inner plate 22
Flows obliquely forward along the inclination of the inner plate 22, flows upstream along the rotational direction along the blades 24, and is blown out from the gap on the outer peripheral side between the inner plate 22 and the outer plate 23. At this time, since the air flows along the blades 24, the fluid pressure is hardly applied to the surface of the blades 24, and the fluctuation of the fluid pressure on the surface of the blades 24 is small, so that the noise is reduced.

Further, by separating the inner plate 22 and the outer plate 41, the weight of the fan main body, which is the rotating portion of the mixed flow blower, can be reduced, and noise can be reduced by reducing the weight.

Therefore, by using such a mixed flow blower as the blower 29 for cooling the inside of the refrigerator, even if the inflow of air from the cooler 4 is a drift from below, the air flow from the center of rotation to the outer periphery is Because it blows air to the direction,
The fluid pressure applied to the surface of the blade 24 is small, and low noise can be realized.

[0019]

【Example】

(First Embodiment) FIG. 1 is a side view of a mixed flow blower according to a first embodiment of the present invention, FIG. 2 is a rear view of the mixed flow blower, and FIG.
FIG. 2 is a detailed view of the back of the freezer of the refrigerator using a mixed flow blower.

As shown in FIGS. 1 and 2, a mixed flow blower (hereinafter referred to as a mixed flow fan) according to the present embodiment includes
A fan motor 5 configured to rotate the main body 20 via a rotary shaft 21; the fan main body 20 includes a conical inner plate 22 mounted on the rotary shaft 21, a ring-shaped outer plate 23, Five blades 24 are provided between the inner plate 22 and the outer plate 23 along the inclination of the inner plate 22.

The inner plate 22 is a thin plate having a cross section of Mt. Fuji, a rear surface 25 of which is formed in a circular flat shape, and is gradually inclined from the rear surface 25 toward the front toward the entire circumference. . This inclination angle is determined by the radius ri of the rear surface 25, the radius ro of the inner plate, and the height h of the inner plate 22.
At the center of the rear surface 25 of the inner plate 22, a bearing portion 26 for fitting the rotating shaft 21 is provided so as to protrude toward the front side of the inner plate 22.

The outer plate 23 has an outer shape of the inner plate 22.
The inner plate 22 is disposed on the rotation shaft 21 side of the inner plate 22, and its entire circumference is inclined at substantially the same angle as the inner plate 22, and covers the outer peripheral side of the inner plate 22 at a fixed interval. The center hole of the outer plate 23 has a larger diameter than the rear surface 25 of the inner plate 22, and an opening between the circular hole and the rear surface 25 of the inner plate 22 serves as an air suction port 27. An opening on the outer peripheral surface between the plate 22 and the outer plate 23 is an outlet 28.

Each of the blades 24 is a linear flat plate having a constant height hf and a lower surface inclined along the inner plate 22 and an upper surface inclined along the outer plate 23. The outer plate 23 is fixed to the inner plate 22 and the upper surface is fixed. As shown in FIG. 2, each blade 24 is attached at a constant angle α toward the upstream side in the rotation direction with respect to the radial direction of the inner plate 22, and five blades 24 are arranged at an equal pitch. . The mounting angle α of the blade 24, as relative turning angle when the air so as not to increase the noise at blade passing frequency even when subjected to drift passes vanes 24 becomes zero, ta
nα = Ui / Vz (Vz: inflow velocity of air, Ui: rotation
Peripheral speed at the radial position on the shaft side) .

This mixed flow fan is, as shown in FIG.
It is mounted on a blower (fan unit) 29 attached to the back of the freezer 2 of the refrigerator. The fan unit 29 is attached to a unit front wall 30 having a cool air opening 9 for blowing cool air into the refrigerator, a unit rear wall 31 having a cool air intake 7 formed therein, and a rear part of the unit rear wall 31. Motor cover 32 for supporting blower motor 5
And In the mixed flow fan, the fan main body 20 is disposed between the unit front wall 30 and the unit rear wall 31,
The rotation is driven by the blower motor 5 via the rotation shaft 21. The cooler 4 is arranged below the blower motor 5. However, the outer diameter Do of the fan body 20 is φ134 mm, the inner diameter Di is φ100 mm, and the height h is 30.
mm. The detailed description of the structure of the refrigerator-freezer is omitted, and the same components as those of the conventional refrigerator are denoted by the same reference numerals.

In the above refrigerator, the cool air cooled by the cooler 4 rises by the rotation of the fan body 20 and reaches the vicinity of the motor 5 behind the fan body 20. And
Cold air is generated by the suction force of the fan body 20 and the rear wall 3 of the unit.
The air flow is changed forward through the cold air inlet 7 and flows to the suction port 27 of the fan body 20. Part of the cool air that passes through the motor 5 and goes further upward is guided to the suction port 27 of the fan body 20 by the motor cover 32.

Then, the cool air sucked into the fan main body 20 from the suction port 27 flows obliquely forward along the inclination of the inner plate 22 toward the blowout port 28, and flows upstream along the blade 24 in the rotational direction. And is blown out from the outlet 28. Thereafter, cool air is blown out from the cool air port 9 of the unit front wall 30 to the freezer 2.

When the noise of the mixed flow fan at this time is measured, as compared with the case where there is a deviated inflow of the conventional propeller fan as shown in the noise spectrum shown in FIG.
The primary noise of the blade passing frequency indicated by the symbol
The noise was reduced by about 15 dB (A).

When the outer diameter of the conventional propeller fan is the same as the outer diameter Do of the fan body 20 of the present embodiment, the number of revolutions of the fan body 20 at which the same static pressure as that of the propeller fan is obtained is determined by a proportional law. 2040rpm to 1530r
pm, and the total noise is about 6 dB
(A) was reduced.

As described above, in the mixed flow fan, the sucked cool air flows along the inclination of the inner plate 22 toward the upstream side in the rotational direction in the outer peripheral direction, and is blown out along the blades 24. Since the fluid pressure is hardly applied to the surface of the blade 24 and the fluctuation of the fluid pressure on the surface of the blade 24 is small, the noise is reduced.

Therefore, by using such a mixed flow fan in a refrigerator-freezer, the fan 4 can be moved from the cooler 4 to the fan body 2.
Even if the inflow of air into the nozzle 0 is a drift from below, the air is blown out from the suction port 27 near the center of rotation to the outlet 28 in the outer peripheral direction, so that the air flows along the blade 24 and Since the fluid pressure applied to the surface is small, it is possible to provide a low-noise refrigerator-freezer.

In the conventional propeller fan 1, the blade 1a is disposed at the unit rear wall 31 of the fan unit 29 because the air inflow radius and the outflow radius are the same. Since the radius is smaller than the outflow radius, the rear wall 31 and the front wall 30 of the fan unit 29
Can be arranged in between.

As a result, the outer diameter of the fan body 20 can be increased, and a static pressure equivalent to that of a conventional propeller fan can be obtained even when the rotation speed of the fan body 20 is reduced, so that noise reduction due to a reduction in the rotation speed is reduced. realizable. Also, since the static pressure does not decrease even if the outer diameter of the fan body 20 is the same,
Aerodynamic performance can be improved. Furthermore, since the fan unit 29 can be made thinner, the capacity in the freezer 2 can be increased, or the refrigerator-freezer body can be made thinner.

(Second Embodiment) The mixed flow fan of this embodiment is
As shown in FIG. 5, the inner plate 22 and the outer plate 41 of the fan body 20 are separated, and only the inner plate 22 is rotatable.

That is, the inner plate 22 is disposed between the unit front wall 30 and the unit rear wall 31 and is supported by the rotating shaft 21. The outer plate 41 is fixed to the rear wall 31 of the unit, and the blades 24 are fixed to the inner plate 22. When the inner plate 22 rotates, a gap of about 3 mm is provided so that the blades 24 do not hit the outer plate 41. Have been. The other configuration is the same as that of the first embodiment.

Here, it is conceivable that the static pressure during rotation of the fan main body 20 is reduced by the gap between the outer plate 41 and the blade 24. However, as shown in FIG. 6 showing the air flow characteristics of the mixed flow fan of the first embodiment and the mixed flow fan of the present embodiment, the decrease in the static pressure of the mixed flow fan of the present embodiment is very small, and It was confirmed that the performance was the same as that of the example mixed flow fan.

Therefore, even if the inner plate 22 and the outer plate 41 are separated, the air volume characteristics do not change, and there is no need to increase the number of revolutions to increase the air volume, so that noise does not increase.

Further, by separating the inner plate 22 and the outer plate 41, the weight of the fan main body 20 can be reduced, and since only the inner plate 22 is rotated, further noise reduction can be realized by reducing the weight.

It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that many modifications and changes can be made to the above-described embodiment within the scope of the present invention.

For example, in the first embodiment, the outer diameter Do of the mixed flow fan is φ134 mm, the inner diameter Di is φ100 mm,
Although the height h was set to 30 mm, it is not limited to this.

Although the blades 24 are linear flat plates,
It may be arc-shaped or streamlined depending on the inflow condition, and the method of determining the mounting angle α may be determined by another method.
The number of blades 24 is not limited to five.

Further, the bearing 26 of the first embodiment is provided
2 may be attached to the rear side of the rear surface 25.

Further, in the second embodiment, the outer plate 41 is separated and fixed to the unit rear wall 31 and only the inner plate 22 is rotated. However, the blades 24 are fixed to the outer plate 41 and the inner plate 22 is fixed. The outer plate 41 may be rotated while being fixed to the unit rear wall 31.

Further, the use of the mixed flow fan is not limited to a refrigerator and a refrigerator, but can be applied to a device in which air flow is uneven due to installation conditions.

[0044]

As is clear from the description above, according to the present invention, according <br/> to the onset bright, obliquely from the center of rotation along the inclination of the inner plate air sucked into the upstream side in the rotation direction of the outer circumferential direction And the relative turning angle when air passes through the blades
Is blown out along the blades,
Does not occur. Therefore, almost no longer applied fluid pressure on the surface of the blade, I Do small variations in fluid pressure at the surface of the blade, it decreases the noise.

Further, since the inflow radius of the air is smaller than the outflow radius, the outer diameter can be increased, and the static pressure equivalent to that of the conventional axial flow fan can be obtained even when the rotation speed is reduced. Noise can be reduced by reducing the number. Further, even if the outer diameter is the same, the static pressure does not decrease, so that the aerodynamic performance is not reduced. And, by arranging it in a place where the drift is received, the low noise effect is enhanced.

In addition , since the static pressure does not decrease even if the inner plate and the outer plate are separated, there is no need to increase the number of revolutions to increase the air volume, and the noise does not increase. Also,
By separating the inner plate and the outer plate, the rotation of the mixed flow fan
Since the weight of the rolling portion can be reduced, and only one of them can be rotated, further noise reduction can be realized by reducing the weight.

Therefore, by using such a mixed flow blower as a blower for cooling the interior of a refrigerator,
Even if it is arranged at a position where the inflow of air into the mixed flow blower is deviated, noise can be reduced. In addition, the blower is
Since it can be placed between the front wall and the rear wall,
The thickness of the refrigerator can be reduced, and the capacity in the freezer can be increased, or the thickness of the refrigerator-freezer body can be reduced. Further
In addition, since the blower can be arranged as described above,
Can increase the outer diameter of conventional blowers.
Reduces the number of revolutions while obtaining the same static pressure, reducing noise
It is.

[Brief description of the drawings]

FIG. 1 is a side view of a mixed flow blower according to a first embodiment of the present invention.

FIG. 2 is a rear view of the mixed flow blower of the first embodiment.

FIG. 3 is a detailed back view of a freezer of a refrigerator using the mixed flow blower of the first embodiment.

FIG. 4 is a diagram showing a noise spectrum of the mixed flow fan of the first embodiment.

FIG. 5 is a side view of the mixed flow blower of the second embodiment.

FIG. 6 is a diagram showing air volume characteristics of the mixed flow blowers of the first embodiment and the second embodiment.

FIG. 7 is a sectional view of a refrigerator-freezer using a conventional propeller fan.

FIG. 8 is a noise spectrum diagram when a conventional propeller fan has a drift.

FIG. 9 is a noise spectrum diagram of a conventional propeller fan when there is no drift.

[Explanation of symbols]

 4 Cooler 21 Rotary Shaft 22 Inner Plate 23 Outer Plate 24 Blade 29 Fan Unit

Continuation of front page (56) References JP-A-4-41992 (JP, A) JP-A-2-238199 (JP, A) JP-A-4-237896 (JP, A) JP-A-4-265497 (JP) , A) JP-A-53-134209 (JP, A) Jikken Sho 29-11781 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F04D 23/00 F04D 29/30

Claims (3)

(57) [Claims] An air inflow is arranged at a position where the air flow is deviated.
A mixed flow blower, comprising a conical inner plate, a ring-shaped outer plate, and a plurality of blades arranged between the inner plate and the outer plate along the inclination of the inner plate, The blade is formed of a straight plate, and is attached at a constant angle toward the upstream in the rotational direction with respect to the radial direction of the inner plate so that the turning angle when air passes through the blade is zero. A mixed flow blower, wherein air is blown from a center of rotation to an outer peripheral direction between an inner plate and the outer plate. 2. An inner plate and an outer plate are separated from each other, and only the inner plate or the outer plate is rotatable.
The mixed flow blower as described. 3. The freezer according to claim 1 or 2, on the back of the freezer.
A blower equipped with a mixed flow blower of
The wind device has a cool air outlet for blowing cold air into the freezer.
The formed front wall and the rear wall where the cold air intake is formed
And the diagonal blower is disposed between the front wall and the rear wall.
Refrigerator, characterized in that it has been.