JPH0979185A - Variable speed centrifugal fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sharply restrain a noise at high speed while obtaining sufficient cooling capacity at low speed. SOLUTION: Radial plural cases 11 fixed to an impeller plate 2 are composed of a flat large case 11a to house a large diameter blade 12a and a flat small case 11b to house a small diameter blade 12b. Air holes 13a and 13b are respectively arranged in the circumferential direction in the large case 11a and the small case 11b. An outside diameter of the small case 11b is smaller than an inside diameter of the air hole 13a of the large case 11b. A wire 14 connect the roots of both blades 12a and 12b to each other is wound round a pulley 15. A compression spring 16 is arranged between the root of the large diameter blade 12a and the root of the large case 11a. The small diameter blade 12b is made sufficiently heavier than the large diameter blade 12a so that the large diameter blade 12a is pulled in and the small diameter blade 12b is pulled out by opposing to force of a spring 16, centrifugal force of the large diameter blade 12a and centrifugal force of the small diameter blade 12b at desired rotating speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable speed centrifugal fan that is suitable for a rotating machine such as an inverter that changes in rotation speed, and is used for a rotating machine including a totally closed fan type and an open self-ventilating type. .

[0002]

2. Description of the Related Art FIG. 7 is a side sectional view of a conventional example, and FIG. 8 is a front view of FIG. In the figure, the impeller has a plurality of blades 71 fixed to the disk-shaped impeller plate 2 fixed to the boss 1 by welding or rivets.

[0003]

In the above-mentioned conventional example, in order to measure the noise reduction, the shape of the impeller blade is slightly changed, or the impeller portion of the rotating electric machine is covered with a cover. However, since it is the fixed blade 71, it is the current situation that it is not an essential solution. In a variable speed rotating electric machine, it is necessary to cool from low speed to high speed by an impeller attached to the shaft of the rotating machine. However, if an attempt is made to obtain a sufficient cooling capacity at a low speed, the impeller becomes large, and at a high speed, the cooling capacity becomes excessive and the noise further increases. If the structure is the same, the noise generated when the blades 71 rotate is
The higher the speed, the larger it becomes. That is, the noise increases in proportion to the peripheral speed of the blade. Generally, the noise of the impeller is proportional to the diameter and the rotation speed.

An object of the present invention is to provide a variable speed centrifugal fan which can obtain a sufficient cooling capacity at low speed and can significantly suppress noise at high speed.

[0005]

A variable speed centrifugal fan according to the present invention has a plurality of radial cases fixed to the outer diameter of an impeller plate, the case being a flat large case for accommodating large diameter blades and a small diameter case. It consists of a small flat case that houses the blades, with an air hole that opens in the circumferential direction near the outer diameter of the large case, an air hole that opens in the circumferential direction near the inner diameter of the small case, and an air hole for the small case in the large case. Air holes that are opened in line with each other in the circumferential direction are provided, the outer diameter of the small case is made smaller than the inner diameter of the air hole of the large case, and the wire connecting the root of the large diameter blade and the root of the small diameter blade is placed on the center side of the case. Wrap around the pulley attached to the impeller plate,
A spring is provided between the root of the large diameter blade and the root of the large case or between the small diameter blade and the tip of the small case to resist the large diameter blade from retracting and pulling out the small diameter blade. The mass of the small-diameter blade is made sufficiently larger than the mass of the large-diameter blade so that the large-diameter blade starts to pull in and the small-diameter blade starts to pull out in opposition to the centrifugal force of the large-diameter blade and the centrifugal force of the large-diameter blade.

According to the present invention, when the impeller is stationary,
The large-diameter blades are stopped at the maximum radius position by the spring, and the small-diameter blades are stopped at the minimum radius position. When the impeller starts to rotate, both the large diameter blade and the small diameter blade receive centrifugal force due to rotation. However, when the rotation speed is slow, the spring force is large and both blades stay in the same position as when stationary. The centrifugal force increases as the speed increases. At the desired number of rotations, the mass of the small-diameter blade is set to be larger than that of the large-diameter blade so that the large-diameter blade begins to pull in and the small-diameter blade begins to pull out against the spring force, the centrifugal force of the large-diameter blade, and the centrifugal force of the small-diameter blade. It's big enough. Therefore, at high speeds above the desired speed, the centrifugal force of the small-diameter blade overcomes the total force of the spring and large-diameter blade, and the small-diameter blade moves toward the larger radius and the large-diameter blade moves toward the smaller radius. . The case has air holes at the top and bottom, allowing air to flow freely if there are no blades. In this way, even if the diameter of the blade is reduced and the rotation speed is increased, the peripheral speed at high speed is suppressed and noise is suppressed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view taken along the line AA of FIG. 4 of an embodiment, FIG. 2 is a front view of FIG. 4, FIG. 3 is a partial top view of FIG. 4, and FIG. 4 is a side sectional view of FIG. FIG. 5 is a dimension determination diagram, and FIG. 6 is an operation principle diagram. In FIGS. 1, 2, 3 and 4, a disc-shaped impeller plate 2 is fixed to a boss 1 of the impeller.
A plurality of cases 11 that are radially arranged near the outer diameter of the impeller plate 2
To fix. The case 11 is composed of a flat large case 11a for accommodating the large diameter blade 12a and a flat small case 11b for accommodating the small diameter blade 12b. An air hole 13a that opens in the circumferential direction is provided near the outer diameter of the large case 11a, and an air hole 13b that opens in the circumferential direction is provided near the inner diameter of the small case 11b. The large case 11a has an air hole 13b in the small case 11b.
And an air hole 13x that opens in a circumferential direction are provided. The outer diameter of the small case 11b is smaller than the inner diameter of the air hole 13a of the large case 11b. The root of the large diameter blade 12a and the small diameter blade 1
A wire 14 connecting the root of 2b is wound around a pulley 15 attached to the impeller plate 2 on the center side of the case 11. Large diameter blade 1
A large diameter blade 1 is provided between the root of 2a and the root of large case 11a.
A compression spring 16 is provided which resists the pulling in of the small diameter blade 12b by the pulling in of the small diameter vane 12b. At the desired number of revolutions, the large-diameter blade 12a is retracted in opposition to the force of the compression spring 16, the centrifugal force of the large-diameter blade 12a, and the centrifugal force of the small-diameter blade 12b.
The mass of the small-diameter blade 12b is made sufficiently larger than that of the large-diameter blade 12a so that b starts to be pulled out. Instead of the compression spring 16, a tension spring may be provided between the small diameter blade 12b and the tip of the small case 11b.

According to this embodiment, when the impeller is stationary, the large diameter blade 12a is stopped at the maximum radius position and the small diameter blade 12b is stopped at the minimum radius position by the spring 16. When the impeller starts to rotate, both the large-diameter blade 12a and the small-diameter blade 12b receive centrifugal force due to the rotation. However, when the rotation speed is low, the force of the spring 16 is large and both blades 12a, 1
2b remains in the same position as when stationary. The centrifugal force increases as the speed increases. At the desired number of revolutions, the small-diameter blade 12 is pulled in by the large-diameter blade 12a and the small-diameter blade 12b begins to pull in, against the centrifugal force of the spring 16, the large-diameter blade 12a, and the small-diameter blade 12b.
The mass of b is made sufficiently larger than the mass of the large diameter blade 12a. Therefore, at high speeds above the desired speed,
The centrifugal force of the small diameter blade 12b causes the spring 16 and the large diameter blade 12a to
The small-diameter blade 12b moves toward the larger radius and the large-diameter blade 12a moves toward the smaller radius. The case 11 has air holes 13a, 13b, 13x at the top and bottom.
However, if both blades 12a and 12b are not provided, air can freely pass. In this way, even if the diameter of the blade is reduced and the rotation speed is increased, the peripheral speed at high speed is suppressed and noise is suppressed.

Next, it will be examined with reference to the operation principle diagram of FIG. 6 what happens with a mathematical expression and how it can be realized with a practical numerical value. N: Rotational speed (rpm) of the impeller F _1n ; Centrifugal force of large diameter blade when the impeller rotates N times (kg) F _2n : Centrifugal force of small diameter blade when the impeller rotates N times (Kg) r _1n ; When the impeller rotates N times, the radius of gyration of the center of gravity of the large diameter blade (mm) r _2n ; When the impeller rotates N, the radius of gyration of the center of gravity of the small diameter blade (mm) F _Sn ; Force (kg) generated by the spring when the impeller rotates N times. Therefore, for example, r ₁₀ and r ₂₀ are the distances from the impeller center of the large diameter blade and the small diameter blade at rest, respectively. r ₁₁₀₀ represents the radius of gyration at 1000 rpm. m ₁ ; mass of large diameter blade (gr) m ₂ ; mass of small diameter blade (gr) L ₁ ; length of large diameter blade (mm) L ₂ ; length of small diameter blade (mm) K _s ; spring constant ( kg / cm) l _s ; Free length of spring (mm) K ₁ ; Constant In order to simplify the explanation below, if L ₁ = L ₂ = L and the moving distance of the blade is L, the following equation is obtained. To establish. F _1n = K ₁ · m ₁ · r _1n · N ² F _2n = K ₁ · m ₂ · r _2n · N ² F _Sn = K _s · [l _s − (r _1n −r ₂₀ )] r _1n + r _2n = R ₁₀ + r ₂₀ F _1n + F _Sn = F _2n However, K ₁ = π · 10 ⁻⁶ /30·9.8 where the blade does not move in the range where F _1n + F _Sn > F _2n . In the range where F _1n + F _Sn <F _2n holds, the blade moves to the center.

[0010] To summarize the _{^{equation, N 2 = K s ÷ 10}} K 1 × _{[l s - (r 1n -r 20} ) ] ÷ [m
₂ (r ₁₀ + r ₂₀ ) − (m ₁ + m ₂ ) r _1n ] These constants may be satisfied, and each constant may be determined so that the blade moves at a practical rotation speed.

When the rotational speed at which movement starts is confirmed using the numerical values of the following embodiment, N = 1082 rpm. Below 1082 rpm, the blade does not move due to the action of the spring. At just 1082 rpm, the spring and centrifugal forces are balanced. At 1082 rpm or more, the centrifugal force of the small-diameter blade always exceeds the total force of the spring and the large-diameter blade, and the blade moves to the center.

As one example, the dimension determination diagram of FIG. 5 and constants are defined as follows. Impeller plate diameter: 600 mmφ Large diameter blade; length 60 mm, width 60 mm, thickness 1.6 m
m, mass 45 gr, material iron, small diameter blade; length 60 mm, width 60 mm, thickness 3.0 m
m, mass 84.2gr, material iron, distance from the center of the impeller rotation axis to the center of gravity of the blade, when the large diameter blade is stationary 270mm After the large diameter blade is moved 210mm When the small diameter blade is stationary 150mm After the small diameter blade is moved 210mm Free length 180 mm Spring constant 1 kg / cm Spring length When the large-diameter blade is stationary 120 mm After moving the large-diameter blade 60 mm At a rotational speed of 2 or 3, try to calculate for reference. Since N = 0 (i.e., at _{rest) F 10 = 0 F 20 =} 0 F s0 = K S [l _s -2L] = 10 ^-1 · 60 = 6kg centrifugal force does not work, keep stopping the blade Is only F _s0 . The force of the spring is large enough for the blade mass so that the blade does not move. N = 900 rpm F ₁₉₀₀ = K ₁ 45.270.900 ² = 105.1 kg F ₂₉₀₀ = K ₁ 84.2.150.900 ² = 109.3 kg F _s900 = [180- (270-30-120)] × 10
^-1 = 6kg F ₁₉₀₀ + F _s900 = 111.1 F ₂₉₀₀ = 109.3 ∴F ₁₉₀₀ + F _s900 > F ₂₉₀₀ and does not move. _{N = 1000rpm F 11000 = K 1} 45 · 270 · 1000 2 = 129.8kg F 21000 = K 1 84.2 · 150 · 1000 2 = 134.9kg F s1000 = [180- (270-30-120)] × 1
0 ^-1 = 6 kg F ₁₁₀₀₀ + F _s1000 = 135.8 F ₂₁₀₀₀ = 134.9 ∴F ₁₁₀₀₀ + F _s1000 > F ₂₁₀₀₀ and the _robot does not move (just before moving). N = 1500 rpm (For example, check at this rotation speed) F ₁₁₅₀₀ = K ₁ 45 ・ 270 ・ 1500 ² = 291.9 kg F ₂₁₅₀₀ = K ₁ 84.2 ・ 150 ・ 1500 ² = 303.7 kg Then, since the spring force at this time is 6 kg, F ₁₁₅₀₀ + F _s1500 = 297.9 <F ₂₁₅₀₀ = 303.7, so the movement should be started. The maximum value of the spring is [180- (210-30-120)] × 10 ^-1 = 12
Since it is kg, it is F ₁₁₅₀₀ + F _s1500 = 303.9 ≈ F ₂₁₅₀₀ = 303.7, and if the centrifugal force is taken into consideration on this, the movement of the impeller has ended.

Generally, the noise of the impeller is proportional to the diameter and the rotation speed. Therefore, when the impeller as shown in the embodiment is used in, for example, a 4-pole induction motor and driven by an inverter power source, 600 mmφ up to 50 Hz (about 1000 rpm).
It can be cooled by the fan and secure sufficient cooling performance. When the rotation speed further increases, the fan is automatically operated with a 480 mmφ. Since the rotation speed increases, cooling performance does not decline,
Fan noise is significantly reduced compared to high-speed operation.

If it is used up to 100 Hz (about 2000 rpm), the noise is [480 × 2000] ÷ [600 × 2000] = 0.8 If the noise at 2000 rpm is 80 db, the impeller of the present invention will be 16 db. It is a value that can be reduced and cannot be achieved by other methods. Considering the hysteresis of blade operation, it is best used for a main motor of a vehicle that repeatedly starts and stops.

[0015]

According to the variable speed centrifugal fan of the present invention,
At the desired rotation speed, the large-diameter blade retracts and the small-diameter blade begins to pull out against the force of the spring, the centrifugal force of the large-diameter blade, and the centrifugal force of the small-diameter blade. The centrifugal force overcomes the total force of the spring and the large-diameter blade, and the small-diameter blade moves toward the larger radius, the large-diameter blade moves toward the smaller radius, and the diameter of the blade becomes smaller, resulting in sufficient cooling capacity at low speed. In addition, there is an effect that noise can be significantly suppressed at high speed.

[Brief description of drawings]

FIG. 1 is a sectional view taken along line AA of FIG. 4 showing an embodiment.

FIG. 2 is a front view of FIG.

FIG. 3 is a partial top view of FIG.

FIG. 4 is a side sectional view of FIG.

[Figure 5] Dimension determination diagram

FIG. 6 Operating principle diagram

FIG. 7 is a side sectional view of a conventional example.

FIG. 8 is a front view of FIG. 7;

[Explanation of symbols]

 1 Boss 2 Impeller plate 11 Case 11a Large case 11b Small case 12a Large diameter blade 12b Small diameter blade 13a Air hole 13b Air hole 13x Air hole 14 Wire 15 Pulley 16 Compression spring

Claims (1)

[Claims] 1. A plurality of radial cases are fixed near the outer diameter of an impeller plate, and the case comprises a large flat case for accommodating large diameter blades and a small flat case for accommodating small diameter blades. Provide an air hole that opens in the circumferential direction near the outer diameter of the case, an air hole that opens in the circumferential direction near the inner diameter of the small case, and an air hole that opens in the circumferential direction in the large case in line with the air hole of the small case. The outer diameter of the small case is smaller than the inner diameter of the air hole of the large case, and the wire that connects the root of the large diameter blade and the root of the small diameter blade is wrapped around the pulley attached to the impeller plate on the center side of the case, A spring is provided between the root of the blade and the root of the large case or between the tip of the small diameter blade and the tip of the small case to prevent the large diameter blade from retracting and pull out the small diameter blade. And the large-diameter blade against the centrifugal force of the large-diameter blade and the centrifugal force of the small-diameter blade. Variable speed centrifugal fan, wherein a pull-diameter blade is sufficiently greater than the mass of the large radius vanes mass of the small-diameter blade to begin drawer.