JPH0229268Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The invention is a cross-flow fan, in particular, a rotor body with a large number of blades arranged around it is connected to the output shaft of a motor via a disk-shaped anti-vibration rubber. Regarding the cross flow fan.

(Prior Art) In general, the noise emitted by this type of crossflow fan can be broadly divided into ventilation noise caused by the rotor body and noise caused by the motor, and the ventilation noise caused by the rotor body has been considerably reduced in recent years. The reduction in noise level during gentle operation at low rotational speeds has been remarkable, with many engines now having 25 to 26 phon or less.

However, at this level of noise, the noise caused by the motor has a greater influence on the noise level than the ventilation noise, and reducing this noise has become a problem. Among the latter types of noise, vibrations twice the frequency of the power supply generated from the rotating shaft system of the motor are becoming the main cause of noise. (For example, National
Technical Report, Volume 24, No. 5, October 28, 1978
(Refer to pages 796 to 803, published by Matsushita Electric Industrial Co., Ltd.) This double vibration occurs when the natural frequency of the torsional vibration system that connects the rotor body and the motor rotor approaches twice the power frequency. This phenomenon occurs to a very large extent when there is resonance.

On the other hand, this type of cross-flow fan is often used in indoor units of separate air conditioners.

In order to improve the installation workability of the indoor unit, efforts are being made to reduce the weight of the indoor unit, and for this reason, the wall thickness of the rotor body of the cross flow fan, which is one of the main parts that make up the indoor unit, has also been reduced. This allows for weight reduction.

However, when the weight of the rotor body is reduced, the moment of inertia Ia of the rotor body becomes smaller, which means that the natural frequency ω of the torsional vibration system (hereinafter abbreviated as the torsional vibration system) connecting the rotor body and the rotor of the motor decreases. becomes high (the relationship between this moment of inertia Ia and the natural frequency ω is clear from the following equation), causing resonance near twice the power frequency (50Hz) (100Hz). .

That is, it is known that the natural frequency ω of the torsional vibration system has the following relationship with the moment of inertia Ia of the rotor body and the rotational spring constant k of the vibration isolating rubber.

(Ib: Moment of inertia of motor rotor) In addition, anti-vibration rubber is generally made of synthetic rubber to prevent the pulsating torque of the motor from being transmitted to the rotor body.
53-57302, as shown in Figure 6, a synthetic rubber anti-vibration rubber c is installed between the connecting plate a and the shaft b.
A coupling groove c2 with the connecting plate a is provided on the peripheral edge of the disc-shaped main body c1, and the groove c2
Insert and hold the connecting plate a, and bolt d.
It is fixed to the shaft by.

Therefore, the applicant focused on the fact that if the hardness of the vibration isolator rubber is decreased, the rotational spring constant k of the vibration isolator rubber becomes smaller, and by decreasing the hardness of the vibration isolator rubber, the natural frequency ω of the torsional vibration system is I was careful not to get close to the double vibration.

(Problem to be solved by the invention) As mentioned above, in the past, the rotor body was further improved to be lighter and the natural frequency of the torsional vibration system became higher. However, if the hardness is lower than the current hardness of anti-vibration rubber (45° ± 5°), the anti-vibration rubber will lose its complete elasticity, lose its ability to return to its shape, and lose its original function. , the hardness of the anti-vibration rubber could not be further reduced;
Due to the resonance in the double vibration, as shown in Figure 7,
The problem was that the sound pressure level of the noise at 100Hz (double vibration) was high.

The noise data shown in Figure 7 is based on the following conditions: rotor body outer diameter is 80 mm, length is 620 mm, weight is 460 g, material is ASG resin, anti-vibration rubber material is chloropyrene rubber, hardness is 45° ± 5°, rotor outer diameter It is 43.5mm and weighs 278g.

On the other hand, the occurrence of double vibration can also be prevented by increasing the hardness of the vibration isolating rubber c and increasing the rotational spring constant k.
Increasing the hardness of the anti-vibration rubber c will reduce the damping coefficient for vibration isolation.
There was a problem in that the original purpose of the vibration damping effect could not be achieved.

The present invention was devised in view of the above-mentioned problems, and the purpose is to improve the vibration-proof rubber without reducing the hardness of the vibration-proof rubber in indoor cross-flow fans of air conditioners. By making the shape and structure special, it is possible to reduce the rotational spring constant of the anti-vibration rubber.
The purpose is to prevent the generation of noise due to resonance based on double vibration.

(Means for solving the problem) However, the configuration of the present invention is such that the disc-shaped anti-vibration rubber of the indoor cross-flow fan of the air conditioner has a hardness of 45°.
±5°, and a plurality of recesses are provided around the vibration isolating rubber, so that the rotational spring constant k of the vibration isolating rubber is However, Ia: Moment of inertia of the rotor body Ib: Moment of inertia of the motor rotor 2f vibration: The vibration is set to twice the power frequency.

(Function) A disk-shaped vibration isolating rubber having a hardness of 45°±5° has a rotational spring constant k of the vibration isolating rubber. However, Ia: Moment of inertia of the rotor body Ib: Moment of inertia of the motor rotor 2f vibration: The hardness of the vibration isolating rubber is reduced by providing multiple recesses around it so that the vibration is twice the power frequency. The rotational spring constant k of the anti-vibration rubber can be reduced without any loss of anti-vibration effect.
The natural frequency of the torsional vibration system can be made smaller than twice the frequency, and the generation of vibrations twice the power supply frequency can be prevented, and the generation of noise due to resonance can be suppressed to an extremely low level.

(Example) Examples of the present invention will be described below based on the drawings.

In the drawing, reference numeral 1 denotes a rotor body having a large number of blades 11 around it, a shaft 12 protruding from one end of the rotor body 1, and a disc-shaped shaft 12 having a hardness of 45°±5° at the other end. A vibration isolating rubber 2 is interposed therebetween, and the rotor main body 1 is connected to an output shaft 3 of a motor (not shown) via the vibration isolating rubber 2. The shaft 12 is supported by an indoor unit main body (not shown) through a cylindrical bearing 13, and the output shaft 3 is supported by a motor bracket 33 through ball bearings 31, 32. Further, 4 is a rotor of the motor, and the power of the motor is first transmitted to this rotor 4, and from this rotor 4 is transmitted to the output shaft 3.

Therefore, in this embodiment, the disc-shaped vibration isolating rubber 2 has a hardness of 45°±5° and is constructed as shown in FIGS. 3 and 4. That is, the rotational spring constant k of the vibration isolating rubber is However, Ia: Moment of inertia of the rotor body Ib: Moment of inertia of the motor rotor 2f vibration: The circumference is divided into eight equal parts on the outer surface of the disc-shaped body 20 so that the vibration is twice the power frequency. Eight recessed portions 21 occupying a circumferential angle are provided around the center in the radial direction, and spaces between these recessed portions 21 are left to form auxiliary rib portions 22. . Further, reference numeral 5 denotes a metal boss portion, in which a through hole 51 through which the output shaft 3 is inserted is provided at the center in the radial direction, and a screw hole 5 is provided through the through hole 51 from the outer circumferential surface of the boss portion 5.
2 is provided, and a bolt (not shown) is screwed into the screw hole 52 to fix the output shaft 3.
Further, a hexagonal rotation stopper 53 is formed on the distal end side of the boss portion 5, and is engaged with the cylindrical boss portion 23 of the vibration-proof rubber body 20 so as not to be relatively rotatable.

The reason why the hardness of the anti-vibration rubber 2 is set to 45°±5° is because if the hardness is less than 45°±5°, the anti-vibration rubber loses its complete elasticity and loses its ability to return to its shape.
Since the original function of the anti-vibration rubber itself is impaired, it is not possible to further reduce the hardness of the anti-vibration rubber.On the other hand, it is possible to increase the hardness of the anti-vibration rubber c to increase the fixed spring constant k. Even according to
Although the occurrence of double vibration can be prevented, increasing the hardness of the anti-vibration rubber c means that the damping coefficient for anti-vibration becomes smaller, which is the original purpose of anti-vibration rubber c. This is because the vibration effect cannot be achieved.

By configuring as described above, the rotational spring constant k of the vibration isolating rubber 2 can be reduced without lowering the hardness of the vibration isolating rubber 2 below 45°±5°. The natural frequency of the torsional vibration system can be made smaller than twice the frequency without any loss in effectiveness, preventing the occurrence of twice the power supply frequency and reducing the noise generated by resonance to a significantly lower level. It can be suppressed.

FIG. 5 shows the noise generation situation of the embodiment configured as described above, and compared to that of FIG. Noise generation has been reduced from approximately 43 dB to 19 dB, which is a noticeable effect.

The noise data shown in FIG. 5 was obtained under the same conditions as the conventional example described above. That is, the outer diameter of the rotor body 1 is 80 mm, the length is 620 mm, the weight is 460 g, and the material is
ASG resin, material of anti-vibration rubber 2 chloroprene rubber,
Hardness 45°±5°, outer diameter of rotor 4 43.5mm, weight 278g
by.

Further, in the embodiment described above, eight recessed portions 21... were provided, but these recessed portions 21...
Of course, the number is not limited to eight.

(Effects of the invention) As is clear from the above explanation, according to the invention, in the indoor cross flow fan of an air conditioner, the vibration isolating rubber 2 has a hardness of 45°±5°, and
A plurality of recesses 21 are provided around the vibration isolating rubber 2, and the rotational spring constant k of the vibration isolating rubber 2 is set as follows. However, Ia: Moment of inertia of the rotor body 1 Ib: Moment of inertia of the rotor 4 of the motor 2f vibration: Since the vibration is set to twice the power frequency, the vibration isolating rubber 2 Although the hardness is such that a sufficient vibration damping effect can be obtained, it is possible to prevent the generation of noise due to resonance based on vibrations twice the frequency of the power supply, which is a problem especially in indoor cross flow fans due to their weight reduction. The effect is remarkable during low-speed operation at low rotational speeds, where the occurrence of noise due to resonance based on this double vibration is a particular problem. This makes it possible to almost eliminate noise generation.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram showing an embodiment of the present invention, Fig. 2 is a modeled explanatory diagram, Fig. 3 is a partial cross-sectional side view of the main part, Fig. 4 is a front view, and Fig. 5 is a frequency diagram.
Sound pressure curve, Figure 6 is a vertical section front view showing a conventional example,
FIG. 7 is a frequency-sound pressure curve. 1... Rotor body, 2... Anti-vibration rubber, 21...
Anti-vibration rubber, 3... Output shaft, 4... Rotor, 11...
...feathers.

Claims (1)

[Claims for Utility Model Registration] An indoor cross-flow air conditioner comprising a rotor body 1 having a large number of blades 11 arranged around it and connected to an output shaft 3 of a motor via a disc-shaped anti-vibration rubber 2. A fan, the vibration isolating rubber 2 has a hardness of 45°±5°,
Moreover, a plurality of recessed portions 21 are provided in this vibration-proof rubber 2...
around the rotational spring constant k of the vibration isolating rubber 2.
of, However, Ia: Moment of inertia of the rotor body 1 Ib: Moment of inertia of the rotor 4 of the motor 2f vibration: A cross flow fan characterized by being set to vibrate twice the power supply frequency.