JPS63100299A - Multi-stage centrifugal fan - Google Patents

Abstract

PURPOSE:To achieve a stable rotary operation, by rotating the rotary shaft of a multi-stage impeller by means of a motor bearing at the motor side and a bearing arranged on a bearing supporting disc. CONSTITUTION:Impellers 7, 9, 11 and guide vane row sections 8, 10 are provided on an impeller shaft 6 extending from a motor shaft 5. A bearing supporting disc 14 is provided to construct a return flow path 21 together with a fixed guide vane 12. A bearing 16 is secured through a vibration isolating rubber on the central portion of the bearing supporting disc 14 so as to support the impeller shaft 6 together with the motor side bearing. In such a manner, the vibration of the impeller shaft can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a configuration for rotating the impeller of a multi-stage centrifugal fan at high speed, which is used in a state where the blowing resistance is high.

2. Description of the Related Art A conventional persimmon fan will be explained using a multi-stage centrifugal fan having a three-stage impeller configuration.

This type of centrifugal fan had a configuration as shown in FIG. That is, a motor 4 is installed inside an axial flow casing 3'' provided with an inlet 1 and an outlet 2, and a third rotary centrifugal impeller is attached from the motor side to an impeller shaft 6 which is an extension of the motor shaft 5 of the motor 4. The wheel 7 and the second guide vane row section 8, the second rotary centrifugal impeller 9 and the first guide vane row section 31, and the first rotary centrifugal impeller 11 are installed in this order. The impeller 11 was configured to be on the suction port side of the axial flow casing 3. 32 is a rotating centrifugal impeller fixing boss, and 18 is a rotating centrifugal impeller suction port.

Here, the blown air flows as shown by the arrow in the figure. Such a multi-stage fan can obtain a high pressure increase by accumulating the pressure increase per stage.

Problems to be Solved by the Invention In this configuration, the rotating centrifugal impeller is rotated around the impeller shaft, which is an extension of the motor shaft, with one end of the impeller shaft being free. Due to an unbalanced rotation of the impeller, at high speeds or when the fan load is high, a slight imbalance creates a large centrifugal force that causes the impeller shaft to bend, and the tip of the impeller shaft to be damaged by rotation. There was a problem with the vibration.

This vibration of the tip of the impeller shaft causes a positional shift between the suction port of the rotary centrifugal impeller and the suction port of the axial flow casing, resulting in a problem of deterioration of air blowing performance. Furthermore, there is a problem in that vibration of the impeller shaft generates low zJ-wave noise proportional to a frequency twice the number of rotations, increasing the noise level (v2). Also, as shown in Figure 5,
The bearing 34 is attached to the bearing fixing part 35 on the suction port side of the axial flow casing.
If an attempt was made to rotate the impeller shaft on both shafts, there was a problem in that the area of the suction port would be reduced and the air blowing capacity would be reduced.

The present invention solves such conventional problems by providing a bearing support plate without increasing the ventilation resistance of the ventilation passage.
The bearing installed in the center of the bearing support plate suppresses the vibration of the impeller shaft, ensuring stable rotation even during high-speed rotation, stabilizing air blowing performance, and reducing noise caused by impeller imbalance. The aim is to reduce noise and reduce noise.

Means for Solving the Problems The present invention solves the above problems by providing an axial flow type casing comprising a first axial flow type casing provided with a suction port and a second axial flow type casing provided with an air outlet. A motor is installed in the flow casing, the first axial flow casing is provided with a first flange on the outer periphery of the casing on the opposite side of the suction port, and the second trickle flow type casing is provided with a casing on the opposite side of the air outlet. A second flange is provided on the outer periphery, two or more rotating centrifugal impellers are installed on an impeller shaft that is an extension of the motor shaft of the motor, and a plurality of fixed guide vanes are installed between each of the rotating centrifugal impellers. A guide vane row section with a return flow path is provided to guide air flow from the outer circumference to the inner circumference side, and the impeller shaft is received between the furthest rotating centrifugal impeller and the furthest guide vane row section from the motor side. A bearing support disk having a bearing part in the center and a ventilation hole in the outer circumference is sandwiched between the first flange and the second flange, and the bearing support disk is The structure is such that the bearing is installed through anti-vibration rubber.

According to the present invention, with the above-described configuration, the impeller shaft is rotated by the motor bearing on the motor side and the bearing installed on the bearing support disk, so that the impeller shaft is rotated in a dual-supported manner. Even if the impeller shaft rotates at high speed or under high load, stable rotational operation can be obtained without the tip of the impeller shaft wobbling. As a result, the air blowing performance is stabilized, and the generation of noise due to the unbalance of the impeller can be suppressed.

EXAMPLE An example of the present invention will be described below regarding a three-stage centrifugal fan.

As shown in FIG. 1, a motor 4 is installed in an axial flow casing composed of a first casing 3 provided with an inlet 1 and a second casing 13 provided with an outlet 2. From the motor side, the third rotary centrifugal impeller 7, the second guide vane row 8, the second rotary centrifugal impeller 9 and the first guide are attached to the impeller shaft 6, which is an extension of the motor ill Blade row section 10. Then, the bearing support disk 14 and the first rotating centrifugal impeller 11 were installed in this order, and the first rotating centrifugal impeller 11 was configured to be on the suction port side of the I-axial flow casing. Here, the guide vane rows 8 and 10 are configured with a return flow path 21 in which a plurality of fixed guide vanes 12 are installed so that air flows from the outer periphery to the center, and the bearing support disk 14 is
As shown in FIG. 2, the bearing 16 is sandwiched between the first casing 3 and the second casing 13, and the bearing 16 is fixed to the central part of the bearing support disk 14 via anti-vibration rubber. This is a configuration in which a large number of ventilation holes 17 are provided. The impeller shaft 6 is fixed as shown in FIG. 3 by being sandwiched between the first flange 21 and the second flange 19 with the shaft tip inserted into the bearing 16.

By fixing in this manner, the bearing can be positioned accurately and the rotational resistance between the bearing and the impeller shaft can be reduced.

Here, the blown air flows as shown by the arrow. 19 is a second flange, 20 is a casing fixing screw, and 22 is a first flange.

In this type of construction, the impeller shaft is rotated on both sides by the motor bearing on the motor side and the bearing installed on the bearing support disk, so even if the rotational balance of each rotating centrifugal impeller is incomplete, , the phenomenon that the tip shakes does not occur. Therefore, there is no deviation in the positional relationship between the suction port of the rotary centrifugal impeller and the suction port of the axial flow casing due to vibration of the tip of the impeller shaft, and the air blowing performance is stabilized. Also,
The noise at a frequency proportional to twice the rotational speed, which was generated by the vibration of the tip of the impeller shaft, is also suppressed 1b! 1 and can reduce the noise level of the fan. Furthermore, since the vibration at the tip of the impeller shaft is suppressed by the vibration-proof rubber installed in the center of the bearing support disk, it is not transmitted to the axial flow casing or the like and induces new noise. Since the bearing support disk is sandwiched and fixed between two casings, the bearing can be stored in a position that matches the position of the impeller shaft, and rotational resistance can be reduced.

Effects of the Invention As described above, according to the present invention, the vibration of the tip of the impeller shaft is suppressed by the bearing installed on the inner periphery of the central part of the bearing support disk, even under severe conditions during high-speed rotation and high-load operation. As a result, the suction port of the rotating centrifugal impeller and the suction port of the axial flow casing are only aligned, which stabilizes the air blowing performance, and also suppresses noise at a frequency proportional to twice the rotation speed.
Fan noise level can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a multistage centrifugal fan 11 according to an embodiment of the present invention, Fig. 2 is a front view of a bearing support disk of the multistage centrifugal fan, and Fig. 3 is a sectional view of essential parts of the multistage centrifugal fan. 4 is a side sectional view of a conventional multistage centrifugal fan, and FIG. 5 is a side sectional view of the same multistage centrifugal fan. 1...Suction port, 2...Blowout outlet, 3...
...First casing, 4...Motor, 5...
... Motor, g, 6 ... Impeller shaft, 7, 9
．． 11...3rd. Second. 1st rotating centrifugal impeller, 8, 10... 2nd. First guide vane row section, 1
2...Fixed guide vane, 13...Second casing, 14...Bearing support disc, 15...Vibration isolating rubber, 16...Bearing, 17・・・・・・Air vent,
19...Second flange, 21...Return flow path. Name of agent: Patent attorney Uneo Nakao and 1 other person 2nd
Figure 3/4 Figure 4

Claims (2)

[Claims] (1) A motor is installed in an axial casing composed of a first axial casing provided with an inlet and a second axial casing provided with an outlet, and A first flange is provided on the outer periphery of the casing on the opposite side of the suction port, and a second flange is provided on the outer periphery of the casing on the opposite side of the air outlet in the second axial flow type casing, and the motor shaft of the motor is Two or more rotating centrifugal impellers are installed on the extended impeller shaft, and a plurality of fixed guide vanes are installed between each of the rotating centrifugal impellers to guide air flow from the outer circumference to the inner circumference. A guide vane row that forms a flow path is provided, and between the furthest rotating centrifugal impeller and the furthest guide vane row from the motor side, a bearing that receives the impeller shaft is provided in the center, and a blow hole is provided in the outer periphery. A multi-stage centrifugal fan comprising a bearing support disk sandwiched between the first flange and the second flange. (2) The multi-stage centrifugal fan according to claim 1, wherein the bearing support disk has a structure in which the bearing is installed via vibration-proof rubber.