JPS5920597A - Centrifugal blower - Google Patents

Abstract

PURPOSE:To reduce noises without the characteristics of a blower being affected, by forming the inlet section of each fan side guide vane 9 in a simple shape of substantially convex-round so that the turbulent flow of fluid is eliminated. CONSTITUTION:The inlet section of a fan side guide vane 9 is formed in such a simple shape that is provided with a substantially rounded part 16 which has a radius of curvature R within a range of 1/3H<=R<=2/3H, where H is the height of the fan side guide vane 9. When an impeller having 7 blades (Z=7), is rotated at a rotational speed N=23,000rpm, the peak level is lowered and as well an effect may be obtained concerning two or three harmonics by applying a countermeasure for noise. It is aimed that noises are reduced without any turbulent flow being brought about.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a centrifugal blower used in a vacuum cleaner or the like, and particularly to a diffuser guide vane that reduces noise while maintaining blower performance.

Figure 1 shows the structure of this type of centrifugal blower.

That is, in FIG. 1, a centrifugal blower 1 is composed of a blower section 2 and a motor section 3. Motor part 3 is approximately 22 mm when in use.
．． It is necessary to rotate at a high speed of 000yp+n to 30.00Orpm, and it is generally constructed of a commutator motor in many cases, but a detailed description thereof will be omitted here.

The blower section 2 includes a synthetic resin guide vane 5 fixed to the front end bracket 4 of the motor section 3, and is press-fitted and fixed to the outer periphery of the front end bracket 4 so as to cover the front and side surfaces of the guide vane 5. It is equipped with a fan cover 6 made of polished sheet metal.

An impeller 7 is directly fastened to a motor shaft 8 and located in a space formed by the fan cover 6 and the front surface of the guide blade 5.

Note that the arrows in FIG. 1 schematically indicate the air flow, and the flow coming out of the impeller 7 is diverted by 360 degrees by the guide vane 5 and flows through the opening of the front end bracket 4 of the rear motor section 3. It flows between main components such as the stator and rotor in the motor, and is discharged from the exhaust hole of the motor section 3 while cooling the motor.

FIG. 2 is a perspective view showing the relationship between the motor section 3 and a general guide vane 5 that does not take measures against noise.

In the figure, a plurality of fan-side guide vanes 9 form a guide vane group, and adjacent guide vanes 9 overlap in an I-fold direction to expand the air passage area in the radial direction and motor axial direction to exert a diffuser effect. ing.

Next, the flow leaving one fan 1 (1) guide vane 9 flows through the front end bracket 4, fan cover 6, and guide vane 5.
While preserving the circumferential velocity component in the gap formed at the outlet, the velocity component is obtained toward the center in the radial direction on the low pressure side.

As a result, the velocity component that was directed radially outward on the side of the fan-side guide vane 9 turns the flow 360' toward the center in the radial direction after exiting the guide vane 9. The motor-side guide vane 11 serves to smoothly guide this flow to the aperture 10 on the motor side.

The motor side guide vane 11 is the fan 1llll guide vane 9.
Similarly, a plurality of guide vanes 9 and 11 are used to form a return flow path between adjacent vanes, but the number of guide vanes 9 and 11 does not necessarily have to be the same, and the guide vanes 9 and 11 have a partition plate 12 as a boundary. There is a distinction between the fan side and the morph side. Further, the axial guide vanes 13 in FIG. 2 are provided to rectify the flow exiting the fan side guide vanes 9 to the motor side guide vanes 11, and may be omitted depending on the type of the guide vanes 5. be.

Next, FIGS. 3 and 4 show examples of conventionally known guide vanes 5 having the above-mentioned configuration in which measures are taken against noise.

Figure 3 shows the inlet part of the guide vane 90 on one fan side and the partition plate 1.
This is a type in which a skew part 14 is provided which is cut diagonally from the root following 2 and is inclined relative to the impeller blade, and FIG. This shows the type of guide vane 5.

The effect of the former skew is as follows.

That is, as shown in FIG. 5, the pressure distribution near the outlet of the rotating impeller 7 is accompanied by pressure fluctuations between the blades 16 and at the exit end of the blades 16, as shown in the figure. Now, if there is a fixed guide vane 9 near the end of the blade 16, if there is no skew at the inlet end of this vane 9, the pressure will fluctuate at the inlet of the fan-side guide vane 9 every time the blade 16 passes. It is specified according to the rotation speed Nrpm and the number Z of 160 blades. In addition, + J′ for f in terms of noise engineering
It is known that when the sound pressure level of o is high, it may have a peak even at a frequency two to three times that frequency.

Therefore, by forming a relatively skewed portion between the blade 16 and the inlet portion of the fan-side guide vane 90 as shown in FIG. 6, the rapid pressure fluctuations each time the blade 16 passes are reduced to pressure fluctuations with a phase shift. It serves to reduce sudden pressure fluctuations that can lead to noise generation.

Next, as a countermeasure for the latter, the notch 15 is created by cutting out a part of the fan-side guide blade 9, as shown in FIG. This is a method that attempts to suppress sudden pressure fluctuations by ejecting a flow from the side that is out of phase with the pressure fluctuations.

However, in order to obtain an actual effect in the skew method as described above, it is preferable that the relationship between the distance tK between the blades 19 on the outer periphery of the impeller 7 (1 pitch) and the skew distance is not t≦L. (Journal of Sound and Vi
bration 1976.45 (3), P375-4
03“N0ISE REDUCTION IN CEN
TI also IF'UGAL FANS: A LITER
It has been reported by AT [Jl (E 5URVEY”) and others.

Therefore, in an electric blower equipped with an impeller outer diameter of φ100 to 110 and a number of blades of about 6 to 8, a considerable skew distance is required, and an appropriate skew must be provided within the determined guide vane outer diameter. This results in shortening the diffuser length S, which reduces the diffuser efficiency and makes it impossible to obtain the desired floor performance. Furthermore, in order to obtain a predetermined blower performance, the length S of the diffuser must be increased, which increases the outer diameter of the guide vanes, making it impossible to downsize the blower.

In addition, with the notch method, it is difficult to lower the noise level while satisfying the proa characteristics over the air flow range, and it is affected by the notch dimensions (a, b) and the notch position (C). has a simple drawback.

In other words, the flow flowing through the cutout portion 15 is instead formed between the fan-side guide vanes 9, which disturbs the flow of air flowing inside the diffuser.

In view of the above-mentioned conventional circumstances, the present invention provides a centrifugal air blower that does not disturb the flow (noise reduction) by changing the shape of the inlet portion of the fan side guide vanes. It is.

That is, the present inventors conducted a test and research with the aim of reducing noise without disturbing the flow by changing the shape of the inlet part of the fan side guide vane, and as a result, the fan side guide vane was changed as shown in Fig. 8. It has been found that changing the shape of the 90 inlet to a simple convex, approximately R-shape is effective in improving characteristics and reducing noise.

In FIG. 8, the shape of the inlet part of the fan side guide vane 90 is different from that of the conventional example and the present invention in order to show the effect of the guide vane 5 of the embodiment of the present invention on the height H of the fan side guide vane 9. Comparison of one example? Figure 9 shows the noise and octave analysis, Figure 10 shows the noise spectrum analysis diagram, Figure 11 shows the proa characteristic diagram, and Figure 12 shows the electric cleaning using the centrifugal blower of one embodiment of the present invention. This figure shows the effect of the ratio of 1■ to normal in the range of use of the machine.

FIGS. 9 and 10 show the noise measurement results when an impeller with grade number Z=7 is rotated at rotation speed N=2300 rpm (air volume Qki 1.8y17mjl+).

Now, if no noise countermeasures are taken, the proa noise will peak at J8K 2680 (Hz) according to the above formula, but if noise countermeasures are taken, f. The peak level of decreases, and the second overtone or third overtone <J'=2f.

Or 3j'. ) also shows that the effect appears.

In addition, Figure 11 shows the characteristics of Proa, although in the air volume range where it is incorporated into a vacuum cleaner and used, the pressure recovery for both the skew method and the notch method is lower than that of products without countermeasures. First, it can be seen that the characteristics of the R-shaped countermeasure product do not deteriorate.

Next, Figure 12 shows the noise results at the air volume points used in a vacuum cleaner, using the ratio (FL/II) of the height H of the fan side guide blade 9 and the approximate size of its inlet part as a parameter. and characteristic results.

From this result, the dimensions of the inlet of the fan side guide vane 9 are /
Good results were obtained in the range of H≦⇠≦/3H.

The above test results show that simply changing the shape of the inlet end of the fan-side guide vane does not reduce the characteristics (in order to have a great effect on reducing the noise level, a part of the skew is installed). As a result, the guide vanes do not have to be made large, and the characteristics do not become unstable, unlike when a notch is provided.

The configuration of the present invention is applicable not only to electric blowers for vacuum cleaners, but also to general remote I
A similar effect can be obtained with a blower.

As explained above, in the present invention, by simply changing the shape of the inlet portion of the fan-side guide vane into a simple convex, approximately R-shape, a large effect on noise reduction can be obtained without affecting the floor characteristics.

Furthermore, since the inlet portion has a simple shape, stable performance can be obtained at low cost.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of a centrifugal blower to which the present invention is applied, Fig. 2 is a perspective view of the electric motor and guide vanes in the same centrifugal blower, and Fig. 3 is a conventional noise countermeasure using the skew method. Figure 4 is a partial perspective view of a guide vane with a notch provided as a conventional noise countermeasure, and Figures 5 and 6 are a partial perspective view of a guide vane with a notch provided. A front view and a side view for explaining the skew method as described above, FIGS. 7 and 7 are front views for explaining the notch method as above, and FIG. 9 and 10 are graphs comparing the noise characteristics of a centrifugal blower equipped with the conventional method and a centrifugal blower equipped with the guide vanes of the present invention. Figure 9 is a graph showing octave analysis, Figure 10 is a graph showing spectrum analysis, and Figure 11 is a graph showing spectrum analysis.
Figure 12 is a graph showing the blower characteristics of a centrifugal blower using the conventional method and a centrifugal blower equipped with the guide vanes of the present invention.
It is a graph showing the relationship between the noise characteristics and the proer characteristics according to the ratio with the dimensions. 5... Guide vane T... Impeller 9...
Fan side guide vane 16... R-shape section agent Shin Kuzuno - (1 other person) Figure 1 Figure 3 Figure 5 Concave Figure 7 Figure 8 9th - M City Akira πm "The day before □ 1,) +n; a! de ((+ [g1z) (1%)) 12th]

Claims (2)

[Claims] (1) A centrifugal blower equipped with a guide vane, characterized in that the tip of the inlet portion of the guide vane located on the outer periphery of the impeller is shaped into a convex, approximately R-shape. (2) The approximately R shape has a blade height of I (if 3H≦1
(, the scope of claims set in the range of ≦VH,
The centrifugal blower according to paragraph 1.