JPS638879Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a blower, particularly a centrifugal blower in which an impeller with a large number of blades arranged on its outer periphery is arranged inside a spiral casing.

The purpose of this invention is to improve the shape of the casing,
To obtain a blower capable of increasing air volume without expanding the mounting space.

The blower of the present invention is a centrifugal blower equipped with an impeller having a large number of small blades arranged on the circumference and a spiral casing that forms a wind guide around the impeller. The theoretical shape of the inner wall whose radius increases at a constant rate according to the advancing angle of the spiral is formed with one or more bulges that smoothly connect with the inner wall, and this bulge controls the set outer dimensions of the casing. It is characterized by a size that cannot be exceeded.

The prior art and embodiments of the centrifugal blower of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a centrifugal blower based on the prior art, in which 1 is a spiral casing, 2 is an impeller, and 3 is a large number of blades arranged around the outer circumference of the impeller 2.
When the impeller 2 is rotated in the direction of arrow 4 by a prime mover such as an electric motor, the air inside the impeller 2 is pushed by the blades 3 and moves to the outside of the impeller 2 due to the centrifugal force caused by the rotation of the impeller 2. It flows along the inside as shown by the arrow 5 and is discharged from the discharge port 6 of the casing 1.

The shape of the casing 1 of the blower in Fig. 1 is a theoretical shape in which the gap gl between the inner wall of the casing 1 and the outer periphery of the impeller 2 is minimum _gl1 at the start point 1-1 of the spiral, and increases monotonically as the spiral angle progresses in the direction of the arrow 4, becoming large at _gl2 at the part 1-2 near the outlet. To increase the air volume with a blower such as that shown in Fig. 1, (1) the rotational speed of the impeller 2 is increased.

(2) Increase the diameter of impeller 2.

(3) Increase the outer dimensions of casing 1.

(4) Increase the axial length of the impeller 2 and casing 1.

Although the above methods are effective, the method (1) requires increasing the output of the electric motor, which requires a motor with higher output. In case (2), the required power of the impeller 2 increases and a higher output electric motor is required. Both (3) and (4) have larger external dimensions. Due to these problems, it is not easy to increase the air volume under conditions where the outer dimensions are limited.

The present invention eliminates the drawbacks of the prior art centrifugal blower as described above and provides a configuration for increasing the air volume without changing the outer dimensions of the casing. An embodiment thereof is shown in FIG. 2.

In FIG. 2, 1' is an improved casing based on the present invention, and 2 is an impeller similar to the conventional one.
In the improved casing 1' of the present invention, the shape of the inner wall of the casing 1' is adjusted to the theoretical curve S.
The casing 1' is located between the starting point part 1'-1 of the spiral and the part 1'-2 proceeding 90 degrees from this point in the direction of arrow 4.
The gap between the inner wall of the impeller 2 and the outer periphery of the impeller 2 is widened, and the space between the portion 1'-2 and the portion 1'-3 further advanced by 90 degrees in the direction of the arrow 4, and the portion b between the portion 1'-3 and this The inner wall of the casing 1' is deformed between the terminal part 1' and 4 of the spiral, which has proceeded 90 degrees in the direction of the arrow 4, to enlarge the air passage, and the whole is connected with a smooth curve. Outer dimension A between parts 1'-1 and 1'-3 and parts 1'-2 and 1'
-4 is made similar to the corresponding dimension in the case of the theoretical curve S. The effects of the flow path enlarged portions a, b, and c are as follows.

Conventionally, the gap GL between the inner wall of the casing 1 and the outer periphery of the impeller 2 follows a theoretical curve that increases monotonically with the advancing angle, being smallest near the starting point of the vortex and largest near the end of the vortex, as described above. It adopted a conforming shape. The reason for this is that the amount of air sent into the inside of the casing 1 by the centrifugal force of the blades 3 was thought to increase proportionally as the spiral angle of the casing 1 progresses, but in reality, the amount of air inside the casing 1 increases. The flow of air is not uniform, with differences in density and speed depending on the location, making it complex and not necessarily increasing the amount of air as expected.

In the present invention, the amount of air pushed out in the centrifugal direction by the blades 3 at portions a, b, and c, where the flow paths are partially enlarged in the casing 1', is equal to the bulge of the inner wall of the casing, as described above. It is thought that the area is moving away from the outside, and the increase in air density is small, which means that the friction loss of the inner wall against the air flow is reduced.The amount of air in this area increases, and the amount of air flowing between it and the outer circumference of the impeller increases. The total amount will increase,
Therefore, the amount of air discharged to the outside from the discharge port increases.

Also, it is more effective to have more bulges without increasing the mounting space.

This effect suggests that we should move away from the idea that the uniformity of air flow due to the theoretical spiral shape contributes to an increase in air volume. It is considered appropriate to regard this as a result of an increase in the total amount of air, and since the outer dimensions A and B remain unchanged, the outer dimensions can be set to be the same as the blower of the theoretical curve S according to the prior art.

Figure 3 shows the air volume characteristics of the blower using the conventional casing 1 and the casing 1' of the present invention.
As is clear from the figure, the improved blower according to the present invention can reach 1.1 to 1.2 without changing the motor output.
You can get double the air volume.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional blower, FIG. 2 is an explanatory diagram of the blower of the present invention, and FIG. 3 is a characteristic comparison diagram thereof. 1,1'...casing, 2...impeller, 3...
...Blade, 6...Exhaust port.

Claims (1)

[Scope of utility model registration request] In a centrifugal blower equipped with an impeller with a large number of small blades arranged on the circumference and a spiral casing that forms a wind guide around the impeller, the shape of the spiral casing is determined by the progression of the spiral. One or more bulges are formed that smoothly connect with the theoretical shape of the inner wall whose radius increases at a constant rate depending on the angle, and the bulge is of a size that does not exceed the set outer dimensions of the casing. A blower characterized by: