JPH0532798U - Blower - Google Patents

Abstract

(57) [Summary] [Purpose] To increase the blower discharge air volume and reduce noise.
It was [Structure] Inner wall of fan casing 2 and fan main plate 6
Is the front side gap δ ₁To the clearance on the trailing edge side δ₂Over
It is characterized by gradually reducing the gap.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a portable blower that achieves both increased discharge air volume and lower noise.

[0002]

[Prior Art]

 2 and 3 show a conventional portable blower. First, in FIG. 2, an intake port 3 is provided above a fan casing 2 that covers the fan 1, and the air sucked from the intake port 3 becomes a main flow shown by a solid line in the drawing and is discharged from a flow duct 4 inside the casing 2. It A part of the main flow is discharged as cooling air to the engine 5 side from a hole (not shown) provided in the fan casing 2.

When the fan 1 rotates, a secondary flow 9 shown by a broken line in the drawing is generated in a gap δ between the inner wall of the fan casing 2 and the fan main plate 6, and the secondary flow 9 leaks to the main flow side and the main flow 10 Disturbs the flow of water and causes fluctuations in the main flow. As a countermeasure against this, a rib 7 is provided on the inner wall of the fan casing 2 to reduce the leakage of the secondary flow to the mainstream side. However, when the width of the fan casing 2 is determined as a measure against the ribs 7, the width B of the blades 8 cannot be increased and the amount of discharged air and the amount of cooling air to the engine cannot be increased.

Further, in FIG. 3, in order to increase the width B of the blade 8, the rib 7 is eliminated and the gap δ between the inner wall of the fan casing 2 and the fan main plate 6 is reduced to increase the air volume. In this case, although the air volume increases due to the expansion of the width B of the blades 8, there is a problem that the noise level becomes high because the flow velocity of the secondary flow generated in the gap δ between the inner wall of the fan casing 2 and the fan main plate 6 increases. In order to suppress the influence of the secondary flow 9, it is necessary to make the gap δ as small as possible, but for that purpose, the dimensional control of each component must be strict, which causes a cost.

[0005]

In the prior art, ribs are provided on the fan casing to reduce the flow fluctuation of the main flow due to the secondary flow generated in the gap between the inner wall of the fan casing and the fan main plate, and ribs are provided to the main flow side of the secondary flow. Although the leakage was reduced, there is a problem that the discharge air volume and the engine cooling air volume cannot be increased because the blade width cannot be made large in the determined fan casing width. Further, in the method of eliminating the ribs to increase the blade width and reducing the gap between the inner wall of the fan casing and the fan main plate, there is a problem that the flow velocity of the secondary flow increases and the noise level increases. In addition, there is a problem in practical use such as dimensional control being difficult. An object of the present invention is to provide a portable blower that solves the above-mentioned problems of the related art and that achieves both increased discharge air volume and lower noise.

[0006]

[Means for Solving the Problems]

The configuration of the present invention for achieving the above object will be described with reference to FIG. 1 corresponding to an embodiment. The present invention shows that a gap δ between a fan casing inner wall and a fan main plate is a front edge side gap δ ₁ (fan boss). Side) to the trailing edge side clearance δ ₂ (outer peripheral side of the fan).

[0007]

[Action]

 In the present invention, the secondary flow generated between the inner wall of the fan casing 2 and the fan main plate 6 by the above means flows from the front edge side to the rear edge side along the inclination of the fan main plate 6. Since the clearance between the fan casing 2 and the fan main plate 6 becomes smaller as the secondary flow flows toward the trailing edge side, the flow resistance of the secondary flow gradually increases, and the leakage resistance from the trailing edge side clearance increases. It also reduces the leakage flow rate of the next flow to the mainstream side. Therefore, it is possible to simultaneously increase the discharge air volume and the engine cooling air volume and reduce the noise.

[0008]

【Example】

An embodiment of the present invention will be described below with reference to FIG. The figure shows the structure of a fan casing and a fan of a portable blower. 1 is a fan, 2 is a fan casing, 3 is a suction port, 4 is a duct, 5 is an engine, 6 is a fan main plate, and 8 is a blade. The gap between the fan casing 2 and the fan main plate 6 is gradually reduced from the front edge side gap δ ₁ on the fan-boss side to the rear edge side gap δ ₂ on the fan outer peripheral side. Therefore, the discharge side width B of the blade 8 can be made large.

Thus, when the engine 5 is started and the fan 1 rotates, the air sucked from the suction inlet 3 of the fan casing 2 becomes the main flow shown by the solid line in the figure and is discharged from the duct 4. Further, a part of the main flow is discharged as cooling air from the hole (not shown) provided in the fan casing 2 to the engine 5 side. When the fan 1 rotates, in the gap between the inner wall of the fan casing 2 and the fan main plate 6, the secondary flow indicated by the broken line in the figure follows the inclination of the fan main plate 6 to the rear edge side gap δ ₂ rather than the front-rear side gap δ ₁ . Flow toward. The flow resistance of the secondary flow gradually increases from the clearance δ _{1 on the} leading edge side to the clearance δ ₂ on the trailing edge side, and the leakage resistance from the clearance δ _{2 on} the trailing edge side increases. Both will be reduced.

[0010]

[Effect of the device]

As described above, according to the present invention, the fan main plate 6 is inclined so that the gap between the inner wall of the fan casing 2 and the fan main plate 6 is gradually reduced from the front edge side gap δ ₁ to the rear edge side gap δ ₂ . The following effects occur. Since the secondary flow flows along the inclination of the fan main plate 6, the leakage resistance from the trailing edge side clearance δ ₂ increases, and both the leakage amount and the flow velocity of the secondary flow to the main flow side are reduced, so that the discharge air volume increases. Noise can be reduced at the same time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional example.

FIG. 3 is a cross-sectional view showing another conventional example.

[Explanation of symbols]

2 Fan casing 6 Fan main plate δ ₁ Front edge side gap δ ₂ Rear edge side gap

Claims (1)

[Scope of utility model registration request] 1. A blower characterized in that a gap between an inner wall of a fan casing and a fan main plate is gradually reduced from a front edge side gap to a rear edge side gap.