JPH02223350A - Electric draft fan - Google Patents

Abstract

PURPOSE:To prevent the occurrence of outbreak noise and the drop of degree of vacuum caused by back flow by reducing the pressure gradient of inclined passages by the clearance formed between the outside circumferential edge of an inclined blade section and a fan cover. CONSTITUTION:By the high-speed rotation of a centrifugal fan 19 the air is sucked in from an inlet 26 of a fan cover 24. The air flow exhausted radially from the outside circumference section 21 of the centrifugal fan 19 is introduced from the surface to the back of a diffuser 22 through a plurality of inclined passages 33 and by going through a plurality of passages 38, the air is exhausted. At this time, due to clearance 36 between the outside circumferential edge of an inclined blade section 31 and the fan cover 24 the pressure at a part A will be the same as at an adjacent part B of the inclined passage 33 through the clearance 36, so that the breakaway of the air flow can be prevented, while a part of the air flow will flow out through the clearance 36. The outbreak noise caused by the occurrence of back flow owing to the breakaway can thereby be prevented and the drop of degree of vacuum also prevented.

Description

[Detailed description of the invention] (b) Industrial application field The present invention relates to an electric blower used in a vacuum cleaner.

(b) Prior Art In this type of electric blower, a diffuser for guiding airflow discharged from a centrifugal fan to a motor is shown in, for example, Japanese Utility Model Publication No. 57-30475 and FIGS. 5 and 6. That is, in FIGS. 5 and 6, the same parts as the structure of the present invention are indicated by the same numbers and explained. The conventional diffuser (60) has a structure in which the conventional diffuser (60) has a structure from the front surface (27) to the back surface (
29) A plurality of inclined wing parts (31) which are inclined toward the side.
It has an inclined passageway (33)... formed by..., and a plurality of ventilation passages are formed on the back surface (29) respectively communicating with each of the inclined passageways (33)..., and this inclined passageway (33) ... from the front side (27) side entrance part to the back side (2
9) Pressure tends to increase at the side outlet, so
In an overspeed state of the electric blower, etc., the inclined passage (33)
When the pressure gradient of ... is large, the inclined passage (33)
The air flow near the wall that makes up the... cannot overcome the pressure increase in the cross section of the exit on the back side (29) and flow, and the air flow in the boundary layer located near this wall will flow through the inclined passage. (33) The airflow flowing through the central portion of the airflow may be separated, resulting in a backflow as shown in FIG. The occurrence of backflow due to the above-mentioned air flow occurs at a certain degree of vacuum and air volume, so it occurs suddenly during boat fishing, and when it occurs, it makes a loud noise and a significant decrease in the degree of vacuum is seen, so electric blowers are not recommended. There are drawbacks such as the risk of being mistaken for an abnormality or failure, and the risk of causing malfunction of the pressure sensor in a vacuum cleaner using a pressure sensor.

(c) Problems to be Solved by the Invention The present invention has been made to solve the above-mentioned drawbacks, and is intended to minimize the reduction in suction efficiency and prevent the occurrence of backflow in the inclined passage. The purpose of the present invention is to provide an electric blower having a diffuser that prevents the generation of sudden noise and a significant decrease in the degree of vacuum due to the above.

(d) Means for Solving the Problems In order to solve the above problems, the vacuum cleaner of the present invention includes a motor, a centrifugal fan fixed to the rotating shaft of the motor, and a surface facing the centrifugal fan. a diffuser disposed between the centrifugal fan and the motor, and a fan cover having an inlet in the center and attached to the motor case of the motor to cover the centrifugal fan and the diffuser, the diffuser having an outer periphery A plurality of slanted wing sections are formed at predetermined intervals on the part, and each slanted passage is formed between the fan cover and the adjacent slanted wing sections. A plurality of ventilation passages are formed, each of which communicates with the inclined passageway and guides the airflow discharged from the centrifugal fan to the motor, and further a gap is formed between an outer peripheral end of at least one inclined blade portion and the fan cover. It is characterized by the fact that it was formed.

The gap may be formed by a flat wall portion made by flattening a part of the outer peripheral end of the inclined wing portion, or may be formed by reducing the outer peripheral diameter of the outer peripheral end.

(E) Effect With the above configuration, the centrifugal fan rotates at high speed when driven by the motor, and sucks air from the inlet of the fan cover. The airflow discharged in a radial direction from the outer circumference of the centrifugal fan is guided from the front surface of the diffuser to the back side through multiple slanted passages, passes through multiple ventilation passages, and is guided to the motor to cool the motor. It is then exhausted.

At this time, due to the gap formed between the outer circumferential end of at least one inclined blade part and the fan cover, the pressures in the A part and B part of the adjacent inclined passage become the same through the gap, and there is no pressure gradient. , it is possible to prevent the occurrence of air flow separation, and at the same time, a portion of the air flow flows through the gap.

Therefore, it is possible to prevent sudden noises caused by the occurrence of backflow due to the above-mentioned explosion, and also to prevent a significant decrease in the degree of vacuum.

Further, at this time, since at least one gap is required between the inclined blade portion and the fan cover, a reduction in suction efficiency due to the gap can be minimized.

(f) Example The structure of the electric blower of the present invention will be explained below based on the example shown in the drawings.

(1) is an electric blower with a motor (2) at the rear.

In the motor (2), (3) is a metal cylindrical rear case with a bottom, seven flange (4) are formed at the front opening, and an exhaust port (5) is bored at the rear of the cylinder circumference. Furthermore, the bottom surface is provided with a support recess (7) for the rear bearing (6). Further, (8) is a front frame which is fixed to the flange (4) with screws (9) and covers the front opening of the rear case (3), and has a bearing holding cylinder with a front bearing (10) in the center. (11), an annular engaging collar (12) is formed on the peripheral edge thereof, and a suction port (13) communicating with the inside of the rear case (3) is bored. The motor case (1) is connected to the rear case (3) and the front frame (8).
4) is formed, which fixes the stator (15) in the motor case (14), and connects the rotating shaft (17) of the rotor (16) to the front part through the through hole (18) of the bearing holding cylinder (11). In the protruding state, it is rotatably supported by a front bearing (10) and a rear bearing (6).

(19) is a centrifugal fan fixed to the tip of the rotating shaft (17), which rotates at high speed to suck in air through the central opening (20) and exhaust air radially through the peripheral opening (21).

(22) is tightened and fixed to the front part of the front frame (8) of the motor case (14) with a tightening screw (23), and is disposed between the centrifugal fan (19) and the motor (2). This is a disc-shaped synthetic resin diffuser.

(24) covers the centrifugal fan (19) and the diffuser (22), and a rear engagement edge (2) is attached to the annular engagement collar (12) of the front frame (8) of the motor case (14).
5) is a metal fan cover that is fitted and engaged, and has an inlet (26) bored in the center.

Next, in the diffuser (22), the surface (27) of the diffuser (22) facing the centrifugal fan (19) is formed in a flat plate shape, and the center part has a loosely extending through the bearing holding cylinder (11). A solid bearing hole (28) is bored. Further, on the outer circumferential portion of this diffuser (22), a surface (
A plurality of guide edges (
30)... are formed, and on the outer surface of this guide edge (30)..., a plurality of inclined wing portions (31)... which are inclined from the front surface (27) side to the back surface (29) side are formed. The guide edge (30) and the side wall (32) of the fan cover (24)
The inclined passages (33) are surrounded by the respective parts. Further, the outer peripheral end (31a) of the inclined wing portion (31)
) is formed with a fan cover contact wall (34) that comes into contact with the side wall (32) of the fan cover (24). The fan cover wall (34) extends from the front (27) side to the back side (
29) side, the shape gradually expands to approximately the center of the inclined wing portion (31) on the motor side.

Furthermore, (35) is the outer peripheral end (3) of one inclined wing part (31).
13) on the fan cover per wall (34),
The flat wall portion (35) is a flat wall portion that is recessed in a flat shape so as to remove a part of the fan cover contact wall (34).
) and the side wall (32) of the fan cover (24) to form a gap (36). The flat wall portion (35) may be formed into a plurality of inclined wing portions (31).

Further, instead of the flat wall portion (35), the gap (36) may be formed by making the outer circumferential diameter of the outer circumferential end (31a) of the inclined wing portion (31) small.

Further, on the back surface (29) of the diffuser (22), there are a plurality of ventilation guide vanes (37) extending from the guide edge (30) toward the solid bearing hole (28) and curved in an arc shape. A ventilation passage (38) is formed between...
This ventilation passage (38)... is the inclined passage (33)...
・Communicates with Furthermore, (39) is the tightening screw (2).
3) is the tightening screw hole.

When the motor (2) of the electric blower (1) is driven, the centrifugal fan (19) rotates at high speed and the fan cover (24) is driven.
) air is sucked in through the inlet (26) of the centrifugal fan (19) and air is discharged radially through the peripheral opening (21) of the centrifugal fan (19). This discharged airflow is routed through a diffuser (22
) is guided from the front surface (27) to the back surface (29) via the inclined passage (33)..., passes through each ventilation passage (38)..., and is connected to the motor (2) from the intake port (13). Go inside,
After the motor (2) is cooled, it is exhausted from the exhaust port (5).

At this time, the flat wall portion (35) of one inclined wing portion (31)
Due to the gap (36) formed between the side wall (32) of the fan cover (24), the pressure in portions A and B of the adjacent inclined passages (33) and (33) is reduced through the gap (36). Since there is no pressure gradient, it is possible to prevent the air flow in the vicinity of the wall surface of the inclined passage (33) from separating from the air flow in the central part. At the same time, a portion of the airflow flows through the gap (36), resulting in a small turbulence as a whole. This small turbulent flow exchanges the airflow near the wall with the airflow in the center, so it is possible to prevent separation of the boundary layer between the airflow near the wall and the airflow in the center. Therefore, there is no occurrence of backflow due to the break-up of the airflow, and it is possible to prevent the generation of sudden noise due to this, and to prevent a significant decrease in the degree of vacuum.

If there is at least one gap (36), the gap (36) first allows the diffuser (22) to pass from the inclined passageway (33) (33) adjacent to the inclined wing section (31) with this gap (36). ) front side (27) side and back side (2
Since the pressure difference on the side (9) becomes smaller, all inclined passages (3)
3) ... prevents the occurrence of airflow separation, therefore, there is no occurrence of backflow due to airflow separation, it is possible to prevent sudden noises, and it is possible to prevent a significant decrease in the degree of vacuum. Furthermore, the reduction in suction efficiency due to the gap (36) can be minimized.

That is, even if the airflow normally flowing through the inclined passageway (33) is in a state where a backflow due to the airflow would occur due to a certain degree of vacuum and air volume of the electric blower, the above-mentioned Due to the existence of the gap (36), as shown in Fig. 4, only a small backflow occurs, which prevents the occurrence of backflow due to the breakage of the airflow, and prevents the generation of sudden noise due to this occurrence. Moreover, a significant decrease in the degree of vacuum can be prevented.

(G) Effects of the Invention Since the present invention is constructed as described above, the pressure gradient in the inclined passage is reduced by the gap formed between the outer peripheral end of the inclined blade portion of the diffuser and the fan cover, thereby reducing the pressure gradient in the inclined passage. To obtain an electric blower which can prevent the occurrence of backflow in a passage, prevent the generation of sudden noise due to the backflow, and prevent a significant decrease in the degree of vacuum, and therefore not be mistaken for abnormality or failure. It has the effect of being able to.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view of the electric blower of the present invention, Fig. 2 is a back view of the diffuser, Fig. 3 is a side view of the diffuser, and Fig. 4 is a side view showing the air flow of the diffuser. . Further, FIG. 5 is a side view of a conventional diffuser during normal operation, and FIG. 6 is a side view of the diffuser when backflow occurs. (2)...Motor, (19)...Centrifugal fan, (
22)... Diffuser 1 (31)... Inclined wing section, (33)... Inclined passage, (35)...
・Flat wall part, (36)... gap.

Claims (1)

[Claims] (1) A motor, a centrifugal fan fixed to a rotating shaft of the motor, a diffuser disposed between the centrifugal fan and the motor with a surface facing the centrifugal fan, and an inlet in the center; The diffuser includes a centrifugal fan and a fan cover that covers the diffuser and is attached to the motor case of the motor. a plurality of inclined passages are formed between the fan cover and adjacent inclined blade parts, and a plurality of inclined passages are formed on the back surface of the fan cover, respectively communicating with the inclined passages to guide airflow discharged from the centrifugal fan to the motor. An electric blower characterized in that a ventilation path is formed, and a gap is further formed between an outer peripheral end of at least one inclined blade portion and the fan cover.