JP2987286B2 - Electric blower - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric blower used for a vacuum cleaner and the like, and more particularly to an electric blower effective for improving the efficiency of a blower.

[0002]

2. Description of the Related Art In an electric blower, a circulating flow is generated in which a part of an airflow discharged from an outer peripheral outlet of a centrifugal impeller flows between a front shroud of the centrifugal impeller and a fan casing and flows into a suction port. There was a drawback that it decreased.

Conventionally, in order to prevent this circulating flow, as described in Japanese Patent Application Laid-Open No. 3-233194, a slidable recirculation shut-off member formed in a cylindrical shape is provided at a suction port of a fan casing, and a centrifugal centrifuge is provided. A technology has been proposed in which the impeller has a front shroud that is substantially in contact with the impeller, and the circulation flow is interrupted by the action of a recirculation shutoff member to improve the blowing efficiency. The recirculation blocking member is attached to the fan casing so as to be pressed against the front shroud of the centrifugal impeller at the time of assembly. It was configured to be.

[0004]

However, in the technique described in Japanese Patent Application Laid-Open No. 3-233194, the cylindrical reflux shut-off member fixed to the fan casing and brought into contact with the front shroud of the centrifugal impeller includes: Since it functions as a guide member that sucks in airflow from the outside, it is necessary that the member has a high shape-retaining property, and parts processing work and parts assembly work that can achieve high assembly accuracy are required. was there.

[0005] That is, in order to prevent the centrifugal impeller from being locked in the first operation after the assembly, the recirculation shutoff member must be an elastic body, but it is also necessary to have rigidity for obtaining shape retention for functioning as a guide member. Therefore, if the assembly accuracy is low, the recirculation cutoff member is excessively pressed by the centrifugal impeller, and the centrifugal impeller is locked and cannot be operated, the frictional resistance during operation increases, or conversely, it may come into contact with the front shroud. Without preventing the circulation flow.

In a high-speed rotating electric blower used for a vacuum cleaner or the like, an increase in frictional resistance causes a reduction in efficiency due to frictional loss more than an improvement in efficiency due to circulating flow prevention, resulting in a total reduction in efficiency of the electric blower. There is fear. Further, the increase in frictional resistance may cause deformation and breakage of the reflux blocking member due to frictional heat, increase the tightness with the impeller, or increase the clearance of the sliding portion, thereby causing a circulating flow. There are many problems.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electric blower in which a circulating flow is reliably prevented while suppressing an increase in frictional loss, thereby improving the efficiency of the blower.

[0008]

SUMMARY OF THE INVENTION The present invention is characterized in that it has a front shroud in which a suction port is formed, an impeller mounted on a rotating shaft of an electric motor, and a flow path downstream side of the impeller. And a fan casing that covers the impeller and the fixed guide blade. The front shroud is located at least at the time of assembling at a position facing the suction port edge of the front shroud of the fan casing. In the electric blower provided with a seal member that comes into contact with the suction port edge of the front shroud and is scraped off at the suction port edge of the front shroud by rotation of the impeller, the seal member has an elastic modulus of 20 to 50 kg / cm ² . The front shroud is suctioned from the center of the sealing member to the outer peripheral side from the center of the sealing member.
From the contact direction of the mouth edge with the inner surface of the fan casing
Fixed as to clamp the support frame between the contact position of the inlet edges of the front shroud and the support frame radially center side than the nip portion by, and the seal member, Porite DOO La Formed by fluoroethylene resin,
The support frame is in an electric blower formed in an annular shape.

[0009]

According to the present invention, at the time of assembling, at least at the time of assembling, the front casing shroud comes into contact with the front casing shroud suction port edge, and the front shroud suction port is rotated by the rotation of the impeller. The seal member arranged so as to be scraped off at the edge has an elastic modulus of 20 kg / cm.
By setting it to ² or more, it is possible to prevent a decrease in handleability and mounting accuracy. Also, by setting it to 50 kg / cm ² or less, even if a slight assembly error occurs, the sealing member has an appropriate elastic deformation. It absorbed to as possible out to prevent the deformation of the mechanical loss and the impeller. Also, the outer peripheral side from the center of the seal member is brought into contact with the inlet edge of the front shroud.
From the direction, it is fixed so as to be sandwiched between the inner surface of the fan casing and the inner surface of the fan casing, and the contact position of the suction port edge of the front shroud is located closer to the radial center than the sandwiched portion by the support frame. Friction resistance due to contact and sliding contact is reduced, and circulating flow can be reliably prevented while suppressing an increase in friction loss. In particular, a seal member formed of a polytetrafluoroethylene resin has a small friction coefficient and thus has a small friction loss, and has a high heat resistance, so that the problem caused by thermal deformation can be solved.

Further, even if a gap is formed between the front shroud of the impeller and the seal member due to variations in assembly or the like, the inner peripheral side of the seal member is bent and drawn in due to the negative pressure generated when the centrifugal impeller rotates. Since it contacts and slides on the shroud end face, circulating flow can be prevented.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a vertical sectional side view of an electric blower according to the present invention.

In FIG. 1, the electric blower 10 includes a motor section 20 and a blower section 30. The motor unit 20 according to the present embodiment is a commutator type motor, and a stator 23 and a rotor 24 are housed in a space defined by a bottomed cylindrical housing 21 having one open end and an end bracket 22. You.

The stator 23 has a stator core 23b provided with a field winding 23a fixed to the housing 21.
The rotor 24 includes an armature winding 24b fitted on a rotating shaft 24a.
The armature core 24c and the commutator 24d connected to the armature winding 24b are rotatably supported by bearings 25 and 26.

A brush holder 27 fixed by screwing is attached to the outer peripheral wall of the housing 21. A carbon brush 28 is housed in the brush holder 27 and is urged by a spring or the like to be provided on the outer peripheral surface of the commutator 24d to supply power.

The blower unit 30 includes a fixed guide blade 31 screwed on the end bracket 22 and a rotary shaft 2 extending through the end bracket 22 and the fixed guide blade 31.
4a, a centrifugal impeller 33 fixed by screws 32;
A fixed guide blade 31 press-fitted and fixed to the outer periphery of the end bracket 22 and a fan casing 34 attached to cover the centrifugal impeller 33 are provided.

The airflow generated by the blower unit 30 is guided into the motor unit 20 from a wind window 22 a formed in the end bracket 22, cools the motor unit 20, and then flows through an exhaust hole 21 a formed in the outer peripheral wall of the housing 21. They are discharged outside the machine.

FIG. 2 is a longitudinal sectional view of a seal portion of a blower section of the electric blower in FIG.

As shown in FIG. 2, the fan casing 34
The suction port edge 33c forming the suction port 34a is formed in the shape of a bell mouth portion 34b curved inside, and the centrifugal impeller 33
The suction port edge 33c forming the suction port 33b of the front shroud 33a extends beyond the inner end of the centrifugal wing 33d to the back of the bell mouth portion 34b.

On the inner surface of the fan casing 34, a convex portion 34 is provided.
and a sealing member 3 fitted to the convex portion 34c and adhesively fixed to the back surface of the bell mouth portion 34b.
5 is located so as to contact the end of the suction port edge 33c of the front shroud 33a of the centrifugal impeller 33.

The seal member 35 is desirably made of a material having high elasticity, a small coefficient of friction, and high heat resistance. As a material of the sealing member, an elastic modulus of 20 to 5 is used.
An elastic body of 0 kg / cm ² , for example, an expanded porous polytetrafluoroethylene resin or the like is used, and these sheet materials are punched to form an annular body.

When the centrifugal impeller 33 rotates, the centrifugal impeller 33
d accelerates the air sucked from the suction port 33b of the front shroud 33a and discharges it from the outer periphery. The discharged air is collected by the fixed guide vanes 31 located on the downstream side of the flow path of the centrifugal impeller 33 and is guided to the electric motor unit 20 side, but a part of the discharged air flows between the front shroud 33 a and the fan casing 34 and becomes external. Increase pressure. The sealing member 35 is
This prevents the discharged air from returning to the suction port 33b.

When the electric blower 10 is assembled, the sealing member 35 comes into contact with the front shroud 33 a of the centrifugal impeller 33 so as to press the suction port edge 33 c to be elastically deformed. The rotation of the centrifugal impeller 33 in the first operation causes the end of the suction port edge 33c of the front shroud 33a to be scraped off, so that the seal member 35 and the suction port edge 33 of the front shroud 33a are removed.
It comes into a light sliding contact state with c. Therefore, it is important that the elastic deformation occurs during assembly, and the elastic modulus of the material is important. In the present invention, if the elastic modulus is 20 kg / cm ² or less, the handling accuracy and the mounting accuracy of the assembling work are reduced, and conversely, 50 kg / cm ^2.
/ Cm ² or more, it was found that problems such as mechanical loss when pressed or deformation of the impeller occurred. The depth at which the seal member 35 slides between the front shroud is set to 50% or less of the thickness t of the seal member 35. 50% depth
In this case, the elastic modulus increases rapidly due to the compression of the seal member 35, and there is a possibility that the above-described problems such as mechanical loss may occur.

In the subsequent blowing operation, the occurrence of circulating flow is prevented in a light sliding state, so that a large frictional resistance does not occur. Further, since the friction coefficient of the polytrafluoroethylene resin itself is low, the friction loss is low. Can be suppressed. Therefore, the calorific value due to friction is small, and the polytetrafluoroethylene resin has high heat resistance, so that there is no need to worry about the occurrence of a solid or circulating flow due to thermal deformation.

[0025] Figure 3 shows the preferred embodiment for attaching the seal member 35 to the fan casing 34.

In order to mount the highly elastic seal member 35 on the inner surface of the fan casing 34 with high accuracy so that the seal member 35 is uniformly pressed against the centrifugal impeller 33, the seal member 35 is accurately positioned at the time of installation. In addition, it is necessary to prevent non-uniform deformation from occurring due to non-uniform force. In this embodiment, the fan casing 3
The outer peripheral portion of the seal member 35 is sandwiched between the inner surfaces of the fan casing 34 by a metal annular support frame 36 welded and fixed to the inner surface of the fan casing 34.

The annular support frame 36 has an annular convex portion 36a for regulating the outer periphery of the seal member 35 and the pushing claw 3 for suppressing the sliding.
6b. Since the fan casing 34 and the seal member 35 are integrally fixed at the outer peripheral portion of the inner diameter d of the annular support frame 36, the seal member 35 on the inner peripheral side of d is formed so as to bend toward the opposite side of the casing. FIG. 3 shows a state in which a gap g has been generated between the front shroud 33a of the centrifugal impeller 33 and the seal member 35 due to the function of assembly work and part processing accuracy.

When the electric blower is operated in the state shown in FIG. 3, a negative pressure is generated inside the centrifugal impeller 33. The inside of the inner diameter d of the annular support frame 36 of the seal member 35 is drawn by the negative pressure and is bent toward the centrifugal impeller, so that the front shroud 3
The circulating flow is prevented from coming into contact with and slidingly contacting 3a. Although it depends on the gap g that occurs, the inner diameter of the centrifugal impeller 33, and the thickness t of the seal member 35, in order to be elastically deformed by the negative pressure, the inner diameter d of the annular support frame 36 is required.
Is required to be 1.5 times or more the plate pressure t.

FIG. 5 shows the power consumption 1 in the embodiment of the present invention.
The characteristic comparison figure with the conventional example of the electric blower for 000W class vacuum cleaners is shown.

As shown in FIG. 5, it can be understood that a static pressure increase of about 50 mmH ₂ O can be obtained aerodynamically without increasing the power consumption, that is, the friction loss of the centrifugal impeller 33.

A sealing member 35 formed of a stretched porous polytetrafluoroethylene resin into a flat annular body is provided at a suction port edge 3 of a front shroud 33 a of a centrifugal impeller 33.
Even if the sealing member 35 is pressed so that the sealing member 35 is elastically deformed, the centrifugal impeller 33 is not locked during the initial operation because the frictional resistance is small. Accordingly, the axial assembly tolerance of the electric blower 10 becomes large, and a large gap for disposing a thick seal member between the suction port edge 33c of the front shroud 33a and the fan casing 34 is not required. An increase in the axial dimension of the electric blower 10 can be suppressed.

In the sliding contact state after the pressing portion has been scraped off by the initial rotation of the centrifugal impeller 33, the frictional resistance of the sliding contact portion is very small, and the friction loss exceeds the efficiency improvement due to the recirculation interruption. I knew it wasn't.

[0033]

As described above, according to the present invention, at least at the time of assembling, it comes into contact with the suction port edge of the front shroud at the position facing the suction port edge of the front shroud of the fan casing, and The seal member arranged so as to be scraped off at the suction port edge of the front shroud by rotation has an elastic modulus of 20 kg / cm ² or more.
It can prevent deterioration in handling and mounting accuracy.
50 kg / cm ² or less and then Ru some also of assembly errors occurs Ki de it possible to prevent deformation of the absorbent to mechanical loss or the impeller by appropriate elastic deformation of the seal member <br/> by the. Further, the outer peripheral side from the center of the seal member is the front surface.
The shroud is fixed so as to be sandwiched by the support frame from the contact direction of the inlet edge of the shroud with the inner surface of the fan casing, and the contact position of the inlet edge of the front shroud is smaller in diameter than the clamping portion by the support frame. By setting the direction center side, the frictional resistance due to contact and sliding contact is reduced, and while suppressing the increase in frictional loss during rotation of the impeller, the occurrence of circulating flow is reliably prevented and the efficiency of the blower is improved. be able to.

In particular, polytetrafluoroethylene resin
The formed seal member has a low friction coefficient,
Thermal loss due to low loss and high heat resistance
Can be solved .

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view of an electric blower according to the present invention.

FIG. 2 is a vertical sectional side view of a seal portion in a blower section of the electric blower shown in FIG.

FIG. 3 is a vertical sectional side view showing a preferred embodiment of a seal portion in a blower unit of the electric blower shown in FIG. 1;

FIG. 4 is a longitudinal sectional view showing a seal portion in a blower unit when the electric blower shown in FIG. 3 is operated.

FIG. 5 is a characteristic comparison diagram between the electric blower according to the present invention shown in FIG. 1 and a conventional electric blower.

[Explanation of symbols]

10: electric blower, 20: electric motor part, 30: blower part,
31: fixed guide blade, 33: centrifugal impeller, 33a: front shroud, 34: fan casing, 35: seal member.

Continuation of the front page (56) References JP-A-2-238196 (JP, A) JP-A-4-262093 (JP, A) JP-A-4-327066 (JP, A) JP-A-5-240167 (JP) JP-A-5-341369 (JP, A) JP-A-5-57400 (JP, U) JP-A-3-59049 (JP, U) (58) Fields studied (Int. Cl. ⁶ , DB Name) F04D 29/00-29/16 F04D 29/40-29/56

Claims (2)

(57) [Claims] 1. An impeller having a front shroud with a suction port formed therein and attached to a rotating shaft of an electric motor, a fixed guide impeller disposed at a downstream side of a flow path of the impeller, and the impeller and A fan casing that covers the fixed guide vanes, at a position facing the suction port edge of the front shroud of the fan casing, at least during assembly, the fan shroud contacts the suction port edge of the front shroud. In an electric blower provided with a seal member that is cut off at the suction port edge of the front shroud by rotation, the seal member is formed in a ring shape with a member having an elastic modulus of 20 to 50 kg / cm ² , and from the center of the seal member. The outer peripheral side is the front shroud
Fixed from the contact direction of the suction port edge to the inner surface of the fan casing so as to be sandwiched by the support frame,
The electric blower according to claim 1, wherein a contact position of an edge of the suction port of the front shroud is closer to a radial center than a holding portion of the support frame. 2. A method according to claim 1, wherein the sealing member is formed by Porite preparative La polyfluoroethylene resin, the support frame, the electric blower, characterized in that the annularly formed.