CN211288240U - End cover, end cover assembly and dust collector - Google Patents

Abstract

The utility model provides an end cover, an end cover component and a dust collector, which comprises a first cover plate, a second cover plate and a third cover plate, wherein the first cover plate is suitable for being internally provided with a diffuser and guiding out airflow; the second cover plate is fixedly connected with the first cover plate and is suitable for internally arranging an air suction impeller; the inner wall of the flow collecting structure comprises an inward contraction section, the end part of the flow collecting structure back to the second cover plate is a flow collecting end, the inward contraction section is arranged at the position close to the flow collecting end, and the inner diameter of the inward contraction section is gradually reduced along the air flow entering direction. By arranging the flow collecting structure, increasing the inward contraction section and gradually reducing the inner diameter, the air flow at the inlet end is guided, the air flow angle is changed, the flow speed of the air flow at the flow collecting end is adjusted, the stall state is reduced, and the irregularity of the air flow at the flow collecting end is improved; the defect of uneven flow field in the motor impeller cavity in the prior art is overcome, the rectification effect is achieved, and the overall efficiency of the impeller is improved.

Description

End cover, end cover assembly and dust collector

Technical Field

The utility model relates to the technical field of household appliances, concretely relates to end cover and end cover subassembly and dust catcher.

Background

GDP in China is continuously and rapidly developed, the income of consumers is continuously increased, particularly the income level of residents in large and medium-sized cities is rapidly increased, and the living conditions of the residents are continuously improved. The number of compound houses and large-area houses is increasing, and the demands of residents on dust collectors are also increasing. The dust suction principle of the dust collector is that the fan impeller discharges air in the impeller out of the fan at high speed under the high-speed driving of the motor, meanwhile, the air in the dust suction part is continuously supplemented to the air inlet fan, high pressure difference is formed between the air and the outside, dust and sundry bits at the suction nozzle are sucked into the dust suction part along with the air, and are filtered by the filter and then collected into the dust barrel.

However, in the prior art, a high-speed motor of the dust collector drives an impeller to rotate at a high speed to do work, under the influence of the high-speed rotation of the impeller, airflow at the inlet end of an impeller cavity generates a certain airflow angle and is relatively disordered after entering the inlet end of the impeller, so that a flow field in the impeller is uneven, a low-speed area with a large range is formed at a wheel cover and a blade top position, the work efficiency of the impeller is influenced, and the overall performance of the motor is reduced.

SUMMERY OF THE UTILITY MODEL

Therefore, the to-be-solved technical problem of the utility model lies in overcoming the defect that motor impeller is inefficient among the prior art to provide an end cover and end cover subassembly and dust catcher.

The utility model provides an end cover, include:

the first cover plate is suitable for internally arranging a diffuser and guiding out airflow;

the second cover plate is fixedly connected with the first cover plate and is suitable for internally arranging an air suction impeller;

the inner wall of the flow collecting structure comprises an inward contraction section, the end part of the flow collecting structure back to the second cover plate is a flow collecting end, the inward contraction section is arranged at the position close to the flow collecting end, and the inner diameter of the inward contraction section is gradually reduced along the air flow entering direction.

The collecting structure and the second cover plate are arranged in a cylindrical shape, the section of the inner contraction section along the axial direction is arranged in an isosceles trapezoid shape, and the inner contraction angle of the inner contraction section is 20-50 degrees.

The inner wall of the flow collecting structure further comprises a transition section, the connection position of the transition section and the inward contraction section is arc-shaped, one end, close to the second cover plate, of the transition section is an inlet end, and the inlet end is fixedly connected with the second cover plate.

The transition section gradually increases or is fixed unchangeable along the direction internal diameter that dorsad the internal contraction section, the transition section with the junction diameter of internal contraction section is 0.8 ~ 1 times of entry end internal diameter.

The vertical distance between the flow collecting end and the inlet end is 0.2-0.45 times of the inner diameter of the inlet end.

The outside of first apron is provided with a plurality of first ring channel.

And a plurality of slotted holes are uniformly formed in the first annular groove at the position corresponding to the first cover plate.

The first cover plate, the second cover plate and the current collecting structure are integrally formed.

And a second annular groove is formed in the top side of the end part, back to the second cover plate, of the current collecting structure, and the second annular groove is suitable for installing a rubber ring.

The utility model also provides an end cover subassembly, including foretell end cover, still including setting up diffuser in the first apron and the impeller of setting in the second apron.

The length of a gap between the inner wall surface of the second cover plate and the blade top of the impeller is 0.2-0.3 mm, and the length of the gap is equal or gradually reduced along the flowing direction of the airflow.

And no gap is reserved between the blade tops of the diffuser and the inner wall of the first cover plate.

The utility model discloses still include a dust catcher, including foretell end cover subassembly.

The utility model discloses technical scheme has following advantage:

1. the utility model provides an end cover, which comprises a first cover plate, a second cover plate and a third cover plate, wherein the first cover plate is suitable for being internally provided with a diffuser and leading out airflow; the second cover plate is fixedly connected with the first cover plate and is suitable for internally arranging an air suction impeller; the inner wall of the flow collecting structure comprises an inward contraction section, the end part of the flow collecting structure back to the second cover plate is a flow collecting end, the inward contraction section is arranged at the position close to the flow collecting end, and the inner diameter of the inward contraction section is gradually reduced along the air flow entering direction.

The air flow enters the flow collecting structure of the end cover from the flow collecting end and then enters the impeller position in the cavity of the second cover plate, the blades drive the air flow to rotate at a high speed, and the air flow enters the diffuser under the action of centrifugal force and finally flows out of the diffuser.

By arranging the flow collecting structure, increasing the inward contraction section and gradually reducing the inner diameter, the air flow at the inlet end is guided, the air flow angle is changed, the flow speed of the air flow at the flow collecting end is adjusted, the stall state is reduced, and the irregularity of the air flow at the flow collecting end is improved; according to a simulation result, an inlet current collector is not arranged, the fluid flow state at the inlet end of the impeller is disordered, a low-speed area and a vortex area in a larger area exist near the blade top of the impeller and the upper cover plate of the impeller, the working efficiency of the impeller is low, an inner contraction section structure is designed and added, the flow state of fluid in the impeller can be improved, the defect of uneven flow field in an impeller cavity of a motor in the prior art is overcome, the rectification effect is achieved, and the overall efficiency of the impeller is improved.

2. The utility model provides an end cover, mass flow structure with the second apron is cylindric setting, the section of contracting in is isosceles trapezoid along axial cross-section and sets up, the interior angle of contracting in is 20 ~ 50 degrees

The setting can increase the expansion angle like this, can increase the entry flow area, makes the air current concentrate more and get into the impeller, but too big entry area leads to the mass flow section to be close to inner wall air current velocity too big, causes to be close to inner wall air current and to be close to central air current velocity difference great to lead to the mass flow section to produce the vortex region that the secondary flow caused. The internal contraction angle is an included angle formed by internal contraction sections on two sides of the central axis in a plane obtained by cutting the central axis of the flow collection structure, is 20-50 degrees, can effectively improve the stable state of a flow field under a small-flow working condition, effectively plays a role in rectification, and effectively improves the work efficiency of the impeller.

3. The utility model provides an end cover, changeover portion along dorsad the direction internal diameter of the section of contracting in increases gradually or is fixed unchangeable, the changeover portion with the junction diameter of the section of contracting in does 0.8 ~ 1 times of entry end internal diameter.

The purpose of reducing the constriction opening is rectification, makes the more smooth entering impeller of air current, but the internal diameter undersize that leads to the transition section and the interior constriction section junction can lead to the air current velocity of flow of entry end to increase fast, appears the fluidic condition, leads to the impact of coming flow in the inside flow field of impeller, makes its inside flow field disorder, has the negative effect to the flow state of having stabilized air current. The junction diameter of changeover portion and internal contraction section is 0.8 ~ 1 times of entry end internal diameter, set up like this, the diameter that makes the relative internal contraction section of changeover portion has the extension distance that reduces or has a section diameter unchangeable, because the range that the diameter reduces is less, or there is the friction in the extension distance air current and the changeover portion inner wall, make the air current that flows into the entry end maintain the flow state unchangeable, reduce under the prerequisite that flows into near impeller blade top vortex, reduce the direct impact of air current to inner chamber and impeller, the stability of impeller work has been improved, and make the flow field in the runner more even, promote impeller overall efficiency.

4. The utility model provides an end cover, the perpendicular distance of mass flow end and entry end does 0.2 ~ 0.45 of entry end internal diameter is doubly.

By the arrangement, the axial relative length of the flow collecting structure is not too short, the inner wall of the flow collecting structure is enough to ensure the rectification effect on the airflow, meanwhile, the axial relative length is not too long, if the axial relative length is continuously increased, the length of a flow channel of the airflow is increased, the friction loss of the airflow is higher, the working efficiency of the device is reduced, the size of the whole device is increased, and the portability is reduced.

5. The utility model provides an end cover, in the first ring channel with the corresponding position of first apron evenly is provided with a plurality of slotted holes.

The slotted hole in the first annular groove is suitable for the diffuser, the diffuser is circumferentially positioned, the rubber ring in the groove is sealed, the diffuser is prevented from circumferentially moving, and the mounting stability of the diffuser is improved.

6. The utility model provides an end cover, first apron with the second apron reaches mass flow structure integrated into one piece.

The end cover is integrally formed in an injection molding mode, no seam or other connecting structures exist, the smoothness of the connecting position of each structure is improved, the precision of an internal cavity of the end cover is guaranteed, and the end cover is convenient to match with an impeller and a diffuser.

7. The utility model provides an end cover assembly, the internal face of second apron and the clearance length between impeller leaf top are 0.2 ~ 0.3mm, just the length in clearance equals or reduces along the direction that the air current flowed in gradually.

By the arrangement, on one hand, the smaller the blade top gap is, the less the air flow escapes from the gap, the higher the working efficiency of the impeller is, and in order to ensure the working performance of the impeller, the blade top gap is reduced as much as possible, and the circumferential eddy of the air flow is reduced; on the other hand, in consideration of the reliability of the impeller, the clearance cannot be too small, the high-speed rotating impeller can deform radially under the action of centrifugal force, and a certain margin needs to be reserved in the clearance to prevent scraping and friction. The length of a gap between the inner wall surface of the second cover plate and the blade top of the impeller is 0.2-0.3 mm, on the premise that the acting performance of the impeller is guaranteed, enough allowance is reserved for deformation of the impeller, and the safety of the end cover assembly is improved. Meanwhile, the clearance on the outlet side of the airflow is more sensitive to the influence of the efficiency of the impeller relative to the clearance on the inlet side of the airflow, and the front edge of the impeller deforms greatly, so that a clearance structure which gradually reduces along the inflow direction of the airflow can be selected.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the technical solutions in the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic cross-sectional view of an end cap assembly provided in an embodiment of the present invention;

fig. 2 is a schematic cross-sectional view of an end cap provided in an embodiment of the present invention;

FIG. 3 is a perspective view of the end cap shown in FIG. 2;

FIG. 4 is an enlarged schematic view of section A of the endcap assembly of FIG. 1;

fig. 5 is a schematic diagram illustrating a variation rule of impeller efficiency according to a ratio λ of a distance between a collector end and an inlet end to an inner diameter of the inlet end, according to an embodiment of the present invention;

fig. 6 is a schematic diagram of the change rule of the impeller efficiency along with the retraction angle provided in the embodiment of the present invention;

FIG. 7 is a meridian velocity cloud chart of impeller meridian plane simulation in the prior art.

Description of reference numerals:

1-a first cover plate; 2-a second cover plate; 3-a current collecting structure; 4-a diffuser; 5-an impeller; 11-a first annular groove; 12-a slot; 31-internal contraction section; 32-a current collecting end; 311-a setback angle; 33-a transition section; 34-an inlet end; 35-a second annular groove; 51-impeller tip.

Detailed Description

The technical solution of the present invention will be described clearly and completely with reference to the accompanying drawings, and obviously, the described embodiments are some, but not all embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Furthermore, the technical features mentioned in the different embodiments of the invention described below can be combined with each other as long as they do not conflict with each other.

As shown in fig. 1-7, the present invention provides an end cap, comprising: the first cover plate 1 is suitable for internally arranging a diffuser 4 and guiding out airflow; the second cover plate 2 is fixedly connected with the first cover plate 1 and is suitable for internally arranging an air suction impeller 5; the collecting structure 3 is fixedly connected with the second cover plate 2, is in a cylindrical shape and is suitable for air flow to enter, the inner wall of the collecting structure 3 comprises an inward contraction section 31, the end part, back to the second cover plate 2, of the collecting structure 3 is a collecting end 32, the inward contraction section 31 is arranged at the position close to the collecting end 32, and the inner diameter of the inward contraction section is gradually reduced along the air flow entering direction.

The airflow enters the flow collecting structure 3 of the end cover from the flow collecting end 32 and then enters the impeller 5 in the cavity of the second cover plate 2, the blades drive the airflow to rotate at a high speed, and the airflow enters the diffuser 4 under the action of centrifugal force and finally flows out of the diffuser 4.

By arranging the collecting structure 3, increasing the inner contraction section 31 and gradually reducing the inner diameter, the airflow at the inlet end 34 is guided, the airflow angle is changed, the airflow speed at the collecting end 32 is adjusted, the stall state is reduced, and the airflow irregularity at the collecting end 32 is improved; as shown in fig. 7, from the simulation result, there is no inlet collecting structure 3, the fluid flow state at the inlet end 34 of the impeller 5 is relatively disordered, which causes a large low-speed region and a large vortex region near the blade top of the impeller 5 and the upper cover plate of the impeller 5, which causes the low work efficiency of the impeller 5, and the structure of the inner contraction section 31 is added, which can improve the flow state of the fluid inside the impeller 5, overcome the defect of non-uniform flow field inside the cavity of the motor impeller 5 in the prior art, achieve the rectification effect, and improve the overall efficiency of the impeller 5.

The collecting structure 3 and the second cover plate 2 are arranged in a cylindrical shape, the inner contracting section 31 is arranged in an isosceles trapezoid shape along the axial section, and the inner contracting angle 311 of the inner contracting section 31 is 20-50 degrees. The expansion angle can be increased by the arrangement, the inlet overflowing area can be increased, the airflow enters the impeller 5 more intensively, but the airflow speed of the collecting section close to the inner wall is too high due to the overlarge inlet area, the speed difference between the airflow close to the inner wall and the airflow close to the center is large, and the vortex area caused by secondary flow generated by the collecting section is caused. The inner contraction angle 311 is an included angle formed by the inner contraction sections 31 on two sides of the central axis in a plane obtained by cutting the central axis of the flow collecting structure 3, as shown in fig. 6, the inner contraction angle 311 is 20-50 degrees, the stable state of a flow field under a small-flow working condition can be effectively improved, the rectification effect is effectively achieved, and the work efficiency of the impeller 5 is effectively improved. In this example, the receding angle 311 is 38.5 ° which corresponds to the highest efficiency, and as an alternative embodiment, the receding angle 311 may be at another temperature within the range of 20 ° to 50 °.

The inner wall of the collecting structure 3 further includes a transition section 33, a connection portion of the transition section 33 and the inward contracting section 31 is arc-shaped, one end of the transition section 33 close to the second cover plate 2 is an inlet end 34, and the inlet end 34 is fixedly connected with the second cover plate 2. The setting of circular arc section can prevent that air current and hookup location from shaking because of the air current that the friction produced, and the noise reduction can also make the flow of air current more smooth and easy in addition, reduces the influence to the air current flow state, guarantees the rectification effect of internal contraction section 31.

The transition section 33 has an inner diameter gradually increasing along a direction away from the inner contraction section 31, and the diameter of the connection between the transition section 33 and the inner contraction section 31 is 0.8-1 times of the inner diameter of the inlet end 34, and as an alternative embodiment, the inner diameter of the transition section 33 may be kept constant.

The purpose of reducing the contraction opening is to rectify the airflow and enable the airflow to enter the impeller 5 more smoothly, but when the inner diameter of the joint of the transition section 33 and the inner contraction section 31 is too small, the airflow velocity at the inlet end 34 is increased rapidly, and the condition of jet flow occurs, so that the flow field inside the impeller 5 is impacted by incoming flow, the flow field inside the impeller 5 is disturbed, and the flow state of the stabilized airflow is negatively affected. The diameter of the connecting part of the transition section 33 and the inner contraction section 31 is 0.8-1 times of the inner diameter of the inlet end 34, the arrangement is carried out, the diameter of the transition section 33 relative to the inner contraction section 31 is reduced or the extending distance with the unchanged diameter is reserved, the diameter reducing range is small, or friction exists between airflow and the inner wall of the transition section 33 in the extending distance, the airflow flowing into the inlet end 34 is kept unchanged in a flowing state, on the premise that the vortex near the blade top 51 of the impeller 5 is reduced, the direct impact of the airflow on the inner cavity and the impeller 5 is reduced, the working stability of the impeller 5 is improved, the flow field in a flow channel is more uniform, and the overall efficiency of the impeller 5 is improved.

As shown in FIG. 5, the ratio of the vertical distance between the collecting end 32 and the inlet end 34 to the inner diameter of the inlet end 34 is λ, and λ is in the range of 0.2-0.45. By the arrangement, the axial relative length of the flow collecting structure 3 is not too short, the inner wall of the flow collecting structure is enough to ensure the rectification effect on the air flow, meanwhile, the axial relative length is not too long, if the axial relative length is continuously increased, the length of a flow channel of the air flow is increased, the friction loss of the air flow is higher, the working efficiency of the device is reduced, the size of the whole device is increased, and the portability is reduced. In the present embodiment, the value of λ takes 0.39.

The outer side of the first cover plate 1 is also provided with a plurality of first annular grooves 11. A plurality of slotted holes 12 are uniformly arranged at the positions corresponding to the first cover plate 1 in the first annular groove 11. The arrangement of slotted hole 12 in the first annular groove 11 is suitable for diffuser 4, and carries out circumference location to diffuser 4, and the inslot rubber ring is sealed, prevents diffuser 4 circumference drunkenness, improves the stability of diffuser 4 installation.

The first cover plate 1, the second cover plate 2 and the current collecting structure 3 are integrally formed. The end cover is integrally formed in an injection molding mode, no seam or other connecting structures exist, the smoothness of the connecting position of each structure is improved, the precision of an internal cavity of the end cover is guaranteed, and the end cover is convenient to match with the impeller 5 and the diffuser 4.

The top side of the end of the current collecting structure 3, which faces away from the second cover plate 2, is provided with a second annular groove 35, and the second annular groove 35 is provided with a rubber ring and used for positioning and sealing a motor connected with the impeller 5.

The utility model also provides an end cover assembly, including foretell end cover, still including setting up diffuser 4 in first apron 1 and setting up impeller 5 in second apron 2.

All the gaps between the inner wall surface of the second shroud 2 and the impeller blade tips 51 are within a range of 0.2 to 0.3mm in length and gradually decrease in the direction in which the airflow flows, for example, as shown in fig. 4, from top to bottom, the gap at the upper portion of the impeller blade tips 51 is 0.3mm in size, the gap at the lower portion of the impeller blade tips 51 is 0.2mm in size, and the gap at the middle portion of the impeller blade tips 51 is 0.25mm in size. As an alternative embodiment, the gaps are of equal length in the direction of the inflow of the air flow.

By the arrangement, on one hand, the smaller the blade top gap is, the less the air flow escapes from the gap, the higher the work efficiency of the impeller 5 is, and in order to ensure the work performance of the impeller 5, the blade top gap is reduced as much as possible, and the circumferential eddy of the air flow is reduced; on the other hand, in consideration of the reliability of the impeller 5, the clearance cannot be too small, the impeller 5 rotating at high speed is radially deformed under the action of centrifugal force, and a certain margin needs to be left in the clearance to prevent scraping and friction. The length of a gap between the inner wall surface of the second cover plate 2 and the impeller blade top 51 is 0.2-0.3 mm, on the premise that the working performance of the impeller 5 is guaranteed, enough allowance is reserved for the deformation of the impeller 5, and the safety of the end cover assembly is improved. Meanwhile, the gap on the outlet side of the airflow is more sensitive to the influence of the efficiency of the impeller 5 relative to the gap on the inlet side of the airflow, and the front edge of the impeller 5 deforms greatly, so that a gap structure which gradually reduces along the inflow direction of the airflow can be selected.

In the embodiment, no gap is left between the blade tips of the diffuser 4 and the inner wall of the first cover plate 1.

The utility model discloses still include a dust catcher, including foretell end cover subassembly.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications can be made without departing from the scope of the invention.

Claims (13)

1. An end cap, comprising:

the first cover plate (1) is suitable for internally arranging a diffuser (4) and guiding out airflow;

the second cover plate (2) is fixedly connected with the first cover plate (1) and is suitable for being internally provided with an air suction impeller (5);

the collecting structure (3) is fixedly connected with the second cover plate (2), is cylindrical and suitable for air flow to enter, the inner wall of the collecting structure (3) comprises an inward-contracting section (31), the end part, back to the second cover plate (2), of the collecting structure (3) is a flow collecting end (32), and the inward-contracting section (31) is arranged at a position close to the flow collecting end (32) and gradually reduces in inner diameter along the air flow entering direction.

2. An end cover according to claim 1, characterized in that the collecting structure (3) and the second cover plate (2) are arranged in a cylindrical shape, the section of the inner contraction section (31) along the axial direction is arranged in an isosceles trapezoid, and the inner contraction angle (311) of the inner contraction section (31) is 20-50 degrees.

3. The end cover according to claim 2, characterized in that the inner wall of the flow collecting structure (3) further comprises a transition section (33), the connection between the transition section (33) and the inner contraction section (31) is in a circular arc shape, one end of the transition section (33) close to the second cover plate (2) is an inlet end (34), and the inlet end (34) is fixedly connected with the second cover plate (2).

4. An end closure according to claim 3, wherein the transition section (33) has an inner diameter which is gradually increased or constant in a direction away from the inner reducing section (31), and the diameter of the connection between the transition section (33) and the inner reducing section (31) is 0.8-1 times the inner diameter of the inlet end (34).

5. An end cap according to claim 4, wherein the perpendicular distance of the collector end (32) from the inlet end (34) is 0.2 to 0.45 times the inner diameter of the inlet end (34).

6. End closure according to claim 1, characterized in that the outer side of the first cover plate (1) is provided with a number of first annular grooves (11).

7. The end cover according to claim 6, characterized in that the first annular groove (11) is uniformly provided with a plurality of slotted holes (12) at the position corresponding to the first cover plate (1).

8. End cap according to claim 1, characterized in that the first and second cover plates (1, 2) and the flow collecting structure (3) are integrally formed.

9. End cap according to claim 1, characterized in that the top side of the end of the collecting structure (3) facing away from the second cover plate (2) is provided with a second annular groove (35), the second annular groove (35) being adapted for mounting a rubber ring.

10. An end cover assembly, comprising an end cover according to any of claims 1-9, further comprising a diffuser (4) arranged in the first cover plate (1) and an impeller (5) arranged in the second cover plate (2).

11. The end cover assembly according to claim 10, wherein the length of the gap between the inner wall surface of the second cover plate (2) and the impeller blade tip (51) is 0.2-0.3 mm, and the length of the gap is equal or gradually reduced along the direction of the inflow of the air flow.

12. End cover assembly according to claim 10, characterized in that the blade tips of the diffuser (4) are free of gaps from the inner wall of the first cover plate (1).

13. A vacuum cleaner comprising the end cap assembly of any one of claims 10-12.

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