BLOWER

Abstract

A blower includes a casing having an air inlet, an electric motor having a rotor and a stator, an impeller driven by the motor, and a diffuser for directing air from the impeller. The impeller and the diffuser are received in the casing. The impeller has a base and blades supported by the base. The diffuser has a plate like portion with diffuser vanes surrounding the impeller. Inlet angles of the impeller blades is between 20˜30 degrees and outlet angles of the impeller blades is between 26˜38 degrees.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application claims priority under 35 U.S.C. §119(a) from Patent Application No. 201210081083.2 filed in The People's Republic of China on Mar. 22, 2012.

FIELD OF THE INVENTION

This invention relates to a blower as used in a vacuum cleaner or the like and in particular to an impeller and a diffuser of the blower.

BACKGROUND OF THE INVENTION

In a vacuum cleaner, air is moved to pick up dirt, dust and debris and deliver it to a dirt container, usually in the form of a filter bag supported within a canister. To cause the air flow, a blower is used to create a vacuum. Hence, the blower is also known as a vacuum blower.

The vacuum blower comprises a motor, an impeller creating the air flow and a diffuser. The impeller is fitted to and rotates with the shaft of the motor to generate high pressure air flow. The diffuser guides the air from the impeller through the motor where it is exhausted through openings in the motor housing after cooling the motor.

The construction of the impeller and the diffuser are very important as it affects the efficiency of the blower. A highly efficient blower can increase the volume of air being moved or reduces the power required to move the same volume of air. Hence, the desire for a more efficient blower is obvious.

SUMMARY OF THE INVENTION

Accordingly, in one aspect thereof, the present invention provides a blower comprising: a casing having an air inlet, an electric motor having a rotor and a stator, an impeller driven by the motor, and a diffuser for directing air from the impeller, the impeller and the diffuser being received in the casing, the impeller having a base and blades supported by the base, the diffuser having a plate like portion with diffuser vanes surrounding the impeller, wherein an inlet angle of the impeller blades is between 20˜30 degrees and an outlet angle of the impeller blades is between 26˜38 degrees.

Preferably, an inlet angle of the diffuser vanes is between 7˜11.5 degrees.

Preferably, an outlet angle of the diffuser vanes is between 15˜17.5 degrees.

Preferably, the rotor comprises a shaft, a rotor core fixed on the shaft, a commutator fixed on the shaft adjacent the rotor core, and rotor windings wound about poles of the rotor core and electrically connected to the commutator, the stator comprises an axially extending housing, at least one permanent magnet fixed to the inner surface of the housing, electrical terminals and at least one pair of brushes for making sliding contact with the commutator, the motor being operable by applying LVDC power to the rotor windings via the commutator.

Preferably, the stator has two magnetic poles, the rotor core has 5 slots, and the commutator has 5 commutator segments.

Preferably, the housing has an outer diameter of 35.7 mm±3%, the rotor core has an axial length of 25.1 mm±1%, and the permanent magnet has a thickness of 4.9 mm±3%.

Preferably, the casing has an outer diameter of 95 mm±3%

Preferably, the rotor is configured to rotate at a speed between 18,000˜22,000 rpm.

Preferably, the diffuser further comprises return guide vanes formed on one surface thereof remote from the impeller.

According to a second aspect, the present invention provides a blower comprising: a casing having an air inlet, an electric motor having a rotor and a stator, an impeller driven by the motor, and a diffuser for directing air from the impeller, the impeller and the diffuser being received in the casing, the impeller having a base and blades supported by the base, the diffuser having a plate like portion with diffuser vanes surrounding the impeller, wherein an inlet angle of the diffuser vanes is between 7˜11.5 degrees and an outlet angle of the diffuser vanes is between 1.5˜17.5 degrees.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described, by way of example only, with reference to figures of the accompanying drawings. In the figures, identical structures, elements or parts that appear in more than one figure are generally labelled with a same reference numeral in all the figures in which they appear. Dimensions of components and features shown in the figures are generally chosen for convenience and clarity of presentation and are not necessarily shown to scale. The figures are listed below.

FIG. 1 shows a blower in accordance with a preferred embodiment of the present invention;

FIG. 2 is a sectional view of the blower of FIG. 1;

FIG. 3 shows an impeller being a part of the blower of FIG. 1;

FIG. 4 shows an impeller and a diffuser being parts of the blower of FIG. 1;

FIG. 5 shows a bracket being a part of the blower of FIG. 1;

FIG. 6 is a top view of the impeller of FIG. 3, with a cover removed; and

FIG. 7 is a top view of the impeller and diffuser of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a blower 10 in accordance with a preferred embodiment of the present invention. FIG. 2 is a sectional view of the blower 10. The blower 10 comprises a casing 12, a bracket 13, an impeller 14, a diffuser 16, and an electric motor 18.

Casing 12, which is formed by drawing a sheet metal disc, is fitted over the bracket 13, the impeller 14 and the diffuser 16 to define a working air chamber. An opening 20 in the casing 12 defines an air inlet for the blower.

FIG. 3 illustrates the impeller 14, which comprises a curved cover 22, a flat base 24 opposite the cover 22, and a plurality of blades 26. The cover 22 has an opening 28 formed at a center thereof and facing the opening 20 defined by the casing 12. The opening 20 has an inwardly formed lip 30 which cooperates with the opening 28 in the cover 22 to restrict air recirculating within the air chamber across the impeller 14. Preferably the lip extends into or through the opening 28. The plurality of blades 26 are disposed between the cover 22 and the base 24, extending in a curved manner and evenly distributed circumferentially to form a plurality of flow passages through which air passing through the opening 28 flows when the impeller 14 is rotating. Each blade 26 has a plurality of tabs 32 on each of the two long edges and holes corresponding to the tabs 32 are formed in the cover 22 and the base 24. A tab 32 and a corresponding hole constitute a clamp structure. The blades 26 are firmly fixed between the cover 22 and the base 24 by crimping or otherwise deforming the tabs after they have been inserted into the holes to prevent their removal, in a manner generally known in the art.

FIG. 4 illustrates the impeller 14 and the diffuser 16. The diffuser 16 has a central plate like portion 36 with diffuser vanes 38 on the upper surface and return guide vanes 40 on the lower surface. The diffuser vanes 38 and the return guide vanes 40 are integrally formed with the portion 36. The diffuser vanes 38 are evenly arranged at the outer periphery of the upper surface of the portion 36, facing the impeller 14 and surrounding the impeller 14. The return guide vanes 40 are evenly arranged at the outer periphery of the lower surface of the portion 36, facing the motor 18. Passageways are formed between adjacent diffuser vanes and between adjacent return guide vanes 40.

The motor 18 is preferably a low voltage direct current (LVDC) motor with a rotor and a stator surrounding the rotor. The rotor comprises a shaft 42, a rotor core 44 fixed on the shaft 42, a commutator 46 fixed on the shaft 42 adjacent the rotor core 44, rotor windings 45 wound about poles of the rotor core 44 and electrically connected to the commutator 46, and a cooling fan 48 fixed on the rotor core 44. Outer surfaces of the rotor poles form a circle. Slots are formed between adjacent rotor poles for accommodating the rotor windings. The stator comprises an axially extending round housing 50 having an open end and a closed end, at least one permanent magnet 52 fixed to the inner surface of the housing 50 and an end cap 54 closing the open end of the housing 50. Electrical terminals 56 for electrically connecting to an external power supply and brush cages 58 are supported by the end cap 54. Brushes 59 are slidably received in the brush cages 58 for making sliding contact with the commutator 46. Each electrical terminal 56 is electrically connected to a corresponding brush. Thus, a LVDC power, preferably between 12˜36 V, can be supplied to the rotor windings via the electrical terminals 56, brushes and the commutator 46. Preferably, the stator has two magnetic poles and two brushes, the rotor core has 5 slots, the commutator has 5 commutator segments, and the rotor windings are lap windings. The shaft 42 is rotatably supported by two bearings 60 received in bearing supports 62 at both ends of the motor.

FIG. 5 illustrates the bracket 13. The bracket 13 has an inner ring 64 and an outer ring 66 connected to the inner ring 64 via bridges 68. The inner ring 64 has a first recessed portion 70 and a hole 72 formed at the center of the first recessed portion 70. The first recessed portion 70 is supported by one axial end surface of the housing at the closed end. The hole 72 is fitted to the bearing support 62 of the motor at the closed end. A flange 74 axially extends from the outer periphery of the outer ring 64. The casing 12 is fitted to the outer surface of the flange 74 such that the casing 12 is firmly fixed to the bracket 13. The central plate like portion 36 of the diffuser 16 has a second recessed portion 76 with a central hole. The second recessed portion 76 is fitted to the bearing support 62 and axially supported by the inner ring 64. The return guide vanes 40 are axially supported by the outer ring 66. The central plate like portion 36 and the bracket 13 are fixed to the housing 50 of the motor 18 by screws (not shown). The impeller 14 is coupled to a shaft 42 of the motor via a spacer 78 fitted to the shaft 42. The spacer 78 has a plate portion 80 which supports the base 24 of the impeller 14. The spacer 78 sits on the inner race of the bearing 60 at the closed end. A washer 82 is placed on top of the base 24 and a nut 84 screws into the end of the shaft 42 clamping the base 24 between the spacer 78 and the washer 82 so that the impeller rotates with the shaft.

In use, a LVDC power supply is connected to the motor 12 to cause the rotor to rotate. The impeller 14, being fixed to the shaft 42, is driven by the rotor causing air to be drawn into the impeller 14 through the inlet 20 in the casing 12 and expelled radially from the impeller 14 and through the passageways defined by the diffuser vanes 38 on the diffuser 16 and with the casing 12 directing the air flow from the upper surface of the diffuser around the outer edge of the diffuser into the passages formed between the return guide vanes 40 on the lower surface of the diffuser 16. The return guide vanes 40 direct the air inwardly and axially through the openings in the bracket 13 and into the housing 50 where the air passes over the stator and rotor before being exhausted through apertures 86 in the lower portion of the housing 50.

Preferably, the motor 18 is a 600 series LVDC motor. The LVDC power supplied to the motor is about 24V. The housing 50 has an outer diameter of 35.7 mm, the rotor core has an axial length of 25.1 mm, and the permanent magnet has a thickness of 4.9 mm, allowing a ±3% variation in these dimensions.

The blower in accordance with the present invention is particularly suitable for air processing apparatus such as hand dryers and vacuum cleaners. When it is used in vacuum cleaners, the motor 18 preferably operates at speed between 18,000 rpm and 22,000 rpm and the casing 12 has an outer diameter of 95 mm±3%.

As may be realized, the impeller 14 and the diffuser 16 play an important part in the efficiency of the air flow and in particular, in the turning and transferring of the air from, the impeller and into the housing.

Preferably, inlet angles α1 of the impeller blades 26 are between 20˜30 degree. The angle α1 means an angle formed by two lines L1, L2. Line L1 represents the tangent to an imaginary circle touching inner ends of all blades 26 at the point A where it touches the blade 26. Line L2 represents the tangent to the curve of the blade 26 at point A. Outlet angles β1 of the impeller blades 26 are between 26˜38 degree. The angle β1 means an angle formed by two lines L3, L4, Line L3 represents the tangent to an imaginary circle touching outer ends of all blades 26 at the point B where it touches the blade 26. Line L4 represents the tangent to the curve of the blade 26 at point B. The inlet angles α1 and the outlet angles β1 of the impeller blades 26 are shown in FIG. 6.

Inlet angles α2 of the diffuser vanes 38 are between 7˜11.5 degree. The angle α2 means an angle formed by two lines L5, L6. Line L5 represents the tangent to an imaginary circle touching inner ends of all, vanes 38 at the point C where it touches the vane 38. Line L6 represents the tangent to the curve of the vane 38 at point C. Outlet angles β2 of the diffuser vanes 38 are between 15˜17.5 degree. The angle β2 means an angle formed by two lines L7, L8. Line L7 represents the tangent to an imaginary circle touching outer ends of all vanes 38 at the point D where it touches the vane 38. Line L8 represents the tangent to the curve of the vane 38 at point D. The inlet angles α2 and the outlet angles of the diffuser vanes 38 are shown in FIG. 7.

We have discovered that if the blower with above configuration is used in a small vacuum cleaner, such as a hand-held vacuum cleaner, an increase in efficiency can be achieved. The inlet angles α1 and the outlet angles β1 of the impeller blades 26 are especially important. Below table shows the efficiency changing when the angles α1, β1 of the impeller blades 6 varies, under the test condition of air flow of the blower being 12.92 L/S and rotational speed of the rotor being 21,000 rpm. According to the table, an efficiency of about 71% or more can be achieved by using the angle α1 in the range of 19° to 29° and the angle β1 in the range of 25.5° to 37°.

	Q (L/S)	α1 (°)	β1 (°)	ΔP (Pa)	n (rpm)	η (%)
	12.92	19.0	30.0	4222	21000	71.00
		22.5	25.5	4099		71.02
		24.8	28.2	4210		71.10
		24.3	34.5	4212		71.58
		26.0	36.0	4222		71.10
		27.0	37.0	4195		71.39
		29.0	27.5	4224		70.99
		32.0	32.0	4215		70.97
		34.0	34.0	4208		70.13
		36.0	36.0	4287		70.25

In the description and claims of the present application, each of the verbs “comprise”, “include”, “contain” and “have”, and variations thereof, are used in an inclusive sense, to specify the presence of the stated item but not to exclude the presence of additional items.

Although the invention is described with reference to one or more preferred embodiments, it should be appreciated by those skilled in the art that various modifications are possible. Therefore, the scope of the invention is to be determined by reference to the claims that follow.

Claims

1. A blower comprising: a casing having an air inlet, an electric motor having a rotor and a stator, an impeller driven by the motor, and a diffuser for directing air from the impeller, the impeller and the diffuser being received in the casing, the impeller having a base and blades supported by the base, the diffuser having a plate like portion with diffuser vanes surrounding the impeller, wherein an inlet angle of the impeller blades is between 20˜30 degrees and an outlet angle of the impeller blades is between 26˜38 degrees.

2. The blower of claim 1, wherein an inlet angle of the diffuser vanes is between 7˜115 degrees.

3. The blower of claim 1, wherein an outlet angle of the diffuser vanes is between 15˜17.5 degrees.

3. The blower of claim 2, wherein an outlet angle of the diffuser vanes is between 15˜17.5 degrees.

4. The blower of claim 1, wherein the rotor comprises: a shaft, a rotor core fixed on the shaft, a commutator fixed on the shaft adjacent the rotor core, and rotor windings wound about poles of the rotor core and electrically connected to the commutator, wherein the stator comprises: an axially extending housing, at least one permanent magnet fixed to the inner surface of the housing, electrical terminals, and at least one pair of brushes for making sliding contact with the commutator, andwherein the motor is operable by applying LVDC power to the rotor windings via the commutator.

5. The blower of claim 4, wherein the stator has two magnetic poles, the rotor core has 5 slots, and the commutator has 5 commutator segments.

6. The blower of claim 4, wherein the housing has an outer diameter of 35.7 mm±3%, the rotor core has an axial length of 25.1 mm±3%, and the permanent magnet has a thickness of 4.9 mm±3%.

7. The blower of claim 1, wherein the casing has an outer diameter of 95 mm±3%

8. The blower of claim 1, wherein the rotor is configured to rotate at a speed between 18,000˜22,000 rpm.

9. The blower of claim 1, wherein the diffuser further comprises return guide vanes formed on one surface thereof remote from the impeller.

10. A blower comprising: a casing having an air inlet, an electric motor having a rotor and a stator, an impeller driven by the motor, and a diffuser for directing air from the impeller, the impeller and the diffuser being received in the casing, the impeller having a base and blades supported by the base, the diffuser having a plate like portion with diffuser vanes surrounding the impeller, wherein an inlet angle of the diffuser vanes is between 7˜11.5 degrees and an outlet angle of the diffuser vanes is between 15˜17.5 degrees.

11. A blower comprising: a casing having an air inlet, a low voltage direct current electric motor, an impeller driven by the motor, and a diffuser for directing air from the impeller, wherein the casing has an outer diameter of 95 mm±3% and accommodates the impeller and the diffuser;wherein the impeller has a base, a cover and blades supported between the base and the cover, an inlet angle of the impeller blades being between 20˜30 degrees and an outlet angle of the impeller blades being between 26˜38 degrees;wherein the diffuser has a plate like portion with diffuser vanes surrounding the impeller and return guide vanes formed on a surface of the plate like portion remote from the impeller, an inlet angle of the diffuser vanes being between 7˜11.5 degrees and an outlet angle of the diffuser vanes being between 15˜17.5 degrees;wherein the motor comprises: a two pole permanent magnet stator having at least one permanent magnet with a thickness of 4.9 mm±3% and a housing accommodating the at least one permanent magnet and having an outer diameter of 35.7 mm±3%; and a wound rotor disposed within the stator, the rotor having a five slot rotor core with an axial length of 25.1 mm±3% and a five segment commutator, the motor being configured to operate on an electrical power supply having a voltage between 12 and 24 volts and to rotate at a speed between 18,000˜22,000 rpm.