GB2260861A

GB2260861A - Two part casing for a flat small blower

Info

Publication number: GB2260861A
Application number: GB9220431A
Authority: GB
Inventors: Wolfgang Amrhein; Fritz Schmider
Original assignee: Papst Motoren GmbH and Co KG
Current assignee: Ebm Papst St Georgen GmbH and Co KG
Priority date: 1991-09-30
Filing date: 1992-09-28
Publication date: 1993-04-28
Anticipated expiration: 2012-09-28
Also published as: GB9220431D0; HK77797A; DE9112159U1; GB2260861B

Abstract

A small blower comprising a brushless direct current motor having a disk rotor (7) carrying a permanent magnet (10) and flat coil stator windings (5). The rotor (7) rotates an impeller (8). The motor and impeller are housed within a casing (1, 2) having an axial suction opening (9) and radial blow-out openings (15). Electrical power and control is provided by way of an electrical circuit board (4). The casing is formed in two parts, a first substantially tubular part (1) housing the motor and impeller, and a second part (2) which closes one end of the tubular first part (1). The second part is a one-piece, moulded carrier plate (2) which supports the motor and impeller and the circuit board (4) and may be provided with integral resilient suspension means 30 for the motor. <IMAGE>

Description

A FLAT SMALL BLOWER The present invention relates to a flat or shallow small blower with a brushless direct current motor, which has a permanent magnet rotor in the form of a disk rotor, at least one stator winding constructed as a flat coil and a circuit board with connections. The blower may also have motor electronics including at least one position indicator for motor commutation, and has an impeller which, together with the direct current motor and a carrier plate, is housed in a common casing.

Such small blowers are, for example, constructed as so-called sensor blowers, in which ambient air, for example, in a motor vehicle, is sucked in over a temperature sensor located in the suction path in order to precisely measure the temperature of the ambient air and optionally initiate adjustment processes. It is frequently necessary to install such sensor blowers under very constricted space conditions and in particular the overall length must be very short. It is also important for such small blowers to operate in a low-noise manner, and to be inexpensive to manufacture and also inexpensive to fit.

DE-OS 2,934,183 discloses a brushless direct current motor, which has a permanent magnet rotor in the form of a disk rotor and several stator windings constructed as flat coils. The stator windings are positively secured in recesses in a shaped plastic part, which is fixed to a metal plate forming an iron yoke of the motor.

Additionally there is a circuit board which carries the motor electronics. The complete motor and in particular also the casing, together with the motor mounting support consequently have numerous parts having a complex shape, which lead to increased manufacturing and fitting costs.

German Utility Model 8,431,241 discloses a small blower, which also has a brushless direct current motor and a radial blower in a common casing. The casing comprises two plastic parts, which surround a radial impeller, as well as a cup-shaped metal casing part, which carries the motor including the mounting support and to which is also fixed a plastic base plate, which in recesses receives a stator coil and motor electronics. This small blower also has numerous parts and is consequently expensive to manufacture and fit. It also has a relatively large overall length.

The present invention seeks to provide a flat or shallow small blower, which has a short overall length and low manufacturing and fitting costs.

According to the present there is provided a small blower comprising an impeller, a brushless direct current motor having a magnet rotor in the form of a disk rotor, and at least one stator winding constructed as a flat coil, a circuit board with connections, and a common casing, wherein said common casing comprises at least two casing parts, a first casing part surrounding in tubular manner the direct current motor and the impeller, and having air flow openings and wherein a second casing part comprises a one-piece profiled carrier plate which is fitted to the first casing part and carries in a centrally arranged recess a bearing arrangement for the rotor.

Preferably, the carrier plate is injection moulded from plastics material, and preferably has depressions and/or elevations for the positive mounting and fixing of the stator windings.

A small blower according to an embodiment of the invention has the important advantage that the entire brushless direct current motor, including the impeller, can be preassembled on the carrier plate and inserted into the first, tubular casing part, which not only facilitates final assembly, but also leads to high accuracy.

A particularly advantageous embodiment of a small blower of the invention has motor electronics located in the casing, which include at least one position indicator for the motor commutation. In such a case the profiled carrier plate has further depressions and/or elevations for the positive mounting and fixing of the position indicator and optionally further position-sensitive parts. The profiled carrier plate is preferably fitted to the first casing in such a way that it closes the axial front end of said first casing part. In an embodiment, the first casing part is constructed in one piece, and the casing only has two casing parts.

A small blower of the invention may be preferably constructed as a radial blower and the circumference of the first casing part has several blow-out openings.

In a preferred embodiment, the carrier plate is provided with additional elevations for the positive mounting of the circuit board and the latter appropriately has holes in which engage the elevations of the carrier plate and the circuit board is fixed by clamping disks mounted on the elevations. It is also possible in simple manner to carry out a mounting and tension relief of connecting cables, in that for this purpose the carrier plate may be provided with additional depressions/elevations. The depressions and/or elevations of the carrier plate are preferably constructed in such a way that from the injection moulding standpoint roughly identical cross-sectional areas are obtained over the entire carrier plate. This ensures that the carrier plate is not deformed after injection moulding and that no tensile effects occur.

The positive mounting of position-sensitive parts, such as, for example, the position indicator for the motor commutation, on the carrier plate leads to high precision with respect to the relative positioning of the parts. The electrical connections of such parts positively mounted on the carrier plate are appropriately produced on the latter following the mounting of the circuit board. The precise position of such parts is consequently not dependent on the accuracy of the connecting wires.

In order to obtain particularly low running noise levels for the small blower, particularly when the latter is installed, further inventive measures may be provided.

It is already known from DE-OS 3,838,367 to resiliently suspend in a surrounding casing the entire driving motor, including the impeller of a small blower by helical springs positioned in the axial direction, so as to avoid the transmission of solid-borne sound. However, this resilient suspension is relatively complicated and also leads to relatively large overall dimensions.

German Utility Model 9,100,952 also discloses a small blower, in which the entire driving motor, including the impeller, is elastically suspended on a spring plate. The spring plate is constructed with spirally arranged spring webs and in the central region is suspended the complete driving motor. This solution also requires numerous parts, which lead to increased manufacturing costs and to larger overall dimensions.

According to a further aspect of the invention there is provided a small blower in which the resilient motor suspension is brought about in that a carrier plate has a resilient, elastic portion between the central portion and an outer portion for the fixing of the carrier plate to the first casing part.

This has the advantage that the carrier plate not only serves as a resilient suspension, but simultaneously the different components of the motor, namely the bearing means, stator windings, motor electronics, may be carried by the same, such that the entire motor may be preassembled on the carrier plate which simultaneously forms a resilient suspension for noise reduction purposes.

The resilient, elastic portion is preferably constructed in the manner of a diaphragm suspension with a concentric corrugated ring portion, which may either extend in cross-section-identical manner around the full circumference, or may be constructed in the form of several, uniformly distributed, radial webs, whose effective lengths are extended in corrugated or undulatory manner. The latter solution has the advantage that between the radial webs it is possible to use the space for other purposes for example, for receiving electronic components.

The resilient portion may either be made from the same material as the remaining carrier plate portions, or from a different, softer material as compared with the remaining portions, but the entire carrier plate is produced in a single injection moulding process.

To the plastics material carrier plate is fixed the bearing arrangement, preferably in the form of a bearing tube, which is inserted and beaded in the central receptacle of the carrier plate constructed as a recess.

In order to protect the softer material of the carrier plate, prior to beading, a metal disk is preferably underlaid. This metal disk is preferably an iron disk and serves simultaneously to produce a magnetic pretension of a bearing shaft of the rotor with respect of a starting cap.

Embodiments of the present invention will hereinafter be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a longitudinal section through a flat, brushless direct current motor of the invention in conjunction with a blower, Figure 2 shows a plan view of a carrier plate of the blower of Figure 1, Figure 3 shows a section of the carrier plate taken along the line Ill-Ill of Figure 2, Figure 4 shows a detail of the blower of Figure 1, illustrating a mounting support and a tension relief for connecting cables, Figure 5 shows a detail of a further embodiment of a carrier plate having a corrugated ring portion, and Figure 6 shows an alternative form of a corrugated ring portion of a carrier plate.

Figure 1 shows a section of a combination of a direct current motor and a small fan or blower. The blower has a casing formed of first and second casing parts 1 and 2, the first casing part 1 being closed at one end by a cover in the form of a carrier plate 2 which is the second casing part. The casing defines a coaxial suction opening 9 and radial blow-out openings 15 and, as well as the brushless d.c. motor, the casing also houses the parts of the blower, namely radial blades 8 positioned on a rotor 7, which parts are surrounded by the casing part 1. This small blower is constructed as a radial blower and is used for sucking in air and passing it over a thermal sensor, so that the latter can measure the ambient temperature of a room or space.

The rotor 7 of the blower is constructed as permanent magnet rotor and is mounted, by means of a rotor shaft 6, in a bearing arrangement constructed as a bearing tube 3.

The bearing tube 3 is fixed in the carrier plate 2. The carrier plate 2 is injection moulded from plastics material and so to avoid deformation thereof, the bearing tube 3 is fixed thereto by beading an inner portion of the bearing tube 3 over an iron disk 11. The rotor shaft 6 runs with a rounded end dome against a starting cap 16 and there is axial pretensioning of the rotor shaft 6 against the starting cap 16 so that the permanent magnet rotor 7 exerts a starting torque on the iron disk 11.

The permanent magnet rotor 7 carries a rotor magnet 10, which in the present case has eight circumferentially alternating poles. Figure 1 shows stator windings 5 arranged below the rotor magnet 10 and which are axially permeated by the magnetic field of the rotor magnet 10.

The permanent magnet rotor also carries an iron yoke 13.

Figure 1 also shows a circuit board 4, supported by the carrier plate 2. This circuit board 4 carries the electrical circuits of the brushless d.c. motor, of which a Hall sensor 12 is shown.

The casing of the small blower generally comprises only two parts, namely the tubular casing part 1, which is preferably injection moulded in one piece from plastics material and which surrounds the d.c. motor and the impeller 8, and the carrier plate 2 closing one end of the casing part 1. In the present embodiment the carrier plate 2 is fixed in the casing part 1 by means of detents 27.

However, the fixing may be made by any means, and it is also possible to form the casing part 1 from several portions.

The carrier plate 2 is shown in detail in Figures 2 and 3. The carrier plate 2 comprises a one-piece, plastics material, injection moulding, in whose central portion is located a central receptacle 20 in the form of a recess for fixing a bearing arrangement in the form of a bearing tube 3. The bearing tube 3 is inserted in the recess 20 and beaded in the area 31 (Figure 1). To ensure that during beading the relatively soft plastics material of the carrier plate 2 is not damaged, a metal disk 11 is underlaid. This metal disk 11 is preferably made from iron, so as to exert an axial pretensioning force on the starting cap 16, as described above.

The carrier plate 2 has circular elevations 22 and depressions 21, so as to positively and precisely secure the stator coils 5 and the Hall sensors 12. This ensures -that after the fitting of the direct current motor to the carrier plate 2, no subsequent adjustments are required in order to ensure completely satisfactory operation of the motor.

In addition, elevations or projections 23 are provided on the carrier plate 2 on which can be engaged the circuit board 4 (Figures 1 and 4) by way of corresponding holes therein. Subsequently the circuit board 4 is fixed in place by the mounting of clamping disks 24 on the elevations 23. In addition, elevations or projections 25 are provided on the carrier plate 2 between which connecting cables 26 are arranged and secured to prevent pulling thereof. The connecting cables 26 are soldered or otherwise electrically connected to connections 35 on the circuit board 11.

A reinforcing ring 33 is provided around the circumference of the carrier plate 2, and this reinforcing ring 33 simultaneously acts as a support for the circuit board 4. Reinforcing ribs 32 are also arranged to extend along different parts of the carrier plate 2 in order to give to the overall carrier plate 2 a better stability. In addition, the depressions 21 and elevations 22, 23 are so constructed, whilst optionally also providing additional recesses 34, that in all the areas of the carrier plate there is a substantially identical cross-section in order to meet injection moulding requirements.

Although the embodiment shown in Figures 1 to 3 has a carrier plate 2, no special precautions are taken for an elastic motor suspension, except for the use of a plastics material with damping characteristics for the carrier plate. Figures 5 and 6 illustrate measures which may be taken to provide a resilient motor suspension. Figures 5 and 6 show how a resilient portion 30 is provided between an outer portion of the carrier plate 2 used for fixing in the casing part 1 and a central portion 28 carrying all the parts of the motor. This resilient portion 30 is extended compared with the portions 28 and 29 and is crosssectionally weakened, so that solid-borne sound of the motor suspended in the portion 28 arrives at the portion 29 in a highly damped or reduced state. The resilient portion 30 is constructed in a manner of a corrugated ring portion and in Figure 1 is in the form of a single, approximately U-shaped part, whereas in the example shown in Figure 6 the portion 30 is cross-sectionally shaped approximately as a sine curve. These resilient portions 30 can be constructed concentrically around the bearing shaft with the same cross-section, or can be in the form of uniformly distributed, radial webs. The latter configuration has the advantage that the areas between the webs can receive parts of the motor, for example, electronic components.

The resilient portion 30 shown in Figures 5 and 6, can independently of its shape, be injection moulded from the same material as the remaining portions 28, 29.

Alternatively, the resilient portion 30 may be formed from a different, and preferably softer material, but still all of the portions may be produced in a single injection moulding process.

It will be appreciated that modifications and variations may be made to the embodiments of the present invention described and illustrated within the scope of the appended claims.

Claims

1. A small blower comprising an impeller, a brushless direct current motor having a magnet rotor in the form of a disk rotor, and at least one stator winding constructed as a flat coil, a circuit board with connections, and a common casing, wherein said common casing comprises at least two casing parts, a first casing part surrounding in tubular manner the direct current motor and the impeller, and having air flow openings and wherein a second casing part comprises a one-piece profiled carrier plate which is fitted to the first casing part and carries in a centrally arranged recess a bearing arrangement for the rotor.

2. A blower assembly as claimed in claim 1, wherein said first casing part has an axial air flow opening in one end thereof, and wherein said carrier plate is injection moulded from plastics material and is formed to have depression and/or elevations which positively fix and mount the stator windings of said motor.

3. A blower as claimed in claim 1 or 2, wherein electrical circuit means, comprising at least one position indicator for motor commutation, are housed within the casing, and wherein the profiled carrier plate has further depressions and/or elevations for the positive mounting and fixing of the position indicator and optionally further position-sensitive parts.

4. A blower as claimed in any preceding claim, wherein the profiled carrier plate closes an axial end of said first casing part.

5. A blower as claimed in any preceding claim, wherein said first casing part is constructed in one piece, and wherein said common casing is formed only from said first and second casing parts.

6. A blower as claimed in any preceding claim, wherein the blower is a radial blower and the first casing part has a suction air flow opening in one axial end thereof, and radial blow openings in its periphery.

7. A blower as claimed in any preceding claim, wherein the profiled carrier plate is provided with additional elevations for the positive mounting of said circuit board.

8. A blower as claimed in claim 6, wherein the circuit board has holes in which elevations of the carrier plate are engaged, and wherein the circuit board is fixed by clamping disks mounted on the said elevations.

9. A blower as claimed in claim 7 or 8, wherein electrical connections to said circuit board are produced on the carrier plate following the mounting of the circuit board.

10. A blower as claimed in any preceding claim, wherein the carrier plate has additional depressions and/or elevations for the mounting and tensioning relief of connecting cables.

11. A blower as claimed in any preceding claim, wherein depressions and/or elevations are provided in the carrier plate for mounting parts of the assembly, and wherein the depressions and/or elevations are shaped such that from the injection moulding standpoint there are approximately identical cross-sectional areas over the entire carrier plate.

12. A blower as claimed in any preceding claim wherein the carrier plate is fixed to the first casing part by detents.

13. A blower as claimed in any preceding claim wherein the carrier plate has a resilient, elastic portion between a central portion and an outer portion thereof fixing the carrier plate to the first casing part, said resilient portion providing resilient suspension for said motor.

14. A blower as claimed in claim 13, wherein said resilient, elastic portion is constructed in the manner of a diaphragm suspension with a concentric corrugated ring portion.

15. A blower as claimed in claim 13, wherein said resilient, elastic portion is constructed in the form of several, uniformly distributed, radial webs, whose effective lengths are extended in undulatory manner.

16. A blower as claimed in any of claims 13 to 15 wherein the resilient portion is made from the same material as the remaining portions of the carrier plate.

17. A blower as claimed in any of claims 13 to 15, wherein the resilient portion is made from a different, softer material than the remaining portions of the carrier plate, but is produced with the remaining portions in one injection moulding process.

18. A blower as claimed in any preceding claim, wherein said bearing arrangement is a bearing tube which extends into and is beaded in a central receptacle of the carrier plate formed by said centrally arranged recess.

19. A blower as claimed in claim 18, wherein prior to beading, a metal disk is underlaid for protecting the softer material of the carrier plate.

20. A blower as claimed in claim 19, wherein the metal disk is an iron disk and is simultaneously used for producing a magnetic pretensioning force of a bearing shaft of the rotor against a starting cap.

21. A blower assembly comprising a blower having an impeller, an electric motor having a rotor coupled to said impeller and a stator, a circuit board electrically coupled to said electric motor, and a casing for said assembly, wherein said casing comprises at least two casing parts, a first casing part being substantially tubular and generally surrounding the electric motor and the impeller, the first casing part having an axial blower opening at a first end thereof and further blower openings in its periphery, and a second casing part fitted at or near a second end of said first casing part spaced from said first end, said second casing part being constructed in one-piece and supporting the electric motor and the impeller.

22. A blower assembly comprising a blower having an impeller, an electric motor having a rotor coupled to said impeller and a stator, a circuit board electrically coupled to said electric motor, and a casing for said assembly, wherein said casing comprises at least two casing parts, a first casing part being substantially tubular and generally surrounding the electric motor and the impeller, the first casing part having an axial blower opening at a first end thereof and further blower openings in its periphery, and a second casing part fitted to said first casing part, said second casing part being constructed as a carrier plate having a resilient portion therein for resiliently supporting said motor.

23. A small blower substantially as hereinbefore described with reference to the accompanying drawings.