DE29821112U1 - Anchor with protective cage for ventilated electric motors - Google Patents

Description

PATENT ATTORNEYS ** * ··· ^DDEiJBAiJIyER strasse 20

D-33602 BIELEFELD

DIPL.- ING. BODO THIELKING _{TELEPHONE: (0521)60621}

DIPL.- ING. OTTO ELBERTZHAGEN fax: (0520 178725

POSTAL ACCOUNT HANNOVER (bank code 25010030)3091 93-302

ATTORNEY FILE·.

5743

DATE:

16.11.1998/Sg

Applicant: Metabowerke GmbH & Co.

Gerberstr. 33
72622 Nuertingen

Designation: Armature with protective cage for open-circuit ventilated electric motors

The invention relates to an armature for open-circuit ventilated electric motors, in particular for use in power tools. The armature has a shaft on which a laminated core provided with axially parallel longitudinal grooves and, at an axial distance from this, a collector smaller in diameter than the laminated core are fixedly arranged. The armature also has a winding emerging from the longitudinal grooves of the laminated core at the front, the wire turns of which are connected to the lamellae of the collector to form a winding head, the collector having a radial shoulder protruding all the way around the winding head in the connection area of the wire turns, and furthermore a protective cage is placed on the winding head, which is connected to the circumference of the laminated core and tapers in diameter in the axial direction towards the collector and is supported on the shoulder of the collector.

An armature with the features described above is known from the German utility model G 86 25 788. As a rule, such an armature has two winding heads, which are located on

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The two ends of the laminated core each have a protective cage which serves to prevent mechanical damage to the winding heads caused by particles carried along in the cooling air flow. Particularly in the case of power tools which generate dust during operation, such as stone drills, hammers, grinders, saws or similar, considerable quantities of dust and dirt particles are transported through the machine together with the cooling air, and these must be prevented from hitting the winding heads of the armature winding. The protective cages, which are more or less closed with regard to the cooling effect, serve this purpose and, due to the relatively high armature speeds, can also perform their protective function if they are only designed like a grid with relatively large openings between the grid bars.

In the present case, the protective cage used in armatures of the generic type is that which protects the winding head of the armature winding located between the laminated core and the commutator. In practice, the assembly of the protective cage on the commutator side is very difficult because the protective cage on the commutator side must be fitted only after the winding has been fitted into the longitudinal grooves of the laminated core, which is initially pressed onto the armature shaft, before the commutator can be pressed onto the armature shaft.

The invention is therefore based on the object of creating an armature of the type mentioned at the beginning, in which the collector-side protective cage is designed in such a way that it can be subsequently, i.e. after the collector has been pressed on and connected to the armature winding, placed on the metal sheet between the

package and the winding head.

This object is achieved in an anchor of the generic type according to the invention in that the protective cage in the collector-sixth end region has an inner diameter that is larger than the largest outer diameter of the collector, and spring tongues are arranged at the end region of the protective cage protruding towards the collector, which are supported on the shoulder of the collector and which can be expanded from a smaller inner diameter at least to an inner diameter that is equal to the largest outer diameter of the collector.

It is essential for the invention that the spring tongues arranged on the protective cage on the collector side, in the non-expanded position, lie with their support surfaces on the inside on a circle whose diameter is smaller than the diameter of the collector in the area of the shoulder facing the laminated core. This is necessary so that the protective cage can support itself via the lamellae on the shoulder of the collector in the attached end position. When attached in the axial direction towards the laminated core over the collector, however, those areas of the protective cage that have a larger inner diameter than the largest outer diameter of the collector can be easily guided over the collector. The spring tongues on the end side, on the other hand, which must be guided over the rotor last when attached, expand away from the smaller diameter mentioned and give way elastically in the radial direction to such an extent that they can be attached in the axial direction over the collector.

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can be pushed away. In the end position, they snap inwards behind the shoulder of the commutator, which ensures that the necessary support of the protective cage in the axial direction on the commutator is ensured. In practice, this simplifies the workflow in armature production considerably. After the lamination pack has been pressed on and insulated, the commutator can first be pressed onto the armature shaft, after which the lamination pack is wound and the winding is connected to the commutator. Only then, if necessary after slot locking wedges have been inserted, is the protective cage pushed over the commutator in the manner described, which is secured in the axial direction by the spring tongues snapping in behind the commutator shoulder. The protective cage can be additionally fixed using the cast resin impregnation that is usually provided for the armature winding. In addition, a positive connection between the protective cage and the sheet metal package can be provided in the circumferential direction; this and other advantageous design features of the invention emerge from the subclaims.

The invention is explained in more detail below with reference to an embodiment example and the drawing.

Fig. 1 the view of an anchor of a universal ventilation
or DC motor, as used in particular
used for power tools,

Fig. 2 the view of the protective cage of the anchor

according to Fig. 1, which is located between the laminated core and the collector,

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Fig. 3 the detail marked with X in Fig. 2
in enlarged reproduction and

Fig. 4 the front view of the changing basket according to Fig. 2
from the side with the larger diameter
seen.

In detail, Fig. 1 shows an armature shaft 1 intended for an armature of a through-ventilated electric motor, and therefore a fan wheel 2 is arranged on the armature shaft 1. At a distance from the fan wheel 2, a laminated core 3 is firmly mounted on the shaft 1, which has a cylindrical peripheral surface interrupted by longitudinal grooves 4 running along axially parallel surface lines and open to the outside. These longitudinal grooves 4 accommodate an electrical winding (not shown in detail in the drawing) consisting of a large number of wire turns, which forms a first winding head 6 towards the fan wheel 2, which is protected by a basket-like cover 7 when rotating against the impact of particles that are carried along in the cooling air flow of the electric motor. The winding also forms a winding head 8 on the side facing away from the fan wheel 2, and the ends of certain wire windings are led out of this at the front in order to be connected to a collector 9, which has a lamella for each wire connection. The collector 9 also has a radially protruding welding collar 10 on the front end facing the laminated core 3, which is penetrated by axially continuous, radially open grooves into which the wire ends are inserted radially from the outside to the inside and then welded. The wire ends of the winding head 8 thus form a welding collar 10 in the circumferential direction of the welding

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collar 10 a ring which has a diameter which is slightly smaller than the outer diameter of the welding collar 10, which represents the largest outer diameter of the collector 9. There is therefore a radial shoulder 11 in the connection area of the collector 9 between the winding head 8 and the welding collar 10, on which a protective cage 12 is supported with one end, which is connected with the laminated core 3 with its ^other end and is thus secured in the axial direction.

In addition to Fig. 1, Figs. 2-4 illustrate the individual features of the protective cage 12. On the side facing the collector 9, the protective cage 12 has an end region formed by a ring 13, which has an inner diameter that is larger than the largest diameter of the collector 9 in the area of its weld collar 10. On the opposite side, facing the laminated core 3, the protective cage 12 has an end ring 14, the diameter of which is larger than that of the opposite ring 13 and approximately the same size as the outer diameter of the laminated core 3. The end ring 14 and the opposite ring 13 of the protective cage 12 are connected by means of webs 15, and overall the protective cage 12 represents a one-piece plastic injection-molded part.

Of particular importance on the collector side of the ring 13 of the protective cage 12 are the spring tongues 16 that protrude parallel to the axis, the configuration of which can be seen in detail in Fig. 3. Each tongue 16 has a locking projection 22 on its inside that protrudes inwards. The locking projections 22 of all spring tongues 16, of which there are four in the embodiment, are in the non-elastically deformed position

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of the spring tongues 16 on a circle that has a diameter that is smaller than the outside diameter of the welding collar 10 of the collector 9. Consequently, for the purpose of assembly, the protective cage 12 with its further end ring 14 can be pushed over the collector 9 onto the winding head 8 until it is supported on the sheet metal package 3, whereby the spring tongues 16 initially expand outwards when driving over the collector 9 and in particular the welding collar 10 on the collector 9, until they snap into place radially inwards in the pushed-on end position of the protective cage 12 when they reach the shoulder 11 on the welding collar 10 of the collector 9. To ensure that this takes place without jamming, the spring tongues 16 have a run-on slope 20 adjacent to the locking projection 22 towards the ring 13, which facilitates the elastic deflection of the spring tongues 16 radially outwards. Towards the free end of the spring tongues 16, a locking recess 18 adjoins the locking projection 22, through which a radial flank 19 is formed towards the locking projection 22, which is intended to rest on the shoulder 11 of the welding collar 10 of the collector 9 in the end position of the protective cage 12.

The end ring 13 of the protective cage 12 also has projections 17 that protrude radially towards the laminated core 3 and have pockets 21 that are open radially on their inward sides and axially on the outside. In the installed position of the protective cage 12, the projections 17 with their pockets 21 are each placed on a protruding end of a slot closure wedge 5, whereby the protective cage 12 is secured both in the circumferential direction and in the axial direction at the end towards the laminated core 3. The protective cage 12 can be additionally or permanently fixed by impregnating the winding of the armature with cast resin in the usual way, which allows the protective cage 12 to be glued at the same time.

Claims (9)

1. Armature for open-circuit ventilated electric motors, in particular for use in power tools, with a shaft, on which a laminated core provided with longitudinal grooves parallel to the axis and, at an axial distance from this, a collector with an external diameter smaller than the laminated core are fixedly arranged, and with a winding emerging from the longitudinal grooves of the laminated core at the front, the wire turns of which are connected to the laminations of the collector to form a winding head, the collector having a radial shoulder protruding all the way around the winding head in the connection area of the wire turns, and a protective cage adjoining the circumference of the laminated core is placed on the winding head, which protective cage tapers in diameter in the axial direction towards the collector and is supported on the shoulder of the collector, characterized, that the protective cage (12) has an inner diameter at the collector-side end region (13) which is larger than the largest outer diameter of the collector (9), and at the end region (13) of the protective cage (12) spring tongues (16) are arranged protruding towards the collector (9), which are supported on the shoulder (11) of the collector (9) and which extend at least from a smaller inner diameter to can be expanded to an inner diameter equal to the largest outer diameter of the collector (9). 2. Anchor according to claim 1,
characterized, that the collector-side end region (13) of the protective cage (12) is formed by a closed ring running in the circumferential direction, on which the spring tongues (16) are arranged in an axially protruding manner. 3. Anchor according to claim 1 or 2,
characterized, that the spring tongues (16) of the protective cage (12) have on their inner side a locking recess (18) with a radial flank (19) supported on the shoulder (11) of the collector (9). 4. Anchor according to one of claims 1-3, characterized in that the spring tongues (16) have run-up slopes (20) on their inner sides that rise inwards away from the end region (13) of the protective cage (12). 5. Anchor according to one of claims 1-4, characterized in that the protective cage (12) has axial projections (17) at its end remote from the collector (9) which have a positive connection to the laminated core (3) in the circumferential direction. 6. Anchor according to claim 5,
characterized, - 3 - 5743 that the projections (17) of the protective cage (12) have open grooves or pockets (21) on their inner sides towards their free ends, into which groove closure wedges (5) protruding from the front side of the laminated core (3) engage. 7. Anchor according to claim 5 or 6,
characterized, that the projections (17) are arranged on an end ring (14) of the protective cage (12) which runs in the circumferential direction and is connected to the collector-side ring (13) by means of webs (15). 8. Anchor according to one of claims 1-7,
characterized, that the protective cage (12) is a one-piece plastic injection-molded part. 9. Anchor according to one of claims 1-8,
characterized, that the collector (9) has a circumferential, radially projecting weld collar (10) in the connection area for connecting the wire turns of the winding, on which the shoulder (11) for supporting the spring tongues (16) of the protective cage (12) is formed.