SI9600209A - Electronically commutated direct drive of a washing machine drum - Google Patents

Abstract

Subject of the invention is an electronically commutated direct drive of a washing machine drum where the rotor (2) is implemented directly on the drum driving shaft, while the stator (1) is located on the drum supporting frame. The construction of the electronically commutated direct drive of a washing machine drum according to the invention provides by an optimum ratio between the width of the stator pole (10) featuring an uneven air gap (8) between the stator (1) and the rotor (2), a low noise level and a relatively large moment on the drive shaft. The number of the rotor terminals which are represented by magnet segments (3) is larger than the number of the stator terminals (6) featuring coils (4) so that the ratio between the rotor and stator terminals is 1,3333, while the ratio between the width of the stator terminal (6) and the gap width (10) between the stator terminals (6) equals 1,868.

Description

The subject of the invention is an electronically switched motor for direct drive of the washing machine drum in which the rotor is made directly on the driving axis of the drum and the stator on the supporting cross of the drum. The subject matter of the invention belongs to class H02K 7/00 of the international patent classification.

A technical problem successfully solved by the proposed engine design is the design of the washing machine drum drive motor, which will allow the washing machine drum to be driven directly at low noise and relatively high torque on the motor shaft.

Existing washing machines use an asynchronous or universal collector motor mounted under the washing machine drum to drive the drum. Power is transferred from the motor to the drum by two pulleys and a belt with a standard gear ratio of 1:12. The described design has some disadvantages such as: high weight counterweight due to the position of the motor outside the center of the drum, high noise especially during the spin phase, relatively short belt and motor life, unadapted engine characteristics load characteristics and poor drive efficiency.

The above disadvantages are eliminated by the implementation of the washing machine with direct drum drive. The stator of such an engine is attached to the drum support cross, and the rotor is mounted directly on the drive axle of the washing machine drum. The motor itself therefore does not have its own bearing, since the existing drum bearings are used. In such a construction of the drive, the drive pulleys and the belt and a considerable part of the counterweight are lost. In addition to the advantages already mentioned, direct drive eliminates the previously mentioned disadvantages of the classic washing machine drum drive.

The well-known direct-drive engines of a machine are generally larger in number of stator poles than the rotor ones, causing large momentum puzzles on the shaft and thus a relatively high noise level. The air gap between the rotor and the stator is usually uniform, giving a trapezoidal form of interfacial induced voltage, which, in the normal form of the current, leads again to a relatively high noise level. The ratio between the stator pole width and the width of the intermediate space must be optimally selected in order to obtain low noise and relatively high torque on the machine shaft. This ratio is not optimal for the direct drives known so far. Since the outer and inner diameters of the motor are relatively large, the conventional method of manufacturing lamellae is very high, which greatly increases the cost of the engine. Up-to-date direct drive designs use the conventional front and groove insulation method, which is an expensive and time-consuming process. The design of the electronically switched motor for direct drive of the washing machine drum according to the invention enables an optimal ratio of the stator pole width to the intermediate space at the uneven air gap between the stator and the rotor to achieve a low noise level and a relatively high torque on the motor shaft.

The electronically commutated motor for direct drive of the washing machine drum according to the invention will be explained in more detail on the basis of an embodiment and the accompanying figures, of which:

Fig. 1 is a cross-sectional view of an engine according to the invention showing a rotor and stator part;

Figure 2 is a segment of the stator motor package of the invention;

Figure 3 shows a portion of the stator and motor rotor according to the invention showing a non-uniform air gap;

Figure 4 shows a stator blade construction;

Fig. 5 is a schematic representation of the electrical circuit of the engine for various washing machine operating operations;

6 is a longitudinal sectional view of the engine according to the invention.

The electronically switched engine for direct drive of the washing machine drum according to the invention has a stator 1, which consists of a stator package made of dynamo plate with a stator yoke 5 with pronounced stator poles 6 along the outer circumference. Coil poles 6 are provided with coils 4, which represent a concentrically wound three-phase stator winding. The rotor 2 of the motor is designed as a soft magnetic core 7 with magnetic segments 3 attached to it.

io The electronically commutated motor of the invention has a stator 1 attached to the washer cross carrier, while the rotor 2 is attached directly to the washer drum axis. The number of rotor poles represented by magnetic segments 3 is greater than the number of expressed stator poles 6. The ratio factor of the rotor pole - stator poles is 1.3333.

The uneven air gap between the rotor and stator poles can be achieved in two ways. In the first case, the magnetic segments 3 attached to the rotor core 7 have a rectangular shape, while the upper surface of the stator poles 9 in the stator package 12 is formed slightly convex so that the air gap 8 is uneven. In the second case, however, the magnetic segments 3 may be radio-shaped stator 9s as flat. With such a non-uniform air gap between the stator and the rotor, a sinusoidal phase-induced induced voltage is achieved, which greatly reduces the noise level during engine operation. The ratio of the width of the stator pole 9 to the width of the intermediate space 10 between the stator poles 9 is 1.868. The ratio chosen in this way represents the optimum choice, as it achieves minimal torque fluctuation and thus a minimum noise level.

A schematic representation of the electrical connection of the motor for the different operating operations of the washing machine is shown in FIG. 4. The three-phase motor winding 19 is star-bound so that each phase has two branches - one for washing and one for centrifuge. For low-speed washes, the motor is connected between terminals U1, V1 and W1. In this case, the entire winding is active. For centrifugation, where high rotational speed is required, the motor is connected between terminals U2, V2 and W2. Only a part of the winding is active in this position. The ratio of active coil to spin and wash is 1: 3, 1: 4 or 1: 5. The coil winding 19 enables us to operate the engine under optimum conditions for all wash cycles, is Figure 4 shows the part of the stator package. The individual stator blades are cut from the strip 11 and then formed by bending the strip to the prescribed diameter. Two stator blades can be cut simultaneously from the strip 11. When bending to the prescribed diameter, bending of the cut strips for the first packet into one and for the second packet into the other side is performed. When cutting the stator blades from the strip, the auxiliary grooves 13 are also cut, which facilitates the subsequent bending of the strip cut to the prescribed diameter.

The stator package itself is embedded in plastic so that it forms the front insulation 14, the groove insulation 15 and the hub 16 for attaching the stator to the drum support cross. The plastic in which the stator pack is embedded has mounting points for the 17 Hall generators, which are three and lie in the middle of adjacent grooves, at an angular distance of 15 °. The position of the circuits 17 is shown in Figure 1.

The magnetic segments 3 together with the iron core 7 are also embedded in the plastic part 18, which, in addition to fixing the magnetic segments 3 on the iron core 7, forms at the same time a hub for attaching the rotor 2 to the drum shaft of the washing machine.

io The electronically switched machine for direct drive of the washing machine drum according to the invention successfully solves the technical problem of the direct drive of the washing machine drum with minimal torque fluctuation and therefore low noise level and relatively high torque on the motor shaft. In addition, the engine design described above also offers the possibility of a simple large-scale production.

Claims (10)

PATENT APPLICATIONS An electronically switched engine for direct drive of a washing machine drum, in which the stator 1 is attached to the carrier cross of the washing machine and the rotor 2 directly to the axis of the washing machine drum, characterized in that the number of rotor poles represented by the magnetic segments ( 3) greater than the number of stator poles (6) with coils (4) such that the ratio factor of the rotor pole - stator pole is 1.3333, while io is the ratio of the width of the stator pole (6) to the width of the intermediate space (10) between the stator poles (6) 1.868. 2. An electronically switched engine for direct drive of the washing machine drum according to claim 1, 15 indicates that the magnetic segments (3) adhered to the rotor core (7) have a rectangular shape, while the upper surface of the stator poles (9) in the stator package (12) is slightly convex so that the air gap (8) is uneven . Electronically switched motor for direct drive of the washing machine drum according to claim 1, characterized in that the magnetic segments (3) radiator-shaped (9) are straight. Electronically commutated drum direct-drive drum washer motor, 5 according to claims 1 to 3, characterized in that the three-phase winding (19) is connected to a star such that each phase has two branches, in which the motor is connected in the first mode. between terminals U1, V1 and W1, with active full winding, and in the second mode, between io terminals U2, V2 and W2, with active winding, with the ratio of active windings in first and second mode 1: 3, 1: 4 or 1: 5. 5. An electronically switched engine for direct drive of the washing machine drum according to claims 1 to 4, 15 indicates that the stator package (12) is made in such a way that the stator blades cut from the strip (11), and then the stator package (12) is formed by bending the cut strip (11) to the prescribed diameter. 20 Electronically switched machine for direct drive of the washing machine drum according to claim 5, characterized in that two stator packages (12) are simultaneously cut from the strip (11) by bending the cut tape (11) for the first package into one and after the other packet to the other side. s Electronically switched motor for direct drive of the washing machine drum according to claims 5 and 6, characterized in that the auxiliary grooves (13) are also cut when cutting the stator blades from the strip (11). The electronically commutated machine for direct drive of the washing machine drum according to claims 1 to 7, characterized in that the stator package (12) is embedded in plastic so that it forms the front 15 insulation (14), the slot insulation (15) and a hub (16) for attaching the stator (1) to the drum support cross. An electrically switched motor for direct drive of a washing machine drum according to claims 1 to 8, 20 indicates that, in the part in which the stator pack is embedded, the mounting points for the three circuits (17) of the Hall generators lying midway between adjacent grooves (10) are at an angular distance of 15 °. 10. An electronically switched machine for direct drive of a washing machine drum according to claims 1 to 9, marked stem, 5 that the magnetic segments (3) together with the iron core (7) are embedded in the plastic part (18), which at the same time forms a hub for attaching the rotor (2) to the drum shaft of the washing machine.