JP2005160275A - Motor and washing machine using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor excellent in efficiency and output characteristics in working rotational speeds of a washing machine, and to realize size and weight reductions for a direct drive motor for the washing machine. <P>SOLUTION: Each of cylindrical permanent magnets 1 is provided with 40 N poles and 40 S poles alternately magnetized on its inner periphery , and a back yoke 2 fixed on its outer periphery. A core 3 is formed by punching silicon steel plate for its shape by pressing and layering the plurality of punched plates. The core 3 is provided with 12 poles 5 wound with a coil 4 provided at uniform intervals, and a portion facing the permanent magnet of a salient pole 5 is provided with two small teeth 6 per one salient pole, namely 24 small teeth 6 in total. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a motor used in a pulsator-type washing machine or a drum-type washing machine. More specifically, these washing machines have a configuration of a motor that is directly driven without using a speed reducer such as a pulsator or a drum, and relates to a motor called a direct drive type.

  Conventionally, washing machines have been required to have higher output motors due to demands such as removal of dirt during washing and shortening of washing / dehydrating time.

  In recent years, not only higher performance of the basic functions but also addition of additional functions such as addition of a drying function has led to a reduction in the space in the housing and a reduction in size and weight of the motor.

  At the same time, due to lifestyle changes, it has become common to use washing machines indoors, and quietness has been demanded. More compact, lighter, higher output, higher efficiency, and lower vibration. It is required to simultaneously achieve characteristics that are usually difficult to achieve.

Conventionally, a driving device for a washing machine generally uses a reduction gear that uses a pulley, a gear, or the like for the output of a motor, and transmits power to a drum or pulsator after the motor output is decelerated. However, the method using a speed reducer requires a space for mounting the speed reducer, so that the space for mounting the motor is reduced. Alternatively, there is a problem that noise is generated by a reduction gear and noise is increased. In recent years, a direct drive motor that directly drives a pulsator or a drum without using a reduction gear has attracted attention. (For example, see Patent Document 1)
However, the direct drive type motor needs to use the motor at a low speed and a large torque. When a motor with a conventional structure is used, the copper loss generated in the motor coil part inevitably increases, and the increase in copper loss can be reduced. In order to compensate, it is necessary to increase the outer diameter and axial thickness of the motor. Therefore, when constructing a drive device with the same output, the amount of material typified by permanent magnets increases, resulting in a large and heavy cost. Tend to be expensive.
JP-A-9-215893

  The present invention applies the motor structure described in the earlier patent application (Japanese Patent Laid-Open No. 2003-61326) filed by the same applicant as the present invention, realizes the improvement of the motor output torque with the same physique, and is used for direct drive. The object is to provide a suitable small, lightweight, high output, high efficiency motor.

A first invention for solving the above-described problems is a direct drive type motor for directly rotating and driving a pulsator of a washing machine and a drum of the washing machine, or a pulsator of the washing machine or a drum of the washing machine.
The motor includes a rotor having a magnet body in which N poles and S poles are alternately magnetized in the rotation direction, and a plurality of protrusions each having a coil that is wound around the magnet body in a radial direction to form a magnetic circuit. And a portion of the salient pole facing the magnet body, a plurality of small teeth having substantially the same pitch as that of two magnet poles are provided, and depending on the position of the rotor The rotor is rotationally driven by energizing a coil, and the magnetic pole of the magnet body is a motor having a multipolar structure of 30 to 60 poles. According to the present invention, the efficiency of the motor can be increased.

In addition, the second invention,
In a direct drive motor that directly rotates and drives a pulsator of a washing machine and a drum of the washing machine, or a pulsator of the washing machine or a drum of the washing machine,
The motor includes a rotor having a magnet body in which N poles and S poles are alternately magnetized in the rotation direction, and a plurality of protrusions each having a coil that is wound around the magnet body in a radial direction to form a magnetic circuit. And a portion of the salient pole facing the magnet body, a plurality of small teeth having substantially the same pitch as that of two magnet poles are provided, and depending on the position of the rotor The rotor is rotationally driven by energizing the coil, and the core has a configuration in which the ratio of the outer diameter to the axial height (outer diameter / axial height) is 6 or more and 10 or less. It is a motor provided. According to the present invention, the efficiency of the motor can be increased.

In addition, the third invention,
In a direct drive motor that directly rotates and drives a pulsator of a washing machine and a drum of the washing machine, or a pulsator of the washing machine or a drum of the washing machine,
The motor includes a rotor having a magnet body in which N poles and S poles are alternately magnetized in the rotation direction, and a plurality of protrusions each having a coil that is wound around the magnet body in a radial direction to form a magnetic circuit. And a portion of the salient pole facing the magnet body, a plurality of small teeth having substantially the same pitch as that of two magnet poles are provided, and depending on the position of the rotor The motor is configured to rotate the rotor by energizing a coil. The rotor further includes a rotor yoke made of a high magnetic permeability material and a rotor frame made of a non-magnetic material, and the rotor yoke is the rotor A motor having a configuration fixed to a frame. According to the present invention, the iron loss of the motor can be reduced and the efficiency of the motor can be increased.

  Moreover, 4th invention is a washing machine provided with the motor of the said 1st invention, 2nd invention, or 3rd invention. According to the present invention, the drive unit can be reduced in size and weight.

  As described above, according to the present invention, it is possible to provide a motor having characteristics excellent in efficiency and output characteristics at the number of revolutions commonly used in a washing machine, and to provide a direct drive motor for a washing machine that has the same output and efficiency but is small and light. .

  In addition, by mounting the motor on the washing machine, the drive portion can be reduced in size and weight, and a high-capacity and lightweight washing machine can be provided even with the same size.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is an explanatory diagram for explaining a magnetic circuit configuration of a direct drive motor for a washing machine according to the present invention.

  In FIG. 1, a cylindrical permanent magnet 1 is evenly magnetized with 40 N poles alternately on the inner peripheral surface, and the back yoke 2 is fixed to the outer periphery. The core 3 is formed by punching a shape of a silicon steel plate by pressing and laminating a plurality of sheets in the axial direction. The core 3 is provided with 12 salient poles 5 around which the coil 4 is wound. The salient poles 5 have a total of 24 small teeth 6 for each salient pole facing the permanent magnet. Is provided.

  Here, the pitch of the small teeth 6 provided at the tip of the salient pole is substantially the same as that of two permanent magnets (electrical angle 345 °), and the opening angle of the small teeth is 150 ° in electrical angle.

  Thus, by setting the pitch and the opening angle of the small teeth, the cogging torque is reduced, and the torque fluctuation when the motor is rotated is reduced, thereby suppressing the vibration.

  In addition, the gap between adjacent salient poles is chamfered so that the gap on the inner peripheral side is increased to suppress magnetic interference between adjacent salient poles.

  As described above, the greatest feature of the direct drive motor for a washing machine according to the first embodiment is that the small teeth 6 are provided at the tip of the salient pole 5 of the core 3 at a pitch of almost two permanent magnets. By pseudo-multipolarization, only the magnetic poles are multipolarized without increasing the number of salient poles. Thus, by providing the small teeth 6 at the tip of the salient pole 5, the salient pole 5 is in a state where the magnetic flux of only the portion of the magnetic pole facing the small teeth 6 can be selectively introduced.

  The characteristics of the motor of the present invention are as shown in the patent application (Japanese Patent Laid-Open No. 2003-61326) filed by the same applicant as the present invention. However, since the torque characteristics of the motor are further improved, A sufficient output can be obtained even with a configuration that is miniaturized like the motor of the invention.

  FIG. 2 is an explanatory diagram showing a magnetic circuit configuration of a motor unit having a conventional structure for comparison.

  In FIG. 2, a cylindrical permanent magnet 1 has N and S poles alternately magnetized on the inner peripheral surface of 16 poles evenly, and a core 3 has 12 salient poles 5 around which a coil 4 is wound. Evenly provided.

  As shown in FIG. 2, when a motor having the same outer diameter is produced with a motor having a conventional structure, it is necessary to increase the number of salient poles of the core 3 in order to increase the number of magnetic poles. Since the coils interfere with each other, the winding space is reduced, and it is difficult to wind the coil 4 to the inner peripheral side of the core 3, and a dead space is generated on the inner peripheral side of the core. It has a donut shape with a large hole in it. Furthermore, it is difficult to increase the number of salient poles to some extent due to the limitation of the winding, and there is a limit to the number of poles.

  On the other hand, in the motor of the present invention, even when the number of magnetic poles is increased, it is not necessary to increase the number of salient poles, and the motor can be designed according to the number of rotations to be used by selecting the number of magnetic poles suitable for the number of rotations. Further, by selecting an appropriate number of slots, the dead space in the inner peripheral portion of the core can be reduced and more coils can be wound, so that the coil resistance is reduced and the motor efficiency is improved.

  Table 1 shows the comparison results when the characteristics of a conventional motor having the same size as the motor of the present invention are calculated by computer simulation.

  For example, the motor size is calculated when the rotor outer diameter is 178 mm and the thickness of the magnetic circuit portion including the coil is 35 mm (core thickness 21 mm).

  The motor operation points are calculated using typical washing operation points and dehydration operation points.

When viewed from the drive side, the washing machine is generally operated in two operating states.

  The first operation state is the operation at the time of washing and rinsing in which the pulsator is inverted and the water in the washing tub is stirred (in the case of the drum system, the water and the laundry are lifted and dropped from about 180 degrees above). There is an operating state in which a large torque of about 10 to 30 Nm is output at a low speed of about 50 to 100 r / min or less.

  Another operation state is an operation at the time of dehydration in which the entire drum is continuously rotated at a high speed, and moisture in the laundry is blown off by centrifugal force. At this time, the motor rotates at about 1000 r / min, but the required torque remains at about 1 to 3 Nm.

  In recent years, a washing machine to which a drying function has been added has an operation of drying laundry, but the operation state during drying is an intermediate operation state between washing and dehydration.

  As described above, the washing machine motor needs to satisfy simultaneously different characteristics of a large torque at a low speed and a high-speed rotation of about 1000 r / min.

  In particular, when a motor is driven at a low speed and a large torque in principle, it is necessary to pass a large current through the coil. Therefore, an energy loss (hereinafter referred to as a copper loss) that is consumed by heat generated by the coil due to the coil's electrical resistance. ) Increases, and the motor efficiency during washing decreases.

  On the other hand, at the time of dehydration, the induced voltage of the motor increases because the motor rotates at high speed, but the voltage of the drive circuit is increased by the booster circuit, and a terminal voltage higher than the power supply voltage is supplied to the motor. Alternatively, there is a method of rotating at a high speed by a method of lowering the motor terminal voltage and using it by advancing the phase of the current flowing through the coil from the phase of the induced voltage.

  The former method has a loss due to a booster circuit, and in the latter case, there is a decrease in efficiency due to an increase in copper loss due to an increase in coil current, etc., but during dehydration, the load torque itself is small and the current flowing through the coil is small. Loss is reduced. In general, the total loss is lower than the loss at the time of washing, and the motor efficiency is high, so there is often no problem.

  Here, as an evaluation of the efficiency of the motor, when comparing the load during the washing operation corresponding to the bad condition, as shown in Table 1, the efficiency is compared when compared under the same load condition (11 Nm, 50 r / min). From 44.1% in the example (conventional type) to 70.2% in the present invention, the efficiency is improved by 26.1%.

  Further, when compared under the same rotational speed of 50 r / min, the motor of the comparative example (conventional type) cannot output a torque of about 15 Nm or more due to the magnetic saturation of the core, but the motor of the present invention has about 18 Nm. Output is possible.

  The loss of the motor generates heat and becomes a factor that restricts the output of the motor. However, the loss of the motor of the present invention is only about 53% of the conventional motor, and a large amount of electric power is supplied as the heat generation amount has a margin. Thus, continuous use with higher torque becomes possible.

  In the case of this calculation example, when the loss was made equal to that of the motor of the comparative example (conventional type), about 1.6 times the torque could be output.

  On the contrary, when the motor of the comparative example (conventional type) is designed to design a motor having the same efficiency as the motor of the present invention, when the outer diameter of the core 3 is made equal, the stack thickness of the core 3 is about 1.5. The motor needs to be doubled, and the motor becomes heavier and larger, and the cost of the motor increases because the material cost increases.

  In this way, by applying this motor structure to a direct drive motor for a washing machine, it is possible to ensure sufficient output and efficiency even with a small motor, and the drive unit can be miniaturized, and the same size laundry The machine can be equipped with a drum with a larger volume, and the washing capacity can be increased. Further, since the material cost and mass of the motor are reduced due to the miniaturization of the motor, a low-cost and lightweight washing machine can be provided.

  In the first embodiment, the case of a cylindrical permanent magnet is shown. However, as shown in FIG. 3A, there is also a method of dividing the permanent magnet for each magnetic pole into a flat magnet for each magnetic pole. Is possible.

  As shown in FIG. 3, when the magnetic poles are divided for each magnetic pole, the labor for assembling increases. However, since one magnet can be made small, it can be mass-produced with a small mold, and the magnet cost can be reduced. At the same time, by combining the magnets after magnetization, full magnetization is facilitated and the performance of the magnets is easily extracted.

  In the first embodiment, the outer rotor type configuration in which the core is on the inner peripheral side and the rotor is on the outer peripheral side is shown. However, an inner rotor type configuration in which the rotor is on the inner peripheral side and the core is on the outer peripheral side is also possible. It is.

  The configuration of the inner rotor type is disadvantageous in terms of torque characteristics because the surface area of the magnet is smaller than that of the outer rotor type and the magnetic flux that can be extracted from the magnet is reduced, but the outer rotor type in which the rotor is exposed to the outside is disadvantageous. In comparison, the inner rotor type has a configuration in which the rotor is housed on the inner circumference side of the core, so it is easy to take a configuration in which dust and water do not easily enter the motor, and the inner rotor type may be more suitable depending on the usage environment. is there.

(Embodiment 2)
Although the first embodiment has described the superiority of the motor structure, the following embodiment will describe several points when the present motor structure is applied to a direct drive motor for a washing machine.

  FIG. 4 is a diagram in which the relationship between the number of magnetic poles of the motor structure and the motor efficiency is obtained by computer simulation.

  For comparison, FIG. 4 uses the same number of salient poles, outer diameter, and thickness as the motor and core shown in the first embodiment, increases the number of small teeth at the salient pole tip, and adjusts the number of magnetic poles accordingly. The motor efficiency (%) at 11 Nm and 50 r / min was calculated.

  Simulation values represented by points on the graph of FIG. 4 are shown below. With 16 magnetic poles, the efficiency is 44.1 (%). With 40 magnetic poles, the efficiency is 70.2 (%). With 64 magnetic poles, the efficiency is 81.6 (%). With 88 magnetic poles, the efficiency is 86.5 (%). The efficiency is 88.8 (%) at 112 magnetic poles. With 136 magnetic poles, the efficiency is 89.9 (%). From the range of these conditions, it selects suitably according to the specification of a motor.

  As shown in FIG. 4, the number of magnetic poles tends to become more efficient as the number of magnetic poles is increased, except when the number of magnetic poles is extremely large. This is because the copper loss of the coil is reduced by increasing the number of poles.

  Therefore, when this motor is applied to a direct drive motor for a washing machine, in the region of about 50 to 100 r / min used at the time of washing, the efficiency increases as the number of magnetic poles increases when considered as a motor-only component.

  However, the situation changes a little when considering the operation during dehydration and the drive circuit.

  A motor driving circuit that is generally used at present is an inverter circuit using a PWM (Pulse width modulation) system. The PWM system is a system that outputs a voltage pulse with a constant frequency called the carrier frequency and controls the load current by changing the width of this pulse. I can't do it. In practice, in order to output current while controlling the current waveform, a carrier frequency of about 20 times the minimum current waveform is required.

  Considering that the carrier frequency of an inverter circuit generally used as a motor driving circuit for a washing machine is about 5 kHz to 10 kHz and the rotation speed is about 1000 r / min at the maximum, the inverter is used when the motor is at the maximum rotation speed. A direct drive motor for a washing machine with high efficiency can be provided by controlling the circuit current waveform and having a multi-pole structure with 30 to 60 poles with high motor efficiency.

  Although the efficiency of the motor drive circuit decreases, a method of further increasing the number of magnetic poles of the motor by increasing the carrier frequency of the circuit is conceivable. However, if the number of magnetic poles of the motor is excessively increased, the position detection accuracy of the rotor deteriorates. Alternatively, there is an adverse effect such as an increase in iron loss of the motor and a reduction in motor efficiency during dehydration. In practice, a multipolar structure of about 40 poles as shown in FIG. 1 is desirable.

(Embodiment 3)
FIG. 5 shows the motor efficiency when the ratio of the outer diameter of the core to the axial height (outer diameter / axial height) is changed while the volume, the number of magnetic poles and the number of salient poles of the magnetic circuit portion of this motor structure are constant. FIG.

  Simulation values represented by points in the graph of FIG. 5 are shown below. When the ratio of the outer diameter of the core to the axial height (outer diameter / axial height) is 2, the motor efficiency (%) is 66.1%. When the ratio of the outer diameter of the core to the axial height (outer diameter / axial height) is 3, the motor efficiency (%) is 68.1%. When the ratio of the core outer diameter to the axial height (outer diameter / axial height) is 4, the motor efficiency (%) is 69.2%. When the ratio of the core outer diameter to the axial height (outer diameter / axial height) is 5, the motor efficiency (%) is 69.7%. When the ratio of the core outer diameter to the axial height (outer diameter / axial height) is 6, the motor efficiency (%) is 70.0%. When the ratio of the core outer diameter to the axial height (outer diameter / axial height) is 7, the motor efficiency (%) is 70.1%. When the ratio of the core outer diameter to the axial height (outer diameter / axial height) is 8, the motor efficiency (%) is 70.2%. When the ratio of the core outer diameter to the axial height (outer diameter / axial height) is 9, the motor efficiency (%) is 70.1%. When the ratio of the outer diameter of the core to the axial height (outer diameter / axial height) is 10, the motor efficiency (%) is 70.0%. When the ratio of the core outer diameter to the axial height (outer diameter / axial height) is 11, the motor efficiency (%) is 69.8%. When the ratio of the core outer diameter to the axial height (outer diameter / axial height) is 12, the motor efficiency (%) is 69.6%. These are appropriately selected from the range of conditions.

  When the ratio of the outer diameter of the core to the axial height (outer diameter / axial height) is in the range of about 4 or more, the efficiency is good at 69 (%) or more. When the ratio of the outer diameter of the core to the axial height (outer diameter / axial height) is in the range of about 6 to 10, the efficiency is particularly good at 70% or more.

  By appropriately selecting from these conditions according to the motor specifications. Even with a small motor, it is possible to ensure sufficient efficiency, the drive unit can be downsized, and a washing machine of the same size can be equipped with a larger volume drum, which can increase the washing capacity. . Further, since the material cost and mass of the motor are reduced due to the miniaturization of the motor, a low-cost and lightweight washing machine can be provided.

(Embodiment 4)
In the first and second embodiments, the magnetic circuit configuration of the motor has been described. In the third embodiment, the structure of the motor will be described.

  FIG. 6 is a view showing the structure of a direct drive motor for a washing machine according to the present invention.

  In FIG. 6, the core 3 and the rotor yoke 2 forming a magnetic circuit are configured by laminating silicon steel plates in the axial direction. The core 3 is insulated and then the coil 4 is wound thereon. A multi-pole magnetized permanent magnet 1 is bonded and fixed to the inner periphery of the rotor yoke 2.

  The core 3 is fixed to the hub 9 with screws 13, and is fixed to the outer tub 11 side via the hub 9.

  The rotor yoke 2 is fixed to the drum 12 side via the rotor frame 7, the rotor boss 14, and the shaft 10.

  The hub 9 and the shaft 11 are rotatably supported by a bearing 8, and the drum 12 is rotated by supplying a current to the coil 4.

  Here, in the case of a general outer rotor type motor, the rotor frame 3 part is generally made of an iron-based material having a high magnetic permeability so as to form a magnetic circuit on the rotor side. Then, the rotor frame is made by pressing aluminum alloy with low magnetic permeability. Since the motor of the present invention has a multi-pole configuration, the iron loss tends to increase as the magnetic flux frequency increases. However, for the core 3 and the rotor yoke 2, thin silicon steel plates are laminated to form the core 3. Although it is possible to reduce the eddy current generated in the rotor yoke 2 and suppress the increase in iron loss, such a countermeasure is difficult for the rotor frame part, and if the rotor frame part is made of an iron plate having a high magnetic permeability, etc. This is because the magnetic flux leaking to the rotor frame is increased, and a large iron loss occurs in the rotor frame.

  In addition, the aluminum alloy has higher strength than iron having the same specific gravity, and the weight can be reduced even with the same strength. In addition, since the aluminum alloy has a higher thermal conductivity than iron, it also has an action of quickly diffusing the heat generated by the motor and suppressing a local temperature rise.

  As described above, the rotor frame is made of a non-magnetic material, so that iron loss can be suppressed and motor efficiency can be increased.

  The motor of the present invention has the effect of being able to output a large torque at a low speed and having high efficiency, and can be used as a direct drive motor for a washing machine to reduce the size, weight and efficiency of the device. Useful as.

Explanatory drawing which shows the magnetic circuit structure of the direct drive motor part for washing machines by Embodiment 1 of this invention Explanatory drawing showing the magnetic circuit configuration of the conventional motor unit Explanatory drawing which shows the magnetic circuit structure of the direct drive motor for another example of the washing machine by Embodiment 1 of this invention The figure which shows the relationship between the number of magnetic poles and motor efficiency by Embodiment 2 of this invention The figure which shows the relationship between core outer diameter / axial direction height and motor efficiency by Embodiment 3 of this invention Structure diagram of direct drive motor for washing machine according to Embodiment 4 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Permanent magnet 2 Rotor yoke 3 Core 4 Coil 5 Salient pole 6 Small tooth 7 Rotor frame 8 Bearing 9 Hub 10 Shaft 11 Outer tank 12 Drum 13 Screw 14 Rotor boss 15 Rotor fixing bolt

Claims (4)

In a direct drive motor that directly rotates and drives a pulsator of a washing machine and a drum of the washing machine, or a pulsator of the washing machine or a drum of the washing machine,
The motor includes a rotor having a magnet body in which N poles and S poles are alternately magnetized in the rotation direction, and a plurality of protrusions each having a coil that is wound around the magnet body in a radial direction to form a magnetic circuit. And a portion of the salient pole facing the magnet body, a plurality of small teeth having substantially the same pitch as that of two magnet poles are provided, and depending on the position of the rotor The motor has a configuration in which the rotor is rotationally driven by energizing a coil, and the magnetic pole of the magnet body has a multipolar structure of 30 to 60 poles. In a direct drive motor that directly rotates and drives a pulsator of a washing machine and a drum of the washing machine, or a pulsator of the washing machine or a drum of the washing machine,
The motor includes a rotor having a magnet body in which N poles and S poles are alternately magnetized in the rotation direction, and a plurality of protrusions each having a coil that is wound around the magnet body in a radial direction to form a magnetic circuit. And a portion of the salient pole facing the magnet body, a plurality of small teeth having substantially the same pitch as that of two magnet poles are provided, and depending on the position of the rotor The rotor is rotationally driven by energizing the coil, and the core has a configuration in which the ratio of the outer diameter to the axial height (outer diameter / axial height) is 6 or more and 10 or less. Motor equipped. In a direct drive motor that directly rotates and drives a pulsator of a washing machine and a drum of the washing machine, or a pulsator of the washing machine or a drum of the washing machine,
The motor includes a rotor having a magnet body in which N poles and S poles are alternately magnetized in the rotation direction, and a plurality of protrusions each having a coil that is wound around the magnet body in a radial direction to form a magnetic circuit. And a portion of the salient pole facing the magnet body, a plurality of small teeth having substantially the same pitch as that of two magnet poles are provided, and depending on the position of the rotor The motor is configured to rotate the rotor by energizing a coil. The rotor further includes a rotor yoke made of a high magnetic permeability material and a rotor frame made of a non-magnetic material, and the rotor yoke is the rotor A motor having a configuration fixed to a frame. A washing machine comprising the motor according to any one of claims 1 to 3.