JP2005124281A - Permanent magnet embedded type motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor where both magnet torque and reluctance torque of the motor are compatible, to reduce leakage of magnetic flux for improved motor efficiency, while the strength of a rotor is maintained without noise, vibration or the like. <P>SOLUTION: The width between adjoining first gaps, with the magnetic pole of a rotor of a permanent magnet embedded type motor in between, is equal to the tooth width of a stator or wider, to assure sufficient path where the reluctance torque acquired by an auxiliary magnetic pole flows in/out. The width of a second gap is extended much toward the magnetic pole center from the width of the first gap, so that the magnet torque acquired from a main magnetic pole of the rotor is concentrated, providing a rotor with no leakage of magnetic flux. Thus the efficiency of a motor is improved, to keep strength of the rotor while the motor is operated, resulting in reduced noise, vibration or the like. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an embedded permanent magnet electric motor (hereinafter referred to as an electric motor) including a stator having a winding wound around a slot of the stator and a rotor having a permanent magnet accommodated in a magnet accommodation hole.

  In recent years, electric vehicles equipped with an electric motor driven at a low voltage due to environmental problems and the like have been developed. In such an electric motor, a rotor in which a permanent magnet is embedded so that adjacent magnetic poles are different from each other is operated by a drive device such as an inverter. For example, it is used for a driving electric motor for driving a vehicle body, a hermetic electric compressor mounted on a vehicle, an electric power steering, or the like.

In a rotor in which permanent magnets are embedded so that adjacent magnetic poles are different from each other, the total torque T of the motor is improved by reconciling reluctance torque and magnet torque, and as a result, the efficiency of the motor is improved. Can do.
The total torque T of the electric motor can be expressed by the following equation.
T = φ · Iq + (Ld−Lq) · Id · Iq (1)
In this case, φ is the amount of magnetic flux, Iq is the q-axis current, Id is the d-axis current, Lq is the q-axis inductance, and Ld is the d-axis inductance. As the amount of magnetic flux φ increases, the total torque T also increases and the efficiency of the motor can be improved.

  A rotor embedded with permanent magnets in this way can obtain both reluctance torque and magnet torque, improve overall torque and improve motor efficiency. However, cogging torque and torque are increased as the motor operates. Sound and vibration are generated due to pulsation.

  Further, the magnetic flux is easily short-circuited between the magnetic poles of the rotor in which the permanent magnets are embedded so that the adjacent magnetic poles have different polarities. For these problems, for example, a rotor as disclosed in Japanese Patent Application Laid-Open No. 11-98731 (see Patent Document 1) is disclosed. This rotor will be described with reference to FIG. In FIG. 7, a magnetic flux short-circuit prevention hole 17 is provided in the circumferential direction so as to be in contact with the end of the permanent magnet 9d embedded in the magnet housing hole 8d inside the rotor 2d so as to follow the outer periphery of the rotor 2d. A short circuit of the magnetic flux at both ends of the magnet 9d is prevented, the magnetic flux of the permanent magnet 9d is prevented from leaking, and the torque is effectively obtained. Further, the circumferential width of the rotor 2d of the magnetic flux short-circuit prevention hole 17 is specified to reduce cogging torque and torque pulsation.

  As another conventional example, a rotor disclosed in Japanese Patent Laid-Open No. 2002-305859 (see Patent Document 2) will be described with reference to FIG. The permanent magnet 9e embedded in the rotor 2e of FIG. 8 is embedded in the magnet housing hole 8e so that adjacent magnetic poles are different from each other, and between the end of the permanent magnet 9e and the outer periphery of the rotor 2e. A notch groove 19 for preventing magnetic flux short-circuiting is provided. In addition, an auxiliary magnetic pole portion is provided by the notch groove 19 to actively use the reluctance torque. Thereby, the short circuit of the magnetic flux is minimized at both ends of the permanent magnet 9e, and the reluctance torque is effectively utilized.

JP 11-98731 A JP 2002-305859 A

  However, as shown in FIG. 7, both ends of the permanent magnet 9d are provided by elongating the magnetic flux short-circuit prevention hole 17 in contact with the end of the permanent magnet 9d in the circumferential direction along the outer periphery of the rotor 2d. The cogging torque and torque pulsation can be reduced, but the rotor 2d strength can be maintained because the elongated magnetic flux short-circuit prevention hole 17 is provided near the outer periphery of the rotor 2d. First, the rotor 2d swells during motor operation, and the outer periphery of the rotor 2d is deformed as shown by the dotted line 18 in the figure. In the worst case, the motor burns out.

  Further, as shown in FIG. 8, the notch grooves 19 are provided adjacent to both ends of the permanent magnet 9e so that leakage magnetic flux at both ends of the permanent magnet 9e can be minimized. Since the large cutout groove 19 is provided so as not to leak, for example, in a hermetic electric compressor having the refrigerant 16 or the like in the apparatus, the refrigerant 16 in the compressor is intentionally mixed and the refrigerant efficiency is lowered. ing.

  Further, the presence of the notch groove 19 generates wind noise and vibration when the rotor 2e rotates. In this case, when a bridge is formed by closing the notch groove 19 provided on the outer periphery of the rotor 2e, the magnetic flux leaks from the main magnetic pole to the auxiliary magnetic pole or from the auxiliary magnetic pole to the main magnetic pole via the stator teeth. . If the bridge portion is elongated and formed along the outer periphery of the rotor 2e so as not to leak, the rotor 2e swells and deforms during motor operation as described above.

  The present invention achieves both the reluctance torque obtained from the auxiliary magnetic pole and the magnet torque obtained from the main magnetic pole, improves the efficiency of the motor without generating leakage magnetic flux as much as possible, and at the same time the rotor during motor operation The purpose of the present invention is to improve the refrigerant efficiency and reduce the sound and vibration in a hermetic electric compressor having a refrigerant and the like, for example, having a refrigerant or the like in the apparatus.

An electric motor in which a winding is wound around a slot of a stator, and the rotor facing the stator tooth portion has a magnet housing hole in which a permanent magnet is embedded in the circumferential direction so that adjacent magnetic poles are different from each other. In the electric motor provided with an auxiliary magnetic pole for sufficiently utilizing the reluctance torque between the adjacent magnetic poles,
A first gap is provided between the end wall of the magnet accommodation hole and the permanent magnet, a second gap is provided between the end wall of the magnet accommodation hole and the outer periphery of the rotor, and
The width between the first gaps adjacent to each other across the magnetic poles is equal to or larger than the tooth width of the stator, and the second gap width is the first gap width. The motor is greatly expanded in the direction of the magnetic pole center.
In particular, it is a concentrated winding type electric motor in which windings are wound directly around the stator teeth,
For example, an electric motor in a hermetic type electric compressor mounted on an outdoor unit for a refrigerator or an air conditioner having a refrigerant or the like in the device,
Alternatively, an excellent effect can be obtained by using an electric motor mounted as a vehicle application.

The present invention relates to an electric motor in which a winding is wound around a slot of a stator, and a rotor facing a stator tooth portion includes a permanent magnet embedded in a circumferential direction so that adjacent magnetic poles are different from each other In the permanent magnet embedded electric motor in which the accommodation holes are provided at equal intervals, and the auxiliary magnetic pole is provided between the magnetic poles adjacent to each other to sufficiently use the reluctance torque.
By providing the first gap between the end wall of the magnet housing hole and the permanent magnet, leakage of magnetic flux from the auxiliary magnetic pole side or the main magnetic pole side can be prevented. Further, by providing a second gap between the end wall of the magnet housing hole and the outer periphery of the rotor, the inflow and outflow of the short-circuit magnetic flux passing through the stator tooth portion is reduced as much as possible.

  Further, since the width between the first gaps adjacent to each other with the magnetic poles between them is equal to or greater than the tooth width of the stator, a passage through which reluctance torque obtained by the auxiliary magnetic poles flows in and out is sufficient. Can be secured. Further, the second gap width is greatly expanded in the direction of the magnetic pole center along the outer periphery of the rotor than the width of the first gap, thereby concentrating the magnet torque obtained from the permanent magnet of the rotor, and the stator teeth. The rotor can be free of short-circuit magnetic flux that passes through the section, improving the efficiency of the motor, maintaining the strength of the rotor during motor operation, and reducing the noise and vibration caused by cogging torque and torque pulsation The motor can be made.

  In particular, the leakage magnetic flux can be reduced and the sound and vibration can be greatly reduced by using the motor with a concentrated winding method in which the winding is directly wound around the stator tooth portion.

  Moreover, the refrigerant etc. are intentionally agitated by using it for the electric motor in the hermetic type electric compressor mounted in the outdoor unit for refrigerator or air conditioner having the refrigerant etc. in the apparatus, and the refrigerant efficiency is lowered. Also disappear.

  Moreover, it can be set as the vehicle which reduced the sound and the vibration by setting it as the electric motor in a vehicle-mounted apparatus.

  Embodiments of the present invention will be described with reference to the drawings. The electric motor shown in FIG. 1 is an electric motor in which a winding is wound around a slot 3 of a stator 1 and the winding forms three phases. Note that windings are not shown in the slots 3 of the stator 1 in the figure for convenience. A permanent magnet embedded rotor in which a permanent magnet 9 is embedded on the inner diameter side of the stator 1 is provided so as to face the tooth portion 4 of the stator 1. The permanent magnet embedded rotor is provided with a magnet accommodation hole 8 for embedding the permanent magnet 9 in a string shape on the outer periphery of the rotor 2. The permanent magnets 9 embedded in the magnet accommodation holes 8 are embedded in a uniform manner in the circumferential direction so that the magnetic poles are alternately different from each other to form four poles. Further, an auxiliary magnetic pole 6 is provided between adjacent magnetic poles, and has a width through which the reluctance torque φ1 flows sufficiently.

  A first gap 10 is provided between the end wall 20 of the magnet housing hole 8 in which the permanent magnet 9 is embedded in a string shape with respect to the outer periphery of the rotor 2 and the permanent magnet 9. In the first gap 10, gaps are formed at both ends of the permanent magnet 9 by inserting permanent magnets 9 smaller than the magnet accommodation holes 8. In this case, the permanent magnet 9 is arranged so as to be located at the approximate center of the magnet housing hole 8.

  As a method of fixing the permanent magnet 9 in the magnet housing hole 8, as shown in FIG. 1, the side wall of the magnet housing hole 8 is tapered from the end of the permanent magnet 9 to the outer periphery of the rotor 2. Thus, the permanent magnet 9 is fixed by the end wall 20 in the magnet accommodation hole 8. Further, the permanent magnet 9 may be fixed to the first gap portion 10 with an insulating material such as resin.

  The presence of the first air gap 10 can reduce the leakage magnetic flux φ4 generated between the auxiliary magnetic pole 14a and the main magnetic pole 15a as shown in FIG. 2, and the first magnetic flux 14 as shown in FIG. By providing the gap 10, the reluctance torque generated at the auxiliary magnetic pole portion 6 and the magnet torque generated at the main magnetic pole portion 7 can be reliably separated.

  Next, FIG. 3 shows a partially enlarged view for explaining in more detail the vicinity between the magnetic poles of the rotor 2 in the electric motor explained in FIG. Permanent magnets 9a and 9b are inserted in the magnet receiving holes 8a and 8b adjacent to each other with the magnetic poles interposed therebetween. Between the permanent magnets 9a and 9b in the magnet housing holes 8a and 8b and the end wall 20, first gap portions 10a and 10b are provided. The distance between the first air gaps 10a and 10b provided at the ends of the permanent magnets 9a and 9b and the width X1 are such that the reluctance torque φ1 obtained by the auxiliary magnetic pole 6 flows sufficiently. By making the width equal to or larger than the width 4, the flow of the magnetic flux of the reluctance torque φ1 can be smoothly flowed without interfering with the magnetic torque φ2 obtained from the main pole 7 and the total torque of the motor is improved. Can be made. As a result, the efficiency of the electric motor can also be improved.

In the magnetic flux path of the reluctance torque φ1 on the stator side, the main trunk portion Y1 of the tooth width 4 of the stator 1 is dominant, and both end portions 5 of the tooth width 4 of the stator 1 are magnetically saturated and effective. Although it cannot be said that the magnetic flux path is sufficient, when a sufficient width of the magnetic flux path through which the reluctance torque φ1 flows is ensured, the dimension including both end portions 5 of the tooth width 4 of the stator 1 at the portion facing the rotor 2 It is more effective. Accordingly, the width X1 between the first air gaps 10a and 10b may be Y1 ≦ X1.
In other words, even if the width X1 between the first gaps 10a and 10b is increased beyond the two end portions 5 of the teeth 4 of the stator 1, it is not very meaningful as a magnetic flux path for the reluctance torque φ1. I will not do it.

  Therefore, the width X1 of the first gaps 10a and 10b at the ends of the permanent magnets 9a and 9b of the magnet receiving holes 8a and 8b adjacent to each other with the magnetic poles sandwiched between them is the tooth width 4 (main trunk portion Y1) of the stator 1. The reluctance torque φ1 can be obtained smoothly by setting the width to be equal to or greater than, and leakage of magnetic flux between the auxiliary magnetic pole 6 and the main magnetic pole 7 can be prevented. In addition, the motor efficiency is improved by using the electric motor with little magnetic resistance and utilizing the reluctance torque φ1 and the magnet torque φ2 to the maximum.

  Next, the second gaps 11a and 11b will be described. As shown in FIG. 3, second gaps 11 a and 11 b are provided between the end walls 20 of the magnet housing holes 8 a and 8 b and the outer periphery of the rotor 2. By providing the second gaps 11a and 11b, the leakage magnetic flux φ5 generated between the auxiliary magnetic pole part 14b and the main magnetic pole part 15b via the teeth 4c of the stator 1 as shown in FIG. 4 is reduced. can do. In this case, needless to say, the leakage magnetic flux φ4 passing through the rotor 2 can be reduced by the first gaps 13a and 13b as described above.

  The second air gaps 11a and 11b have a structure that is greatly extended in the direction of the magnetic pole center. In this case, the depth of the second air gaps 11a and 11b is such that the magnetic flux is short-circuited between the auxiliary magnetic pole portion 6 and the main magnetic pole portion 7 via the teeth 4 of the stator 1 and no leakage magnetic flux is generated. Good.

  Further, for example, in a sealed electric compressor having a refrigerant or the like in the apparatus, the refrigerant in the compressor is intentionally agitated in the second gaps 11a and 11b provided on the outer periphery of the rotor 2, and the refrigerant flow is And the refrigerant efficiency may be lowered, and the depth may be such that the motor temperature rises and the motor efficiency does not deteriorate.

  FIG. 5 shows the relationship between the refrigerant resistance and L / g when the depth of the second gap provided on the outer periphery of the rotor is L and the gap between the stator and the rotor is g. The graph is shown. In this case, considering the refrigerant resistance, the depth may satisfy L / g ≦ 0.5.

  FIG. 6 is a partially enlarged view for explaining in more detail the vicinity between the magnetic poles of the rotor 2 described in FIG. 1 as in FIG. Here, the width Z in the rotor circumferential direction of the second gap portions 11a and 11b will be described. The second gaps 11a and 11b of the rotor 2 are provided between the end walls 20 of the magnet housing holes 8a and 8b into which the permanent magnets 9a and 9b are inserted and the outer periphery of the rotor. Here, the width Z in the rotor circumferential direction of the second gap portions 11a and 11b provided in the outer peripheral portion of the rotor can reliably obtain the reluctance torque φ1 of the auxiliary magnetic pole as described above. The second air gaps 11a and 11b are provided along the outer periphery of the rotor so as not to generate a leakage magnetic flux between the auxiliary magnetic pole part 6 and the main magnetic pole part 7 via one tooth part 4. .

  Specifically, the width of the second gaps 11a and 11b is set to be greater than that of both end portions 5 of the tooth width 4 of the stator 1 at the portion facing the rotor 2, so that rotation with less magnetic flux leakage is achieved. Child 2 can be used. If the width Z of the second gaps 11a and 11b is narrower than the both end portions 5 of the tooth width 4 of the stator 1, the magnetic flux is applied to the tooth portions 4 of the stator 1 or both end portions 5 of the tooth portions 4. Will leak through. Therefore, if the width of the both end portions 5 of the tooth width 4 is Y2, Y2 ≦ Z may be satisfied.

  Further, the width of the second gaps 11a and 11b is set so that the reluctance torque φ1 flows between the magnetic poles with the first gaps 10a and 10b so that the reluctance torque φ1 flows without hindrance from the gap X1. Yes. This is because, of course, the magnetic flux path of the reluctance torque φ1 secured between the magnetic poles is narrowed. Also, the magnet torque φ2 generated in the main magnetic pole 7 is maintained while maintaining the strength of the end wall 20 by widening the width of the second air gaps 11a and 11b to the magnetic pole center direction larger than the width of the first air gaps 10a and 10b. The magnetic flux can be concentrated on the magnetic pole center, and the magnetic flux can be concentrated on the energization section as viewed from the inverter side. In this case, the distance between the second air gaps 11 in one magnetic pole may be about 50 to 70 degrees (in electrical angle) with respect to the rotor shaft hole.

  In the second gaps 11a and 11b of the embodiment, since the gap is slightly concave with respect to the outer periphery of the rotor, a large magnetic flux short-circuit prevention hole is not formed as shown in FIG. In addition, it is not necessary to provide an elongated bridge on the outer periphery of the rotor 2, and the rotor can be excellent in strength.

  Therefore, the auxiliary magnetic pole 6 and the main magnetic pole 7 are provided by providing the first gap 10 (10a, 10b) between the end wall 20 of the magnet housing hole 8 (8a, 8b) and the permanent magnet 9 (9a, 9b). Can be reliably separated, and leakage of magnetic flux from each can be prevented. By making the widths of the first gaps 10a and 10b adjacent to each other with the gap between the magnetic poles equal to or larger than the tooth width 4 of the stator 1, the reluctance torque φ1 obtained by the auxiliary magnetic pole 6 can be smoothly increased. It can flow.

  Further, the second gap 11 (11a, 11b) is provided between the end wall 20 of the magnet housing hole 8 (8a, 8b) and the outer periphery of the rotor 2, and the width of the second gap 11 (11a, 11b) is provided. Is greatly expanded in the direction of the magnetic pole center from the width of the first gap 10 (10a, 10b), and the auxiliary magnetic pole 6 and the main magnetic pole 7 are interposed via the teeth 4 of the stator 1 while maintaining the strength of the end wall 20. The leakage magnetic flux between the two can be reduced. As a result, the reluctance torque φ1 obtained by the auxiliary magnetic pole 6 and the magnet torque φ2 obtained by the main magnetic pole 7 can both be achieved, and the total torque of the electric motor can be increased.

  Further, since the flow of magnetic flux does not change abruptly by providing the second gap 11 (11a, 11b), it is possible to reduce noise, vibration, and the like caused by cogging torque and torque pulsation. In addition, since the second gap 11 (11a, 11b) does not need to have a large and deep notch groove on the outer periphery of the rotor 2, for example, the refrigerant efficiency of a hermetic electric compressor having a refrigerant or the like in the apparatus can be improved. It is possible to reduce wind noise, vibration and the like caused by notch grooves.

By using such a rotor 2 in a concentrated winding type motor in which a winding is directly wound around the tooth portion 4 of the stator 1 where the concentration of magnetic flux increases, the reluctance torque φ1 obtained by the auxiliary magnetic pole 6 and the main magnetic pole The obtained magnet torque φ2 can be reliably achieved and the total torque can be increased. Further, it is possible to obtain an electric motor with less cogging torque and torque pulsation, less leakage magnetic flux, excellent strength, and less noise, vibration and the like.
In particular, in the concentrated winding type motor in which the winding is directly wound around the tooth portion 4 of the stator 1, the magnetic flux concentrates on the tooth portion 4 of the stator 1, and thus, for example, a 6-slot, 9-slot, 12-slot stator. The effect is tremendous when used for.

  In addition, as described above, the rotor 2 stirs the refrigerant by using an electric motor in a hermetic electric compressor that is installed in an outdoor unit for a refrigerator or air conditioner that has a refrigerant or the like in the apparatus. Thus, the refrigerant efficiency is not reduced by biasing in the compressor, and the reluctance torque φ1 obtained by the auxiliary magnetic pole 6 and the magnet torque φ2 obtained by the main magnetic pole 7 can be reliably made compatible and the total torque can be increased. . Further, the cogging torque and torque pulsation are reduced, the leakage magnetic flux is small, and an electric motor with little wind noise and vibration can be obtained.

  Further, by mounting the electric motor on an electric vehicle driven at a low voltage by an inverter or the like, the reluctance torque φ1 obtained from the auxiliary magnetic pole 6 and the magnet torque φ2 obtained from the main magnetic pole 7 are both compatible, and the leakage magnetic flux is as much as possible. It is possible to make the electric vehicle more energy-saving by improving the efficiency of the electric motor without being generated. Furthermore, it can be set as the electric vehicle of the silent design which maintained the intensity | strength of the rotor 2 at the time of an electric motor driving | operation, and reduced the sound and vibration. For example, an excellent effect can be obtained by using it for a driving motor for driving a vehicle body, a hermetic electric compressor mounted on a vehicle, an electric power steering, or the like.

  In particular, this electric motor uses a concentrated winding method in which a winding having a wire diameter of φ0.8 to φ1.2 is directly wound around the tooth portion 4 of the stator 1 in a motor driven by an inverter at a low voltage of 60 V or less. When used in an electric motor, the reluctance torque φ1 and the magnet torque φ2 can flow smoothly, the total torque can be increased, and an electric motor with less cogging torque and torque pulsation can be obtained.

  In the present invention, the description has been given of the rotor in which the permanent magnet 9 is embedded in the magnet housing hole 8 in a string shape with respect to the outer periphery of the rotor 2, but the embedded shape of the permanent magnet is V-shaped, concave-shaped, A reverse arc type or the like may be used, and the present invention can be similarly applied when a permanent magnet is embedded in multiple layers.

Sectional drawing of the electric motor in embodiment of this invention. The figure explaining the magnetic flux leakage φ4 when there is no first gap. The elements on larger scale explaining the 1st space | gap part of embodiment described in FIG. The figure explaining leakage magnetic flux (phi) 5 in the case of only a 1st clearance part. The graph which showed the relationship between refrigerant resistance and the 2nd space | gap depth. The elements on larger scale explaining the 2nd space | gap part of embodiment described in FIG. Sectional drawing of the permanent magnet embedded type rotor of a prior art example. Sectional drawing of the permanent magnet embedded type rotor of another prior art example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Stator, 2, 2a, 2b, 2c, 2d, 2e ... Rotor, 3 ... Slot, 4, 4b, 4c ... Teeth width, 5, 5b, 5c ... Teeth Tip part, 6, 14a, 14b ... auxiliary magnetic pole, 7, 15a, 15b ... main magnetic pole, 8, 8a, 8b, 8c, 8d ... magnet housing hole, 9, 9a, 9b, 9c, 9d ... Permanent magnet 10, 10a, 10b, 13a, 13b ... First gap, 11, 11a, 11b ... Second gap, 12 ... Tip details, 16 ... -Refrigerant, 17 ... Magnetic flux short-circuit prevention hole, 18 ... Deformed portion, 19 ... Notch groove, 20 ... End wall, φ1 ... Reluctance torque, φ2 ... Magnet torque, φ4, φ5 ... Magnetic flux leakage.

Claims (4)

An electric motor in which a winding is wound around a slot of a stator, and the rotor facing the stator tooth portion has a magnet housing hole in which a permanent magnet is embedded in the circumferential direction so that adjacent magnetic poles are different from each other. In the permanent magnet embedded electric motor provided with an auxiliary magnetic pole for sufficiently utilizing the reluctance torque between the magnetic poles adjacent to each other,
A first gap is provided between the end wall of the magnet accommodation hole and the permanent magnet, a second gap is provided between the end wall of the magnet accommodation hole and the outer periphery of the rotor, and
The width between adjacent first gaps across the magnetic poles is equal to or greater than the tooth width of the stator;
In addition, the permanent magnet embedded type electric motor is characterized in that the second gap width is larger than the first gap width in the magnetic pole center direction. 2. The permanent magnet embedded type electric motor according to claim 1, wherein a concentrated winding system in which a winding is directly wound around a stator tooth portion. 3. The permanent magnet-embedded electric motor according to claim 1, wherein the electric motor is a motor in a hermetic electric compressor having a refrigerant in the apparatus and mounted in an outdoor unit for a refrigerator or an air conditioner. . 3. The permanent magnet embedded type electric motor according to claim 1, wherein the electric motor is mounted for use in a vehicle.

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