Internal-mounted permanent magnet synchronous motor structure for horizontal machining center electric spindle

Abstract

The present invention provides an internal permanent magnet synchronous motor structure for a horizontal machining center, which includes a stator water-cooling jacket, a stator core, a rotor core, permanent magnets, and an electric spindle rotating shaft. The electric spindle motor is actually a motor without a housing, which combines the electric spindle rotating shaft with the machine tool spindle and combines the electric spindle housing with the stator water-cooling jacket. In the electric spindle motor structure disclosed by the present invention, unequal-width virtual teeth are added to the tooth tips of the stator core, and the tooth tips are chamfered at unequal angles; the rotor core adopts non-uniform segmented herringbone-shaped inclined poles, and the magnetic steel included angles are arranged in an arithmetic progression, and the pole misalignment is realized through the installation of auxiliary round holes; the permanent magnets adopt non-uniform blocks with unequal widths and unequal thicknesses; the magnetic isolation bridges adopt different shapes. The present invention has the advantages of compact structure, short transmission chain length, smaller harmonic content, and electromagnetic vibration suppression.

Description

Technical Field

[0001] The invention relates to the field of a built-in electric spindle permanent magnet synchronous motor for a horizontal machining center, and in particular to a built-in electric spindle permanent magnet synchronous motor structure for a horizontal machining center. Background Art

[0002] The electric spindle motor is the power source of the electric spindle, and its product design performance has a decisive influence on the machining accuracy, machining efficiency and reliability of the parts. In order to ensure the best cutting conditions under any circumstances, the electric spindle is required to maintain high precision regardless of whether it is running at high or low speed. However, the vibration or torque pulsation of the electric spindle will leave machining marks on the surface of the parts. Excessive harmonic content of the motor will produce large losses, aggravate the heat dissipation problem of the high-speed electric spindle motor, and cause heating and deformation of the output shaft end. How to suppress the electric spindle cogging torque, torque pulsation, and harmonics from the perspective of the design of the electric spindle motor body is an urgent problem to be solved. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a built-in electric spindle permanent magnet synchronous motor structure for a horizontal machining center, which can weaken the motor torque pulsation and cogging torque, has a smaller harmonic content, and can suppress electromagnetic vibration. The design of unequal width virtual tooth stator core, non-uniform segmented herringbone skewed pole rotor core, unequal width and thickness non-uniform block permanent magnets, and differentiated magnetic isolation bridge shapes, using complementary structures to offset most of the cogging torque fundamental wave, the total amplitude of spatial harmonics is significantly reduced.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme:

[0005] An internal permanent magnet synchronous motor structure for a horizontal machining center, comprising a stator water-cooling jacket, an unequal-width virtual-tooth stator core, a non-uniformly segmented herringbone-shaped inclined pole rotor core, unequal-width and unequal-thickness non-uniformly segmented permanent magnets, and an electric spindle rotating shaft; the unequal-width and unequal-thickness non-uniformly segmented permanent magnets are inserted into the non-uniformly segmented herringbone-shaped inclined pole rotor core, the non-uniformly segmented herringbone-shaped inclined pole rotor core is sleeved on the electric spindle rotating shaft, the unequal-width virtual-tooth stator core is pressed into the stator water-cooling jacket, and the non-uniformly segmented herringbone-shaped inclined pole rotor core, the unequal-width and unequal-thickness non-uniformly segmented permanent magnets, and the electric spindle rotating shaft are integrally installed in the electric spindle housing formed by the stator water-cooling jacket and the unequal-width virtual-tooth stator core; the unequal-width and unequal-thickness non-uniformly segmented permanent magnets include multiple groups of N-pole permanent magnets and S-pole permanent magnets, and the widths and heights of the multiple groups of N-pole permanent magnets and S-pole permanent magnets are different. After the surface of the unequal-width and unequal-thickness non-uniformly segmented permanent magnets is coated with adhesive, they are inserted into the card slots of the unequal-width virtual-tooth stator core; the non-uniformly segmented herringbone-shaped inclined pole rotor core is hot-sleeved on the electric spindle rotating shaft in an interference fit manner, the electric spindle housing and the stator water-cooling jacket are integrated, and the unequal-width virtual-tooth stator core is hot-pressed into the stator water-cooling jacket in an interference fit manner; the unequal-width virtual-tooth stator core, the non-uniformly segmented herringbone-shaped inclined pole rotor core, the unequal-width and unequal-thickness non-uniformly segmented permanent magnets, and the differential magnetic isolation bridge are combined with complementary shapes to cancel the fundamental wave of the cogging torque and reduce the total amplitude of the space harmonics.

[0006] Further, semi-elliptical auxiliary grooves are opened at the stator tooth tips of the unequal-width virtual-tooth stator core, and π / 4 chamfers are provided at the quarter positions on both sides of the teeth.

[0007] Further, rectangular auxiliary grooves are opened at adjacent stator tooth tips, and π / 6 chamfers are provided at the two-fifths positions on both sides of the teeth.

[0008] Further, the semi-elliptical auxiliary grooves and the rectangular auxiliary grooves are evenly distributed in a staggered manner in the circumferential direction.

[0009] Further, the axial direction of the non-uniformly segmented herringbone-shaped inclined pole rotor core is divided into non-uniform six segments, where L1 = L6 > L2 = L5 > L3 = L4, and L1 + L3 = 2L2 satisfies the arithmetic progression relationship. The six segments of magnetic poles are arranged axially in a herringbone shape; L1 - L6 is the axial length of each segment of the non-uniformly segmented herringbone-shaped inclined pole rotor core.

[0010] Further, the included angle θ 1 + θ 3 = 2θ 2 satisfies the arithmetic progression relationship, and θ 1、 θ 2、 θ 3 are respectively the included angles formed by the extension lines of the lower edges of two groups of unequal-width and unequal-thickness segmented permanent magnets with the same polarity.

[0011] Further, the distance R1 + R3 from the intersection of the lower edges of two groups of magnets with the same polarity to the center line of the rotating shaft satisfies the arithmetic progression relationship; R1, R2, and R3 are the distances from the intersection of the extension lines of the lower edges of two groups of permanent magnets with the same polarity to the center line of the rotating shaft, respectively.

[0012] Further, an auxiliary circular hole is opened on the center line at an angle of π / 4 - α for the rotor core segment with a length of L1, an auxiliary circular hole is opened on the center line at an angle of π / 4 for the rotor core segment with a length of L2, and an auxiliary circular hole is opened on the center line at an angle of π / 4 + α for the rotor core segment with a length of L3.

[0013] Further, the non-uniformly divided permanent magnet with unequal width and unequal thickness includes three segments of permanent magnets, the widths of the three segments of permanent magnets are b1, b2, and b3 respectively, and the thicknesses are h1, h2, and h3 respectively; among them, b1 + b2 = 2b3 satisfies the arithmetic progression relationship, the thickness h1 = h3 = 0.8h2, and the magnetic pole of the non-uniformly segmented chevron-shaped inclined pole rotor core corresponding to the permanent magnet with a thickness of h1 is provided with an isosceles triangle chamfer.

[0014] Further, a fillet is provided for the magnetic isolation bridge at the permanent magnet with a thickness of h3 corresponding to the L1 segment of the rotor core, an extended triangle is provided for the magnetic isolation bridge at the permanent magnet with a thickness of h3 corresponding to the L2 segment of the rotor core, and an internal chamfer is provided for the magnetic isolation bridge at the permanent magnet with a thickness of h3 corresponding to the L3 segment of the rotor core.

[0015] The beneficial effects of the present invention compared with the prior art are as follows:

[0016] 1. The non-uniformly wide virtual-tooth stator core designed in the present invention not only adopts non-traditional non-uniformly wide virtual teeth, but also adopts unequal-angle chamfers for the tooth tips of different virtual teeth. This structure can reduce the lever effect of the stator teeth and minimize the possibility of converting the tangential torque fluctuation into the radial vibration of the stator yoke. These virtual slots without winding insertion expand the least common multiple of the number of poles and the number of slots, making the magnetic circuit more optimized.

[0017] 2. The traditional segmented inclined pole of the rotor core is axially uniformly segmented and has the same magnet included angle, ignoring the existence of the pole edge effect, which will cause the amplitude and phase of the cogging torque of each segment of the motor teeth to deviate from the ideal state. As a result, after phasor superposition, both the fundamental wave and harmonic components cannot be completely cancelled. In the present invention, an axially non-uniform six-segment design is adopted to change the axial length and skew angle of the magnetic poles of each segment of the rotor core to compensate for the changes in the cogging torque and phase caused by the segmented pole edge effect as much as possible, so that the radial electromagnetic force of the motor undergoes a phase shift along the axis, and the average radial electromagnetic force wave is reduced, weakening the torque ripple and cogging torque of the motor.

[0018] 3. The present invention adopts a non - traditional non - uniform block structure of permanent magnets with unequal widths and unequal thicknesses and chamfers the isosceles triangles. By changing the contour of the permanent magnets, the purpose of optimizing the air - gap magnetic - flux density is achieved, which can make its sinusoidality higher and the harmonic content smaller.

[0019] 4. The present invention adopts a non - traditional differential magnetic - isolation bridge shape in combination with non - uniform block permanent magnets with unequal widths and unequal thicknesses, which can optimize the air - gap magnetic - field distribution, eliminate specific - order high - order harmonics, and improve the field - weakening speed - increasing ability while effectively reducing the cogging torque.

[0020] 5. The four structures adopted by the present invention cooperate with each other and are indispensable. Such a complementary structure can cancel most of the fundamental wave of the cogging torque, and the total amplitude of the spatial harmonics decreases significantly. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the built - in type motor - spindle permanent - magnet synchronous motor for horizontal machining centers of the present invention;

[0022] Figure 2 It is a schematic diagram of the unequal - width virtual teeth of the stator core;

[0023] Figure 3 It is a schematic diagram of the non - uniform segmented herringbone - shaped inclined poles of the rotor core;

[0024] Figure 4 It is a comparison diagram of three different rotor - core structures;

[0025] Figure 5 It is a diagram of non - uniform block of permanent magnets with unequal widths and unequal thicknesses.

[0026] Among them, the reference numerals are: stator water - cooling jacket 1, stator core with unequal - width virtual teeth 2, non - uniform segmented herringbone - shaped inclined - pole rotor core 3, non - uniform block permanent magnet with unequal widths and unequal thicknesses 4, motor - spindle rotating shaft 5, stator tooth tip 6, adjacent stator tooth tips 7, semi - elliptical auxiliary groove 8, rectangular auxiliary groove 9, rounded corner 10, extended triangle 11, inner chamfer 12, isosceles - triangle chamfer 13. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. The present invention will be specifically described below with reference to the drawings.

[0028] The present invention designs an unequal-width virtual-tooth stator core 2, a non-uniform segmented herringbone-shaped skew-pole rotor core 3, an unequal-width and unequal-thickness non-uniformly segmented permanent magnet 4, and a differential magnetic isolation bridge shape, and uses a complementary structure to cancel out most of the fundamental wave of the cogging torque, and the total amplitude of the spatial harmonics decreases significantly.

[0029] As Figure 1 shown, the structure of the built-in type motorized spindle permanent magnet synchronous motor for horizontal machining centers of the present invention includes a stator water-cooling sleeve 1, an unequal-width virtual-tooth stator core 2, a non-uniform segmented herringbone-shaped skew-pole rotor core 3, an unequal-width and unequal-thickness non-uniformly segmented permanent magnet 4, and a motorized spindle rotating shaft 5.

[0030] The structure of the built-in type motorized spindle permanent magnet synchronous motor for horizontal machining centers is a shell-less motor, and its installation sequence is as follows: First, insert the unequal-width and unequal-thickness non-uniformly segmented permanent magnet 4 into the non-uniform segmented herringbone-shaped skew-pole rotor core 3, then sleevethe non-uniform segmented herringbone-shaped skew-pole rotor core 3 on the motorized spindle rotating shaft 5, then press the unequal-width virtual-tooth stator core 2 into the stator water-cooling sleeve 1, and finally integrally install the non-uniform segmented herringbone-shaped skew-pole rotor core 3, the unequal-width and unequal-thickness non-uniformly segmented permanent magnet 4, and the motorized spindle rotating shaft 5 into the motorized spindle housing which is an integral body of the stator water-cooling sleeve 1 and the unequal-width virtual-tooth stator core 2.

[0031] The unequal-width and unequal-thickness non-uniformly segmented permanent magnet 4 includes multiple groups of N-pole permanent magnets and S-pole permanent magnets. The widths and heights of the multiple groups of N-pole permanent magnets and S-pole permanent magnets are different from each other. Preferably, there are 8 groups, with 4 groups of N-pole permanent magnets and 4 groups of S-pole permanent magnets respectively; two groups of N-pole permanent magnets are arranged adjacent to each other, and are symmetrically arranged with respect to the motorized spindle rotating shaft 5 with the other two adjacent groups of N-pole permanent magnets; two groups of S-pole permanent magnets are arranged adjacent to each other, and are symmetrically arranged with respect to the motorized spindle rotating shaft 5 with the other two adjacent groups of S-pole permanent magnets.

[0032] After the surface of the unequal-width and unequal-thickness non-uniformly segmented permanent magnet 4 is coated with adhesive, it is respectively inserted into the corresponding card slots of the rotor cores with lengths of L1-L6 in 6 segments. The rotor cores with lengths of L1-L6 are installed through auxiliary round holes to form a non-uniform segmented herringbone-shaped skew-pole rotor core 3; the non-uniform segmented herringbone-shaped skew-pole rotor core 3 is hot-sleeved on the motorized spindle rotating shaft 5 in an interference fit manner. The motorized spindle housing and the stator water-cooling sleeve 1 are an integral body, and the unequal-width virtual-tooth stator core 2 is hot-pressed into the stator water-cooling sleeve 1 in an interference fit manner; the non-uniform segmented herringbone-shaped skew-pole rotor core 3, the unequal-width and unequal-thickness non-uniformly segmented permanent magnet 4, and the motorized spindle rotating shaft 5 are integrally installed in the motorized spindle housing, and it is ensured that the motorized spindle rotating shaft 5 is located at the center of the stator water-cooling sleeve 1.

[0033] As Figure 2As shown, a semi-elliptical auxiliary groove 8 is opened at the top of the stator tooth 6, and chamfers of π / 4 are made at the quarter positions on both sides of the tooth; a rectangular auxiliary groove 9 is opened at the top of the adjacent stator tooth 7, and chamfers of π / 6 are made at the two-fifths positions on both sides of the tooth. The semi-elliptical auxiliary groove 8 and the rectangular auxiliary groove 9 are evenly distributed in a staggered manner in the circumferential direction.

[0034] Figure 3 As shown, the axial direction of the non-uniformly segmented chevron-shaped inclined pole rotor core 3 is divided into non-uniform six segments, where L1 = L6 > L2 = L5 > L3 = L4, and L1 + L3 = 2L2 satisfies the arithmetic progression relationship. The six segments of magnetic poles are arranged axially in a chevron shape. Here, L1 - L6 refers to the axial length of each segment of the non-uniformly segmented chevron-shaped inclined pole rotor core 3, and also refers to the number of each segment.

[0035] As Figure 4 shown, the included angle θ 1 + θ 3 = 2θ 2 satisfies the arithmetic progression relationship, where θ 1 , θ 2 , θ 3 are respectively the included angles formed by the extension lines of the lower edges of two groups of permanent magnets with the same polarity; the distance R1 + R3 = 2R2 from the intersection point of the extension lines of the lower edges of two groups of permanent magnets with the same polarity to the center line of the rotating shaft satisfies the arithmetic progression relationship. Here, R1, R2, and R3 are respectively the distances from the intersection point of the extension lines of the lower edges of two groups of permanent magnets with the same polarity to the center line of the rotating shaft; an auxiliary circular hole is opened on the center line of the L1 segment rotor core at an angle of π / 4 - α ( Figure 4 in the left figure ), an auxiliary circular hole is opened on the center line of the L2 segment rotor core at an angle of π / 4 ( Figure 4 in the middle figure ), an auxiliary circular hole is opened on the center line of the L3 segment rotor core at an angle of π / 4 + α ( Figure 4 in the right figure ), and the 6-segment rotor cores L1 - L6 are assembled through the auxiliary circular holes to form Figure 3 the non-uniformly segmented chevron-shaped inclined pole rotor core. Figure 4 Among them, R0 represents the distance from the center of the auxiliary circular hole to the center line of the rotating shaft.

[0036] As Figure 5As shown, the non-uniformly segmented permanent magnet 4 with unequal widths and unequal thicknesses includes three segments of permanent magnets. The widths of the three segments of permanent magnets are b1, b2, and b3 respectively, and the thicknesses are h1, h2, and h3 respectively. b1, b2, and b3 are not equal to each other, and h1, h2, and h3 are not equal to each other. The width b1 + b2 = 2b3 satisfies the arithmetic progression relationship, the thickness h1 = h3 = 0.8h2, and the permanent magnet with the thickness of h1 has an isosceles triangle chamfer 13. The non-uniformly segmented structure of the permanent magnet with unequal widths and unequal thicknesses and the isosceles triangle chamfer can optimize the air-gap flux density by changing the contour of the permanent magnet, making its sinusoidality higher and the harmonic content smaller.

[0037] In order to cooperate with the non-uniformly segmented permanent magnet structure with unequal widths and unequal thicknesses, a rounded corner 10 is provided at the magnetic isolation bridge corresponding to the permanent magnet with the thickness of h3 in the L1 section of the rotor core, an extended triangle 11 is provided at the magnetic isolation bridge corresponding to the permanent magnet with the thickness of h3 in the L2 section of the rotor core, and an inner chamfer 12 is provided at the magnetic isolation bridge corresponding to the permanent magnet with the thickness of h3 in the L3 section of the rotor core. The different magnetic isolation bridge shapes cooperate with the non-uniformly segmented permanent magnet with unequal widths and unequal thicknesses to optimize the air-gap magnetic field distribution, eliminate high-order harmonics of specific orders, and can improve the field weakening and speed increasing ability while effectively reducing the cogging torque.

Claims

1. A built-in electric spindle permanent magnet synchronous motor structure for a horizontal machining center, characterized in that: It comprises a stator water cooling jacket, an unequal width virtual tooth stator core, a non-uniform segmented herringbone skewed pole rotor core, unequal width, unequal thickness, non-uniform block permanent magnets, and an electric spindle shaft; the unequal width, unequal thickness, non-uniform block permanent magnets are inserted into the non-uniform segmented herringbone skewed pole rotor core, the non-uniform segmented herringbone skewed pole rotor core is sleeved on the electric spindle shaft, the unequal width virtual tooth stator core is pressed into the stator water cooling jacket, and the non-uniform segmented herringbone skewed pole rotor core, the unequal width, unequal thickness, non-uniform block permanent magnets, and the electric spindle shaft are integrally installed in the stator water cooling jacket and the unequal width virtual tooth stator core as a whole in the electric spindle housing; The non-uniform block permanent magnets with unequal width and thickness include multiple groups of N-pole permanent magnets and S-pole permanent magnets, and the widths and heights of the multiple groups of N-pole permanent magnets and S-pole permanent magnets are different. The surfaces of the non-uniform block permanent magnets with unequal width and thickness are coated with adhesive and then inserted into the slots of the stator core with unequal width virtual teeth. The non-uniform segmented herringbone skewed pole rotor core is heat-fitted on the electric spindle shaft in an interference fit manner, the electric spindle housing is integrated with the stator water cooling jacket, and the stator core with unequal width virtual teeth is heat-pressed in the stator water cooling jacket in an interference fit manner. The unequal width virtual tooth stator core, the non-uniform segmented herringbone skew pole rotor core, the unequal width, unequal thickness and non-uniform block permanent magnets, and the differentiated magnetic isolation bridge shapes are complementary to offset the fundamental wave of the tooth slot torque and reduce the total amplitude of the spatial harmonics. The virtual teeth with different widths are used, and the tops of different virtual teeth are chamfered with different angles to reduce the lever effect of the stator teeth, minimize the possibility of converting the tangential torque fluctuation into the radial vibration of the stator yoke, do not embed the virtual slots of the winding, expand the lowest common multiple of the number of poles and slots, and optimize the magnetic circuit; The axial non-uniform six-segment design is adopted to change the axial length and skew angle of the magnetic poles of each segment of the rotor core; A non-uniform block structure with unequal width and thickness of permanent magnets is adopted, and isosceles triangle chamfers are used; a differentiated magnetic isolation bridge shape is used in combination with non-uniform block permanent magnets with unequal width and thickness to optimize the air gap magnetic field distribution.

2. The structure of a built-in electric spindle permanent magnet synchronous motor for a horizontal machining center according to claim 1, characterized in that: The stator teeth of the unequal width virtual tooth stator core are provided with semi-elliptical auxiliary slots on the tops, and a π / 4 chamfer is provided at one quarter of the sides of the teeth.

3. The structure of a built-in electric spindle permanent magnet synchronous motor for a horizontal machining center according to claim 2, characterized in that: Rectangular auxiliary slots are opened on the tops of adjacent stator teeth, and π / 6 chamfers are set at two-fifths of the sides of the teeth.

4. The structure of a built-in electric spindle permanent magnet synchronous motor for a horizontal machining center according to claim 3, characterized in that: The semi-elliptical auxiliary grooves and the rectangular auxiliary grooves are staggered and evenly distributed in the circumferential direction.

5. The structure of a built-in electric spindle permanent magnet synchronous motor for a horizontal machining center according to claim 1, characterized in that: The non-uniform segmented herringbone skewed pole rotor core is divided into six non-uniform segments in the axial direction, among which L1=L6>L2=L5>L3=L4, and L1+L3=2L2 satisfies the arithmetic progression relationship, and the six segments of magnetic poles are arranged in a herringbone shape in the axial direction; L1-L6 is the axial length of each segment of the non-uniform segmented herringbone skewed pole rotor core.

6. The structure of a built-in electric spindle permanent magnet synchronous motor for a horizontal machining center according to claim 5, characterized in that: The angle between two sets of permanent magnets with the same polarity θ1+ θ3=2θ2 satisfies the arithmetic progression relationship, θ 1、 θ 2、 θ3 is the angle formed between the extended lines of the lower edges of two groups of permanent magnets of unequal width and thickness with the same polarity.

7. The structure of a built-in electric spindle permanent magnet synchronous motor for a horizontal machining center according to claim 5, characterized in that: The distance R1+R3=2R2 from the intersection of the lower edges of the two sets of magnets with the same polarity to the center line of the rotating shaft satisfies an arithmetic progression relationship; R1, R2, and R3 are respectively the distances from the intersection of the extended lines of the lower edges of the two sets of permanent magnets with the same polarity to the center line of the rotating shaft.

8. The structure of a built-in electric spindle permanent magnet synchronous motor for a horizontal machining center according to claim 5, characterized in that: The rotor core segment with a length of L1 has an auxiliary circular hole on the center line of the angle of π / 4-α, the rotor core segment with a length of L2 has an auxiliary circular hole on the center line of the angle of π / 4, and the rotor core segment with a length of L3 has an auxiliary circular hole on the center line of the angle of π / 4+α.

9. The structure of a built-in electric spindle permanent magnet synchronous motor for a horizontal machining center according to claim 4, characterized in that: The non-uniform segmented permanent magnets with unequal width and thickness include three segments of permanent magnets, the widths of the three segments of permanent magnets are b1, b2, and b3, and the thicknesses are h1, h2, and h3, respectively; wherein, b1+b2=2b3 satisfies an arithmetic progression relationship, the thickness h1=h3=0.8h2, and the magnetic poles of the non-uniform segmented herringbone skew-pole rotor core corresponding to the permanent magnet at the thickness h1 are arranged with isosceles triangle chamfers.

10. The structure of a built-in electric spindle permanent magnet synchronous motor for a horizontal machining center according to claim 8, characterized in that: The permanent magnets with a thickness of h3 corresponding to the L1 segment of the rotor core are provided with rounded corners at the magnetic isolation bridges, the permanent magnets with a thickness of h3 corresponding to the L2 segment of the rotor core are provided with overhanging triangles at the magnetic isolation bridges, and the permanent magnets with a thickness of h3 corresponding to the L3 segment of the rotor core are provided with inner chamfers at the magnetic isolation bridges.

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