Low-pulsation rotor integrated permanent magnet magnetic lead screw suitable for long-stroke linear motion

Abstract

The invention discloses a low-pulsation rotor integrated permanent magnet magnetic lead screw suitable for long-stroke linear motion, and belongs to the technical field of electromechanics. The permanent magnet magnetic lead screw comprises a stator, a rotor and a mover; the rotor is of an integrated structure composed of a rotor cylinder and a threaded iron core, the stator comprises a stator iron core and stator magnetic steel, and the rotor comprises a rotor iron core and rotor magnetic steel. Rotor magnetic steel is fixed on the outer circumferential surface of the rotor iron core; the rotor cylinder is sleeved outside the rotor, and a threaded iron core is arranged on the outer circumferential surface of the rotor cylinder; a stator core is sleeved on the outer side of the rotor, stator magnetic steel is fixed on the inner circumferential surface of the stator core, the polarities of the stator magnetic steel on the same circumference are the same, and the stator magnetic steel on adjacent circumferences are arranged in a staggered pole mode along the axial direction and are magnetized in parallel. The three-dimensional magnetic field modulation principle is adopted, the rotor is of a ferromagnetic material integrated structure, and the rotor has the advantages of being easy to machine, high in mechanical strength, low in cost and capable of achieving a long stroke conveniently; the staggered pole arrangement of the stator magnetic steel can realize low pulsation.

Description

Technical Field

[0001] The invention belongs to the field of electromechanical technology, and in particular relates to a low-pulsation mover-integrated permanent magnetic lead screw suitable for long-stroke linear motion. Background Art

[0002] The realization of a linear motion system with long stroke, high thrust density and high reliability is a key issue in national defense, aerospace and other strategic fields. Although high thrust density and suitable for long stroke applications can be achieved by using a high-performance rotary motor with a mechanical lead screw to achieve linear motion, the introduction of a mechanical transmission chain can cause the system to become stuck, break teeth and other problems, which reduces the reliability of the system.

[0003] Compared with traditional mechanical screws, permanent magnetic screws have the characteristics of high reliability, no damage when overloaded, and no maintenance. At the same time, its permanent magnetic structure gives it a higher torque density than reluctance magnetic screws. At present, permanent magnetic screws have a wide range of applications in mechanical transmission and extreme environments, but their travel is limited by the cost and processing of permanent magnets.

[0004] For the traditional permanent magnetic screw, its rotor and mover are composed of an iron core and a spiral permanent magnet, which can be regarded as replacing the thread of the mechanical screw with a permanent magnet. Its rotor is driven by other equipment to rotate, and the spiral structure allows the mover to translate in the axial direction. However, the stroke of the permanent magnetic screw is limited by the length of the mover, and the mover has problems such as high cost and difficult processing due to the spiral permanent magnet, which makes the stroke of the traditional permanent magnetic screw short.

[0005] The magnetic field modulation permanent magnetic screw is a new structure that has emerged in recent years by applying the magnetic field modulation principle on the basis of the permanent magnetic screw. The permanent magnetic screw consists of three parts: an outer stator, an inner rotor, and a unique modulation mover. The structure of the outer stator and the inner rotor consists of an iron core and a spiral permanent magnet. The difference is that the number of pole pairs of the stator and the rotor is different, and the structure of the modulation mover is a spiral ferromagnetic material. The rotor rotates, the stator is fixed, and the mover moves in translation. However, due to the principle of magnetic field modulation, torque fluctuations and thrust fluctuations are inevitable.

[0006] In summary, the traditional permanent magnet lead screw has the problems of short stroke and high cost; while the magnetic field modulation permanent magnet lead screw has the problems of torque fluctuation and thrust fluctuation. Summary of the invention

[0007] The purpose of the present invention is to eliminate torque and thrust fluctuations and realize long-stroke movement of a magnetic screw at a low cost, and to propose a low-pulsation mover-integrated permanent magnet magnetic screw suitable for long-stroke linear motion.

[0008] The present invention specifically relates to a permanent magnetic screw that uses magnetic field modulation to achieve long-stroke motion. Through the three-dimensional magnetic field modulation effect, the mover, as a modulation external thread sleeve, forms a non-planar structure with the magnetic poles of the stator and the rotor, thereby avoiding the asymmetric magnetic resistance caused by the parallel arrangement of the magnetic poles and the modulation external thread sleeve, and the output pulsation generated. At the same time, in order to further reduce the output pulsation and improve the mechanical strength, the present invention adopts an integrated mover structure and uses the saturation effect of the remote magnetic circuit to reduce the leakage magnetic loss.

[0009] To achieve the above object, the technical solution adopted by the present invention is:

[0010] A low-pulsation mover integrated permanent magnetic screw suitable for long-stroke linear motion comprises a stator, a rotor and a mover; the stator comprises a stator core and N stator magnets, wherein N is an even number; the rotor comprises a rotor core and rotor magnets, both of which are arc-shaped; the mover comprises a threaded core and a mover cylinder, the thread thickness of the threaded core is two-thirds of the axial length of a single stator magnet; the stator magnet and the rotor magnet are both permanent magnets; the pole pitch of the stator magnet is equal to the pitch of the mover thread, and the number of rotor poles is equal to the number of mover thread lines;

[0011] A rotor core is fixed on the shaft, and a rotor magnet is fixed on the outer circumference of the rotor core; a mover cylinder is sleeved on the outer side of the rotor, a gap is provided between the inner circumference of the mover cylinder and the outer side of the rotor, and a threaded iron core is provided on the outer circumference of the mover cylinder;

[0012] A stator core is mounted on the outside of the mover, and N stator magnets are fixed on the inner circumference of the stator core. The polarities of the N stator magnets are alternately arranged in the axial direction. A gap is provided between the inner side surface of the stator magnet and the tooth top circle of the threaded core of the mover. The N stator magnets on the same circumference have the same polarity, and the N stator magnets on adjacent circumferences are staggered in the axial direction and magnetized in parallel.

[0013] Furthermore, the N stator magnets on adjacent circumferences are arranged in an axially staggered manner, and the staggered angle is the central angle of the stator magnets divided by the number of stator pole pairs. The positioning force suppression effect is the best.

[0014] Furthermore, the mover is made of ferromagnetic material and is formed in one piece (different from the traditional separate iron core).

[0015] Furthermore, the stator also includes a stator shell; the stator shell is fixedly sleeved on the outside of the stator core.

[0016] Since the present invention adopts the three-dimensional magnetic field modulation effect, the low-pulsation mover integrated permanent magnetic magnetic lead screw suitable for long-stroke linear motion of the present invention has the following characteristics:

[0017] 1. Compared with the traditional permanent magnetic screw, the permanent magnetic screw of the present invention uses the magnetic field modulation effect to introduce a modulated external thread sleeve structure. Only the permanent magnets are distributed on the stator and the rotor, and the mover is composed of a mover cylinder and a threaded iron core (different from the traditional separate iron core) to form an integrated structure. It uses ferromagnetic materials, has the characteristics of low cost, and is easy to achieve long-stroke linear motion;

[0018] 2. Compared with the magnetic screw with magnetic field modulation, the magnetic poles of the magnetic field modulation in the present invention are not parallel to the modulated external thread sleeve. The magnetic poles on both sides of each stator magnetic steel present a certain angle, and the modulated external thread sleeve structure spans the magnetic poles. Its special structure can effectively eliminate thrust fluctuations and torque fluctuations;

[0019] 3. The present invention uses the principle of three-dimensional magnetic field modulation, through theoretical calculation and simulation, under the structural parameter requirement that the number of rotor poles is equal to the number of rotor thread lines, to verify that the stator generates a magnetic field on the inner side of the mover with the same number of rotor poles, and different numbers of rotor poles correspond to different output characteristics;

[0020] 4. Compared with the traditional mover structure composed of spiral or block ferromagnetic materials, the mover integrated structure proposed in the present invention has higher mechanical strength and is easy to process. At the same time, the inner wall of the mover cylinder can guide the rotor magnetic circuit to close with the stator through the modulated external thread sleeve, thereby improving the utilization rate of the rotor permanent magnet;

[0021] 5. Compared with the existing spiral permanent magnets composed of permanent magnets divided into blocks, the block magnetic steel arrangement of the stator and rotor can greatly reduce the processing difficulty and improve the processing accuracy;

[0022] 6. The positioning torque can be suppressed by axially staggered distribution of the stator magnets, and there is an optimal staggered angle, which has been verified by simulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the low pulsation mover integrated permanent magnetic screw of the present invention;

[0024] Figure 2 This is a cross-sectional view of the low-pulsation mover integrated permanent magnetic lead screw of the present invention;

[0025] Figure 3 This is a schematic diagram of the magnetization of the stator and rotor, where: Figure 3 (a) is a schematic diagram of stator magnetization; Figure 3 (b) is a schematic diagram of rotor magnetization;

[0026] Figure 4 It is the schematic diagram of the mover structure;

[0027] Figure 5 is a schematic diagram of the stator structure;

[0028] Figure 6 is a schematic diagram of the rotor structure;

[0029] Figure 7 It is the frequency domain distribution diagram of the magnetic field after the stator and rotor of the magnetic screw of the present invention are modulated, wherein: Figure 7 (a) is a frequency domain distribution diagram of the magnetic field after the rotor of the magnetic screw of the present invention is modulated; Figure 7 (b) is a frequency domain distribution diagram of the magnetic field after the stator of the magnetic screw of the present invention is modulated;

[0030] Figure 8 It is a static characteristic diagram of the magnetic screw of the present invention, wherein: Figure 8 (a) is the thrust displacement characteristic diagram; Figure 8 (b) is the torque angular displacement characteristic diagram;

[0031] Fig. 9 is a steady-state characteristic diagram of the magnetic screw of the present invention;

[0032] Fig.10 This is a schematic diagram of the stator structure of the alternative solution, where: Fig.10 (a) is a schematic diagram of the Halbach stator structure; Fig.10 (b) is a schematic diagram of the magnetic field concentrated stator structure.

[0033] The names and reference numerals of the components involved in the above drawings are as follows:

[0034] 1- stator housing; 2- stator core; 3- stator magnet; 4- integrated mover; 5- rotor magnet; 6- rotor core; 7- shaft; 8- threaded core; 9- mover cylinder. DETAILED DESCRIPTION

[0035] Specific implementation method 1: Figure 1-Figure 6 As shown, this embodiment discloses a low-pulsation mover integrated permanent magnetic screw suitable for long-stroke linear motion, including a stator, a rotor and a mover; the stator includes a stator core 2 and N stator magnets 3, wherein N is an even number; the rotor consists of a rotor core 6 and a rotor magnet 5; the stator core 2 and the rotor core 6 are both made of ferromagnetic materials and formed by turning; the rotor magnet 5 and the stator magnet 3 are both arc-shaped, made of permanent magnet materials, and formed by wire cutting; the mover consists of a threaded core 8 and a mover cylinder 9 (the action principle of the mover is similar to that of a magnetic field modulated permanent magnetic screw), which is integrally formed by turning, and the thread thickness of the threaded core 8 is two-thirds of the axial length of a single stator magnet 3 (to eliminate some leakage magnetic effects); the pole pitch of the stator magnet 3 is equal to the pitch of the mover thread, and the number of rotor poles is equal to the number of mover thread lines;

[0036] The shaft 7 is fixed with a rotor core 6 (in a cylindrical shape) by a shrink-fit method, and the outer circumferential surface of the rotor core 6 is fixed with a rotor magnet 5 that is butt-jointed in blocks by bonding, and the rotor magnet 5 that is butt-jointed in blocks forms an annular permanent magnet (radial magnetization); the mover cylinder 9 is sleeved on the outer side of the rotor, and a gap is provided between the inner circumferential surface of the mover cylinder 9 and the outer side surface of the rotor, and a threaded core 8 is milled on the outer circumferential surface of the mover cylinder 9 (thereby forming an integrated mover 4);

[0037] A stator core 2 is mounted on the outside of the mover, and N stator magnets 3 are bonded and fixed on the inner circumferential surface of the stator core 2. The polarities of the N stator magnets 3 are arranged alternately in the axial direction. A gap is provided between the inner side surface of the stator magnet 3 and the tooth top circle of the threaded core 8 of the mover. The N stator magnets 3 located on the same circumference have the same polarity, and the N stator magnets 3 on adjacent circles are arranged with staggered poles in the axial direction (the N stator magnets 3 on adjacent circles are arranged in a staggered manner, and the NS poles are arranged alternately in sequence), and are magnetized in parallel.

[0038] Furthermore, the N stator magnets 3 on adjacent circumferences are arranged in an axially staggered manner, and the staggered angle is the central angle of the stator magnet 3 divided by the number of stator pole pairs. The staggered pole structure is as follows: Figure 5 shown.

[0039] Furthermore, the stator further comprises a stator housing 1; the stator housing 1 is fixedly sleeved on the outside of the stator core 2, such as Figure 1 shown.

[0040] Furthermore, for a larger rotor structure, when magnetization is difficult, a segmented rotor magnet 5 (parallel magnetization) should be used, and an additional bushing should be added to the outside of the rotor magnet 5 .

[0041] The innovative structure of the present invention is:

[0042] 1. The mover is composed of a threaded core 8 and a mover cylinder 9. The threaded core 8 is arranged on the outer circumference of the mover cylinder 9. The thread thickness of the threaded core 8 on the outer side of the mover is two-thirds of the axial length of the single stator magnetic steel 3 (to eliminate the influence of partial magnetic leakage). Its structure is as follows: Figure 4 , Figure 5 As shown;

[0043] 2. The stator permanent magnet is magnetized in parallel by segmented permanent magnets instead of radial magnetization by annular permanent magnets. The NS pole magnetization method is as follows: Figure 3 As shown in (a), the processing technology is simplified and the processing difficulty is reduced;

[0044] 3. N stator magnets 3 should be arranged in axial staggered poles to eliminate the torque and thrust fluctuations caused by the stator magnets 3. The staggered angle should be the central angle of the stator magnet 3 divided by the number of stator pole pairs. The positioning torque suppression effect is the best. The staggered pole structure is as follows: Figure 5 As shown, the center angle of the magnetic poles on both sides of each stator magnet 3 located on the same circumference is 360° / N.

[0045] The present invention changes the direction of magnetic field modulation and uses a staggered pole method to design a mover with a special shape, which has the characteristics of low cost, long stroke and no pulsation.

[0046] Figure 7 is a frequency domain distribution diagram of the magnetic field after the stator and rotor of the magnetic screw of the present invention are modulated, wherein Figure 7 (a) is a frequency domain distribution diagram of the magnetic field after the rotor of the magnetic screw of the present invention is modulated (i.e., the frequency spectrum of the modulated magnetic field on the outside of the inner rotor modulated by the modulation ring). It can be seen that magnetic field harmonics with the same number of stator poles are generated on the outside of the mover; Figure 7 (b) is the frequency domain distribution diagram of the magnetic field after stator modulation of the magnetic screw of the present invention (i.e., the modulated magnetic field spectrum on the inner side of the outer stator modulated by the modulation ring). It can be seen that a magnetic field with the same number of rotor poles is generated on the inner side of the mover.

[0047] Figure 8 (a) is a thrust displacement characteristic diagram of the magnetic screw of the present invention, Figure 8 (b) is the torque angular displacement characteristic diagram of the magnetic screw of the present invention, verifying the correctness of the principle.

[0048] Fig. 9 This is a steady-state characteristic diagram of the magnetic screw of the present invention. It can be seen from the diagram that the thrust pulsation of the magnetic screw of the present invention is basically 0, which verifies the correctness of the structure.

[0049] Fig.10 These are two alternatives to the magnetic screw stator of the present invention, which improve the utilization rate of the permanent magnets but increase the difficulty of processing.

[0050] The present invention has two alternatives:

[0051] Alternative 1:

[0052] The distribution of stator magnetic steel 3 is changed to Fig.10 In the Halbach structure shown in (a), the magnetic poles of the permanent magnets are arranged in the order of axially upward, radially inward, axially downward, and radially outward. While increasing the air gap flux density, it can reduce the leakage flux caused by modulating the cross-pole of the external threaded sleeve.

[0053] Alternative 2:

[0054] The structure of the stator is changed to Fig.10 (b) shows a magnetic field structure in which the stator has the permanent magnet poles axially upward and the ferromagnetic material and the permanent magnet poles axially downward, and the ferromagnetic material is arranged in sequence, which can effectively reduce leakage flux while reducing the use of permanent magnets and lowering production costs.

[0055] The working process of the permanent magnetic screw of the present invention is:

[0056] During operation, the rotor rotates, while the stator remains stationary, and the mover is fixed on the guide rail slider and moves in translation along the guide rail. Different from the conventional design, the magnetic field arrangement direction of the stator and the rotor in the present invention is perpendicular, so that the modulating mover intersects the magnetic poles of the stator and the rotor obliquely, effectively avoiding the asymmetry of magnetic resistance, thereby eliminating the fluctuation of thrust and torque.

[0057] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A low-pulsation mover integrated permanent magnetic screw suitable for long-stroke linear motion, comprising a stator, a rotor and a mover; characterized in that: The stator comprises a stator core (2) and N stator magnetic steels (3), wherein N is an even number; the rotor comprises a rotor core (6) and a rotor magnetic steel (5), wherein the rotor magnetic steel (5) and the stator magnetic steel (3) are both in the shape of an arc; the mover comprises a threaded core (8) and a mover cylinder (9), wherein the thread thickness of the threaded core (8) is two-thirds of the axial length of a single stator magnetic steel (3); the stator magnetic steel (3) and the rotor magnetic steel (5) are both permanent magnets; the pole pitch of the stator magnetic steel (3) is equal to the thread pitch of the mover thread, and the number of rotor poles is equal to the number of thread lines of the mover thread; A rotor core (6) is fixed on the shaft (7), and a rotor magnet (5) is fixed on the outer circumferential surface of the rotor core (6); a mover cylinder (9) is sleeved on the outer side of the rotor, a gap is provided between the inner circumferential surface of the mover cylinder (9) and the outer side surface of the rotor, and a threaded iron core (8) is provided on the outer circumferential surface of the mover cylinder (9); A stator core (2) is sleeved on the outer side of the mover, and N stator magnetic steels (3) are fixed on the inner circumferential surface of the stator core (2). The polarities of the N stator magnetic steels (3) are arranged alternately in the axial direction, and a gap is provided between the inner side surface of the stator magnetic steel (3) and the tooth top circle of the threaded core (8) of the mover. The N stator magnetic steels (3) located on the same circumference have the same polarity, and the N stator magnetic steels (3) on adjacent circumferences are arranged with staggered polarity along the axial direction and are magnetized in parallel.

2. The low-pulsation mover integrated permanent magnetic lead screw suitable for long-stroke linear motion according to claim 1 is characterized in that: The N stator magnetic steels (3) on adjacent circumferences are arranged with staggered poles along the axial direction, and the staggered angle is the central angle corresponding to the stator magnetic steel (3) divided by the number of stator pole pairs.

3. The low-pulsation mover integrated permanent magnetic lead screw suitable for long-stroke linear motion according to claim 1 or 2, characterized in that: The mover is made of ferromagnetic material and is formed in one piece.

4. The low-pulsation mover integrated permanent magnetic lead screw suitable for long-stroke linear motion according to claim 1, characterized in that: The stator further comprises a stator housing (1); the stator housing (1) is fixedly sleeved on the outside of the stator core (2).

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