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

Abstract

This invention relates to a low-pulsation, integrated permanent magnet screw suitable for long-stroke linear motion, belonging to the field of electromechanical technology. The permanent magnet screw includes a stator, a rotor, and a mover. The mover is an integrated structure consisting of a mover cylinder and a threaded iron core. The stator includes a stator iron core and stator magnets, and the rotor includes a rotor iron core and rotor magnets. Rotor magnets are fixed on the outer circumference of the rotor iron core. The mover cylinder is fitted onto the outside of the rotor, and a threaded iron core is provided on its outer circumference. The stator iron core is fitted onto the outside of the mover, and the stator magnets are fixed on the inner circumference of the stator iron core. Stator magnets on the same circumference have the same polarity, and stator magnets on adjacent circumferences are arranged with staggered poles along the axial direction and magnetized in parallel. This invention adopts the principle of three-dimensional magnetic field modulation. The mover uses an integrated structure of ferromagnetic material, which has the characteristics of simple processing, high mechanical strength, low cost, and ease of achieving long stroke. The staggered pole arrangement of the stator magnets enables low pulsation.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of electromechanical technology, and particularly relates to a low-pulsation mover integrated permanent magnetic magnetic force screw suitable for long-stroke linear motion. BACKGROUND

[0002] The realization of a linear motion system with large stroke, high thrust density and high reliability is a key problem in the fields of national defense, aerospace and other strategic fields. Linear motion can be realized by a high-performance rotary motor in cooperation with a mechanical screw, which can realize high thrust density and is suitable for large-stroke applications. However, due to the introduction of a mechanical transmission chain, the system has the phenomena of jamming and tooth collapse, resulting in reduced system reliability.

[0003] Compared with a traditional mechanical screw, a permanent magnetic magnetic force screw has the characteristics of high reliability, no damage under overload, and no maintenance. At the same time, the permanent magnetic structure gives it a higher torque density than a magnetic resistance magnetic force screw. At present, the permanent magnetic magnetic force screw has a wide application space in mechanical transmission and extreme environments, but its stroke is limited due to the cost and processing problems of the permanent magnet.

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

[0005] The magnetic field modulation permanent magnetic magnetic force screw is a new structure that appeared in recent years on the basis of the permanent magnetic magnetic force screw and applies the principle of magnetic field modulation. The permanent magnetic magnetic force screw is composed of an outer stator, an inner rotor and a unique modulation mover. The structure of the outer stator and the inner rotor is composed of a core and a spiral permanent magnet, and 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 the axial direction. However, due to the use of the principle of magnetic field modulation, torque fluctuation and thrust fluctuation inevitably exist.

[0006] In summary, the traditional permanent magnetic magnetic force screw has the problems of short stroke and high cost, and the magnetic field modulation permanent magnetic magnetic force screw has the problems of torque fluctuation and thrust fluctuation. SUMMARY

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

[0008] The application relates to a permanent magnetic force screw rod for realizing long-stroke movement by magnetic field modulation, and through a three-dimensional magnetic field modulation effect, a mover is arranged as a modulated outer threaded sleeve to form a non-planar structure with magnetic poles of a stator and a rotor, so that magnetic resistance asymmetry caused by parallel arrangement of the magnetic poles and the modulated outer threaded sleeve is avoided, and output pulsation is further generated.

[0009] To achieve the above object, the application adopts the technical scheme of:

[0010] The application relates to a low-pulsation mover integrated permanent magnetic force screw rod suitable for long-stroke linear movement, which comprises a stator, a rotor and a mover.

[0011] The rotor iron core is fixed on the shaft, and the rotor magnetic steel is fixed on the outer circumferential surface of the rotor iron core.

[0012] The stator iron core is sleeved outside the mover, the N stator magnetic steels are fixed on the inner circumferential surface of the stator iron core, the polarities of the N stator magnetic steels are arranged alternately along the axial direction in sequence, the inner side surface of the stator magnetic steel is arranged with a gap between the tooth top circle of the threaded iron core of the mover, the polarities of the N stator magnetic steels on the same circumference are the same, the N stator magnetic steels on the adjacent circumferences are arranged with a polar error along the axial direction, and the N stator magnetic steels on the adjacent circumferences are arranged with a polar error along the axial direction.

[0013] Further, the N stator magnetic steels on the adjacent circumferences are arranged with a polar error along the axial direction, and the polar error angle is the central angle corresponding to the stator magnetic steel divided by the stator pole pair number.

[0014] Further, the mover is made of a ferromagnetic material and is integrally formed (different from a traditional separated iron core).

[0015] Further, the stator further comprises a stator shell.

[0016] The application adopts the three-dimensional magnetic field modulation effect, so that the low-pulsation mover integrated permanent magnetic force screw rod suitable for long-stroke linear movement has the following characteristics:

[0017] 1. Compared with the traditional permanent magnetic force screw, the permanent magnetic force screw of the application introduces the modulation outer thread sleeve structure by using the magnetic field modulation effect. Permanent magnets are distributed on the stator and the rotor only, and the mover is composed of the mover cylinder and the threaded core (different from the traditional separated core) in an integrated structure, which adopts ferromagnetic material and has the characteristics of low cost, facilitating the realization of long-stroke linear motion;

[0018] 2. Compared with the magnetic force screw using the magnetic field modulation only, the magnetic poles of the magnetic field modulation in the application are not parallel to the modulation outer thread sleeve, the magnetic poles on both sides of each stator magnetic steel present a certain angle, and the modulation outer thread sleeve structure spans the magnetic poles, and the special structure can effectively eliminate the thrust fluctuation and torque fluctuation;

[0019] 3. The application uses the three-dimensional magnetic field modulation principle, and through theoretical calculation and simulation, it verifies that the stator generates the same magnetic field as the rotor pole number on the inside of the mover under the structure parameter requirement that the rotor pole number is equal to the number of threads of the mover, and different rotor pole numbers correspond to different output characteristics;

[0020] 4. Compared with the traditional mover structure composed of spiral or block ferromagnetic material, the integrated structure of the mover proposed by the application has higher mechanical strength and is easy to process, and at the same time, the inner wall of the mover cylinder can guide the rotor magnetic circuit to close through the modulation outer thread sleeve and the stator, improving the utilization rate of the rotor permanent magnet;

[0021] 5. The block magnetic steel arrangement of the stator and the rotor can greatly reduce the processing difficulty and improve the processing precision compared with the existing spiral permanent magnet composed of block permanent magnet division;

[0022] 6. By axially misaligned distribution of the stator magnetic steel, the positioning torque is suppressed, and there is an optimal misaligned angle, which has been verified by simulation. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a schematic diagram of the low-pulse integrated mover permanent magnetic force screw of the application;

[0024] Figure 2 It is a sectional view of the low-pulse integrated mover permanent magnetic force screw of the application;

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

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

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

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

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

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

[0031] Figure 9 This is a diagram showing the steady-state characteristics of the magnetic lead screw of the present invention.

[0032] Figure 10 This is a schematic diagram of the stator structure for the alternative solution, where: Figure 10 (a) is a schematic diagram of the Halbach stator structure; Figure 10 (b) is a schematic diagram of a magnetically focused stator structure.

[0033] The component names and reference numerals in the above figures 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-Motor cylinder. Detailed Implementation

[0035] Specific implementation method one: as follows Figures 1-6 As shown, this embodiment discloses a low-pulsation integrated permanent magnet screw suitable for long-stroke linear motion, comprising a stator, a rotor, and a mover. The stator includes a stator core 2 and N stator magnets 3, where N is an even number. The rotor consists of a rotor core 6 and rotor magnets 5. Both the stator core 2 and the rotor core 6 are made of ferromagnetic material and are machined by turning. Both the rotor magnets 5 and the stator magnets 3 are arc-shaped, made of permanent magnet material, and machined by wire cutting. The mover consists of a threaded core 8 and a mover cylinder 9 (the working principle of the mover is similar to that of a magnetic field-modulated permanent magnet screw), and is integrally formed by turning. 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 influence). The pole pitch of the stator magnets 3 is equal to the thread pitch of the mover, and the number of rotor poles is equal to the number of thread lines of the mover.

[0036] The rotor iron core 6 is fixed on the shaft 7 by hot fitting, the rotor magnetic steel 5 is fixed on the outer circumferential surface of the rotor iron core 6 by bonding, the rotor magnetic steel 5 is composed of a ring-shaped permanent magnet (radial magnetization), the mover cylinder 9 is sleeved outside the rotor, a gap is arranged between the inner circumferential surface of the mover cylinder 9 and the outer surface of the rotor, and the threaded iron core 8 is milled on the outer circumferential surface of the mover cylinder 9 (so as to form an integrated mover 4);

[0037] The stator iron core 2 is sleeved outside the mover, N pieces of stator magnetic steels 3 are bonded and fixed on the inner circumferential surface of the stator iron core 2, the polarities of the N pieces of stator magnetic steels 3 are arranged alternately along the axial direction, a gap is arranged between the inner side surface of the stator magnetic steel 3 and the tooth top circle of the threaded iron core 8 of the mover, the polarities of the N pieces of stator magnetic steels 3 on the same circumference are the same, the N pieces of stator magnetic steels 3 on the adjacent circumferences are arranged in an axial error pole manner (the N pieces of stator magnetic steels 3 on the adjacent circumferences are arranged in an error position manner in turn, and the NS poles are arranged alternately), and the N pieces of stator magnetic steels 3 are parallel magnetized.

[0038] Further, the N pieces of stator magnetic steels 3 on the adjacent circumferences are arranged in an axial error pole manner, the error angle is the central angle corresponding to the stator magnetic steel 3 divided by the stator pole pair number, and the error pole structure is as shown in Figure 5 .

[0039] Further, the stator further comprises a stator shell 1, the stator shell 1 is fixed and sleeved outside the stator iron core 2, and the stator shell 1 is as shown in Figure 1 .

[0040] Further, for a larger rotor structure, when magnetization is difficult, the segmented rotor magnetic steel 5 (parallel magnetization) should be used, and a bushing is additionally arranged outside the rotor magnetic steel 5.

[0041] The innovative structure of the application is as follows:

[0042] 1. The mover is composed of the threaded iron core 8 and the mover cylinder 9, the threaded iron core 8 is arranged on the outer circumferential surface of the mover cylinder 9, the thread thickness of the threaded iron core 8 on the outer side of the mover is two-thirds of the axial length of the single piece of stator magnetic steel 3 (so as to eliminate the influence of part of the magnetic flux leakage), and the structure is as shown in Figure 4 , Figure 5 .

[0043] 2. The stator permanent magnet is replaced by the segmented permanent magnet parallel magnetization instead of the ring-shaped permanent magnet radial magnetization, the NS pole magnetization mode is as shown in Figure 3 (a), the processing technology is simplified, and the processing difficulty is reduced;

[0044] 3. The N pieces of stator magnetic steels 3 should be arranged in an axial error pole manner to eliminate the torque and thrust fluctuation caused by the stator magnetic steel 3, the error angle should be the central angle corresponding to the stator magnetic steel 3 divided by the stator pole pair number, the positioning torque suppression effect is best, and the error pole structure is as shown inFigure 5 The central angle of the magnetic poles on both sides of each stator magnetic steel 3 located on the same circumference = 360° / N.

[0045] The present application has the characteristics of low cost, long stroke and no pulsation by changing the direction of magnetic field modulation, using the method of wrong poles and designing special shape of the mover.

[0046] Figure 7 The frequency domain distribution diagram of the modulated magnetic field of the stator and rotor of the magnetic force screw of the present application, wherein Figure 7 (a) is the frequency domain distribution diagram of the modulated magnetic field of the rotor of the magnetic force screw of the present application (i.e. the modulated magnetic field spectrum on the outside of the inner rotor modulated by the modulating ring), it can be seen that the same number of magnetic field harmonics as the stator poles are generated on the outside of the mover; Figure 7 (b) is the frequency domain distribution diagram of the modulated magnetic field of the stator of the magnetic force screw of the present application (i.e. the modulated magnetic field spectrum on the inside of the outer stator modulated by the modulating ring), it can be seen that the same number of magnetic fields as the rotor poles are generated on the inside of the mover.

[0047] Figure 8 (a) is the thrust displacement characteristic diagram of the magnetic force screw of the present application, Figure 8 (b) is the torque angle displacement characteristic diagram of the magnetic force screw of the present application, which verifies the correctness of the principle.

[0048] Figure 9 The steady state characteristic diagram of the magnetic force screw of the present application, from which it can be seen that the thrust pulsation of the magnetic force screw of the present application is basically 0, which verifies the correctness of the structure.

[0049] Figure 10 Two alternative schemes for the stator of the magnetic force screw of the present application, which improve the utilization rate of permanent magnets but increase the processing difficulty.

[0050] The present application has two alternative schemes:

[0051] Alternative scheme one:

[0052] The distribution of the stator magnetic steel 3 is changed to the Halbach structure as shown in Figure 10 (a), the directions of the magnetic poles of the permanent magnets are arranged in sequence as axially upward, radially inward, axially downward and radially outward, which can increase the air gap magnetic density and reduce the leakage magnetic of the modulated outer threaded sleeve.

[0053] Alternative scheme two:

[0054] The structure of the stator is changed to the magnetic concentrating structure as shown in Figure 10 (b), the permanent magnets are arranged in sequence as axially upward, ferromagnetic material and axially downward, which can effectively reduce the leakage magnetic and the use amount of the permanent magnets, and reduce the production cost.

[0055] The working process of the permanent magnetic magnetic force screw rod of the present application is as follows:

[0056] During working, the rotor rotates, while the stator remains fixed, and the mover is fixed on the guide rail slider to make translational movement along the guide rail direction. Different from the conventional design, the magnetic field arrangement direction of the stator and the rotor is vertical in the present application, so that the modulation mover is obliquely intersected with the magnetic poles of the stator and the rotor, effectively avoiding the asymmetry of magnetic resistance, and further eliminating the fluctuation of thrust and torque.

[0057] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the art, according to the technical solution and the inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A low-ripple integrated permanent-magnetic magnetic-force lead 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 blocks of stator magnetic steel (3), wherein N is an even number; the rotor is composed of a rotor core (6) and rotor magnetic steel (5), the rotor magnetic steel (5) and the stator magnetic steel (3) are both in the shape of a circular arc; the mover is composed of a threaded core (8) and a mover cylinder (9), the thread thickness of the threaded core (8) is two-thirds of the axial length of the single block of 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, and the number of rotor poles is equal to the number of threads of the mover; The rotor core (6) is fixed on the shaft (7), and the rotor magnetic steel (5) is fixed on the outer circumferential surface of the rotor core (6); the mover cylinder (9) is sleeved outside the rotor, a gap is arranged between the inner circumferential surface of the mover cylinder (9) and the outer surface of the rotor, and the threaded core (8) is arranged on the outer circumferential surface of the mover cylinder (9); the magnetic field arrangement directions of the stator and the rotor are perpendicular; The stator core (2) is sleeved outside the mover, the N blocks of stator magnetic steel (3) are fixed on the inner circumferential surface of the stator core (2), the polarities of the N blocks of stator magnetic steel (3) are alternately arranged along the axial direction in sequence, a gap is arranged 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 polarities of the N blocks of stator magnetic steel (3) on the same circumference are the same, the N blocks of stator magnetic steel (3) on the adjacent circumferences are arranged in the axial direction with the polarities being staggered and magnetized in parallel; the mover is made of ferromagnetic material and is integrally machined and formed.

2. The low ripple mover integrated permanent magnet magnetic force ball screw suitable for long stroke linear motion according to claim 1, characterized in that: The N blocks of stator magnetic steel (3) on the adjacent circumferences are arranged in the axial direction with the polarities being staggered, and the staggered angle is the corresponding central angle of the stator magnetic steel (3) divided by the number of stator pole pairs.

3. The low ripple mover integrated permanent magnet magnetic force ball screw suitable for long stroke linear motion according to claim 1, characterized in that: The stator further comprises a stator shell (1); the stator shell (1) is fixedly sleeved outside the stator core (2).

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