CN111490659A

CN111490659A - Symmetric permanent magnet type unidirectional proportional electromagnet based on air gap compensation

Info

Publication number: CN111490659A
Application number: CN201910071547.3A
Authority: CN
Inventors: 赖永江; 孟彬; 裘信国; 姜伟
Original assignee: Zhejiang University of Technology ZJUT
Current assignee: Zhejiang University of Technology ZJUT
Priority date: 2019-01-25
Filing date: 2019-01-25
Publication date: 2020-08-04

Abstract

A front end cover and a rear end cover are respectively arranged on the front side and the rear side of a stator of the symmetrical permanent magnet type unidirectional proportional electromagnet based on air gap compensation, N convex teeth are uniformly distributed on the circumference of a yoke ring, the convex teeth form yoke magnetic poles, and the stator magnetic poles on each yoke are identical in shape and are axially aligned; a control coil is arranged between the second yoke iron and the third yoke iron to form a control magnetic flux; a first magnetic isolating block and first magnetic steel are arranged between the first yoke and the second yoke; a second magnetic isolating block and second magnetic steel are arranged between the third yoke and the fourth yoke; the first armature and the second armature are uniformly distributed with armature magnetic poles along the circumferential direction, the end faces of the armature magnetic poles comprise circumferential tooth surfaces and side elevation surfaces, and the tooth surfaces and the yoke magnetic poles form radial air gaps; the side elevation is positioned at one end of the tooth surface and forms an axial air gap with the side surface of the stator magnetic pole; the positions of the side elevation surfaces of the armature magnetic poles of the first armature and the second armature are opposite on the tooth surface, so that axial air gaps are symmetrically distributed on two sides of the yoke magnetic pole.

Description

Symmetric permanent magnet type unidirectional proportional electromagnet based on air gap compensation

Technical Field

The invention relates to a proportional electromagnet.

Background

The rotary valve is a reversing valve which changes the relative position of a valve core and a valve sleeve by utilizing rotary motion to change a flow path in the rotary valve and finally realizes the opening and closing or reversing of the flow path. The rotary valve can be driven manually, mechanically or directly by an electric motor, a motor and a rotary electromagnet to achieve precise servo/proportional control. Compared with a slide valve or a cone valve, the rotary valve has the advantages of high reliability, simple structure, high working frequency, strong oil pollution resistance and the like, can be widely applied to hydraulic systems of high-speed switching, high-speed excitation and high-speed reversing, and can obtain rated flow which is larger than that of a multi-stage slide valve by a single-stage rotary valve particularly when the number of throttling grooves of a valve core and a valve sleeve is large. However, in the prior electro-hydraulic servo/proportional control system, the rotary valve is far less widely used than the slide valve. The reason is that firstly, the throttling groove/window of the rotary valve is complex to process, secondly, the rotary electromagnet for driving the rotary valve is more difficult to obtain the proportion control characteristic than the direct-acting proportion electromagnet, the latter adopts a magnetism isolating ring structure, a magnetic circuit is divided into two paths of axial and radial at the magnetism isolating ring during excitation, the horizontal stroke-thrust characteristic required by the proportion control can be obtained after synthesis, although the welding of a magnetism isolating sleeve is more complicated, the problem is not big for mass automatic production, and the rotary electromagnet always needs to carry out special optimization design on the shapes of stator teeth and armature teeth to obtain the flatter moment-corner characteristic, thereby greatly limiting the practical application of the rotary electromagnet.

In order to popularize and apply the rotary valve in an electro-hydraulic servo/proportional system, people make a great deal of research on the optimization of the magnetic circuit topological structure and the moment angle characteristic of the rotary electromagnet. The torque motor is widely applied to nozzle flapper valves and jet pipe servo valves, proportional position control characteristics can be obtained through reasonable design of an elastic element, but a large working angle is difficult to obtain due to the fact that a magnetic circuit of the torque motor is based on an axial air gap. The improved torque motor based on the radial working air gap, which is proposed by Montagu of the American general detection company, has the advantages that the working rotation angle range is further expanded, and the torque motor has positive electromagnetic rigidity, so that the proportional position control characteristic can be obtained without adding an elastic element. To obtain a flat torque angle characteristic, Fumio of Hitachi designs the shape of the magnetic steel on the armature of the moving magnet torque motor, and cuts grooves along the radial direction on the pole surface and fills non-magnetic conductive material, so as to compensate the torque pulsation accompanied by the rotation of the armature. In the permanent magnet torque motor designed by the shin-teng-Erlang of Denso corporation, two magnetic poles formed by discrete magnetic steels are asymmetrically arranged on the outer side of a rotating shaft in a way of half magnetic pole angle difference, so that torque pulsation caused by the periphery of a polygonal magnetic pole is compensated, and stable torque-corner characteristics are obtained. The electric excitation torque motor developed by Zhang Guangqiong of Zhejiang university, etc. specially designs the shapes of the pole faces of the stator and the armature, and changes the torque angle characteristic of the motor by controlling the magnetic flux saturation degree at the tip of the pole shoe of the stator. The trekker et al propose a moving-magnet type rotary proportional electromagnet based on a radial working air gap, which is based on a differential magnetic circuit and has positive electromagnetic stiffness, but the structure is complicated, and the moving-magnet type rotary proportional electromagnet is not beneficial to industrial application and large-scale batch production.

Disclosure of Invention

In order to overcome the defects that the existing rotary electromagnet is difficult to obtain the horizontal moment-corner characteristic, has a complex structure and is not beneficial to industrial application and large-scale batch production, the invention provides a symmetrical permanent magnet type unidirectional proportion electromagnet based on air gap compensation, which is based on a mixed air gap, has the horizontal moment-corner characteristic and has a simple structure.

The basic principle of the invention is as follows: the common working air gaps in the electro-mechanical converter comprise a radial air gap and an axial air gap, the radial air gap can have a larger working rotation angle, but with the increase of the misalignment angle (the fixed armature is gradually aligned), the output torque can be reduced, namely the slope of a torque angle characteristic curve is negative; the axial air gap working range is narrower, but the output torque increases along with the increase of the misalignment angle, namely the slope of the torque angle characteristic curve is positive. Therefore, the working air gap is divided into two parts, the main working air gap is a radial air gap, and an axial air gap is added on the basis of the radial air gap. The moments generated by the radial air gap and the axial air gap are mutually modulated, a moment-angle characteristic curve close to the horizontal can be obtained through reasonable parameter optimization, and a proportional position control characteristic can be obtained through the addition of a spring balance mechanism.

The technical scheme adopted by the invention for solving the technical problems is as follows:

as shown in figures 1 and 2, the front side and the rear side of a yoke are respectively provided with a front end cover 2 and a rear end cover 12, a stator is internally provided with a first armature 3 and a second armature 13, and the first armature 3 and the second armature 13 are coaxially arranged on an output shaft 1. The stator consists of a first yoke 4, a second yoke 7, a third yoke 8 and a fourth yoke 10 which are axially and sequentially arranged, N convex teeth are uniformly distributed on the circumferences of the first yoke 4, the second yoke 7, the third yoke 8 and the fourth yoke 10, the convex teeth form yoke magnetic poles 15, and the stator magnetic poles 15 on the first yoke 4, the second yoke 7, the third yoke 8 and the fourth yoke 10 are identical in shape and are axially aligned, so that the output torque is increased. The second yoke iron 7 and the third yoke iron 8 are respectively provided with symmetrical grooves along the interface, and are spliced to form an annular groove, and a control coil 14 is placed in the annular groove to form control magnetic flux. A first magnetism isolating block 5 is arranged between the first yoke iron 4 and the second yoke iron 7; a second magnetism isolating block 9 is arranged between the third yoke 8 and the fourth yoke 10; first magnet steel 6 has been placed between first yoke 4 and second yoke 7, and second magnet steel 11 has been placed to third yoke 8 and fourth yoke 10 centre for form the bias magnetic flux.

The first armature 3 and the second armature 13 are coaxially spliced, N armature teeth are uniformly distributed on the first armature 3 and the second armature 13 along the circumferential direction, the armature teeth form an armature magnetic pole, the magnetic pole end face of the armature comprises a circumferential arc-shaped tooth face 31 and a side elevation face 32, and the tooth face 31 and the end part of the yoke magnetic pole 15 form a radial air gap. The side elevations 32 are located at one end of the tooth flanks 31, the side elevations 32 forming an axial air gap with the sides of the stator pole 15. The side elevation 32 of the armature pole of the first armature 3 is located at one end of the tooth flank 31 and the side elevation 32 of the armature pole of the second armature 13 is located at the other end of the tooth flank 31, so that the axial air gaps are symmetrically distributed on both sides of the yoke pole 15. In order to make the electromagnet work normally, the mode of the axial staggered teeth of the armature iron needs to be changed, namely the armature teeth of the second armature iron 13 need to lead the convex teeth of the yoke iron by an angle in the clockwise direction, and the armature teeth of the first armature iron 3 lag behind the convex teeth of the yoke iron by the same angle in the clockwise direction.

Preferably, the armature adopts a hollow cup structure, so that the rotational inertia is reduced, and the corresponding speed is increased. The front end cover 2, the rear end cover 12, the output shaft 1, the first magnet isolating block 5 and the second magnet isolating block 9 are made of non-magnetic-conductive metal materials, and the first armature 3, the second rotor 13, the first yoke 4, the second yoke 7, the third yoke 8 and the fourth yoke 10 are made of high-magnetic-conductivity metal soft magnetic materials.

All armature components and yokes of the invention have the same axial lead and are coaxial with the output shaft 1, and the axial direction of the invention refers to the axial lead of the output shaft 1.

Preferably, the first yoke 4, the second yoke 7, the third yoke 8 and the fourth yoke 10 are evenly distributed with 8 yoke poles 15 around the circumference, and each yoke pole 15 is separated by 45 °; the first armature 3 and the second armature 13 are circumferentially and uniformly distributed with 8 armature teeth.

Preferably, the teeth of the second armature 13 need to lead the teeth 1/4 of the yoke in the clockwise direction, and the armature teeth of the first armature 3 lag the armature teeth 1/4 of the yoke in the clockwise direction.

The invention has the following beneficial effects:

1. a hybrid working air gap is used to achieve a horizontal torque-turn angle characteristic. The working air gap is divided into two parts, the main working air gap is a radial air gap, and an axial air gap is added on the basis of the radial air gap. The moments generated by the radial air gap and the axial air gap are mutually modulated, a moment-angle characteristic curve close to the horizontal can be obtained through reasonable parameter optimization, and a proportional position control characteristic can be obtained through the addition of a spring balance mechanism.

2. The response speed is fast, and the output torque is large. Compared with other cylindrical structures of the armature of the rotary proportional electromagnet, the armature of the scheme provided by the invention is of a hollow cup structure, the rotational inertia is small, and higher dynamic response speed is favorably obtained. And the design of a multi-magnetic pole structure is adopted, so that the output torque is favorably improved.

3. An axial magnetic circuit symmetrical structure is adopted. Compared with an asymmetric axial magnetic circuit structure, the moment angle characteristic of the proportional electromagnet keeps symmetry no matter clockwise or anticlockwise rotation, and the working precision of the proportional electromagnet is guaranteed.

4. And single coil excitation is adopted, so that the control is simple. Compared with a double-phase excitation structure, the single-coil excitation structure can effectively reduce the complexity of a driving circuit and is simpler to control.

5. Simple structure and low cost. Compared with other rotary proportional electromagnets, the rotary proportional electromagnet has the advantages of small number of parts, easiness in processing and assembling, low manufacturing cost and contribution to industrial practical application and large-scale batch production.

Drawings

FIG. 1 is a schematic view of the present invention;

FIG. 2 is an assembly schematic of the present invention;

FIG. 3 is a schematic view of the output shaft of the present invention;

FIG. 4 is a schematic view of the front end cap construction of the present invention;

fig. 5 is a schematic structural view of a first armature of the present invention;

fig. 6 is a schematic structural view of a first yoke of the present invention;

FIG. 7 is a schematic view of the magnetic spacer structure of the present invention;

FIG. 8 is a schematic view of the magnetic steel structure of the present invention;

FIG. 9 is a schematic view showing the structure of a second yoke according to the present invention

FIG. 10 is a schematic view of the construction of the rear end cap of the present invention;

fig. 11 is a schematic structural view of a second armature of the present invention;

FIG. 12 is a graphical illustration of the torque angle characteristics of the radial air gap, axial air gap, and hybrid air gap;

FIG. 13 is a schematic diagram of the working principle of the present invention;

FIG. 14 is a schematic diagram of the working principle of the present invention, wherein the control coil 14 is supplied with current in one direction;

fig. 15 is a schematic diagram of the working principle of the present invention, and the control coil 14 is supplied with current in another direction.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

Referring to fig. 1 to 11, the front and rear sides of the yoke are respectively provided with a front end cover 2 and a rear end cover 12, the yoke is internally provided with a first armature 3 and a second armature 13, and the first armature 3 and the second armature 13 are coaxially arranged on an output shaft 1.

The yoke is composed of a first yoke 4, a second yoke 7, a third yoke 8 and a fourth yoke 10 which are axially arranged in sequence, 8 convex teeth are uniformly distributed on the circumference of each yoke ring, the convex teeth form yoke magnetic poles 15, each yoke magnetic pole 15 is separated by 45 degrees, and the yoke magnetic poles 15 on the first yoke 4, the second yoke 7, the third yoke 8 and the fourth yoke 10 are identical in shape and axially aligned, so that the increase of output torque is facilitated. The yoke iron 7 and the yoke iron 8 are respectively provided with symmetrical grooves along the interface, and are spliced to form an annular groove, and a control coil 14 is placed in the annular groove to form control magnetic flux. A first magnetism isolating block 5 is arranged between the first yoke 4 and the second yoke 7, and a first magnetic steel 6 is arranged on the inner ring of the first magnetism isolating block 5; a second magnetism isolating block 9 is arranged between the third yoke 8 and the fourth yoke 10, and a second magnetic steel 11 is arranged on the inner ring of the second magnetism isolating block 9 and used for forming bias magnetic flux.

The first armature 3 and the second armature 13 are coaxially spliced, 8 armature teeth are uniformly distributed on the first armature 3 and the second armature 13 along the radial direction, the armature teeth form armature magnetic poles, the end surface of each armature magnetic pole comprises a tooth surface 31 and a side elevation 32 which are circular arc-shaped, and the tooth surface 31 and the end surface of the stator magnetic pole 15 form a radial air gap; the side elevation 32 is located at one end of the tooth surface 31, and the side elevation 32 and the side surface of the stator pole 15 form an axial air gap. The side elevation 32 of the armature pole of the first armature 3 is located at one end of the tooth surface 31 and the side elevation 32 of the armature pole of the second armature 13 is located at the other end of the tooth surface 31, so that the axial air gaps are symmetrically distributed on both sides of the yoke pole. In order to make the electromagnet work normally, the way of the axial staggered teeth of the armature needs to be changed, namely, the armature teeth of the second armature 13 need to lead the yoke teeth 1/4 in the clockwise direction, and the armature teeth of the first armature 3 lag the yoke teeth 1/4 in the clockwise direction. The armature adopts a hollow cup structure, so that the rotational inertia is reduced, and the corresponding speed is increased. The front end cover 2, the rear end cover 12, the output shaft 1, the magnetic isolating block 5 and the magnetic isolating block 9 are made of non-magnetic-conductive metal materials, and the first armature 3, the second armature 13, the first yoke 4, the second yoke 7, the third yoke 8 and the fourth yoke 10 are made of high-magnetic-permeability metal soft magnetic materials.

As shown in fig. 13, when the control coil 14 is not energized, the air-gap flux thereof depends only on the bias flux of the magnetic steel, and the position relationship of the fixed armature under each magnetic pole of the electromagnet is the same, that is, the magnetic pole of the yoke and the respective armature tooth are staggered by the same arc surface, the radial air gap and the axial air gap in the four magnetic poles are the same, and the first armature 3 and the second armature 13 are at the initial positions of the middle positions.

When the control coil 14 is simultaneously energized with a forward current as shown in fig. 14, the first pole g1 and the fourth pole g4 are not affected by the control coil field and the air gap flux remains unchanged. The excitation magnetic field of the control coil under the working air gap of the second magnetic pole g2 is overlapped with the bias magnetic field of the magnetic steel in the same direction, and the air gap magnetic flux is increased; the excitation magnetic field of the control coil under the working air gap of the third magnetic pole g3 is opposite to the bias magnetic field of the magnetic steel and counteracts each other, the air gap flux is reduced, the third armature g3 rotates anticlockwise under the action of electromagnetic torque, and the torque generated by the radial air gap and the axial air gap is modulated with each other, so that the electromagnet obtains a nearly horizontal torque angle characteristic, the magnitude of the output torque can be adjusted by controlling the magnitude of current, and when the electromagnet is matched with a linear spring to use, a position control effect proportional to the current can be obtained.

When the control coil 14 is energized with a reverse current as shown in fig. 15, the first pole g1 and the fourth pole g4 are not affected by the control coil field and the air gap flux remains unchanged. The excitation magnetic field of the control coil under the working air gap of the third magnetic pole g3 is overlapped with the bias magnetic field of the magnetic steel in the same direction, and the air gap magnetic flux is increased; the excitation magnetic field of the control coil under the working air gap of the second magnetic pole g2 is opposite to the bias magnetic field of the magnetic steel and counteracts each other, the air gap flux is reduced, the second armature 13 rotates clockwise under the action of electromagnetic torque, and the torque generated by the radial air gap and the axial air gap is modulated with each other, so that the electromagnet obtains a nearly horizontal torque angle characteristic, the magnitude of the output torque can be adjusted by controlling the magnitude of the current, and when the electromagnetic torque control device is used in cooperation with a linear spring, the position control effect proportional to the current can be obtained.

The embodiments described in this specification are merely illustrative of implementations of the inventive concept and the scope of the present invention should not be considered limited to the specific forms set forth in the embodiments but rather by the equivalents thereof as may occur to those skilled in the art upon consideration of the present inventive concept.

Claims

1. The symmetrical permanent magnet type unidirectional proportion electromagnet based on air gap compensation is characterized in that: the front side and the rear side of the stator are respectively provided with a front end cover (2) and a rear end cover (12), the stator is internally provided with a first armature (3) and a second armature (13), and the first armature (3) and the second armature (13) are coaxially arranged on the output shaft (1); the stator consists of a first yoke (4), a second yoke (7), a third yoke (8) and a fourth yoke (10) which are axially and sequentially arranged, N convex teeth are uniformly distributed on the circumferences of the first yoke (4), the second yoke (7), the third yoke (8) and the fourth yoke (10) and form yoke magnetic poles (15), and the yoke magnetic poles (15) on the first yoke (4), the second yoke (7), the third yoke (8) and the fourth yoke (10) are identical in shape and axially aligned; the second yoke iron (7) and the third yoke iron (8) are respectively provided with symmetrical grooves along the interface, and are spliced to form an annular groove, and a control coil (14) is placed in the annular groove to form a control magnetic flux; a first magnetic isolating block (5) is arranged between the first yoke (4) and the second yoke (7); a second magnetism isolating block (9) is arranged between the third yoke (8) and the fourth yoke (10); a first permanent magnet (6) is arranged between the first yoke (4) and the second yoke (7), and a second permanent magnet (11) is arranged between the third yoke (8) and the fourth yoke (10) and used for forming bias magnetic flux.

The first armature (3) and the second armature (13) are coaxially spliced, N teeth are uniformly distributed on the first armature (3) and the second armature (13) along the circumferential direction, the teeth form an armature magnetic pole, the end face of the armature magnetic pole comprises a circular arc circumferential tooth surface (31) and a side elevation surface (32), and the tooth surface (31) and the end part of the stator magnetic pole (15) form a radial air gap; the side elevation (32) is positioned at one end of the tooth surface (31) and forms an axial air gap with the side surface of the stator magnetic pole (15); the side vertical surface (32) of the armature magnetic pole of the first armature (3) is positioned at one end of the tooth surface (31), and the side vertical surface (32) of the armature magnetic pole of the second armature (13) is positioned at the other end of the tooth surface (31), so that axial air gaps are symmetrically distributed at two sides of the stator magnetic pole (15); the armature teeth of the second armature (13) lead the teeth of the yoke by an angle in the clockwise direction, and the armature teeth of the first armature (3) lag the teeth of the yoke by the same amount in the clockwise direction.

2. The symmetric permanent magnet type uni-directional proportional electromagnet based on air gap compensation of claim 1 wherein: the armature adopts a hollow cup structure; the front end cover (2), the rear end cover (12), the output shaft (1), the first magnet isolating block (5) and the second magnet isolating block (9) are made of non-magnetic metal materials, and the first armature (3), the second armature (13), the first yoke (4), the second yoke (7), the third yoke (8) and the fourth yoke (10) are made of high-magnetic-permeability metal soft magnetic materials.

3. A symmetric permanent magnet type uni-directional proportional electromagnet based on air gap compensation as claimed in claim 1 or 2 wherein: the first yoke (4), the second yoke (7), the third yoke (8) and the fourth yoke (10) are uniformly distributed with 8 yoke magnetic poles (15) around the circumference, and each yoke magnetic pole (15) is separated by 45 degrees; the first armature (3) and the second armature (13) are uniformly distributed with 8 armature teeth along the circumferential direction.

4. A symmetric permanent magnet uni-directional proportional electromagnet based on air gap compensation as claimed in claim 3 wherein: the armature teeth of the second armature (13) lead the teeth 1/4 of the yoke in the clockwise direction and the armature teeth of the first armature (3) lag the teeth 1/4 of the yoke in the clockwise direction.