Proportional electromagnetic actuator with variable working air gap

Abstract

The invention provides a proportional electromagnetic actuator with a variable working air gap. The proportional electromagnetic actuator is mainly composed of an output shaft (1), a movable iron core (2), a shell (3), a magnet exciting coil (4), a static iron core (5) and the like. A radial working air gap (9) which becomes smaller and then becomes larger gradually in the direction of a static iron core circular slotted hole (12) is formed between a movable iron core front end peripheral surface (8) and a static iron core variable cross-section hole (14), and along with the increase of a last working stroke, the radial working air gap (9) becomes larger gradually, the magnetic resistance is increased, and the magnetic flux is reduced; meanwhile, a boss of the static iron core (5) is provided with a circular groove hole (12), and an axial working air gap (10) between the front end face (7) of the movable iron core and the static iron core (5) is relatively large. Therefore, when the movable iron core (2) is close to the tail end of the working stroke, the working magnetic flux can be prevented from being increased, the situation that the output electromagnetic force of the actuator is remarkably increased is relieved, deterioration of the horizontal characteristic of the output electromagnetic force is avoided, and the effective working stroke range is expanded.

Description

Technical Field

[0001] The invention belongs to the field of electromagnetic mechanism design, relates to an electric-mechanical conversion mechanism of an automatic control system, and in particular to a proportional electromagnetic actuator with a variable working air gap. Background Art

[0002] A proportional solenoid valve is a solenoid valve that can proportionally control parameters such as fluid flow, pressure or direction according to the input electrical signal. It mainly consists of an electromagnetic part (proportional electromagnetic actuator) and a valve part. The proportional electromagnetic actuator generates electromagnetic force by energizing, and the electromagnetic force acts on movable parts such as the valve core or armature, so that the valve opening can change continuously according to the size of the electrical signal. For example, in a hydraulic system, a proportional solenoid valve can accurately control the flow of hydraulic oil, thereby achieving precise adjustment of the movement speed of the actuator (such as a hydraulic cylinder); in a pneumatic system, it can adjust the flow and pressure of the gas to meet different working requirements; such as in the pneumatic clamp of an automated production line, the clamping force can be flexibly adjusted through a proportional solenoid valve. Compared with ordinary solenoid valves, the advantages of proportional solenoid valves lie in their control accuracy and continuity, and they can adapt to more complex and higher precision industrial automation control scenarios. They are widely used in many fields such as machinery manufacturing, automobile industry, aerospace, and industrial automation. The constant force characteristic of the proportional electromagnetic actuator is the key to the proportional solenoid valve to achieve proportional or linear control of the controlled quantity.

[0003] Figure 1This is a simplified structural diagram of a conventional proportional electromagnetic actuator, which mainly includes an output shaft 1, a moving iron core 2, a housing 3, an excitation coil 4, a static iron core 5, etc. When current is passed through the excitation coil, the housing, the moving iron core, and the static iron core are magnetized. The main magnetic flux Φ is divided into three magnetic fluxes Φ1, Φ2, and Φ3; the magnetic flux Φ1 enters the static iron core through the air gap between the outer circumference of the moving iron core and the inner circumference of the static iron core; the magnetic flux Φ2 enters the static iron core through the air gap between the end face of the moving iron core and the inner circumference of the static iron core; the magnetic flux Φ3 enters the static iron core through the air gap between the end face of the moving iron core and the bottom end face of the static iron core. As the moving iron core gradually approaches the stationary iron core, the working air gap between the outer circumference of the moving iron core and the inner circumference of the stationary iron core in the Φ1 magnetic flux circuit gradually becomes smaller, and the opposite suction area increases, and the magnetic resistance gradually decreases, so that the additional axial electromagnetic force F1 on the outer circumference of the moving iron core gradually increases; at the same time, the end face of the moving iron core also gradually approaches the bottom end face of the stationary iron core, the working air gap between the two end faces decreases, and the magnetic resistance weakens, so that the axial electromagnetic force F2 on the end face of the moving iron core first gradually increases; but as the working stroke increases, the degree of reduction in magnetic resistance between the outer circumference of the moving iron core and the inner circumference of the stationary iron core is greater than the degree of reduction in magnetic resistance between the end face of the moving iron core and the bottom end face of the stationary iron core, so that the magnetic flux Φ1 increases, and the sum of the magnetic fluxes Φ2 and Φ3 decreases, causing the axial electromagnetic force F2 on the end face of the moving iron core to fall back to a certain extent. Therefore, the output electromagnetic force F obtained by superimposing the two forces F1 and F2 can remain approximately unchanged within a certain stroke. This characteristic is called the "constant force characteristic" (or "horizontal characteristic") (such as Figure 2 shown).

[0004] However, when the working stroke is near the end, the working air gap between the end face of the moving iron core and the bottom end face of the static iron core is significantly reduced, the magnetic resistance of the magnetic flux Φ3 loop decreases rapidly, the axial electromagnetic force F2 rebounds rapidly, and the additional axial electromagnetic force F1 continues to increase, which leads to an increase in the output electromagnetic force F at the end of the working stroke and a decrease in the overall horizontal characteristics. Ultimately, the actual effective working stroke of the proportional electromagnetic actuator is not conducive to further extension, which limits the performance improvement of the proportional electromagnetic actuator (Wang Ruiting. Geometric parameter modeling analysis and performance optimization research of moving iron proportional electromagnets [D]. Mechanical Engineering, Wenzhou University, 2019.). Summary of the invention

[0005] The technical problem to be solved by the present invention is to alleviate the problems of short working stroke, significant increase in output electromagnetic force near the end of the working stroke, and poor horizontal characteristics of the output electromagnetic force of the traditional proportional electromagnetic actuator.

[0006] The object of the present invention is to provide a proportional electromagnetic actuator with a variable working air gap, which has a long working stroke and excellent output electromagnetic force level characteristics.

[0007] In order to solve the above existing technical problems and achieve the above objectives, the solution of the present invention is:

[0008] A proportional electromagnetic actuator with a variable working air gap is proposed, which comprises an output shaft, a moving iron core, a housing, an excitation coil, a stationary iron core and the like.

[0009] A stepped through hole is opened in the middle of the shell, in which a static iron core, a moving iron core and an excitation coil are built, and the central axes of the stepped through hole, the static iron core, the moving iron core and the excitation coil are in a straight line;

[0010] The static iron core is a cylindrical boss structure with a three-level stepped hole in the center, which is a variable-section hole, a circular slot hole and a through hole in sequence from the end face of the boss inward, and the generatrix of the revolution curved surface of the variable-section hole is a stepped line segment whose radius gradually increases toward the end face of the boss or an inward convex curve, and the inward convex curve is a quadratic parabola, a spline curve or a combination of multiple quadratic curves;

[0011] The excitation coil is nested on the boss of the static iron core;

[0012] The moving iron core has a through hole in the center, the rear end of the moving iron core is cylindrical, the outer peripheral surface of the front end of the moving iron core is a stepped surface with a radius gradually increasing toward the rear end surface or a convex rotational surface, and the generatrix of the convex rotational surface is a quadratic parabola, a spline curve, or a combination of multiple quadratic curves;

[0013] The front end of the moving iron core can reciprocate along the axis in the variable cross-section hole of the static iron core, and a radial working air gap is formed between the outer peripheral surface of the front end of the moving iron core and the variable cross-section hole of the static iron core, which first becomes smaller and then gradually increases toward the circular slot hole of the static iron core;

[0014] The front end surface of the moving iron core and the bottom surface of the circular slot hole of the static iron core form an axial working air gap;

[0015] The output shaft passes through the central through holes of the moving iron core and the stationary iron core. When the proportional electromagnetic actuator is working, the moving iron core pushes the output shaft to move.

[0016] When the excitation coil is energized, by adjusting the outer circumferential surface of the front end of the moving iron core, the variable cross-section hole and the circular slot hole structure of the static iron core, when the moving iron core approaches the end of the working stroke, compared with the traditional proportional electromagnetic actuator, the radial working air gap between the outer circumferential surface of the front end of the moving iron core and the variable cross-section hole of the static iron core becomes larger, and the axial working air gap between the end face of the front end of the moving iron core and the bottom surface of the circular slot hole of the static iron core also becomes larger, causing the magnetic resistance of the Φ1, Φ2 and Φ3 flux circuits to increase, thereby attenuating the increase in the output electromagnetic force F of the proportional electromagnetic actuator at the end of the working stroke, improving the horizontal characteristics of the output electromagnetic force, and expanding the range of the effective working stroke (such as Figure 3 shown).

[0017] Compared with the background technology, the advantages of the present invention are:

[0018] 1. The variable working air gap proportional electromagnetic actuator proposed in the present invention can avoid a significant increase in the output electromagnetic force at the end of the working stroke, improve the overall output electromagnetic force level characteristics of the actuator and expand the effective working stroke range of the proportional electromagnetic actuator;

[0019] 2. The variable working air gap proportional electromagnetic actuator described in the present invention has a longer effective working stroke and better output electromagnetic force level characteristics. It can be widely used in electric-mechanical conversion mechanisms in complex control systems such as automotive engines and marine engines, as well as in more engineering applications, and has practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of a traditional proportional electromagnetic actuator;

[0021] Figure 2 It is a schematic diagram of the working stroke-force characteristics of the proportional electromagnetic actuator;

[0022] Figure 3 A schematic structural diagram of a proportional electromagnetic actuator with a variable working air gap, wherein the outer peripheral surface of the front end of a moving iron core is a stepped curved surface with a radius gradually increasing toward the rear end surface, and the generatrix of the revolution curved surface of the variable cross-section hole of the stationary iron core is a stepped line segment with a radius gradually increasing toward the end surface of the boss;

[0023] Figure 4 It is a structural schematic diagram of a proportional electromagnetic actuator with a variable working air gap according to the present invention when the moving iron core is close to the end of the working stroke;

[0024] Figure 5 It is a schematic diagram of the structure of a traditional proportional electromagnetic actuator when the moving iron core is close to the end of the working stroke;

[0025] Figure 6 A schematic diagram of the structure of a static iron core of a proportional electromagnetic actuator with a variable working air gap according to the present invention;

[0026] Figure 7 A schematic diagram of the structure of a moving iron core of a proportional electromagnetic actuator with a variable working air gap according to the present invention;

[0027] Figure 8 This is the magnetic field line distribution of the traditional proportional electromagnetic actuator;

[0028] Fig. 9 The magnetic force line distribution of a proportional electromagnetic actuator with a variable working air gap according to the present invention;

[0029] Fig.10 It is a graph showing the electromagnetic force variation between a proportional electromagnetic actuator with a variable working air gap according to the present invention and a conventional proportional electromagnetic actuator;

[0030] Fig.11 It is a structural schematic diagram of a proportional electromagnetic actuator with a variable working air gap, wherein the front end outer peripheral surface of the moving iron core and the revolution curved surfaces of the variable cross-section hole of the static iron core are respectively convex and inwardly convex revolution curved surfaces;

[0031] In the above figure: 1. output shaft, 2. moving iron core, 3. casing, 4. excitation coil, 5. stationary iron core, 6. bottom surface of circular slot hole of stationary iron core, 7. front end surface of moving iron core, 8. outer peripheral surface of front end of moving iron core, 9. radial working air gap, 10. axial working air gap, 11. through hole of stationary iron core, 12. circular slot hole of stationary iron core, 13. end surface of boss of stationary iron core, 14. variable cross-section hole of stationary iron core, 15. rear end of moving iron core. DETAILED DESCRIPTION

[0032] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0033] like Figure 3 , Figure 6 , Figure 7 and Fig.11 The present invention discloses a variable working air gap ratio electromagnetic actuator, which includes an output shaft 1, a moving iron core 2, a housing 3, an excitation coil 4, a static iron core 5, etc.

[0034] A stepped through hole is opened in the middle of the shell, in which a static iron core 5, a moving iron core 2 and an excitation coil 4 are built, and the central axes of the stepped through hole, the static iron core 5, the moving iron core 2 and the excitation coil 4 are in a straight line;

[0035] The static iron core 5 is a cylindrical boss structure with a three-level stepped hole in the center. From the static iron core boss end face 13 to the inside, there are variable cross-section holes 14, circular slot holes 12 and through holes 11. The generatrix of the revolution surface of the variable cross-section hole is a step line segment with a radius gradually increasing toward the boss end face or an inward convex curve. The inward convex curve can be a quadratic parabola, a spline curve, or a combination of multiple quadratic curves.

[0036] The excitation coil 4 is nested on the boss of the static iron core 5;

[0037] The moving iron core has a through hole in the center, the rear end 15 of the moving iron core is cylindrical, the outer peripheral surface 8 of the front end of the moving iron core is a stepped surface with a radius gradually increasing toward the rear end surface or a convex revolution surface, and the generatrix of the convex revolution surface can be a quadratic parabola, a spline curve, or a combination of multiple quadratic curves;

[0038] The front end of the moving iron core 2 can reciprocate along the axis in the variable cross-section hole 14 of the stationary iron core, and a radial working air gap 9 is formed between the outer peripheral surface 8 of the front end of the moving iron core and the variable cross-section hole 14 of the stationary iron core, which first becomes smaller and then gradually increases toward the circular groove hole 12 of the stationary iron core;

[0039] The front end surface 7 of the moving iron core and the bottom surface 6 of the circular slot hole of the stationary iron core form an axial working air gap 10;

[0040] The output shaft 1 passes through the central through holes of the moving iron core 2 and the stationary iron core 5. When the proportional electromagnetic actuator is working, the moving iron core 2 pushes the output shaft 1 to move.

[0041] Depend on Figure 5 and Figure 8 It can be seen that when the traditional proportional electromagnetic actuator approaches the end of the working stroke, the radial working air gap 9 with equal spacing and getting smaller and smaller is formed between the front end peripheral surface of the moving iron core 2 and the static iron core 5. At the same time, the axial working air gap 10 between the front end surface of the moving iron core 2 and the static iron core 5 is also getting smaller and smaller, making the total magnetic resistance of the working magnetic circuit smaller and smaller, resulting in the working magnetic flux Φ gradually increasing, so that the output electromagnetic force will increase significantly. Figure 4 and Fig. 9 It can be known that the proportional electromagnetic actuator with a variable working air gap described in the present invention forms a radial working air gap 9 between the outer peripheral surface 8 of the front end of the moving iron core and the variable cross-section hole 14 of the static iron core when approaching the end of the working stroke, which first becomes smaller and then gradually increases toward the circular groove hole 12 of the static iron core, and as the final working stroke increases, the radial working air gap 9 will gradually increase, the magnetic resistance will increase, and the magnetic flux Φ1 and Φ2 will decrease; at the same time, since the circular groove hole 12 is opened on the boss of the static iron core 5, the axial working air gap 10 between the front end face 7 of the moving iron core and the static iron core 5 is also relatively large, so that the magnetic flux Φ3 is also reduced; therefore, the situation in which the output electromagnetic force increases significantly at the end of the working stroke can be alleviated.

[0042] To sum up, by improving the structure of the outer circumferential surface 8 at the front end of the moving iron core and the circular groove hole 12 and the variable cross-section hole 14 of the static iron core, the working air gap between the outer circumferential surface 8 and the end face 7 of the moving iron core and the static iron core 5 is increased at the end of the working stroke, thereby attenuating the significant increase in the output electromagnetic force at the end of the working stroke, thereby improving the horizontal characteristics of the output electromagnetic force and expanding the effective working stroke range. This improvement plan is feasible.

[0043] To further illustrate the practical application of the present invention, the following are specific examples.

[0044] Example:

[0045] In order to further illustrate the effectiveness of the performance of a variable working air gap proportional electromagnetic actuator, a variable working air gap proportional electromagnetic actuator (such as Figure 3 ) is an embodiment for further explanation.

[0046] Embodiments Electromagnetic simulation software is used to construct finite element models of a conventional proportional electromagnetic actuator and a proportional electromagnetic actuator with a variable working air gap according to the present invention, and simulation analysis is performed.

[0047] Under the working conditions consisting of excitation current I=2.5, 3.5, 4.5A and working stroke S=5, 6, 7, ..., 15mm, numerical simulation was carried out group by group, and the average output electromagnetic force variation coefficient of the three excitation current levels was calculated to evaluate the horizontal characteristics of the output electromagnetic force of the electromagnetic actuator.

[0048] The average value of the electromagnetic force output by the electromagnetic actuator is F(I y ) a ,

[0049]

[0050] where y∈[1,3] and y∈Z, x∈[1,11] and x∈Z,

[0051] Among them I y represents the yth current operating point within the excitation current range, S x represents the xth working stroke operating point within the full working stroke range, F(S x ,I y ) represents the electromagnetic actuator when the excitation current is I y The moving iron core 2 is in the working stroke position S x The output electromagnetic force at .

[0052] The standard deviation of the electromagnetic force output by the electromagnetic actuator is F(I y ) s ,

[0053]

[0054] The output electromagnetic force variation coefficient of the electromagnetic actuator is CV(I y ),

[0055]

[0056] The coefficient of variation of the electromagnetic force output by the electromagnetic actuator can measure the quality of the horizontal characteristics of the electromagnetic force output by the electromagnetic actuator under any intensity of the excitation current. If the coefficient of variation of the output electromagnetic force is smaller, it means that the horizontal characteristics of the output electromagnetic force are better.

[0057] The weighted coefficient of variation of the output electromagnetic force at the three excitation current levels is CV,

[0058] CV=0.6×CV(2.5)+0.2×CV(3.5)+0.2×CV(4.5).

[0059] Through simulation calculation, it is found that the weighted variation coefficient of the output electromagnetic force of the variable working air gap proportional electromagnetic actuator of the present invention is CV1 = 0.64%; while the weighted variation coefficient of the output electromagnetic force of the traditional proportional electromagnetic actuator under the same design size is CV2 = 6.77%. The weighted variation coefficient of the output electromagnetic force of the variable working air gap proportional electromagnetic actuator of the present invention is reduced by about 90.5% compared with the traditional proportional electromagnetic actuator, which effectively improves the output electromagnetic force level characteristics of the proportional electromagnetic actuator.

[0060] Depend on Fig.10 It can be seen that, within the effective working stroke range of 5-15mm and under the excitation current of 2.5-4.5A, the output electromagnetic force curve of the traditional proportional electromagnetic actuator changes with the working stroke, all show a trend of gradually increasing with the advancement of the working stroke, and the electromagnetic force is significantly enhanced at the end of the stroke; while the output electromagnetic force curve of the proportional electromagnetic actuator with a variable working air gap described in the present invention changes with the working stroke, which is smoother than the output electromagnetic force curve of the traditional proportional electromagnetic actuator. In the process of gradually approaching the end of the working stroke, the output electromagnetic force curve of the proportional electromagnetic actuator described in the present invention does not warp upward, and the output electromagnetic force does not increase significantly at the end of the stroke.

[0061] This shows that the variable working air gap proportional electromagnetic actuator described in the present invention has better output electromagnetic force level characteristics and performance of further extending the actual effective working stroke.

[0062] In summary, the technical features disclosed in this invention are feasible and have significant innovation and practicality.

[0063] Finally, it should be noted that the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A proportional electromagnetic actuator with a variable working air gap, comprising: An output shaft (1), a moving iron core (2), a housing (3), an excitation coil (4), and a stationary iron core (5), characterized in that: The housing (3) has a stepped through hole in the middle, in which a static iron core (5), a moving iron core (2) and an excitation coil (4) are built, and the central axes of the stepped through hole, the static iron core (5), the moving iron core (2) and the excitation coil (4) are in a straight line; The static iron core (5) is a cylindrical boss structure with a three-level stepped hole in the center, which is a variable cross-section hole (14), a circular groove hole (12) and a through hole (11) in sequence from the boss end surface (13) inward, and the generatrix of the revolution curved surface of the variable cross-section hole (14) is a stepped line segment with a radius gradually increasing toward the boss end surface (13) or an inward convex curve; The excitation coil (4) is nested on the boss of the static iron core (5); The moving iron core (2) has a through hole at its center, the moving iron core rear end (15) is cylindrical, and the outer peripheral surface (8) at the front end of the moving iron core is a stepped curved surface or a convex rotational curved surface with a radius gradually increasing toward the rear end. The front end of the moving iron core can reciprocate along the axis in the variable cross-section hole (14) of the stationary iron core, and a radial working air gap (9) is formed between the outer peripheral surface (8) of the front end of the moving iron core and the variable cross-section hole (14) of the stationary iron core, which first becomes smaller and then gradually increases toward the circular groove hole (12) of the stationary iron core; The front end surface (7) of the moving iron core and the bottom surface (6) of the circular slot hole of the stationary iron core form an axial working air gap (10); The output shaft (1) passes through the central through holes of the moving iron core (2) and the stationary iron core (5); when the proportional electromagnetic actuator is working, the moving iron core (2) pushes the output shaft (1) to move.

2. A proportional electromagnetic actuator with a variable working air gap according to claim 1, characterized in that: The inward convex curve is a quadratic parabola, a spline curve, or is composed of a combination of multiple quadratic curves.

3. The variable working air gap proportional electromagnetic actuator according to claim 1, characterized in that: The generatrix of the convex surface of revolution is a quadratic parabola, a spline curve, or is composed of a combination of multiple quadratic curves.

Images