Limited angle motor with damping mechanism

Abstract

The invention discloses a limited angle motor with a damping mechanism, which comprises a stator assembly and a rotor assembly, and is characterized in that the stator assembly comprises an annular stator core and a winding coil, and the rotor assembly comprises a rotating shaft and a permanent magnet; the inner side of the stator core is also provided with a damping device, the damping device is fixedly connected with the stator core, and a gap is arranged between the damping device and the permanent magnet to form an annular working air gap. According to the invention, the dynamic torque of the motor is reduced and the angular acceleration of the rotating shaft is reduced while the static torque of the motor is not reduced and the size of the motor is not increased, and the rotation time of the motor is adjusted and controlled.

Description

Technical Field

[0001] The invention relates to the field of motors, and in particular to a limited-angle motor with a damping mechanism. Background Art

[0002] At present, limited-angle motors are widely used in various servo systems and control mechanisms, with the advantages of simple structure, easy control, high reliability, etc. There are various principles and structural forms of limited-angle motors, most of which adopt a structure similar to that of traditional DC brushless motors. One of them adopts a circular iron core structure. Because of its simple structure and low production cost, it is particularly suitable for occasions without special requirements for torque fluctuations, such as electric switching switches.

[0003] The limited-angle motor with a circular iron core stator structure has a continuous and uniform working air gap in the shape of a circular ring, and the magnetic flux density in the working air gap is sinusoidally arranged. When power is turned on, the torque of the rotor also fluctuates sinusoidally with the angle change. The fluctuation is large, causing the angular acceleration of the limited-angle motor shaft to be too large. The rotation time within the limited angle is very short, and the impact force when hitting the mechanical limit is too large, which can easily cause wear and failure of the mechanical limit. If the motor torque is reduced directly, the motor will be difficult to start because it cannot overcome the static friction torque.

[0004] Therefore, for situations where there is a rotation time limit, how to ensure that the rotation time is within the limit without reducing the static torque of the motor and without significantly increasing the size of the motor becomes a technical problem that needs to be solved. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to solve the problems of small static torque, large torque fluctuation, large angular acceleration of the shaft, fast rotation time, and easy wear and failure of the mechanical limiter in the existing limited angle motor, and to provide a limited angle motor with a damping mechanism, which can reduce the dynamic torque of the motor, reduce the angular acceleration of the shaft, and adjust and control the rotation time of the motor without reducing the static torque of the motor and without increasing the size of the motor.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: a limited-angle motor with a damping mechanism, comprising a stator assembly and a rotor assembly, the stator assembly comprising an annular stator core and a winding coil, and the rotor assembly comprising a rotating shaft and a permanent magnet; characterized in that: a damping device is also provided on the inner side of the stator core, the damping device is fixedly connected to the stator core, and there is a gap between the damping device and the permanent magnet to form an annular working air gap.

[0007] Furthermore, the damping device is ring-shaped, and the damping device as a whole is a conductor.

[0008] Furthermore, the damping device is made of metal.

[0009] Furthermore, the metal is copper.

[0010] Furthermore, the winding coil includes an inner coil and an outer coil, and the inner coil and the outer coil are symmetrically distributed on both sides of the stator core.

[0011] Furthermore, coil slots are provided on the inner side and the outer side of the stator core corresponding to the inner coil and the outer coil, and the inner coil and the outer coil are embedded in the coil slots at corresponding positions.

[0012] Furthermore, the damping device is tightly fitted with the stator core, and the outer wall of the damping device is in contact with the inner plate of the stator core.

[0013] Compared with the prior art, the present invention has the following advantages: the overall structure is simple, and it can weaken the dynamic torque of the motor, reduce the angular acceleration of the shaft, and adjust and control the rotation time of the motor without reducing the static torque of the motor and significantly increasing the size of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the structure of the present invention.

[0015] In the figure: 1—stator core, 2—winding coil, 3—rotating shaft, 4—permanent magnet, 5—damping device. DETAILED DESCRIPTION

[0016] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0017] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invention product is usually placed when used, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In addition, the terms "horizontal", "vertical", etc. do not mean that the components are absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0019] Example: See Figure 1 A limited-angle motor with a damping mechanism comprises a stator assembly and a rotor assembly. The stator assembly comprises a ring-shaped stator core 1 and a winding coil 2. The rotor assembly comprises a rotating shaft 3 and a permanent magnet 4 (magnetic steel); the permanent magnet 4 is evenly distributed around the rotating shaft 3 and is fixedly connected to the rotating shaft 3 (by gluing or other means). The rotating shaft 3 is arranged coaxially with the stator core 1; during implementation, a motor end cover is also included, and the rotating shaft 3 is connected to the stator core 1 through the motor end cover. The winding coil 2 comprises an inner coil and an outer coil, wherein the inner coil and the outer coil are both distributed in an arc shape as a whole, and the inner coil and the outer coil are symmetrically distributed on both sides of the stator core 1; thereby realizing the limited-angle rotation of the rotor assembly. During implementation, coil slots are provided on the inner and outer sides of the stator core 1 corresponding to the inner coil and the outer coil, and the inner coil and the outer coil are embedded in the coil slots at corresponding positions.

[0020] A damping device 5 is also provided on the inner side of the stator core 1, which is fixedly connected to the stator core 1, and there is a gap between the damping device 5 and the permanent magnet 4 to form an annular working air gap. The damping device 5 is annular, and the damping device 5 is a conductor as a whole, so that it can generate an induced current (eddy current) under a changing magnetic field environment (when the rotor assembly rotates). Specifically, the damping device 5 is made of metal; preferably, the metal is copper, including brass, copper, etc. As needed, by setting the axial length and thickness of the damping device 5, the rotation time of the motor can be adjusted and controlled. For ease of assembly, the damping device 5 is tightly fitted (interference fit) with the stator core 1, and the outer wall of the damping device 5 is fitted with the inner plate of the stator core 1. As another way, the damping device 5 is fixedly connected to the stator core 1 by adhesive to make the connection more stable.

[0021] In this solution, the damping device 5 is made of a material with low resistivity so as to induce eddy currents in a dynamic magnetic field. The eddy currents will also produce a reaction force on the dynamic magnetic field, generating a damping torque that prevents the magnetic field from moving. The damping torque is opposite to the driving torque of the motor, so that the driving torque during the rotation of the motor can be reduced to reduce the angular acceleration of the shaft 3, and ultimately achieve the purpose of reducing the rotation speed of the shaft 3 and increasing the rotation time. At the same time, since the damping torque is generated only after the shaft 3 rotates, the shaft 3 has not yet rotated at the moment the motor shaft starts, so no damping torque will be generated. Therefore, installing the damping device 5 of this patent will not reduce the static torque (including the starting torque) of the motor. In addition, the damping device 5 is arranged between the stator core 1 and the permanent magnet 4. Since there is a gap between the stator core 1 and the permanent magnet 4, when the thickness of the damping device 5 is relatively low, there is no need to increase the overall volume of the motor; when the thickness of the damping device 5 is relatively large, it is only necessary to enlarge the stator core 1 or reduce the permanent magnet 4, and there is no need to significantly increase the overall volume of the motor.

[0022] During operation, the magnetic lines of force of the permanent magnet 4 start from the N pole, pass through the working air gap, the damping device 5 and the inner coil, enter the stator core 1, reach the vicinity of the magnetic steel S pole, then pass through the stator core 1, and pass through the inner coil, the damping device 5 and the working air gap again to reach the magnetic steel S pole, and reach the magnetic steel N pole, forming a closed loop. In this process, according to the law of electromagnetic induction, when the magnetic flux passing through the closed loop changes, an induced electromotive force will be induced in the closed loop. Since it is a closed loop, there must be a loop resistance. According to Ohm's law, the induced electromotive force will form a loop current in the closed loop. According to Lenz's law, the magnetic field of the loop current will always hinder the change of the magnetic flux that causes the current change. The damping device 5 is fixed to the stator core 1, so that when the rotor rotates counterclockwise, the magnetic lines of force of the magnetic steel on the rotor also rotate counterclockwise with it. At this time, the magnetic flux passing through the cross section of the copper ring becomes larger, generating an induced voltage. The loop current generated by the induced voltage is in the clockwise direction. According to the right-hand rule, the magnetic field direction of the loop current is toward the axis, that is, the inner side of the loop (close to the axis) is the N pole, and the like poles of the magnetic field repel each other, which hinders the magnetic field from continuing to rotate clockwise and generates a damping torque. Similarly, when the rotor rotates clockwise, the magnetic flux passing through the cross section of the copper ring becomes smaller, generating a reverse induced voltage, and the loop current also reverses. The inner side of the loop is the S pole, and the opposite poles attract each other, which hinders the magnetic field from continuing to rotate counterclockwise and generates a damping torque.

[0023] It is known from the law of electromagnetic induction that the magnitude of the induced voltage is proportional to the rate of change of the magnetic flux passing through the cross section. Inside the motor, the rate of change of the magnetic flux is proportional to the rotation speed of the rotating shaft 3. The loop current generated by the induced voltage in the damping device 5 is proportional to the conductivity of the damping device 5, the thickness and length of the cross section of the damping device 5, and the magnetic field density generated by the loop current is proportional to the current. When the rotation speed is constant, if the damping torque is to be increased, the magnetic field density of the loop current needs to be increased, that is, the loop current needs to be increased, which can be achieved by reducing the resistivity of the damping device 5 material and increasing the thickness and length of the cross section of the damping device 5. Among the commonly used materials at present, considering the economy, it is more appropriate to use copper for the damping device 5. After the material is selected, the damping torque can be adjusted by adjusting the thickness and length of the copper ring.

[0024] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A limited-angle motor with a damping mechanism, comprising a stator assembly and a rotor assembly, wherein the stator assembly comprises an annular stator core and a winding coil, and the rotor assembly comprises a rotating shaft and a permanent magnet; characterized in that: A damping device is also provided on the inner side of the stator core. The damping device is fixedly connected to the stator core, and there is a gap between the damping device and the permanent magnet to form an annular working air gap.

2. A limited-angle motor with a damping mechanism according to claim 1, characterized in that: The damping device is annular in shape, and the damping device as a whole is a conductor.

3. A limited-angle motor with a damping mechanism according to claim 1 or 2, characterized in that: The damping device is made of metal.

4. A limited-angle motor with a damping mechanism according to claim 3, characterized in that: The metal is copper.

5. The limited-angle motor with a damping mechanism according to claim 1, characterized in that: The winding coil comprises an inner coil and an outer coil, and the inner coil and the outer coil are symmetrically distributed on both sides of the stator core.

6. The limited-angle motor with a damping mechanism according to claim 5, characterized in that: Coil slots are provided on the inner side and the outer side of the stator core corresponding to the inner coil and the outer coil, and the inner coil and the outer coil are embedded in the coil slots at corresponding positions.

7. The limited-angle motor with a damping mechanism according to claim 1, characterized in that: The damping device is tightly matched with the stator core, and the outer wall of the damping device is in contact with the inner plate of the stator core.

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