An electromagnetic brake and method for preventing frictional noise

Abstract

This invention relates to the field of electromagnetic brake technology, providing an electromagnetic brake and method for preventing friction noise. The electromagnetic brake includes a stator, an armature, a rotor, and a flange arranged sequentially. The flange is fixedly connected to the stator. The stator is provided with several springs for pressing the armature. The rotor is circumferentially fixed to a drive shaft. A first permanent magnet is provided on the side of the armature near the rotor, and a second permanent magnet is provided on the side of the rotor near the rotor. The first and second permanent magnets attract each other, and the attraction force is less than the preload force of the springs. A limiting shoulder is provided on the drive shaft. In the braking state, the gap between the end face of the rotor near the stator and the limiting shoulder is smaller than the braking gap. This invention ensures that when the brake is released, gaps are formed between the rotor and the flange, and between the rotor and the armature, preventing friction on both sides of the rotor and thus preventing friction noise.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic brake technology, and more specifically, to an electromagnetic brake and method for preventing friction noise. Background Technology

[0002] Electromagnetic brakes are widely used in elevators, lifting equipment, industrial robots, wind power pitch control systems, and various precision transmission devices due to their advantages such as rapid response, convenient control, and compact structure. A typical electromagnetic brake usually consists of a stator (composed of a magnetic yoke and coils), an armature, a rotor, and a flange arranged in sequence. The flange is fixedly connected to the stator. Several springs are provided on one side of the stator's contact surface. Its working principle is as follows: when the coil is energized, it generates an electromagnetic force to attract the armature and release the braking state; when the coil is de-energized, the spring force pushes the armature to press the rotor, realizing the braking function.

[0003] However, when the electromagnetic brake with the above structure is released, the rotor side will still rub against the flange or armature. This will not only cause the rotor to wear more quickly and affect its service life, but also cause friction noise when the rotor rotates, which will seriously reduce the comfort of using the equipment, especially in applications with high requirements for quietness, such as elevators and home appliances. Summary of the Invention

[0004] The purpose of this invention is to provide an electromagnetic brake and method for preventing friction noise, so as to solve the above-mentioned defects of the prior art.

[0005] This invention is achieved through the following technical solution: An electromagnetic brake for preventing friction noise includes a stator, an armature, a rotor, and a flange arranged in sequence. The flange is fixedly connected to the stator. The stator is provided with several springs for pressing the armature. The rotor is circumferentially fixed to the drive shaft. A first permanent magnet is provided on the side of the armature near the rotor, and a second permanent magnet is provided on the side of the rotor near the armature. The first and second permanent magnets attract each other, and the attraction force is less than the preload force of the springs. A limiting shoulder is provided on the drive shaft. In the braking state, the gap between the end face of the rotor near the stator and the limiting shoulder is smaller than the braking gap.

[0006] Preferably, under braking conditions, the gap between the end face of the rotor near the stator and the limiting shoulder is equal to 1 / 2 of the braking gap.

[0007] Preferably, the rotor is provided with an internal spline hole and connected to a spline bushing, and the spline bushing is fixedly connected to the drive shaft.

[0008] Preferably, the drive shaft is provided with a positioning shoulder for abutting the end face of the spline bushing near the stator. The diameter of the journal at the limiting shoulder is greater than the diameter of the journal at the positioning shoulder and smaller than the minor diameter of the inner spline hole.

[0009] Preferably, the flange is connected to the stator by screws.

[0010] Preferably, a limiting sleeve is fitted onto the screw to limit the distance between the flange and the stator.

[0011] Preferably, the armature is provided with a guide opening that slides with the limiting sleeve.

[0012] Preferably, the guide opening is a notch located at the edge of the armature.

[0013] Preferably, friction plates are provided on both sides of the rotor.

[0014] The present invention also provides a method for preventing friction noise, which is applied to the electromagnetic brake for preventing friction noise as described in any of the above. When the electromagnetic brake is released, the armature is attracted by the stator, the first permanent magnet attracts the second permanent magnet, and drives the rotor to move toward the armature. During the movement of the rotor, it is blocked by the limiting shoulder on the transmission shaft, so that gaps are formed between the rotor and the flange and between the rotor and the armature.

[0015] The technical solution of this invention has at least the following advantages and beneficial effects: By setting a first permanent magnet and a second permanent magnet that can attract each other between the armature and the rotor, the rotor can move with the armature under the action of permanent magnetic force when the brake is released. The axial movement of the rotor is limited to less than the brake gap by a limiting shoulder on the transmission shaft. In this way, when the electromagnetic brake is released, the armature is attracted by the stator, the first permanent magnet attracts the second permanent magnet, and the rotor moves towards the armature. During the rotor's movement, it is blocked by the limiting shoulder on the transmission shaft, creating gaps between the rotor and the flange, and between the rotor and the armature. This prevents friction on both sides of the rotor when the brake is released, thus preventing abnormal frictional noise. Attached Figure Description

[0016] Figure 1 A schematic diagram of an electromagnetic brake structure for preventing friction noise (braking state) provided for this invention. Figure 2 A schematic diagram of an electromagnetic brake structure for preventing friction noise (brake released state) provided by the present invention. Figure 3 This is a schematic diagram of the drive shaft structure; Reference numerals: 1-Stator, 101-Yoke, 102-Coil, 2-Armature, 201-Guide port, 3-Rotor, 4-Flange, 5-Spring, 6-First permanent magnet, 7-Second permanent magnet, 8-Drive shaft, 801-Limiting shoulder, 802-Positioning shoulder, 9-Splined bushing, 10-Screw, 11-Limiting sleeve, 12-Friction plate. Detailed Implementation

[0017] refer to Figure 1 and Figure 2 An electromagnetic brake for preventing friction noise includes a stator 1, an armature 2, a rotor 3, and a flange 4 arranged sequentially. The flange 4 is fixedly connected to the stator 1, meaning that the positions of the flange 4 and the stator 1 are relatively fixed. The stator 1 is provided with several springs 5 ​​for pressing the armature 2. It is easy to understand that the springs 5 ​​are evenly spaced along the circumference of the stator 1, and are used to provide a preload force towards the rotor 3 for the armature 2 when the power is off. In practical applications, the stator 1 has mounting holes for installing the springs 5 ​​on the side near the armature 2. In addition, those skilled in the art should understand that the stator 1 consists of a magnetic yoke 101 and a coil 102 installed inside the magnetic yoke 101. Unless otherwise stated, the "stator 1" mentioned in this invention refers to the magnetic yoke 101.

[0018] refer to Figures 1-3 The rotor 3 is mounted on the drive shaft 8 of the equipment (not shown in the figure), and is circumferentially fixed relative to the drive shaft 8 while being axially movable. A first permanent magnet 6 is provided on the side of the armature 2 near the rotor 3, and a second permanent magnet 7 is provided on the side of the rotor 3 near the armature 2. In practical applications, several of the first permanent magnets 6 and the second permanent magnets 7 are arranged circumferentially in a one-to-one correspondence. The magnetic poles of the first permanent magnet 6 and the second permanent magnet 7 are arranged such that they attract each other in the axial direction, that is, the magnetic poles of the end of the first permanent magnet 6 facing the second permanent magnet 7 are opposite to the magnetic poles of the end of the second permanent magnet 7 facing the first permanent magnet 6. A limiting shoulder 801 is provided on the drive shaft 8. In the braking state, the gap between the end face of the rotor 3 near the stator 1 and the limiting shoulder 801 is smaller than the braking gap. Those skilled in the art should understand that the "braking gap" refers to the gap between the armature 2 and the stator 1 in the braking state.

[0019] Based on the above, when the electromagnetic brake is released, the armature 2 is attracted by the stator 1, the first permanent magnet 6 attracts the second permanent magnet 7, and drives the rotor 3 to move toward the armature 2. During the movement of the rotor 3, it is blocked by the limiting shoulder 801 on the transmission shaft 8, so that gaps are formed between the rotor 3 and the flange 4 and between the rotor 3 and the armature 2, so as to avoid friction on both sides of the rotor 3 when the brake is released, thereby preventing the friction noise caused by this.

[0020] It should be understood that the attraction between the first permanent magnet 6 and the second permanent magnet 7 should be less than the preload of the spring 5, so as to ensure that the armature 2 will not be pulled back by the attraction between the first permanent magnet 6 and the second permanent magnet 7 after being attracted by the stator 1, that is, to ensure that the electromagnetic brake can be released normally.

[0021] In this embodiment, under braking conditions, the gap between the end face of the rotor 3 near the stator 1 and the limiting shoulder 801 (for ease of description, this gap is defined as the limiting gap below) is equal to half the braking gap. For example, if the braking gap is 0.3 mm, the limiting gap is 0.15 mm. It should be understood that in other embodiments, the limiting gap can of course be other ratios relative to the braking gap, as long as it ensures that the travel distance of the rotor 3 following the armature 2 is less than the braking gap.

[0022] In this embodiment, the rotor 3 is mounted on the transmission shaft 8 as follows: the rotor 3 has an internal spline hole and is connected to a spline bushing 9, achieving circumferential fixation and axial sliding connection between the rotor 3 and the spline bushing 9. The spline bushing 9 is fixedly connected to the transmission shaft 8, and the specific connection method is not limited; for example, key connection, interference fit, etc. are all acceptable. Furthermore, the transmission shaft 8 has a positioning shoulder 802, which abuts against the end face of the spline bushing 9 near the stator 1, achieving axial positioning of the spline bushing 9. It is easy to understand that the diameter of the journal at the positioning shoulder 801 is larger than the diameter of the journal at the positioning shoulder 802 but smaller than the minor diameter of the internal spline hole. This design ensures that the end face of the rotor 3 near the stator 1 can contact the positioning shoulder 801, ensuring that the limiting function of the positioning shoulder 801 can be realized.

[0023] In this embodiment, friction plates 12 are provided on both sides of the rotor 3, and are fixed to both sides of the rotor 3 by means of bonding or other methods.

[0024] In this embodiment, the flange 4 and stator 1 are connected by screws 10. A limiting sleeve 11 is fitted onto the screws 10, with one end abutting against the stator 1 and the other end against the flange 4, thus limiting the distance between the flange 4 and the stator 1 and indirectly ensuring the braking clearance. This eliminates the need for manual adjustment of the braking clearance, making installation more convenient. Furthermore, the armature 2 has a guide opening 201 that slides with the limiting sleeve 11, providing guidance for the movement of the armature 2 and limiting its radial position. Alternatively, in this embodiment, the guide opening 201 is a notch located on the edge of the armature 2; in other embodiments, the guide opening 201 can also be in other forms, such as a through hole on the armature 2.

[0025] This embodiment also provides a method for preventing friction noise, applied to the aforementioned electromagnetic brake for preventing friction noise. When the electromagnetic brake is released, the armature 2 is attracted by the stator 1, the first permanent magnet 6 attracts the second permanent magnet 7, and drives the rotor 3 to move toward the armature 2. During the movement of the rotor 3, it is blocked by the limiting shoulder 801 on the transmission shaft 8, so that gaps are formed between the rotor 3 and the flange 4 and between the rotor 3 and the armature 2, so that the rotor 3 can be suspended between the flange 4 and the armature 2, avoiding contact friction between the rotor 3 and the components on both sides, thereby preventing the friction noise caused by it.

[0026] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An electromagnetic brake for preventing friction noise, comprising a stator, an armature, a rotor, and a flange arranged sequentially, the flange being fixedly connected to the stator, the stator being provided with a plurality of springs for pressing the armature, and the rotor being circumferentially fixed to a transmission shaft, characterized in that, The armature is provided with a first permanent magnet on the side near the rotor, and the rotor is provided with a second permanent magnet on the side near the armature. The first permanent magnet and the second permanent magnet attract each other and the attraction force is less than the preload of the spring. The transmission shaft is provided with a limiting shoulder. In the braking state, the gap between the end face of the rotor near the stator and the limiting shoulder is less than the braking gap.

2. The electromagnetic brake for preventing friction noise according to claim 1, characterized in that, In the braking state, the gap between the end face of the rotor near the stator and the limiting shoulder is equal to 1 / 2 of the braking gap.

3. The electromagnetic brake for preventing friction noise according to claim 1, characterized in that, The rotor is provided with an internal spline hole and connected to a spline bushing, which is fixedly connected to the drive shaft.

4. The electromagnetic brake for preventing friction noise according to claim 3, characterized in that, The drive shaft is provided with a positioning shoulder for abutting the end face of the spline bushing near the stator. The diameter of the journal at the limiting shoulder is greater than the diameter of the journal at the positioning shoulder and smaller than the minor diameter of the inner spline hole.

5. The electromagnetic brake for preventing friction noise according to claim 1, characterized in that, The flange is connected to the stator by screws.

6. The electromagnetic brake for preventing friction noise according to claim 5, characterized in that, A limiting sleeve is fitted onto the screw to limit the distance between the flange and the stator.

7. The electromagnetic brake for preventing friction noise according to claim 6, characterized in that, The armature is provided with a guide opening that slides with the limiting sleeve.

8. The electromagnetic brake for preventing friction noise according to claim 7, characterized in that, The guide opening is a notch located on the edge of the armature.

9. The electromagnetic brake for preventing friction noise according to claim 1, characterized in that, Friction plates are provided on both sides of the rotor.

10. A method for preventing friction noise, applied to the electromagnetic brake for preventing friction noise as described in any one of claims 1-9, characterized in that, When the electromagnetic brake is released, the armature is attracted by the stator, the first permanent magnet attracts the second permanent magnet, and the rotor moves toward the armature. During the rotor's movement, it is blocked by the limiting shoulder on the transmission shaft, which creates gaps between the rotor and the flange and between the rotor and the armature.

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