WO2018126353A1

WO2018126353A1 - Permanent magnet brake and servo drive motor

Info

Publication number: WO2018126353A1
Application number: PCT/CN2017/070120
Authority: WO
Inventors: Jian Zhong Zhang; Sheng You WANG; Xin Long LI
Original assignee: Siemens Aktiengesellschaft
Priority date: 2017-01-04
Filing date: 2017-01-04
Publication date: 2018-07-12

Abstract

A permanent magnet brake (1) includes a first brake pad (2) and the brake disc is arranged on a first side of the stator (3), the stator (3) further comprises a stator yoke (4), a stator yoke (4) on the side facing the first brake pad (2) is provided with a spring hole (7), a spring (8) is arranged in the spring hole (7); a coil (5) disposed in the stator yoke (4), and a permanent magnet (6), arranged on the stator yoke (4), wherein the first brake pad (2) includes a ferromagnetic body. A servo drive motor includes motor, output shaft and a permanent magnet brake (1).The permanent magnet brake (1) may utilize a forward pulse current or a reverse pulse current to achieve permanent magnetic brake (1) of a brake and brake release.

Description

PERMANENT MAGNET BRAKE AND SERVO DRIVE MOTOR

Technical Field

The present invention relates to a permanent magnet brake and a servo drive motor, especially relates to a permanent magnet brake adapted to be controlled by a pulse current.

Background Art

Brake is one of most important components of a servo drive motor, which is used for fast positioning, keeping work piece with no deviation, or ensuring safety, e.g., preventing accidents caused by mechanical movement at the time of power failure. Thus, the brake is critical to personal safety and equipment safety.

Conventional brakes are typically in one of braking state and releasing state when coil is energized, while in the other of the braking state and releasing state when the coil is de-energized. Current waveform of such conventional brakes, for example, is shown by Fig. 5B, in which “A” represents the releasing state and “B” represents the braking state.

Summary of the Invention

Embodiments of the present invention direct to a permanent magnet brake with new structure and operation mode. In particular, the embodiments of the present invention, thanks to its new structural design, make the permanent magnet brake switching between braking and releasing state by inputting pulse current to coil, with no need to provide continuous current to the coil to maintain in a certain state.

In particular, the invention provides a permanent magnet brake, comprises a first brake pad and a stator that locates at one side of the first brake pad, characterized in that, the stator further includes:

a stator yoke, having at least one of spring holes at one side of the stator yoke facing the first brake pad, and a spring is provided within the spring hole；

a coil, being positioned in the stator yoke； and

a permanent magnet, being positioned in the stator yoke,

wherein, the first brake pad comprises a ferromagnetic body.

In accordance with one embodiment of the invention, in the permanent magnet brake, further including a pulse current generator, the pulse current generator is electrically connected to the coil, which generates a forward pulse current or a reverse pulse current for the coil.

In accordance with one embodiment of the invention, in the permanent magnet brake, when the forward pulse current is provided to the coil, the stator yoke attracts the first brake pad, and when the reverse pulse current is provided to the coil, the stator yoke repels the first brake pad.

In accordance with one embodiment of the invention, in the permanent magnet brake, the coil and the permanent magnet are in annular shape and embedded in the stator yoke, wherein the permanent magnet is fixed at a side of the stator yoke that is far away from the first brake pad.

In accordance with one embodiment of the invention, in the permanent magnet brake, the stator yoke comprises:

an inner yoke, having an annular wall and an annular projecting portion, which protrudes from inner ring of the annular wall； and

an outer yoke, being in annular shape, outer diameter of the annular projecting portion of the inner yoke is smaller than inner diameter of the outer yoke,

wherein the coil is sandwiched between the annular projecting portion of the inner yoke and the outer yoke；

wherein, the permanent magnet is in annular shape, and sandwiched between the annular wall of the inner yoke and the outer yoke.

In accordance with one embodiment of the invention, in the permanent magnet brake, further including:

a second brake pad； and

a friction plate, being disposed between the first brake pad and the second brake pad, wherein inner ring of the friction plate is provided with an inner gear, the inner gear is coupled with an outer gear of a coupling gear.

In accordance with one embodiment of the invention, in the permanent magnet brake, the stator yoke, the first brake pad and the second brake pad are provided with guide rail holes respectively, and the permanent magnet brake further includes a guide rail penetrating through the guide rail holes.

Further, the invention provides a servo drive motor, includes motor, output shaft and a permanent magnet brake as discussed above, the output shaft extends from the motor to be driven by the motor to rotate, the permanent magnet brake is installed on the output shaft, wherein the permanent magnet brake is braked or released by introducing pulse currents opposite in direction into the coil, so as to stop or rotate the output shaft.

It should be understood that the above general description and the following detail description of the invention are examples and illustrations, and it is intended that a further explanation of the invention as described by the Claims will be further provided.

Brief Description of the Drawings

Drawings, which are collected and form a portion of the application, are included, in order to provide further understanding of the invention, the embodiments of the invention are illustrated in the drawings, and the drawings together with the description has the function of explaining the principle of the invention. In the drawings:

FIG. 1 illustrates structure of one embodiment of the permanent magnet according to the present invention.

FIG. 2 is a sectional view illustrating one embodiment of the stator according to the present invention.

FIG. 3 is a stator exploded view illustrating another embodiment of the stator according to the present invention.

FIG. 4 illustrates one embodiment of the permanent magnet brake according to the present invention.

FIG. 5A illustrates pulse current waveforms of one embodiment of the present invention.

FIG. 5B illustrates a current waveform of the prior art.

Reference Numbers:

1 permanent magnet brake

2 first brake pad

3 stator

4 stator yoke

5 coil

6 permanent magnet

7 spring hole

8 spring

9 second brake pad

10 friction plate

11 coupling gear

12 guide rail hole

13 guide rail

14 inner yoke

15 outer yoke

16 annular wall

17 annular projecting portion

Detailed Description of Example Embodiments

The embodiments of the invention will now be described in detail by referring to the drawings.

The basic principle of the invention will now be discussed in detail by referring firstly to Fig. 1 ～ Fig. 5A as follows. The permanent magnet brake 1 of the invention comprises mainly: a first brake pad (inner side brake pad) 2 and a stator 3 that locates at one side of the first brake pad 2. The stator 3 can further include a stator yoke 4, a coil 5 and a permanent magnet 6. The stator yoke 4 has at least one of spring holes 7 at one side of the stator yoke 4 facing the first brake pad 2, and a spring 8 is provided within the spring hole 7. One end of the spring 8 is embodied within the spring hole 7 of the stator yoke 4, while the other end presses against the first brake pad 2. Additionally, a coil 5 and a permanent magnet 6 are positioned in the stator yoke 4, respectively. Said first brake pad 2 comprises a ferromagnetic body, so that it might be attracted by the permanent magnet 6.

Based on the above structure, the permanent magnet brake 1 might implement braking or releasing by merely introducing pulse currents opposite in direction into the coil 5. For example, Fig. 5A illustrates pulse current waveforms of one embodiment of the present invention, in which “A” represents the releasing state and “B” represents the braking state.

For example, at the time of releasing (activating) , the first brake pad 2 is initially far away from the stator 3, so that the permanent magnets 6 has little attraction to the first brake pad 2； by introducing pulse current in one direction to strengthen magnetic field for the attraction, the first brake pad 2 will be attracted to move towards the stator 3； during this movement, attraction of the permanent magnet 6 to the first brake pad 2 increases until attraction force of the permanent magnet 6 per se becomes sufficient to overcome elastic force of the spring 8 to suck the first brake pad 2 to the stator yoke 4, and then there is no need to introduce any more current into the coil 5. In this case, in accordance with the invention, it is only required to introduce a pulse current to the coil 5 in the process of releasing of the permanent magnet brake 1, with no need to provide continuous current.

Further, at the time of braking (stopping) , the first brake pad 2 is initially close to the stator 3, so that the permanent magnets 6 has great attraction to the first brake pad 2； by introducing pulse current in the other (opposite) direction to eliminate magnetic field of the permanent magnet 6 for the attraction, the first brake pad 2 will be repelled to move away from the stator 3； during this movement, attraction of the permanent magnet 6 to the first brake pad 2 decreases until elastic force of the spring 8 per se becomes sufficient to overcome attraction force of the permanent magnet 6, and then there is no need to introduce any more current into the coil 5. At this moment, the first brake pad 2, under the elastic force of the spring 8, together with the second brake pad 9, presses towards the friction plate 10 to implement braking, and then machine will stop running. After the stop, current provided to the coil 5 might be removed, since the first brake pad 2 will form static friction force with the friction plate 10 by overcoming attraction from the permanent magnet 6 in the presence of the elastic force from the spring 8, so that the machine could hold in stop position. Thus, in accordance with the invention, it is only required to introduce a reverse pulse current, which is in opposite direction to the pulse current provided during releasing, to the coil 5 in the process of braking of the permanent magnet brake 1, with no need to provide continuous current.

In a preferred embodiment, the permanent magnet brake 1 of the invention can further comprise a pulse current generator (not illustrated in the figures) . The pulse current generator is electrically connected to the coil 5, which generates a forward pulse current or a reverse pulse current for the coil 5 for releasing operation and braking operation, respectively. For example, when the forward pulse current is provided to the coil 5, the stator yoke 4 attracts the first brake pad 2, and when the reverse pulse current is provided to the coil 5, the stator yoke 4 repels the first brake pad 2.

Moreover, as illustrated by Fig. 1, the permanent magnet brake 1 can further includes a second brake pad (outer brake pad) 9 and a friction plate 10. The friction plate 10 is disposed between the first brake pad 2 and the second brake pad 9. Inner ring of the friction plate 10 is provided with an inner gear, which is coupled with an outer gear of a coupling gear 11. As shown by Fig. 4, the stator yoke 4, the first brake pad 2 and the second brake pad 9 are provided with guide rail holes 12 respectively. A guide rail 13 penetrates through the guide rail holes 12, so that the first brake pad 2 can slide along the guide rail 13. The second brake pad 9 is fixed at one end of the guide rail 13, and the stator yoke 4 is fixed at the other end of the guide rail 13.

Turning to Fig. 2, this figure illustrates one embodiment of the stator according to the present invention. In the embodiment shown by Fig. 2, the coil 5 and the permanent magnets 6 are in a ring shape and are embedded in the stator yoke 4. Especially, the permanent magnet 6 is fixed at one side of the stator yoke 4 that is far away from the first brake pad 2, while the coil 5 is fixed at the other side of the stator yoke 4 that is close to the first brake pad 2.

FIG. 3 is a stator exploded view illustrating another embodiment of the stator according to the present invention. In the embodiment shown by Fig. 3, the stator yoke 4 further comprises an inner yoke 14 and an outer yoke 15. The inner yoke 14 has an annular wall 16 and an annular projecting portion 17, which protrudes from inner ring of the annular wall 16. The outer yoke 15 is in annular shape, and outer diameter of the annular projecting portion 17 of the inner yoke 14 is smaller than inner diameter of the outer yoke 15, in order to allow the outer yoke 15 being installed on the inner yoke 14. In this embodiment, the coil 5 is suitable to be sandwiched between the annular projecting portion 17 of the inner yoke 14 and the outer yoke 15. The permanent magnet 6 is in annular shape, and is suitable to be sandwiched between the annular wall 16 of the inner yoke 14 and the outer yoke 15.

In summary, the permanent magnet brake 1 only requires to introduce into the coil 5 pulse current, instead of continuous current, during braking and releasing process, and thus it is able to reduce power consumption and heat generation of the permanent magnet brake 1. In the permanent magnet brake 1 of the invention, due to application of the permanent magnet 6, brake armature turns can be reduced, which will in turn reduce amount of copper used for the turns.

It will be apparent to those skilled in the art, various modifications and variants of the above example embodiments of the invention can be made without departing the sprit and scope of the invention. Therefore, it is intended that the modifications and variants of the invention falling within the scope of the Claims and its equivalent technical scheme can be covered by the invention.

Claims

A permanent magnet brake (1) , comprises a first brake pad (2) and a stator (3) that locates at one side of the first brake pad (2) , characterized in that, the stator (3) further includes:

a stator yoke (4) , having at least one of spring holes (7) at one side of the stator yoke (4) facing the first brake pad (2) , and a spring (8) is provided within the spring hole (7) ；

a coil (5) , being positioned in the stator yoke (4) ； and

a permanent magnet (6) , being positioned in the stator yoke (4) ,

wherein, the first brake pad (2) comprises a ferromagnetic body.
The permanent magnet brake (1) of the claim 1, characterized in that, further including a pulse current generator, the pulse current generator is electrically connected to the coil (5) , which generates a forward pulse current or a reverse pulse current for the coil (5) .
The permanent magnet brake (1) of the claim 2, characterized in that, when the forward pulse current is provided to the coil (5) , the stator yoke (4) attracts the first brake pad (2) , and when the reverse pulse current is provided to the coil (5) , the stator yoke (4) repels the first brake pad (2) .
The permanent magnet brake (1) of the claim 1, characterized in that, the coil (5) and the permanent magnet (6) are in annular shape and embedded in the stator yoke (4) , wherein the permanent magnet (6) is fixed at a side of the stator yoke (4) that is far away from the first brake pad (2) .
The permanent magnet brake (1) of the claim 1, characterized in that, the stator yoke (4) comprises:

an inner yoke (14) , having an annular wall (16) and an annular projecting portion (17) , which protrudes from inner ring of the annular wall (16) ； and

an outer yoke (15) , being in annular shape, outer diameter of the annular projecting portion (17) of the inner yoke (14) is smaller than inner diameter of the outer yoke (15) ,

wherein the coil (5) is sandwiched between the annular projecting portion (17) of the inner yoke (14) and the outer yoke (15) ；

wherein, the permanent magnet (6) is in annular shape, and sandwiched between the annular wall (16) of the inner yoke (14) and the outer yoke (15) .
The permanent magnet brake (1) of the claim 1, characterized in that, further including:

a second brake pad (9) ； and

a friction plate (10) , being disposed between the first brake pad (2) and the second brake pad (9) , wherein inner ring of the friction plate (10) is provided with an inner gear, the inner gear is coupled with an outer gear of a coupling gear (11) .
The permanent magnet brake (1) of the claim 1, characterized in that, the stator yoke (4) , the first brake pad (2) and the second brake pad (9) are provided with guide rail holes (12) respectively, and the permanent magnet brake (1) further includes a guide rail (13) penetrating through the guide rail holes (12) .
A servo drive motor, characterized in that, includes motor, output shaft and a permanent magnet brake (1) of any of the claims 1-7, the output shaft extends from the motor to be driven by the motor to rotate, the permanent magnet brake (1) is installed on the output shaft, wherein the permanent magnet brake (1) is braked or released by introducing pulse currents opposite in direction into the coil (5) , so as to stop or rotate the output shaft.