EP3394963A1

EP3394963A1 - Brake for rotary electric machine

Info

Publication number: EP3394963A1
Application number: EP16809097.5A
Authority: EP
Inventors: Pascal Carriot; Benoît VINCENT; Joël MAYSOUNABE; Pascal Beynaud
Original assignee: Moteurs Leroy Somer SA
Current assignee: Moteurs Leroy Somer SA
Priority date: 2015-12-23
Filing date: 2016-12-14
Publication date: 2018-10-31
Also published as: FR3046307A1; WO2017108527A1; FR3046307B1; US20190013715A1; CN108475965A

Abstract

A brake (10) for a rotary electric machine including a rotor having a shaft, the brake including: - at least one fixed armature (34); at least one yoke (31) that can be moved between a position of braking the shaft of the machine and a position in which the shaft rotates freely; at least one coil (33) borne by the yoke; at least one brake disc (20) borne by the shaft of the rotor; at least one elastic return system (38) for applying the yoke against the brake disc in the absence of electrical excitation of the coil, the armature being positioned such that the excitation of the coil causes the yoke to approach the armature and distances the yoke from the brake disc.

Description

Brake for rotating electric machine

The present invention relates to the brakes for electric motors. In some applications, such as lifting or elevator car drives, the motors are equipped with power-down brakes, which block the motor rotor when they stop being electrically powered.

These brakes conventionally comprise a fixed yoke relative to the motor housing, which houses a coil, and a movable armature that can be moved under the effect of a magnetic field generated by the coil. Return springs urge the armature to hold it in the locked position of the rotor when the coil is not energized. To release the brake, a current is sent into the coil, which moves the armature from its blocking position, against the spring return action.

For safety reasons, the engines are often equipped with several redundant brakes. The brakes are thus stacked axially or arranged side by side on either side of the rotor shaft.

DE 7146345 discloses a brake comprising a movable armature.

EP 1 715 564 A2 discloses an engine equipped with two brakes, each in the form of a stirrup, with two moving armatures and two independent fixed yokes.

EP 1 883 756 A2 describes an engine equipped with two independent brakes, each with a movable armature and a fixed yoke. The yokes have a rectangular shape, and the coils an elliptical or annular shape.

The known brakes are relatively noisy.

There is a need to have a brake easy to implement on an electric motor, reliable operation, reduced space and low noise.

The invention achieves this goal by means of a rotating electric machine brake comprising a rotor having a shaft, the brake comprising:

at least one fixed armature,

at least one yoke movable between a braking position of the machine shaft and a position of free rotation of the shaft,

at least one spool carried by the bolt,

at least one brake disc carried by the rotor shaft,

at least one elastic return system for applying the bolt against the brake disk in the absence of electrical excitation of the coil, the armature being arranged so that the excitation of the coil causes a reconciliation of the yoke of the armature and moves the cylinder head away from the brake disc.

The fact that the yoke is movable, in the invention, tends to reduce the operating noise because the yoke with its coil is more massive than the armature. The speed of the bolt is lower because it takes longer to accelerate. The brake can use a single disc, which reduces weight and bulk.

Preferably, the elastic return system is interposed between the armature and the cylinder head. It is constituted for example by several helical springs. These springs can be housed in the thickness of a wall of the cylinder head which defines the housing receiving the coil. When this housing has an elongated shape, the springs are preferably arranged along the long sides of the cylinder head. The springs are advantageously received in blind holes of the cylinder head.

Preferably, the yoke is open towards the armature. This makes it easier to provide the bolt with a clean surface to contact the brake lining of the brake disc.

To enable the brake to be actuated manually in the absence of current, an operating lever may be provided to act on the yoke through the frame, for example being engaged under a screw head fixed on the yoke and protruding from the yoke. armature opposite the motor housing. This lever can, when it is actuated, be supported on the frame, in particular via a plate which it is secured at its base, to pull the breech.

The frame may have substantially the same outer contour as the breech. The armature and / or the cylinder head may in particular have a substantially polygonal contour. Preferably, the coil is elongated.

The cylinder head is preferably a casting, which allows to achieve it at a lower cost. It is the same with the frame.

The frame can carry removable caps that face the breech housing that can receive additional compression springs of the elastic return system, thereby increasing the braking torque without having to disassemble the brake.

The invention also relates to an electric rotary machine comprising at least one brake according to the invention, as defined above. It is particularly advantageous that the brake is multiple, preferably double, that is to say that the machine comprises at least two identical brake units disposed on either side of the axis of the rotor. In a variant, the brake comprises a plurality of yokes, in particular two yokes disposed on either side of the axis of the rotor, and a reinforcement common to them. Such an armature may comprise two parts arranged on either side of the rotor axis, connected by bridges of material, preferably integral with said parts. Each part of the frame is associated with a corresponding breech.

The or each brake may have its armature fixed to the housing of the machine by screws and spacers between which and / or on which moves the corresponding yoke.

Preferably, damping elements are interposed between the yoke and the housing on the one hand, and the yoke and the frame on the other hand. These damping elements are preferably constituted by rings of an elastically deformable material, such as an elastomer, engaged on the spacers. In certain known brakes, the damping element is constituted by an O-ring disposed between the yoke and the armature

The invention applies to any rotary electrical machine, but is particularly suitable for those for which the rotor drives a winch or a pulley.

Preferably, the brake disc is axially movable on the shaft of the machine, thanks to a grooved connection for example.

The invention will be better understood on reading the detailed description which follows, examples of non-limiting implementation thereof, and on examining the appended drawing, in which:

FIG. 1 represents in isolation and in perspective a brake produced according to a first example of implementation of the invention,

FIG. 2 shows the brake of FIG. 1 from another angle of view, after the removal of certain components, in particular from the yoke of one of the brake units,

FIG. 3 partially and schematically represents, in perspective, the brake of FIG. 1 with certain components removed, in particular the armature,

FIG. 4 is another partial schematic view of the brake of FIG. 1, reinforcement and coil removed, FIG. 5 schematically and partially, in perspective, an example of an engine equipped with a second example of a brake according to the invention, and

FIG. 6 is a schematic axial section of a brake unit of FIG. 5.

FIGS. 1 to 4 show a brake 10 according to a first embodiment of the invention. This brake 10 is intended to equip an electric motor not shown in the figures, comprising a rotor rotating with a shaft relative to a housing on which the brake is fixed.

The rotor can be wound and / or permanent magnet or squirrel cage. The shaft rotates a brake disc which carries brake linings 21 and 22. The brake disk is connected to the shaft by a splined connection, which allows it to transmit the braking torque to the shaft while being able to move axially with respect thereto.

In the example of Figures 1 to 4 the brake 10 comprises two identical brake units 30, which share a common armature 34, divided into two parts 34a and 34b connected by material bridges 34c. Parts 34a and 34b are respectively associated with brake units 30.

Each brake unit 30 comprises a yoke 31 which has a housing 32 open on the opposite side to the housing.

A coil 33 of elongate shape is received in the housing 32. The yoke 31 is for example made of magnetic iron. In a variant, the yoke 31 is made with a bundle of assembled magnetic sheets, like the sheet packs of the rotors or stators conventionally used.

The armature 34 is fixed on the casing of the machine by means of screws 36 and spacers 37.

Each yoke 31 is located between the frame 34 and the housing, and it is biased against the housing by compression springs 38, apparent in FIG. 4.

These springs 38 are housed in blind holes 41 machined in the peripheral wall 42 of the yoke 31, which delimits laterally the housing 32. The springs 38 are for example twelve in number for each yoke 31, being distributed in two groups of three along the long sides of the cylinder head 31. Thus, when the coil 33 is not electrically powered, the yoke 31 is pressed against the brake disk by the springs 38, and the latter is pushed against the housing. The brake linings 21 and 22 thus apply respectively against the housing and the cylinder head 31 and the rotor is locked in rotation. The brake is said to "lack of current" because it exerts its braking action when the power supply to the coil is cut off. The yokes 31 are applied on the brake disk on either side of the axis of rotation thereof.

When the coil 33 is electrically powered, the yoke 31 approaches by magnetic attraction of the armature 34 and away from the brake disk 20, which is released and can rotate freely again.

The yoke 31 has extensions 51 at its longitudinal ends, which are traversed by the spacers 37, as can be seen in Figure 2 in particular.

Damping elements constituted by rings 53 of an elastically deformable material are mounted on each spacer 37 on either side of the corresponding extension 51. One of the rings 53 thus interposes axially between the yoke 31 and the frame 34 and the other ring 53 between the yoke 31 and the casing 7.

These rings 53 do not prevent the axial displacement of the yoke 31 between the braking and free rotation positions, but allow to dampen the movement of the cylinder head at the end of travel and further reduce the operating noise.

To allow maneuvering the brake manually in the absence of power supply of the coils 33, a lever 60, visible in particular in Figure 3, is provided.

This lever 60 comprises at its base a plate 61 provided with two openings 62 for engaging between the head 64 of screw 65 and the outer face 66 of the frame 34.

The screws 65 are each fixed in a corresponding yoke 31, as can be seen in particular in Figure 4, and through the armature 34 in favor of bores of sufficient diameter.

When the operator wishes to release the brake 10, he pushes on the lever 60. The plate 61 bears on the outer face 66 of the parts 34a and 34b of the armature 34 and pivots slightly, which pulls on the screws 65 by lifting their head 64. The screws 65 cause the cylinder heads 31 to move back and away from the brake disk against the action of the springs 38.

The openings 62 do not hinder the pivoting of the wafer 61, because they are open in the opposite direction to the lever 60.

The armature carries plugs 70, visible in particular in Figure 1, which are accessible through corresponding openings 73 of the armature 34. These plugs 70 face housing 75 of the breech, constituted by blind holes, which can receive additional compression springs that increase the braking torque. It is possible to add these springs without disassembling the brake, by removing the plugs 70, by introducing the springs, then by replacing the plugs 70. The springs then bear against the plugs 70.

In the example of FIGS. 1 to 4, the two brake units 30 share the same reinforcement 34, this being made in the form of a single piece by casting, for example.

It is possible to make each brake unit 30 with a clean armature 34, as illustrated in FIGS. 5 and 6.

In this case, each brake unit 30 can be put in place and removed independently of the other unit.

These figures show the casing 7 of the motor on which the brake is fixed, as well as the brake disk 20 which carries the brake linings 21 and 22.

Figures 5 and 6, the unlocking lever has not been shown, but it can be the same as the lever 60 of the example of Figures 1 to 4.

The invention is not limited to the examples which have just been described.

The brake can be made with more than two brake units or alternatively with a single unit. In this case, the cylinder head is for example ring-shaped.

Claims

A brake (10) for a rotary electric machine having a rotor having a shaft, the brake comprising:

at least one fixed armature (34),

at least one yoke (31) movable between a braking position of the shaft of the machine and a position of free rotation of the shaft,

at least one coil (33) carried by the breech,

at least one brake disk (20) carried by the rotor shaft; - at least one elastic return system (38) for applying the bolt against the brake disk in the absence of electrical excitation of the coil; armature being arranged so that the excitation of the coil causes a reconciliation of the yoke of the armature and moves the cylinder head away from the brake disc.

2. Brake according to claim 1, the elastic return system (38) interposed between the armature and the cylinder head.

3. Brake according to claim 1 or 2, the yoke (31) being open towards the armature.

4. Brake according to any one of the preceding claims, comprising an operating lever (60) for acting on the yoke through the frame, this lever being preferably engaged in at least one head (64) of screw fixed on the cylinder head and protruding from the frame opposite the engine crankcase.

5. Brake according to any one of the preceding claims, the armature having substantially the same outer contour as the cylinder head.

6. Brake according to any one of the preceding claims, the armature and / or the yoke having a substantially polygonal contour.

7. Brake according to any one of the preceding claims, the coil (33) being of elongate shape.

8. Brake according to any one of the preceding claims, the yoke (31) being a casting.

9. Brake according to any one of the preceding claims, wherein damper elements (53) interposed between the yoke and the housing on the one hand, and the yoke and the frame on the other.

10. Brake according to the preceding claim, the damping elements (53) being constituted by rings of an elastically deformable material, such as an elastomer.

11. Brake according to any one of the preceding claims, the armature (34) carrying removable caps (70) which face the housing (75) of the cylinder head can receive additional compression springs to increase the torque These springs can be put in place without disassembling the brake.

12. Electrical rotating machine comprising at least one brake (10) as defined in any one of claims 1 to 11.

13. Machine according to claim 12, comprising at least two identical brake units disposed on either side of the axis of the rotor.

14. Machine according to one of claims 12 and 13, the armature being fixed to the housing of the machine by screws and spacers between which and / or on which moves the cylinder head (31).

15. Machine according to any one of claims 12 to 14, the rotor driving a winch or a pulley.

16. Machine according to any one of claims 12 to 15, the brake disc (20) being axially movable on the shaft of the machine.