JPS5921263A - Cage-shaped rotor motor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention includes an armature made of a magnetic material and attached to a rotor and coupled to a brake body, and this armature is provided so as to be movable in the axial direction. is moved axially against the force of a pressure spring with the help of at least a stator magnetic field, by means of which the damping body coupled to the armature is pressed against a brake friction surface fixed to the housing in the braking position. The present invention relates to a squirrel cage rotor motor incorporating an electromagnetically releasable spring pressure brake.

[Prior art and its problems]

This type of electric motor is described in the Siemens instruction manual (MP6A
4/Id June 1969).

In this electric motor, there is a
A special frame is provided which is excited by the stator magnetic field. This frame arrangement necessitates an axial extension of the stator, which results in a greater material outlay of sheet metal and copper. There is a brake retainer at the axial end of the frame. Therefore, the total length of an electric motor equipped with a brake is significantly longer than the total length of an electric motor of the same capacity without a brake.

[Purpose of the invention]

The basic object of the present invention, as stated at the beginning, is to prevent the overall length in the axial direction from becoming longer than that of an electric motor of the same capacity without a brake. There are different types of electric motors.

[Key points of the invention]

According to the invention, the above object is achieved by forming the armature as a shell ring with a U-shaped cross-section overlying the short-circuit ring;
A protrusion extending in the axial direction from the inner leg is provided on the outer leg of the shell ring in the radial direction. The depth in the direction is equal to the protrusion length of the protrusion, and the radial depth is set in the radial direction between the protrusion protruding into the external corner notch and the edge of the external corner notch extending in the axial direction. This is achieved by sizing the area so that there is a void of . Since the shell ring can be provided in the space defined by the coil ends of the stator winding between the rotor and the bearing housing, this shell ring requires an increase in the overall axial length of the motor. do not have. Furthermore, the magnetic field generated by the current flowing in the short-circuit ring when the brake is released is utilized by the shell ring. Furthermore, the protrusions of the shell ring are attracted into the external corner cuts of the rotor laminations by the stator magnetic field. In this way, a sufficiently large force is generated to open and to hold the brake in the open position.

The circumferentially acting connection between the shell ring and the rotor is achieved by drilling a hole in the bottom of the shell ring, connecting the short circuit ring through this hole, and axially projecting cooling fins or balance pins. It can be easily configured by fitting.

According to another embodiment of the invention, a connecting body with an axial hole is coupled to the outside of the bottom of the shell ring, and a pressure spring is provided radially inside the short-circuit ring between the connecting body and the end face of the rotor. is,
Furthermore, a disk with a brake lining as a braking body is connected to a shell ring via a coupling body and a brake friction surface fixed to the housing is formed on the bearing cover, which saves space for the electric motor and brake. Contribute to configuring it so that it does not take.

By connecting the coupling body and the disk to each other via spacer bolts, the braking device can be adapted to different overall length dimensions of the electric motor. For motors with the same rotor diameter but different overall lengths, it is only necessary to use spacer bolts of corresponding length. No other parts of the brake need to be changed.

Further, the connecting body and the disc can also be integrally formed with a spacer interposed between them.

In this case, components formed according to the length of each electric motor are required, but there is no need to assemble spacer bolts.

[Embodiments of the invention]

Hereinafter, the subject matter of the present application will be explained in more detail by means of the following examples.

Reference numeral 1 indicates a stator, and reference numeral 2 indicates a rotor with squirrel cage conductors of the motor. The motor shaft 3 that supports the rotor 2 is
It is supported by a spherical bearing 5 provided in a bearing housing of a bearing stand flange-mounted to the motor housing. A bearing cover 6 placed over the bearing housing inside the bearing stand 4 closes the bearing housing and protects the spherical bearing 5.

On the end face side of the rotor 2, there is a short circuit ring 7 that connects the rotor bar.
is being cast. This shorting ring 7 is provided with individual axially projecting cooling fins or balancing bins 8 . A shell ring 9 having a U-shaped cross section is placed over the shorting ring 7. The bottom part 10 of the six shell ring 9 is provided with a hole through which a cooling fin or balance pin 8 is fitted.

By doing this, the rotor 2 and the shell ring 9
A circumferentially acting connection is made between. moreover,
A connecting body 11 having a shaft hole is fixed to the outside of the bottom part 10. A pressure spring 12 is installed in the radial gap between the shaft 3 and the short-circuit ring 7, which acts in the axial direction and is supported by the rotor end face 13 and the coupling body 11. A disc 16 with a brake lining 15 is attached to the spacer bolt 14
It is connected to the connecting body 11 via. Disk 16 is preferably made of a non-magnetic material or magnetically insulated from the coupling body to avoid magnetic shunting. A brake friction surface 17 is formed on the bearing cover 6 facing the brake lining 15 .

The shell ring 9 made of magnetic material is provided with an axially projecting projection 19 on its radially outer leg 18 . An external corner notch 20 is formed in the laminated portion of the rotor thin plate facing this protrusion 19 .

When the electric motor is switched off, the pressure spring 12 causes the coupling body 11 and the disk 16 and shell ring 9 connected thereto to move in the axial direction. The brake lining 15 is then attracted to the brake friction surface 17, whereby the rotor is braked. When the electric motor is powered on, a magnetic field is generated by the current flowing through the short circuit ring 7,
This magnetic field attracts the shell ring 9. At the same time, the stator magnetic field of the electric motor acts on the projection 19, which causes an axially directed force to act on the shell ring 9 in a circular manner.

In order to obtain such an axially directed force, the magnetic flux starting from the stator and entering the projection 19 must be directed to the end side edge 21 of the projection 19 and the end side edge 21 of the inner leg 23 of the shell ring. It is necessary to enter the radially extending edge 24 of the external corner cut 20 and the rotor end face 13 as completely as possible via the section 22 . To achieve this, a gap 26 is formed between the axial projection 19 and the axially extending edge 25 of the external corner notch 20 . This gap 26 has a high magnetic reluctance, so that the magnetic flux induced by the stator field essentially flows through the shell-like ring and into the said location of the rotor laminations.

In the suctioned state, the shell ring 9 rests with its edges 21 and 22 on its two end faces against the radially extending edge 24 of the external corner notch. Due to the magnetic force acting on the shell ring 9 by the stator magnetic field, the shell ring 9 is held in the attracted position shown in dotted lines, especially during no-load operation of the motor. In this way, it is ensured that the brake remains reliably in the open position even during no-load operation, when the magnetic field acting on the short-circuit ring 7 is relatively weak.

The above-mentioned squirrel cage rotor motor is
It is particularly suitable as a drive device for a circular saw that requires the electric motor to be stopped within 10 seconds after being shut off. A further advantage is that the installation of this braking device requires virtually no essential structural changes. It is sufficient to simply provide the rotor with the external angle notch.

〔Effect of the invention〕

As explained above, in the present invention, when the motor is energized and a rotor magnetic field is generated, the armature, which is attracted by the magnetic field and releases braking, is formed into a U-shaped cross section that covers the short-circuited ring of the rotor conductor. Because of this, the axial dimension required to incorporate the armature into the motor is extremely small, and the total length of the motor in the axial direction can be shortened compared to conventional motors. In addition, as is well known, the secondary current of the motor at startup is close to its maximum value, so the ionization that flows through the short-circuit ring at this time is also significant. A large magnetic flux is generated within the pole,
Since it is attracted to the end face of the rotor with a large magnetic force, it is possible to reliably release the brake on the rotor at startup.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention, and FIG. 2 is an enlarged sectional view showing a shell-like ring constituting the device of the present invention shown in FIG. 1: Stator, 2: Rotor, 3: Motor shaft, 4: Bearing stand,
5: Spherical bearing, 6: Bearing cover, 7: Short circuit ring. 8: Balance pin, 9: Shell ring, 10: Bottom, 11: Connector, 12: Pressing spring, 13: End face of rotor. 14: Spacer bolt, 15: Brake lining, 1
6: Disc, 17: Brake friction surface, 18: Shell-like ring leg, 19: Projection, 20: External corner notch, 21, 22:
Shell-shaped ring edge, 23: shell-shaped: gap.

Claims (1)

[Claims] 1) An armature made of a magnetic material and attached to the rotor and coupled to the brake body, the armature being movable in the axial direction and resisting the force of the pressing spring with the help of at least the stator magnetic field. An electromagnetically releasable spring pressure brake is incorporated which is moved in the axial direction and by means of which a pressure spring causes the braking body coupled to the armature to be pressed against a brake friction surface fixed to the housing in the braking position. In squirrel cage rotor motors, the armature is formed as a shell ring with a U-shaped cross section that overlies the shorting ring;
A protrusion extending in the axial direction from the inner leg is provided on the outer leg of the shell ring in the radial direction. The depth in the direction is equal to the protrusion length of the protrusion, and the radial depth is set in the radial direction between the protrusion protruding into the external corner notch and the edge of the external corner notch extending in the axial direction. A squirrel-cage rotor electric motor characterized by being dog-shaped so that a cavity is formed.