JPS5822937B2 - Jikuhou Koukahen Ikagogata Kaitenshidendouki - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a laminated rotor core comprising: a longer stratified rotor core portion having rotor conductor bars and a short-circuit ring at an axial end;
The shorter rotor core part has no conductor bars, and the shorter rotor core part protrudes axially outward of the corresponding end face of the stator in the first displacement position, and the stator winding The present invention relates to an axially variable squirrel cage rotor motor in which at least a portion of the stator enters the inner hole of the stator in a second displacement position when the stator is in a prescribed excited state.

The axial force determined by the principal reactance is particularly influenced by the air gap flux in the region of the rotor section which is displaced relative to the corresponding axial end of the stratified stator core when the rotor moves axially. Based on the recognition that the above-mentioned type of electric motor has already been proposed (see West German Patent Application No. 2246962), almost all of the current flowing through the rotor conductor bars flows from the end face of the stator core. The rotor ends are also short-circuited through the intermediate short-circuit ring near the rotor ends that protrude outward, and the suppressing effect on the air gap magnetic field of the rotor current is caused by the shorter rotor that protrudes outward from the intermediate short-circuit ring. It decreases in the area of the iron core.

That is, the axial force on the rotor is caused by the magnetic flux produced by the short ring current, and the magnitude of the axial force therefore depends on the magnetic flux density between the stator core and the rotor end core.

When this magnetic flux density or axial force is maximum, the reactance to short circuit current is maximum.

However, in the conventional structure, the magnetic flux due to the intermediate short-circuit ring current and the magnetic flux due to the current in the outermost end short-circuit ring flow in opposite directions within the rotor end core, so they cancel each other out, reducing the rotor current suppression effect. .

That is, the reactance becomes small and the axial force becomes small.

The squirrel-cage rotor of this type of axially self-displacing rotor electric motor, for example in the case of a squirrel-cage rotor with one intermediate short-circuit ring and two end-face short-circuit rings, is located in the vicinity of the intermediate short-circuit ring. One end face short-circuit ring can be made by die-casting a squirrel-cage rotor conductor and lathe-processing it after solidification, but in that case, in order to obtain good rotational torque characteristics, it is necessary to The total resistance of each shorting ring relative to the child conductor bar must be as large as possible.

The object of the invention is to make it possible to further increase the axial force compared to already proposed electric motors.

According to the present invention, in the squirrel-cage co-trochanter motor with axial co-migration displacement described at the beginning, the shorter rotor core portion has a larger outer diameter than the longer rotor core portion. In addition, there is a gap between the outer diameter of the longer rotor core and the inner diameter of the stator inner hole and the inner diameter of the stator inner hole of the shorter rotor core. This is achieved by having a portion of the gap smaller than the gap between the inner diameter of the hole and the inner diameter of the hole.

By doing this, in the shorter rotor core part, the rotor conductor bars with the steel plate of this core part are connected between the rotor conductor bars that protrude beyond the intermediate short-circuit ring without a unique short-circuit ring end face connection. It is possible to avoid the formation of a short-circuit bridge that undesirably suppresses the air gap magnetic flux in that part via the slot contact surface and the iron core steel plate.

On the other hand, the axial force can be further increased by particularly simple constructional and manufacturing measures, and the characteristics of the axial force can also be determined as a function of the displacement position of the rotor.

The outer diameter of the shorter rotor core may be equal over the entire length of the core, and may be larger than the outer diameter of the longer rotor core, or The outer diameter of the portion may be increased stepwise from the intermediate short-circuit ring to the end face.

In particular, by the latter means, the axial force of the axially displaced rotor can be changed stepwise to a predetermined magnitude depending on the displacement position, and when the rotor enters the hole in the stator, the axial force The force is increased stepwise in a stepwise manner at a given position, thereby making it possible, for example, to reliably achieve a release of frictional braking.

Such measures are particularly suitable, for example, if large tolerances of the damping spring force and of the construction dimensions are permitted in order to reduce manufacturing costs.

In the motor of the present invention, when the shorter rotor core is made of a circular core steel plate without slots, the rotor core is made without a squirrel-cage winding conductor, that is, without a rotor winding conductor. It is particularly easy to configure.

Moreover, in that case, it is easy to manufacture iron-core steel sheets, and
In such a core steel plate, the punching of the slots is noncontact, and the effective air gap within the shorter rotor core portion can be further increased, which has the advantage that the axial force can be further increased.

When manufacturing and assembling the shorter rotor core of the electric motor of the present invention, each steel plate is used as an individual steel plate and the corresponding extended shaft end of the longer rotor core is fitted with a squirrel cage winding in advance. It is preferable to attach the core to the top of the auxiliary core, or to assemble it in advance as an auxiliary core by, for example, riveting, and place it on the corresponding end of the extension shaft as an independent core.

In order to increase the axial force at the moment of switching on the variable rotor motor on the one hand, and on the other hand to increase the capacity and starting torque of the motor, the total length of the rotor core must be longer than the length of the stator core. , and the length of the longer rotor core portion existing between both short-circuited rings may be made smaller than or equal to the length of the stator core.

The initial position of the protruding side end of the rotor core is such that when the stator winding and stator winding are in a non-excited state, the inner end surface of the shorter rotor core portion is the same as the end surface of the corresponding stator core. It is best to select it so that it is within the center or inside the end face of the stator core.

Next, the present invention will be described in detail with reference to the drawings.

Figures 1 and 2 show an electric motor of the type that has already been proposed, and Figure 3 shows the same motor that has been improved from the one shown in Figures 1 and 2.
A conventional electric motor is shown, and FIG. 4 and subsequent figures show an embodiment of the electric motor according to the present invention, and the same parts are designated by the same reference numerals.

1 to 4 each show a longitudinal section of a squirrel cage rotor having a stratified rotor core 2 attached to a motor shaft 6.
This is schematically shown in the initial position of the stator and rotor in a non-excited state, and the facing surfaces of the intermediate short-circuit ring 1 and the shorter rotor core portion 21 are the same as the corresponding end surfaces of the stratified stator core 7. are in the same plane.

When this electric motor is connected to a power source, the rotor moves to the right to an equilibrium position against the axial spring force Ff of an axial spring (not shown); The brake plate is loosened from the opposing brake lining.

At the same time, the rotor is accelerated in the circumferential direction by the generated rotational torque.

In Fig. 1, short-circuit rings 4,
5 is placed.

The shorting rings 4, 5 are respectively joined to one another with rotor conductor bars 8 of the squirrel cage rotor, which are inserted into straight or diagonal slots and die-cast at the same time as the shorting rings 4, 5.

Furthermore, as can be seen from the embodiments shown in FIGS. 1 to 5,
An intermediate shorting ring 1 is disposed near the end of the rotor core 2 that protrudes outward from the left end surface of the stator core 1 when the squirrel cage rotor moves in the axial direction. .

The intermediate shorting ring 1 divides the rotor core 2 into a longer rotor core portion 22 having an axial length b and a shorter rotor core portion 21 having a length a.

The ratio of the cross-sectional area of the left end short-circuit ring 5 to the cross-sectional area of the intermediate short-circuit ring 1 is arbitrarily selected depending on what kind of air gap magnetic flux is desired on the shorter rotor core portion 21.

can do.

The total resistance of both shorting rings 1 and 5 must be equal to the resistance of the shorting ring 4 on the right end face at the other end of the rotor core 2.

The intermediate short-circuit ring 1 is cast simultaneously with the rotor conductor bar 8 and the short-circuit rings 4 and 5 of the normal structure of the squirrel cage rotor.

made by.

For this reason, it is preferable to insert the spacing pieces 3 when laminating the steel plates of the rotor core 2 prior to die casting.

That is, after casting, the desired radial dimension is obtained between the outer periphery of this spacing piece 3 and the outer periphery of the entire rotor, and the adjacent turns on both sides of the spacing piece 3 are obtained.

A desired axial dimension is formed between the trochanter core steel plates, so that the resistance of the intermediate short circuit ring 1 can be set to a desired value.

This squirrel-cage rotor is die-cast and lathed in the usual manner.

A portion of the rotor current flows through the rotor conductor bar 8 into the intermediate furnace.

Since short-circuiting occurs via the connecting ring 1, the effect of suppressing the rotor current on the air gap magnetic flux via the shorter rotor core portion 21 is weakened.

The short-circuit ring 5 at the left-hand end can be omitted altogether if the axial force Fa has to be further increased.

An example of such a configuration is shown in FIG.

FIG. 3 shows a conventional configuration which is an improvement on the electric motor shown in FIGS. 1 and 2, which is advantageous in terms of structure and manufacturing technology, and which is also advantageous in obtaining a large predetermined axial force. There is.

Here, the shorter rotor core portion 21 is made of only a core steel plate without rotor conductor bars, and only the longer rotor core portion 22 is provided with rotor conductor bars.

The outer diameter of the shorter rotor core section 21 and the outer diameter of the longer rotor core section 22 are equal, so that a uniform gap is created between the rotor core section and the stator over the entire length. It is formed.

The individual steel plates of the shorter rotor core section 21 are either individually mounted on the rotor shaft 6 after die-casting the squirrel cage conductor of the long rotor core section 22, or they are pre-riveted together as one laminated core. can be installed.

As the individual core steel plates, it is advantageous to use rotor core steel plates that are so-called completely cut and have vertical slots, or to use circular steel plates without slots that are simply cut in a circular shape.

4 and 5 show an embodiment of the present invention for further increasing the axial force Fa.

According to this embodiment, the increase in the axial force Fa is possible due to manufacturing technology within the range of the short rotor core portion 21 with respect to the specific gap size d1 between the squirrel cage rotor and the stator. This is achieved by reducing the minimum dimension d2 to a minimum dimension d2.

Such a rotor can be placed within the stator bore in the motor of the invention without causing major alignment problems.

This is because the small-sized air gap exists only at the short end of the rotor, and it is near the bearings that support the rotor.

In this case, there is no great difficulty in maintaining the dimensions of the rotor core 21 to be made for the reduced air gap area.

This is because when using a circular steel plate that is easy to cut, there is only a slight manufacturing error, but when using a rotor core steel plate made by the complete cutting method, the entire rotor is cut into a slightly oversized part of the core steel plate. (Because of the sharp protrusions caused by cutting), it had to be finished using a lathe,
In that case, after die-casting the longer rotor core part 22 and installing the shorter rotor core part 21 (additional core), the rotor can be easily shaped into various outer diameters using the corresponding guide plate templates. This is because lathe finishing can be done.

In this way, as shown in FIGS. 4a and 5a, the shorter rotor core section 21 is moved in order to effect a predetermined change in the axial force in relation to the axial displacement of the rotor. It is also possible to make the external diameters in particular stepwise different by simple manufacturing techniques (for example, cutting circular steel plates into correspondingly different sizes, turning the rotor into correspondingly different sizes, etc.) ) is possible.

4 and 4a respectively show the stopping position of the rotor in the braking state of the variable rotor brake motor when the stator and rotor are not energized and therefore the spring force Ff is applied.

This initial position therefore simultaneously corresponds to short-circuit operation of the squirrel cage rotor motor at the moment of power-on.

At this moment, the axial force Fa acts on the rotor, resisting the spring force Ff, and attempts to attract the inside of the stator to the right in the axial direction.

In order to obtain a large axial force at the first moment of power-on, the starting position of the protruding end of the rotor core 2 is
The axially inner plane of the shorter rotor core portion 21 is selected to be in the same plane as the end face of the stator core 1 on the same side.

Figures 5 and 5a respectively show the stable equilibrium position of the rotor during rotation, and in this position the spring force Ff acting in the axial direction and the opposite direction acting in the excited state of the stator and rotor. The axial force F3 is balanced.

The ratio of the lengths of both rotor core parts 21 and 22 is such that the total length a + b of the rotor core 2 is longer than the length C of the stator core 7, and the longer one existing between the short circuit rings 1 and 4 It is advantageous for the length b of the rotor core section 22 to be selected to be shorter than or equal to the length C of the stator core 7; a particularly preferred ratio is such that the length b of the shorter rotor core section 21 The length a should be approximately 0.1 to 0.15 times the length C of the stator core 7.

Note that the length a is selected to a specific value based on the absolute value of the length b of the longer rotor core portion 22.

In addition, if the number of steel plates in the shorter rotor core, that is, the additional core, is small, the axial force will rise rapidly, and if a larger number of steel plates are used, the axial force will increase after the motor is turned on. The force builds up relatively slowly and the absolute value of the axial force initially becomes large, but since the length of the additional core is too long, the axial force Fa can no longer become large.

However, in this case a larger displacement is achieved,
This can be advantageous in some cases to compensate for large manufacturing tolerances.

Figure 6 is a diagram showing the relationship between the axial displacement of the rotor and the axial force, with the axial force Fa on the vertical axis and the rotor displacement X in Figures 4 and 4a. The stopping position is x =
0 on the horizontal axis, and the solid curve A
1 and B1 show the characteristics of a so-called circular steel plate core without slots regarding the shorter rotor core portion 21,
The dashed curves A2 and B2 show the characteristics of the slotted steel plate core, and the curves A2 and A2 show the characteristics of the slotted steel plate core.
Curves B1 and B2 show the characteristics when the number of steel plates is 14, respectively.

Figure 1 shows the axial force F for rotors with different configurations.
Let a be a function of the rotor displacement amount X, that is, Fa = f(
x), where ■ is the characteristic of a normal rotor, ■ is the characteristic of the rotor according to Fig. 2, and ■ and I
4 shows the characteristics of the rotor shown in Fig. 4, where the characteristic curve ■ is the one when a core steel plate with slots is used, and the characteristic curve I is the one when a simple circular iron core steel plate without slots is used. It shows.

According to the rotor of the electric motor according to the present invention, it is possible to obtain an axial force acting on the rotor in a predetermined manner and with a predetermined specific value in a simple manner in terms of structure and manufacturing technology.

[Brief explanation of the drawing]

1, 2 and 3 are longitudinal sectional views of main parts of different electric motors that have already been proposed, and FIGS. 4 and 4a are respectively different embodiments of an axial displacement rotor electric motor according to the present invention. FIGS. 5 and 5a are longitudinal sectional views of the main parts of the motor shown in FIGS. 4 and 4a, respectively, and FIGS. FIG. 3 is a diagram for explaining axial force characteristics. 1.4... Short circuit ring, 2... Stratified rotor core, 6... Rotor shaft, 7... Stratified stator core, 8... ...Rotor conductor bar, 21...
...Shorter rotor core part, 22...Longer rotor core part.

Claims (1)

[Claims] 1. Divide the stratified rotor core into a longer stratified rotor core section that has rotor conductor bars and a short-circuit ring at the axial end, and a shorter stratified rotor core section that does not have a conductor bar. The rotor core protrudes axially outward from the corresponding end of the stator in the first displacement position, and protrudes at least once in the second displacement position when the stator winding is in a prescribed excited state. In an axially variable squirrel-cage rotor motor in which the rotor cage part is inserted into the inner hole of the stator, the shorter rotor core part has a part with an outer diameter larger than the outer diameter of the longer rotor core part. Moreover, between the outer diameter of the portion of the shorter rotor core that is inside the stator inner hole and the inner diameter of the stator inner hole, there is a gap between the outer diameter of the longer rotor core and the stator inner hole. An axially variable squirrel cage rotor motor characterized in that it has a portion of the gap smaller than the gap between the inner diameter of the rotor cage and the inner diameter of the rotor cage.