FR2728741A1 - DIRECT CURRENT MOTOR WITH COIL STATOR - Google Patents

Abstract

The present invention relates to a direct current motor with stators 1 carrying the coils 2 between which the rotors 3 circulate. Allowing the construction of brushless or commutator motors, the type of winding employed allows the construction of radial field motors as well as axial.

Description

The present invention relates to a current motor type device

  continuous with wound stator, possibly without brush or collector, generating simultaneously with the mechanical power the electrical orders necessary for its commutation and its regulation (generation

tachometer signal).

  The types of known electric motors, intended for the servocontrol of physical quantities: speed, position, torque, require to control the appropriate parameter the addition of ancillary servocontrol members such as: tachometric dynamo, wheels

phonic, coders, selsyns, etc ...

  We can currently distinguish on the market three main types of electric motors intended for servocontrol, these are: current motors with axial field or with

  radial field, reciprocating motors, so-called stepping motors.

  The vast majority of DC motors are of conventional structure, equipped with a collector and brushes and those called "brushless", brushless, seem designed with a digital servo-control in mind (internal or external addition of hall effect elements,

  position encoders etc ...) all associated with complex electronics.

  Polyphase reciprocating motors also require complicated electronic support from the straightened sector. The reconstitution of a network with variable frequency and voltage is necessary which does not adapt well, if good precision is sought,

engines of current construction.

  The stepper motors proceed by quantity of movement and, by construction deliver a movement of minimum amplitude which cannot be reduced. This movement is a shock or a succession of identical shocks which generate in the driven mechanisms

  vibrations often detrimental to the precision and life of the equipment.

  The device according to the invention overcomes the drawbacks of one or other of these types of machines while preserving the qualities of each and, in particular by combining the simplicity of construction of AC motors with the flexibility of control of DC motors while maintaining regularity of torque throughout the speed range. To this end, it should be noted that the essential handicap preventing the industrial development of the POIRSON dynamo is largely due to the structure

  unipolar of this machine prohibiting the placing in series of the conductors equipping it.

  The present invention proposes nothing other than a sectoring of this machine to make it compatible with a bi or better multipolar structure and thus to escape

  the impossibility of associating the conductors constituting it in series.

  Consider, as shown in Figure 1, index A and B, a ring (1). made of magnetic material, fixed on a base (2). In the axis of the ring (1) and in abutment in the base (2)

2 2728741

  let us introduce a tree (3) whose only freedom is to be able to turn on itself.

  Perpendicular to this shaft (3) and at a sufficient distance from the ring, let's fix a magnetic bar of length equal to the outside diameter of the ring (1). Let us equip this bar (4), at its ends and facing the ring (1) with two magnets (5) and (6) with opposite signs. The field of magnets, by the air gap thus formed, closes with the magnetic mass of the ring (1). This air gap being of constant length whatever the position of the shaft (3), the movable assembly in rotation consisting of the shaft (3) of the bar (4) of the magnetic poles (5) and (6) n ' none

  preferential rest position above the ring (1).

  If in the air gap on the ring (1) we stick an electrical conductor (7), insulated, according to a diameter, with however a bypass in the internal recess of the ring (1) to avoid the shaft (3 ) and that we inject a direct current into the conductor (7) we prohibit the mobile assembly from resting above this conductor. If we continue the wiring of one face of the ring (1) by making the conductor (7) run outside the ring (1) in order to deposit it on a second diameter close to the previous one and juxtaposed to it , continuing the entire winding of one face of the ring (1), we will have on one half-face of the ring (1) conductors "entering" and, seen from the tree, on the other half -face of the ring,

"outgoing" conductors.

  By injecting a direct current into the conductor (7) we note that for the mobile assembly constituted by the shaft (3) the bar (4), the magnetic poles (5) and (6) it does not

  only one point of rest remains on the circular path.

  This position is practically that occupied opposite by the first conductor deposited on the magnetic ring and which. when he was alone and seat of a direct current,

  chased the bar carrying magnets.

  With all the conductors under direct current the effect seems opposite, in reality the magnetic poles are positioned to sprinkle with their flux as many conductors "entering" as conductors "leaving", thus undergoing from them forces of the same intensity but opposite signs, forces which they cannot escape without one of the forces becoming

  preponderant over the other.

  In order for the machine thus produced to be able to ensure complete rotation, it is necessary that, throughout its journey, each pole passes over only conductors deposited in the same direction when they are activated by a current. To obtain this result, it is necessary to use at least three identical windings, superimposed and offset with respect to each other so that an observer can see conductors "entering" at all points.

  example, this implies that he may also choose to see only "outgoing" conductors.

  In the case of a bipolar motor for example the origin of circuits offset by one hundred and twenty

3 2728741

  degrees with overlap from one circuit to another of conductors deposited in the same direction on a

  range of sixty degrees can be achieved.

  If we call tablecloth a set made up of an equal number of conductors "entering" and conductors "leaving" produced from a single conductor, nothing prevents us from realizing it on a restricted sector of the magnetic ring and d 'juxtapose other identical layers to cover the surface of the ring, this assumes that we have made

  tablecloths of equal surface and that we multiply by the same figure the number of poles.

  Such a type of winding can be applied to all known structures of electric motors, whether they are in the radial or axial field with, however, a significant modification, here it is the stators and not the rotors which carry the windings delivering the power of the motors, and, the fact that the rotors carry the pole pieces gives the possibility of building brushless DC motors, without a collector, at the cost of an external switching of the part

  properly engine but, we will see. under his orders.

  However, a simplified version with rings and brushes allows the motor to be used with a conventional DC motor control without any external addition. In

  With this in mind, it is possible to produce a universal type motor.

  Also note the possibility of winding a motor from superimposed layers but strictly reversed one with respect to the other, in this case it is enough to have two layers of circuit instead of three. but at the switching points, the latter requires superimposing two auxiliary switching circuits, the layers of which may be narrow, this winding may be advantageous for motors with a low number of poles or for linear motors.

  The accompanying drawings illustrate the invention.

  Figure 2 symbolizes the development of a rotary motor winding with two pairs of poles. To facilitate understanding, each circuit is represented from its original offset, one circuit per line. If we consider the image at the top of the sheet in Figure 2 / A the arrow and the solid rising line represents the first conductor. The entry of the circuit which continues in solid line to come in dotted line on the right of the entry conductor and to leave to describe a second loop. The winding is to be constituted thus until the sheet is covered. At the end of the sheet the conductor is directed by a cusp point (1) to carry out the winding

of the second circuit layer.

  Such a representation by square signals alone can also be interpreted as the image of the electromotive forces delivered by each of the circuits for one direction.

given engine rotation.

  In the chosen case of an engine with two pairs of poles, each layer covers one hundred and eighty degrees, two layers are necessary to constitute a circuit. The entrances of the three

4 2728741

  circuits may for example be offset from one another by sixty degrees with circuit overlap by thirty degrees but, and this seems obvious in such a structure, the sectors of overlap of the circuits between them must be of greater surface or at least worst

equal to the surface of the poles.

  The next three lines in Figure 2 / B symbolize the space or rather the place where the switches must be made so that a given pole only flies over active conductors of the same direction. And this, at the moment when the electromotive force of the circuit to be disconnected is equal to the electromotive force of the circuit to be connected with of course the same polarity. The switching of the power source obeys for a direction of rotation a circular permutation resulting from the reading of the electromotive forces developed by two circuits simultaneously. The order of this permutation is given at the start of each of the three lines in Figure 2 / B which should be read as follows: ONE-TWO means power cut in ONE. current establishment in

OF THEM.

  TWO-THREE means a break in TWO. establishment of the current in THREE etc ... The last three lines of figure 2 / C read in the same way. It should be noted that the coincidences they mention result from a reverse circular permutation of the previous one. Its application has the effect of turning the engine in reverse, without changing

  the polarities of the motor power supply.

  There are at least two other means for generating the switching signals driving the activation of the motor circuits apart from the comparison of the phases and amplitudes of the electromotive forces: a system of two concentric rings on an insulating support, one continues , bringing the power taken by a brush in permanent contact with another brush circulating on the second ring which is interrupted in sections the number of which is equal to the number of

  poles multiplied by three in the case of identical windings, superimposed and offset.

  - a very narrow "reading" coil system arranged superimposed on the switching points of the circuits, giving signals identical to those represented in FIGS. 2 / B and 2 / C which can be used by a commercial up-down counter and drive a power circuit. The latter solution has the advantage of only working under tension. the wire constituting the winding can be fine therefore repeated several times in the same place, all possibilities which facilitate precision, especially at very low speeds of rotation of the

engines.

2728741

  It is obvious that the usual switching devices can be used (the

  Hall effect systems for example), this invention first aims to avoid them.

  Figure 3 / A shows a front view of a magnetic ring with the path of a conductor (1) entering and continuing its path by following the path of the four layers constituting the circuit (1), of this four-pair motor of poles. This conductor returns to its starting point on the face of the ring by slightly exceeding it if we deposit the conductors in a counterclockwise direction, to describe a second diameter of the ring, identical and very close to the first. Continuing thus the deposit of the conductor the face of the ring will be completely covered for half, of conductors

  "incoming", and "outgoing" for the second half.

  The inputs of the conductors of the two other circuits, identical to the first in their construction but offset and superimposed as explained in figure two are marked (2) for the

  second and (3) for the third circuit.

  The shadow of the poles on the ring is represented with alternating North and South notation, at

  switching points from circuit (1) to circuit (2) for an imposed direction of rotation.

  Figure 3 / B shows the sectional view of an axial field motor with multiple stator (1) and rotors (3) stacked at the correct distance on a shaft (4) to which these rotors (3) are rigidly connected. These rotors (3) are made of a non-magnetic material in which the magnets are embedded so as to present a field perpendicular to the plane of the rotors. Referring to FIG. 3 / A, one can imagine, according to the section denoted A in this figure, the space occupied by a stator half (1) of FIG. 3 / B, supporting the three windings (2) merged here into one alone so as not to load the drawing. This unusual structure in conventional engines has the advantage of using. to generate the motor function, the two poles of the magnets, the central stator (1) used thus being able to be equipped with a set of circuits on both

of its faces.

  Similarly, it is possible to design and produce self-excited motors, the rotors being made up only of poles made of soft magnetic material, electrically insulated from each other in the case of motors with an axial field, or cut from the magnetic material constituting the

  rotor, sheets or ferrites in the case of radial field motors.

  This achievement is particularly interesting if one has to realize motors without

  notch torque or having to reach high rotational speeds.

6 -2728741

Claims (5)

  1 - DC motor, optionally brushless and collector whose rotor carries the pole pieces and the stator the windings, characterized in that the circuits (2) making up the winding are at least three in number, only if they are three in number, they are identical in all points of their geometry, they are superimposed on each other and fixed to the stator (1) rigidly. The origin of the second circuit is offset from the origin of the first circuit as well as the origin of the third circuit from the origin of the second circuit. The angle of offset of a circuit with respect to the previous circuit is a function of the number of pairs of poles carried by the rotor (3). Each circuit is composed of at least one layer of conductors, each layer is composed of as many conductors "entering" as conductors "leaving". The offset of the circuits between them is such that when they are activated by a current by circular permutation any pole of the rotor only flies over conductors of the same direction during a rotation of three hundred and sixty degrees. Under a given pole, choosing not to fly over, when activated by a current, only "incoming" conductors and not "outgoing" conductors means choosing a direction of rotation of the motor shaft. This winding configuration is applicable to stator circuits of field motors   axial as well as radial field motors.   2 - Motor according to claim i characterized in that the winding deposited on the stator can be produced with two identical main circuits but superimposed in such a way that the conductors "entering" from one are superimposed to the conductors "leaving" from the other. Such a configuration requires adding to the two main circuits, two auxiliary switching circuits. This winding mode can be preferred for the construction of,   motors with a low number of poles, or to equip linear motors.   3 - Motor according to the preceding claims characterized in that the orders   switching circuits can be developed from reading and processing the   force against electromotive of each of the circuits. 7 2728741   4 - Motor according to the preceding claims characterized in that a   so-called "reading" conductor can be deposited in superposition of the motor circuits at the points or a switching must be carried out to ensure a constant rotation in the desired direction. The nesting of such a conductor in the stator winding greatly simplifies the processing of switching order signals. - Motor according to claim 1 characterized in that the rotor of an axial field motor can be repeated on the same shaft. The repetition of a rotor on a single shaft results in the consistent repetition of the stators, any stator nested between two rotors being able to carry   a group of circuits on each of its faces.   6 - Motor according to claim 1 characterized in that a system of 2 concentric rings on insulating support, one continues, bringing the power that draws a brush in permanent contact with another brush circulating on the second ring, which is interrupted in sections whose number is equal to the number of poles multiplied by three in the case of   identical windings, superimposed and offset.