FR2680920A1 - Electric motor with a device for detecting the position of the rotor, the speed of rotation and/or the direction of rotation - Google Patents

Abstract

a) Electric motor with a device for detecting the position of the rotor, the speed of rotation and/or the direction of rotation, b) electric motor characterised in that the possibly single element sensitive to the magnetic field (18 to 23) is attached to the stator of the motor in order to detect the variations in the magnetic flux caused by the rotor, and in that there is provision for electronic means for interpreting the signals from this element which is sensitive to the magnetic field (18 to 23). c) The invention relates to electric motors with a device for detecting the position of the rotor, the speed of rotation and/or the direction of rotation.

Description

"Electric motor with a device for detecting

  tion of the rotor position of the speed of rotation and / or of the direction of rotation "The invention relates to a direct current electric motor excited by permanent magnets, with a device for detecting the position of the rotor, the speed of rotation and / or the direction of rotation, which

  contains at least one element sensitive to the magnetic field

  tick. For many applications of electric motors, it is necessary to detect the position

  of the rotor, its speed of rotation and / or its direction of rotation

  tation, for example for window regulators or sunroofs driven by electric motors in motor vehicles, in order to be able to provide effective protection against jamming For this purpose, it is for example known from document EP-A O 359 853, or by document US 4,857,784, from

  place a wheel on the shaft of the electric motor

  radially magnetized surface with alternating polarity

  born, in which case the magnetic fields alternating during

  of rotation, are detected on the stator by a de-

  Hall guardian or a Hall element, the signals of which are processed in an electronic circuit

  for information on the speed of ro-

  By counting these signals, it can also

  be carried out a position detection in the drive

  positioning disadvantage of these arrangements

  sitive known is that the polar wheel causes a de-

  think of additional construction, while a subsequent addition seems almost excluded for reasons of construction In addition, the additional pole wheel entails for the electric motor a heavier weight, a larger volume and a cost

higher.

  The object of the invention is to remedy these in-

  suitable for this purpose, an electric motor

  stick characterized in that the possibly unique element, sensitive to the magnetic field is attached to the stator of the motor to detect variations in the magnetic flux caused by the rotor, and in this

  that electronic means are provided to operate

  ter the signals of this element sensitive to the ma-

  genetic. The electric motor, according to the invention,

  with the characteristics indicated above, present

  the advantage that a device for detecting the position of the rotor, its speed of rotation and / or its direction of rotation, can be added at low cost

  without modification of the construction of the electric motor

  trique For this purpose, essentially, uni-

  only an element sensitive to the magnetic field, no-

  both a Hall element and an operating circuit

  tion necessary in all cases The location o

  is reported the element is then variable in large

  these limits, so that we can take into account

  respective construction data of electric motors

  triques existent The electric motor is thus

  capable of being produced with or without detection of the speed of rotation for a substantially identical constructive construction In particular, in both cases, the same armature as standard can be used A posteriori equipment of a motor with a detection of the position of the rotor of its speed of rotation and / or its direction of rotation, is easily possible.

  Thanks to other features of the in-

  vention, advantageous supplements and improvements

  the electric motor defined above are pos-

sibles.

  The element sensitive to the magnetic field can be attached, either inside or outside on the magnetic yoke of the stator. When it is attached inside, a higher amplitude of the useful signal is obtained, while that when it is brought outside, retrospective equipment is

  ease and any intervention in the engine is

due unnecessary.

  For the installation of the sensitive element

  in the magnetic field, there are various possibilities.

  Thus, for example, the element can be placed between two magnetic poles, in which case this element sensitive to the magnetic field can be placed

  inside on the magnetic yoke being

  tig to a magnetic pole When the magnet poles

  which are poles of permanent magnets, and are held by a spring on the magnetic yoke,

  the element sensitive to the magnetic field can be

  tigu to the retaining spring, or else apply di-

  directly against a magnetic blade, in a location without retaining spring Another possibility is to

  place the element sensitive to the magnetic field in an-

  gle between two magnetic poles but by shifting it, however, axially with respect to these poles It can

  also be reported in the vicinity of a front face

  axial size of one of the magnetic blades, inside on the magnetic yoke or slightly spaced from it In the case where it is attached to the outside on the magnetic yoke, locations between two magnetic poles are more particularly indicated,

  but not in the middle of the interval

  be the poles because, depending on the case, the action of the armature field has a disadvantageous influence on the desired signal. The element sensitive to the magnetic field can

  advantageously be produced in the form of an element

  Also Hall o, in the form of a material coil

  Genetics To increase the useful signal, it has proved advantageous to have this element sensitive to the magnetic field on a conductive part of the flux, which forms a bypass for the flux on the magnetic yoke. When produced in the form of a

  magnetic coil, this surrounds the conductive part

  flow conformation This conformation only allows the detection of the speed of rotation and / or the direction of rotation, because by its nature, the magnetic coil can only detect magnetic changes in the

  flow In the case of a realization in the form of

  Hall element, this is magnetically arranged in series with respect to the conductive part of the flux or

  well compared to partial areas of this part

  this, to get an optimal useful signal In this case,

  detection of the rotor position when the engine stops

tor is also possible.

  In the case of an implementation in the form

  Hall element, a simple, eco-friendly embodiment

  nomic and of an advantageous construction, consists in placing the Hall element between the magnetic yoke and one end of the conductive part of the flux produced in the form of a stirrup or a holding arm,

  the other end of which is connected directly to the cu-

  magnetic lasse To increase the field crossing the Hall element, it is advantageous to push it at least partially into the magnetic yoke. An advantageous variant of the construction is that the Hall element is arranged between two

  parts of the conductive part of the flux, which apply

  quent respectively on the magnetic yoke These

  two parts and the Hall element can advantageously

  be held together by a clamp or by a clamp-shaped housing, in which case the part

  flow conductor is fixed on the magnetised cylinder head

  only by a tightening band, or by a case

made of plastic.

  To optimize the magnetic properties, the conductive part of the flux can be made up of a

  laminated ferromagnetic material.

  For the detection of the direction of rotation, a device should be used in which two elements sensitive to the magnetic field are offset

  one relative to the other in the peripheral direction.

  To this end, these elements can advantageously be arranged in a groove on the magnetic yoke,

  groove extending obliquely to the direction

axial tion.

  Other improvements of the invention are characterized in that: the element sensitive to the magnetic field

  is attached inside or outside on the cu-

  magnetic wear of the stator; the element sensitive to the magnetic field is placed between two magnetic poles; the element sensitive to the magnetic field is placed inside on the magnetic yoke in the vicinity of a magnetic pole;

  the magnetic poles are light blades

  permanent mantles and are held by springs

  on the magnetic yoke and in that the element

  sensitive to the magnetic field is contiguous to the retaining spring or else applies directly against a magnetic blade at a location where there is no retaining spring; the element sensitive to the magnetic field

  is arranged at an angle between two magnet poles

  ques, being however offset axially with respect to them; the element sensitive to the magnetic field is attached in the vicinity of an axial front face

  one of the magnetic blades inside on the cylinder head-

  get magnetic or be slightly away from it; the element sensitive to the magnetic field is produced in the form of a Hall element or else in the form of a magnetic coil; the element sensitive to the magnetic field is placed on a conductive part of the flux, which

  forms a bypass for the flow in the ma-

  genetics; the element sensitive to the magnetic field produced in the form of a magnetic coil surrounds the conductive part of the flux; the element sensitive to the magnetic field produced in the form of a Hall element is arranged

  magnetically in series with respect to the conductive part

  flow or in relation to areas

tials of it;

  the Hall element is arranged between the cu-

  magnetic lasse and an end zone of the conductive part of the flux produced in the form of a stirrup or a holding arm, and the other end of which is directly connected to the magnetic yoke; the Hall element is pressed at least partially into the magnetic yoke; the Hall element is placed between two

  parts of the conductive part of the flux which apply

  quent respectively against the magnetic yoke; the two parts of the flux conducting part and the Hall element are held together

  by pliers or by a clamp-shaped housing.

  the conductive part of the flow is fixed to the magnetic yoke by a clamping band or by a plastic casing;

  the conductive part of the flow is constituted

  slain ferromagnetic material in strips;

  the two elements sensitive to the ma-

  gnetics are arranged in the peripheral direction of the magnetic yoke by being offset from each other;

  the two elements sensitive to the ma-

  gnetics are arranged in a groove on the magnetic yoke, this groove extending obliquely relative to the axial direction;

  the motor stator has a tube for

  milk playing the role of magnetic yoke; Examples of embodiments of the invention are shown in the accompanying drawings and will

  be explained in more detail in the description below

  after. Figure 1 shows an electric motor in longitudinal section with different variants for the installation of a Hall element in order to detect the speed of rotation and the position, Figure 2 shows the electric motor shown in Figure 1 in section transverse along the section line AA of Figure 1, Figure 3 shows a small part of the pole tube of the electric motor shown in the

  Figure 1 with an external Hall element

  stirrup-shaped flow conductor,

  Figure 4 shows an ana-

  log to that of FIG. 3 of a Hall element which is arranged in a cavity of the polar tube,

  Figure 5 shows a variant of

  sation compared to the arrangements according to Figure 3

  and Figure 4 with a conductive part of the di-

  seen in two parts, Figure 6 is an exterior view of a

  electric motor, which carries two external elements

  Hall elements arranged in an oblique groove for the

  detection of the speed of rotation and the direction of ro-

tation,

  Figure 7 shows the arrangement of a box

  magnetic bin on the polar tube for detection

of the speed of rotation.

  The electric motor shown in the figures

  gures 1 and 2 is produced in the form of a DC motor excited by permanent magnets In a

  polar tube 10 in the form of a pot, which comprises,

  Also in Figure 2, a cross section

  partially round with two opposite flattened faces 11, 12, two permanent magnets 13, 14 acting as magnetic poles, are placed face to face in the two round zones These magnets are held in their position by two springs 15, 16 in the form of U.

  Between the permanent magnets 13, 14 is mounted, so

  Less to be able to turn, a rotor 17 shown diagrammatically

  For reasons of simplification, this ro-

  tor 17 has not been shown in Figure 1 Equale-

  ment for the sake of simplification, the manifold and the ballets which are applied there elastically and which are usual members of a direct current motor, are not shown since it is, in this case, a device known who is not affected by the

present invention.

  The two permanent magnets 13, 14 have a different shape from each other. This is how the

  frontal surfaces of the permanent magnet 13 apply

  as for the retaining springs 15, 16 extend essentially in the radial direction, while the

  corresponding frontal surfaces of the permanent magnet

  nent 14 applying to the retaining springs 15, 16 extend perpendicular to the flattened side 11,

  12 To simplify the representation, the two

  laughing have been shown in a single figure, although the two permanent magnets are identical

  in the practical realization of an engine.

  In the electric motor shown in the

  Figures 1 and 2, six Hall elements 18 to 23 are available

  seated inside on the polar tube 10, which constitutes

  kills the magnetic breech of the electric motor The five positions represented again concern

  variants, that is to say that in a practical realization

  tick, only a single Hall element is provided which takes one of the positions shown This is how

  that Hall elements 18 to 21 are arranged inside

  laughing on the flattened sides 11, 12 of the pole tube 10, while the Hall element 18 is applied to the longest arm of the retaining spring 15, and the Hall element 19 directly on the permanent magnet 13, because in this position according to Figure 1, the shortest arm of the holding spring 16 does not reach

  the position of this element Hall 19 Correspondingly

  the Hall 20 element applies directly

  against the front face of the permanent magnet 14, tan-

  say that the Hall 21 element only reaches the arm

  the longest of the retaining spring 16.

  The Hall element 22 is slightly spaced from the pole tube 10 in the region of the front face of the permanent magnet 13 opposite the open end of the pole tube 10. In another embodiment of the pole tube 10, this can also take a round shape. This is represented by the zone of polar tube 24 in dashes. The element Hall 23 is then attached to the interior on this zone of polar tube.

  24 between the permanent magnets 13, 14, and it is

  axially wedged with respect to these permanent magnets

  13, 14, as shown in Figure 1.

  The principle of speed detection

  rotation by such a Hall element on the polar tube

  re or else the polar casing, consists in that, con-

  added by the magnetic saturation of the polar tube

  re, a small part of the magnetic flux extends over

  the air route outside this polar box, for example

  that iron in this case is no longer a conduc-

  ideal magnetic field This marginal field can be

  tectect by a magnetic detector, therefore in accordance with

  the example of embodiment shown here, by an element

  Hall in the normal direction of the marginal field.

  During rotation of the rotor, there is a slight fluctuation in the total flux of a motor which is due to the notching of the rotor. This periodic fluctuation in flux for a fixed speed of rotation of the armature is detected by the element. Hall In the vicinity of the edges

  magnets, the amplitudes are particularly high

  so that periodic fluctuations in the flow can also be particularly well detected

  in the intervals between poles Correspondingly

  the total armature flux, the amplitudes of the

  leakage fields also fluctuate in the posi-

  tions shown in Figures 1 and 2 of the elements

  from Hall 18 to 23, the fluctuations in the flow which

  come are particularly important.

  If an analog Hall element is used, it must be taken into account that the measurement signal

  thus obtained may still contain a component

  which is far more important than the composition

  alternative health desired A magnetic coil

  delivers a measurement signal free of conti- nent components

  naked, the amplitude of this signal depending however li-

  of the speed of rotation By an exploit-

  However, these problems can be solved easily.

  in the case of the initially indicated state of the tech-

  nique, the generally low amplitudes of the signals, are processed electronically to give rectangular signals with TTL level In the case where the electric motor already has all

  electronic ways for command and control

  the motor, or else for the regulation of the speed of rotation, the additional expenditure necessary is practically negligible The frequency of the signals of

  measurement obtained corresponds to the product "frequency of vi-

  rotation speed x number of rotor notches "and thus constitutes a measure for the speed of rotation

of the electric motor.

  In the other embodiment example shown

  felt in FIG. 3, an element of Hall 25 is dis-

  placed outside on one of the flattened sides 11 of the pole tube 10 between the two permanent magnets 13,

  14 The installation on the external side of the tube

  area 10 allows simple retrofitting of an electric motor with a device to detect the

  rotation speed Because of the leakage fields

  that slightly weaker outside, there is provision for a

  conductive part of the flux 26 produced in the form of a

  sort, which is applied by an end part on the pole tube 10 and by the other end part on the Hall element 25 The magnetic flux extending in the external space is thus given a path with a

  reduced magnetic resistance, therefore a ma-

  Genetically more favorable The conductive part of the flow 26 constitutes a bypass for the flow in the polar tube 10 Thanks to the arrangement of the element

  Hall 25 between a terminal part of the conductive room

  trice of the flow 26 and the pole tube 10, the Hall element is crossed perpendicularly by the field even if this element is arranged tangentially to the pole tube 10 The Hall element 25 is magnetically in

  series with respect to the conductive part of flow 26.

  The magnetic flux passing through Hall element 25 is

indicated by an arrow.

  In the embodiment shown in Figure 4, the Hall element 25 is disposed in a cavity 27 on the outer face of the flattened side 11 of the pole tube 10 It projects slightly out of this cavity 27 A conductive part of the flow 28 in the form of a support arm, consisting of a piece of

  contoured sheet metal, connects the edge surface in a sail-

  binds and faces outward from Hall element 25 to the outer surface of the pole tube 10, so that

  the effect obtained is the same as in the case of the example

  ple of realization according to figure 3 A connection

  29 of the Hall element 25 is connected by the

  intermediate of a conductor 30 and of a plug connection to an electronic operating circuit to give the speed of rotation as has already been described in conjunction with FIGS. 1 and 2 For fixing and protecting the assembly of the device

  against damage, a plastic casing

  tick 33 surrounds the conductive part of the flow 28, the

  Hall 25 and conductor 30, while the

  plug connection 31 is arranged in a non-re-

  shown on an outer side of this plastic housing 33 This plastic housing 33

  can, for example, be obtained by projection or

  plastic strip A second electrical connection

  size of Hall 25 can be obtained by liai-

  grounded, or a second connection is provided

  according to the first electrical connection

stick 29.

  In the case of the other example of realization

  tion shown in Figure 5, a conductive part of the flow 34 in two parts is arranged outside on the flat side 11 of the pole tube 10 Between the two separate parts of the conductive part of the flow

  34, the element Hall 25 is arranged.

  nales, opposite the Hall element, of the two parts in

  wing shape of the conductive part of flow 34, is

  bend against the pole tube 10, so that the

* derivative magnetic flux crosses again perpendicular to

  the Hall element 25 A clamp 35, which can also be produced in the form of a housing made of

  pliers, surrounds the piece from the outside

  ducting of the flow 34 which has a cross section es-

  substantially triangular, and penetrates on the termi-

  nal in cavities 36 of the conductive part of the

  flow 34 Thus, the conductive part of flow 34, the e-

  element Hall 25, and the clamp 35 constitute a unit capable of being mounted beforehand, and which can be pressed by means of a clamping band 37, against the

  outer face of the pole tube 10 Because of the

  ties of the conductive part of the flux 34 extend

  obliquely towards the polar tube or the polar housing

  re, this arrangement is also suitable for

round polar bes.

  Of course, Hall elements placed inside on the pole tube 10 can also be provided with a flow conducting part and / or with a separate plastic casing, as indicated in FIGS. 3 to 5 for Hall elements

arranged outside.

  To be able to detect the

  direction of rotation, two Hall 25 elements are required

  res, which are offset from each other, in

  peripheral direction and which are electrically offset

  ment of 900 within a period Figure 6

  shows the outer side of the pole tube 10 of a mo-

  electric tor, in which a reason was practiced

  nure 38 offset by a small angle to the di-

  axial rection In this groove 38 are housed two Hall elements 25 As in the case of a motor

  with N notches, N periods occur for a re-

  evolution of the armature, the two elements of Hall must

  can be offset from each other by only-

ment: a = (360 '/ n) / 4

  This offset can be established by a provision

  appropriate sition of the groove extending obliquely on the pole tube Of course, these elements

  Hall 25 can also be fitted with a conduc-

  flow trice In a simpler embodiment, they can also be arranged without groove 38 on the outer side of the pole tube 10 or else on its inner side The leakage fields fluctuating periodically, obtained during the rotation of the rotor, are detected in the two Hall 25 elements being offset in

  time after time, so that an association

  tion in the direction of rotation is possible.

  As an alternative to Hall elements, the periodic leakage fields can also be detected by a magnetic coil 39 which, according to FIG. 7,

  is disposed on the flat side 11 of the pole tube 10.

  For this magnetic coil 39, it is also possible to choose other positions, as indicated in the examples of embodiment described. Two magnetic coils can also be provided corresponding to FIG. 6 for detection.

  direction of rotation The magnetic coil 39 can also

  LEMENT be arranged on a conductive part of the flow which, as a bypass, is applied by its two end parts, on the pole tube 10 and which is surrounded by the magnetic coil 39 Such a conductive part of the flow 40 is shown schematically

in dashes in Figure 7.

  The use of detecting the position of the rotor, its speed of rotation and / or its direction of rotation, as just described, is not

  of course not limited to constant current motors

  continuously excited by permanent magnets but can

  find its application in the case of all mo-

  electrical sensors in which changes in the leakage fields caused by the rotational movement,

  occur on the magnetic yoke.

Claims (20)

  1. Electric motor, in particular direct current motor excited by permanent magnets, with a device for detecting the position of the rotor, the speed of rotation and / or the direction of rotation, which   contains at least one element sensitive to the magnetic field   tick, electric motor characterized in that the ele   possibly unique, sensitive to the magnetic field   that (18 to 23; 25; 39) is attached to the stator of the motor to detect variations in the magnetic flux caused by the rotor, and in that electronic means (32) are provided for processing the signals of this element sensitive to magnetic field (18 to 23; ; 39).   2 electric motor according to claim 1, characterized in that the element sensitive to the field   magnetic (18 to 23; 25; 39) is related to the interior   laughing or outside on the magnetic yoke (10) of the stator.   3 Electric motor according to claim 2, characterized in that the element sensitive to the magnetic field (18 to 21; 25; 39) is disposed between two magnetic poles (13, 14).   4. Electric motor according to claim 3, characterized in that the element sensitive to the magnetic field (18 to 21) is arranged inside on the   magnetic yoke (10) in the vicinity of a magnetic pole tick (13, 14).   5. Electric motor according to claim 4, characterized in that the magnetic poles (13,   14) are permanent magnet poles and are main-   held by springs (15, 16) on the magnetic cylinder head   tick (10), and in that the field-sensitive element   magnetic (18 to 21) adjoins the hand spring-   yours (15, 16) or is applied directly against a magnetic pole (13, 14) at a location where there is no retaining spring.   6. Electric motor according to claim 2, characterized in that the element sensitive to the magnetic field (23) is arranged at an angle between two   magnetic poles, being however offset axially- in relation to these.   7. Electric motor according to claim 2, characterized in that the element sensitive to the magnetic field (22) is attached in the vicinity of an axial front face of one of the magnetic poles (13, 14) inside on the magnetic yoke (10) or   being slightly moved away from it.   8. Electric motor according to any one   claims 1 to 7, characterized in that the element   ment sensitive to the magnetic field (18 to 23; 25; 39) is produced in the form of a Hall element or else   in the form of a magnetic coil.   9. Electric motor according to claim 8, characterized in that the element sensitive to the magnetic field (25) is disposed on a conductive part of the flux (26; 28; 34; 40), which forms a bypass   for flow in the magnetic yoke (10).   10. Electric motor according to the claim   tion 9, characterized in that the element sensitive to   magnetic field (39) produced in the form of a bo-   magnetic bine surrounds the conductive part of the flux (40).   11. Electric motor according to the claim   tion 9, characterized in that the element sensitive to   magnetic field (25) produced in the form of an element   Hall is magnetically arranged in series with respect to   port to the conductive part of the flow (26; 28; 34) or   well compared to partial areas thereof.   12 Electric motor as claimed   tion 11, characterized in that the Hall element (25) is arranged between the magnetic yoke (10) and an end zone of the conductive part of the flux (26; 28) produced in the form of a stirrup or a holding arm, and the other end of which is directly   connected to the magnetic yoke (10).   13. Electric motor according to the claim   tion 12, characterized in that the Hall element (25)   is inserted at least partially into the cylinder head genetic (10).   14. Electric motor according to the claim   tion 11, characterized in that the Hall element (25) is arranged between two parts of the conductive part of the flux (34) which are applied respectively against the magnetic yoke (10).   15. Electric motor according to the claim   tion 14, characterized in that the two parts of the flow conducting part (34) and the Hall element (25) are held together by a clamp (35) or by a clamp-shaped housing.   16. Electric motor according to any one   as in claims 11 to 15, characterized in that   the flow conducting part (28; 34) is fixed to the magnetic yoke (10) by a tightening band (37)   or by a plastic casing (33).   17. Electric motor according to any one   as in claims 1 to 16, characterized in that   the conductive part of the flow consists of a material ferromagnetic strip in strips.   18 Electric motor according to any one   as claims 1 to 17, characterized in that   two elements sensitive to the magnetic field (25) are   arranged in the peripheral direction of the cylinder head   genetic (10) being offset one with respect to the other.   19. Electric motor according to the claim   tion 18, characterized in that the two elements   magnetic field (25) are arranged in a groove (38) on the magnetic yoke (10), this groove extending obliquely to the direction axial tion.   20. Electric motor according to any one   as in claims 1 to 19, characterized in that   the stator of the motor comprises a polar tube playing the role of magnetic yoke (10).