WO2000005803A1

WO2000005803A1 - Stepping motor combination and mirror for a vehicle, provided with such a stepping motor combination

Info

Publication number: WO2000005803A1
Application number: PCT/NL1999/000472
Authority: WO
Inventors: Jean Armiroli; Gillian Escandell; Oswin Vogl; Onno Dirk Oenema
Original assignee: Iku Holding Montfoort B.V.
Priority date: 1998-07-24
Filing date: 1999-07-21
Publication date: 2000-02-03
Also published as: NL1009735C2; AU5071999A

Abstract

In a stepping motor combination to be disposed on a mounting part each stepping motor is provided with a number of electrically controlled coils, cooperating with one or more core parts, and a magnetic body rotatable with respect thereto. In this combination two or each two stepping motors juxtaposed on the mounting part have at least a coil and preferably also a core part in common. With two thus combined steeping motors the stepping motor combination is particularly suitable for use in a controlled rear view or wing mirror for vehicles.

Description

Title: Stepping motor combination and mirror for a vehicle, provided with such a stepping motor combination

The present invention relates to a stepping motor combination to be disposed on a mounting part, in which combination each stepping motor is provided with a number of electrically controlled coils, cooperating with one or more core parts, and a magnetic body rotatable with respect thereto.

Stepping motors and combinations of stepping motors have long since been known and are commercially available everywhere. In particular when a number of these stepping motors is to be disposed on a mounting part in a relatively small housing, such as, e.g., the housing to be fitted in or on a vehicle for an electrically controlled reflective element of a rear view or wing mirror, these stepping motors, in spite of being obtainable in small dimensions, yet occupy too much space owing to their form. Moreover, they are relatively expensive .

It is therefore an object of the invention to remove this drawback at least to a substantial degree and in particular to provide a stepping motor combination which is suitable for being mounted in the housing of a reflective element to be fitted on a vehicle, and which is not expensive either.

To that end, the stepping motor combination as defined in the opening paragraph is characterized according to the invention in that two or each two stepping motors juxtaposed on the mounting part have at least a coil in common.

Although this common coil may be disposed round a core part separately present for both stepping motors, it is favorable in terms of manufacture and from a viewpoint of cost if two or each two stepping motors juxtaposed on the mounting part also have at least the core part cooperating with the common coil in common. To prevent the occurrence of a leakage flux current between the coils of the same stepping motor, each coil of a similar stepping motor is further disposed round an associated core part. Of course, this cannot prevent a leakage flux current becoming possible between two stepping motors via the common core part; to this end, separate measures directed towards the specific use of the stepping motor combination are to be taken, which will be discussed below. In a first embodiment of the stepping motor combination the rotatable magnetic body is formed by an annular element within which a core part is located while the further core parts are located outside that element, the arrangement being such that when the coils are suitably controlled the annular element rotates through the air gaps between the core part located within the annular element and the core parts located outside that element .

In a second embodiment the stepping motor combination is characterized in that a core part is formed by two superposed plate parts which are connected together by connecting parts extending through the coils and forming part of the core part, and which comprise projecting parts arranged according to a cylindrical form and meanderingly locking together but forming air gaps within which the magnetic body rotates when the coils are suitably controlled.

Since the mounting part, in particular a mounting plate, is often determined as to form by the space within which it is to be disposed, it is favorable for an optimally efficient use of this space if the form of one or more core parts is adapted to the form of the mounting part on which the stepping motor combination is to be mounted. In particular the form of the core parts may then be determined by the form of the mounting part on which the stepping motor combination is to be disposed. Thus, it is favorable in a simple embodiment of a stepping motor combination on a mounting plate if at least part of the contour form of the eligible core parts corresponds to the contour form of the mounting plate. If the mounting plate has a round form, then the core parts will show a corresponding roundness over a part of their contour, if the mounting plate is angular, then the core parts will follow this angular form over a part of their contour.

To adjust a reflective element in a rear view or wing mirror of a vehicle, electrical adjusting means, for financial reasons hitherto often provided with dc motors, have long since been used. To rotate the reflective element on each of two mutually perpendicular axes, these adjusting means act on a support for this reflective element at two relevant points located at a specific distance from the pivot point of the reflective element on the above axes. This distance will often be equal for both points of action. Both points of action then determine together with the pivot point an isosceles triangle having an apex angle of 90°, the magnitude of which will depend on the mirror. In particular the magnitude of the legs determines the strength and stability of the fastening of the reflective element in the housing of the mirror. In passenger cars, which often have relatively small mirrors, it therefore suffices to have a shorter leg length than in trucks, for which a different and substantially larger type of mirrors is used, and for which the above leg length, to meet the requirements with respect to strength and stability of the fastening of the reflective element in the housing of the mirror, will therefore be larger. Accordingly, the invention particularly also relates to a mirror for a vehicle provided with a housing to be fitted in or on the vehicle, a reflective element disposed therein and rotatable on two substantially mutually perpendicular axes and adjusting means disposed within the housing on a mounting part, which mirror is then characterized in that the adjusting means for rotating the reflective element on the respective axes are provided with a stepping motor combination as indicated above.

When, in particular in such a mirror, one of the motors is energized while the other motor remains non- energized and, therefore, a rotation on only one of the axes is obtained, the problem occurring in the case that the stepping motors have a coil with a core part in common is that the energized motor also generates a magnetic flux in the non-energized motor, with the result that the non-energized motor is going to vibrate. To remove this drawback, the stepping motors are characterized in that in the mirror they act on both axes in such a manner to a substantially equal degree and the adjusting means are further of such design that, depending on an equally directed or an oppositely directed rotation of the individual stepping motors in one or in the other direction, a rotation of the reflective element is obtained round one of both axes in a desired direction. For a rotation on one of the axes both motors are therefore energized. The adjusting means driven by the individual stepping motors are then, as it were, active at an angle of 45° to both axes. Not only does this prevent the above vibration of a non-energized motor, but also the driving force of both motors together is increased by a factor of 2 , so that it suffices to have a smaller size of stepping motors, which further improves the sound behavior of the motors .

The invention will now be explained in more detail with reference to the accompanying drawings, in which:

Fig. 1 diagrammatically shows the structure of a stepping motor combination according to the invention, in which each two stepping motors have a coil in common; Fig. 2 diagrammatically shows the structure of a stepping motor combination according to the invention, in which two stepping motors have both a coil and a core part in common; Fig. 3 diagrammatically shows a first embodiment of a stepping motor combination according to the invention;

Figs. 4A and 4B diagrammatically show respectively a top plan view and a side view of a second embodiment of such a stepping motor combination on a rectangular mounting plate; while

Fig. 5 diagrammatically shows a round mounting plate with a stepping motor combination according to the invention for use in the housing of a car mirror;

In the figures similar parts are denoted by the same reference numerals.

Fig. 1 shows a stepping motor combination composed of three stepping motors 1, 2 and 3. The stepping motor 1 is built up from a rotatable magnetic body 4, two coils 5 and 6, and soft iron core parts 7 and 8 cooperating therewith. The stepping motor 2 is built up from a rotatable magnetic body 9, the coil 6 and a further coil 10, and the above core part 8, cooperating with these two last-mentioned coils, and a further soft iron core part 11. The stepping motor 3 is built up from a rotatable magnetic body 12, the coil 10 and a further coil 13, and the core part 11, cooperating with these two last -mentioned coils, and a further soft iron core part

14. Since stepping motors have long since been known, the operation thereof need not be discussed herein; reference is made to Rummich c . s . , Elektrische Schri ttmotoren und

-antriebe (Expert Verlag, 1992) . By energizing the coils at a specific frequency, a magnetic flux is generated in the relevant core parts and a magnetic rotating field causing the relevant magnetic body to rotate is generated at the location of the magnetic body. The above-mentioned publication also shows that more than two coils can be used, each preferably with its own core part, while the rotatable magnetic body need not be limited to a two-pole body; preferably, a large number of poles is even present, as also appears from the practical examples shown in Figs. 3 and 4. Furthermore, the stepping motor combination may also comprise only two stepping motors, as will be further described below, or an arbitrary number always coupled together by a common coil and optionally also a common associated core part. Fig. 2 shows the stepping motors 1 and 2 with only the coil 6 in common; each of both stepping motors has two core parts 7, 8 and 8', 11. The core parts 8, 8' wound on the coil 6 are separated from each other. In the more concrete embodiment shown in Fig. 3 a stepping motor 15 is built up from a rotatable magnetic body 16 in the form of an annular element provided all round with a large number of poles N (North) , S (South) , N (North) , etc. Located within the annular body 16 is a stationary four-pole soft iron core part 17, while outside the annular element 16 two core parts 18 and 19 and coils 20 and 21 wound thereon are present. The coil 20 and the core part 18 cooperating therewith have a second stepping motor, not shown, in common. When the coils are suitably controlled, the annular element 16 rotates through the air gaps between the core part 17 and the core parts 18 and 19.

Figs . 4A and 4B show a second embodiment of a stepping motor combination. The combination shows two multi-pole magnetic bodies 22 and 23, soft iron core parts 24, 25 and 26, with both stepping motors having the core part 25 in common, and coils 26 and 27, with both stepping motors having the coil 27 in common. Each core part consists of an upper plate 28 and a lower plate 29. These plates are connected together by connecting parts 30 extending through the coils 26 and 27. Furthermore, the core parts comprise projecting parts 32, 32' arranged according to a cylindrical form 31 and meanderingly locking together. Between each two of these projecting parts 32, 32' an air gap is present. For each of the stepping motors a magnetic flux conduction is then always obtained from a connecting part 30, an upper plate 28, a projecting part 32 connected therewith, the air gap between this projecting part 32 and a pole of the magnetic body 22, and via this magnetic body 22 and the air gap between this body and a projecting part 32' and a lower plate 29 back to the connecting part 30, or conversely, depending on the control of the relevant coil. When the coils 26 and 27 are suitably controlled, the magnetic body 22 rotates within the projecting parts 32, 32' forming a cylinder casing. In this embodiment the core parts, in particular the lower plates 29 thereof, are disposed on a mounting plate 33, with a part of the contour form of the core parts corresponding to the contour form of the rectangular mounting plate 33.

Fig. 5 shows a round mounting plate 34. Disposed on this round mounting plate 34 is a stepping motor combination built up from two magnetic bodies 35 and 36, core parts 37, 38 and 39, and coils 40, 41 and 42. Both stepping motors have the coil 41 and the core part 38 in common. The mounting plate shown herein is intended to be mounted within the housing of a rear view or wing mirror of a vehicle. In order yet to optimally utilize the space in the mirror housing, small as it is, the form of the core parts 37, 38 and 39 is adapted to the round form of the mounting plate 34. In particular, a part of the contour form of each core part corresponds to the round contour form of the mounting plate.

Disposed in the mirror housing is a supporting plate provided with a reflective element, which supporting plate is movable on two mutually perpendicular axes. The movability of this supporting plate in the mirror housing is realized by means of the stepping motor combination disposed within this mirror housing on the mounting plate 34. The magnetic bodies 35 and 36 are each connected by means of transmission elements, only indicated by an arrow, with a screw spindle 43 and 44, respectively. These transmission elements may be formed in the known manner by a worm connected with a magnetic body, a worm wheel gearing with this worm and optionally further toothed wheels or similar transmission elements. Through the transmission elements the screw spindles 43 and 44 can be moved linearly to and fro in their longitudinal direction, perpendicularly to the mounting plate 34, depending on the direction of rotation of the respective stepping motors. Disposed at corresponding ends of each screw spindle is a ball joint, by means of which the screw spindles are connected with a supporting plate provided with a reflective element in a housing of the car mirror. This is extensively described in Dutch patent application 10.07676, the contents of which are inserted herein by reference .

If in this case, e.g., the coils 40 and 41 are correctly energized, a rotating movement of the magnetic body 35 is obtained. In this embodiment, if no countermeasures are taken and even if the coil 42 is not energized at all, the magnetic flux generated in the core part 38 may cause a vibrating movement of the magnetic body 8' . Hence the magnetic bodies 35 and 36 are both coupled to both screw spindles 43 and 44. Depending on the direction of rotation of both magnetic bodies 35 and

36, four situations may occur which, at a proper dimensioning, render it possible that simultaneous energization of both motors yet enables a rotation on each of the axes x, y separately and in both directions. Since the rotational speed of the stepping motors is independent of their load and is only determined by the frequency of the control of the coils, it can be easily realized that each of the screw spindles exerts a force on the support of the reflective element at a point P and Q, respectively, located on a circle at the location of a relevant bisector h₁ and b₂, respectively, between both axial directions x, y, which force effects that, depending on the absolute and relative direction of rotation of both stepping motors, the torque components of these forces round one axis cancel each other and round the other axis enhance each other, namely by a factor of 2 relative to the situation in which each of the spindles would effect a rotation on one of the axes, and in which, therefore, the points of action are located on the axes themselves.

The invention is not limited to the embodiments shown herein with reference to the drawings, but comprises all kinds of modifications thereof, of course as far as falling within the scope of protection of the following claims. Moreover, the use of the stepping motor combination is not limited to car mirrors. Thus, in situations in which, e.g., a number of axes, whether or not being parallel or perpendicular to each other, are to be motor driven, it is possible to arrange the stepping motors used therefor on a mounting part, while, for economy of space, when using an arbitrary number of stepping motors, it always suffices to have fewer coils and core parts than would be the case if no common components for the stepping motors were present. This economy of space is increased if the core parts are always adapted as much as possible to the form of the mounting part.

Claims

1. A stepping motor combination to be disposed on a mounting part, in which combination each stepping motor is provided with a number of electrically controlled coils, cooperating with one or more core parts, and a magnetic body rotatable with respect thereto, characterized in that two or each two stepping motors juxtaposed on the mounting part have at least a coil in common .

2. A stepping motor combination according to claim 1, characterized in that two or each two stepping motors juxtaposed on the mounting part have at least the core part cooperating with the common coil in common.

3. A stepping motor combination according to claim 1 or 2, characterized in that each coil of a similar stepping motor is disposed round an associated core part.

4. A stepping motor combination according to any one of the preceding claims, characterized in that the rotatable magnetic body is formed by an annular element within which a core part is located while the further core parts are located outside that element, the arrangement being such that when the coils are suitably controlled the annular element rotates through the air gaps between the core part located within the annular element and the core parts located outside that element.

5. A stepping motor combination according to any one of claims 1-3, characterized in that a core part is formed by two superposed plate parts which are connected together by connecting parts extending through the coils and forming part of the core part, and which comprise projecting parts arranged according to a cylindrical form and meanderingly locking together but forming air gaps within which the magnetic body rotates when the coils are suitably controlled.

6. A stepping motor combination according to any one of the preceding claims, characterized in that the form of one or more core parts is adapted to the form of the mounting part on which the stepping motors are to be mounted.

7. A mirror for a vehicle, provided with a housing to be fitted in or on the vehicle, a reflective element disposed therein and rotatable on two substantially mutually perpendicular axes and adjusting means disposed within the housing on a mounting part, characterized in that the adjusting means for rotating the reflective element on the respective axes are provided with a stepping motor combination according to any one of the preceding claims.

8. A mirror according to claim 7, characterized in that in the mirror the stepping motors act on both axes in such a manner to a substantially equal degree and the adjusting means are further of such design that, depending on an equally directed or an oppositely directed rotation of the individual stepping motors in one or in the other direction, a rotation of the reflective element is obtained round one of both axes in a desired direction.