MXPA98008183A - An electromagnetically controlled drive device, in particular a logome - Google Patents

Abstract

The present invention relates to an electromagnetically controlled drive device, in particular a logometer, the device is of the type comprising: a group of control coils, a frame supporting the group of coils, equipment including a magnet suitable for be pivotally removed by the group of control coils, and magnetic shield surrounding the group of coils and the support frame at least in part. The device is characterized by the fact that the protector comprises an annular skirt that is not a circular cylinder.

Description

A DEVICE OF CONTROLLED OPERATION SUECTTO QUICKLY »IN PAmcm.? VN OSQUETRQ FIELD OF THE INVENTION The present invention relates to the field of electromagnetically controlled drive devices »in particular» devices known as "logometers". A particular application of the present invention is for indicator covers for the instrument panels of automotive vehicles.

BACKGROUND OF THE INVENTION It is generally known that a logometer comprises: - two crossed control coils - a magnet magnetized radially - mounted rotatably in an internal chamber defined by said coils - an arrow associated with the magnet and on its axis - the arrow is adapted to receive the cube from a dial needle; and - magnetic guard that surrounds the coils »at least in part. The control coils are usually held by means of a support frame made of plastic materials. The direction in which the needle points "depends on the resultant of the magnetic fields created by the two coils. In this way »if the two coils are fed with signals representing the sine / cosine or the tangent of an input quantity» then the angle raised by the magnet in relation to a reference position is directly representative of said input quantity . Until now »the magnetic shield has usually been provided in the form of a cylindrical metal bell. Also up to now, the inactive position of the mobile equipment of said electromagnetically controlled actuator "has been established by adding magnets or auxiliary springs" leading with and or to structures which are complex. DE-A-3 541 395 describes a magnetic protector formed by a spiral winding of thin metal sheet. DE-A-3541 395 describes an indicator having a magnet and a coil and includes two screws located inside the external protector and suitable to be adjusted to fix the inactive position of the device.

PESGfUPCIQN PE 1 ,? ? NVENCIQN The present invention now seeks to improve the known electromagnetically controlled actuators. In accordance with the present invention, this object is achieved by an electromagnetically controlled driving device, comprising: a group of control coils (10.20); - a frame (50) that holds the group of coils (10. 20); - equipment that includes a magnet suitable to be moved pivotally by the group of control coils (10.20); and - magnetic protector (100) surrounding the group of coils (10.20) and the support frame »at least in part; the device is characterized by the fact that the protector (100). which is made by stamping a sheet of soft magnetic metal »comprises an annular skirt (110) which is not a circular cylinder. According to an advantageous feature of the present invention, the protector comprises an annular skirt which is generally a circular cylinder, but which has at least one reentrant shape which is reentrant in relation to the circular cylinder. In a variant, two forms that are reentrant in relation to the circular cylinder are provided in this way. These reentrant forms can comprise planes. However, the reentrant forms can be of a different geometry. The reentrant forms may be diametrically opposed around the axis of the device. However, in certain variants these two reentrant forms are not, on the contrary, diametrically opposed. In accordance with an advantageous feature of the invention, the protector comprises an annular skirt that is not a circular cylinder and has two orthogonal planes of symmetry that intersect the axis of rotation of the equipment. In another variant of the invention, the annular skirt of the protector is generally in the form of an ellipse. According to another advantageous feature of the invention, the annular skirt comprises two diametrically opposed sectors of a circular cylinder interconnected by two parallel planes. Other features "objects and advantages of the present invention" appear from the reading of the following detailed description with reference to the accompanying drawings given by way of non-limiting example, and in which: Figure 1 is an axial plane view of a support frame for a logometer according to the present invention; Figure 2 is an end view of the magnetic shield in accordance with the present invention. Figure 3 is a first section view through the shield over a section plane referred to III-III in Figure 2; Figure 4 is a second sectional view through the same protector on a section plane referred to as IV-IV in Figure 3; and Figure 5 is a diagrammatic view of a logometer according to the present invention. The general internal structure of the logometer comprising coils 10. 20. a magnet 200. and an arrow carrying a needle 210. is known per se and is not described in detail below. The two coils 10. 20 are placed on a support frame 50 as shown in Figure 1. The support frame 50 is preferably made by molding plastic materials. The frame 50 defines a central hub 52 centered on the axis of rotation 0-0 of the mobile equipment, and two pairs of projections 54, 55, and 56, 57 arranged in a cross configuration. The projections in each pair 54 and 55. and 56 and 57 »are diametrically opposite each other» with the projections of the second pair 56 and 57 being orthogonal to those of the first pair 54 and 55 about the central axis 0-0. The aforementioned projections 54, 55, and 56, 57 extend in directions that are generally radial relative to the 0-0 axis. Between them. the two pairs of projections 54 and 55. and 56 and 57. define the two annular housings 60 and 62 suitable for receiving the coils 10 and 20 »respectively; these coils by themselves are centered on the axes 12 and 22 which extend transversely in relation to the central axis 0-0. The hub 52 is adapted to guide the mobile equipment 202 comprising the magnet 200 and the arrow carrying the needle 210. The two projections 54 and 55 of the first pair define on their outer peripheries cylindrical caps 70 and 72 »respectively» of the same radius »centered on the axis 0-0.

The two projections 56 and 57 of the second pair can likewise define sections of cylindrical lids 74 of the same radius. However, as shown in FIG. 1, these last two projections 56 and 57 also define on their outer peripheries two respective mutually parallel planes 76 and 78 which are diagonally opposed about the axis 0-0. The frame 50 also defines an internal splice (not shown in Figure 1 to simplify the lustration). adapted to cooperate with the mobile equipment »for example» the magnet »in such a way as to limit the angle through which it can move pivotally. In the example shown in the attached figure 1, the two coils 10 and 20 are mutually inclined at 110 °. However, this inclination should not be considered as limiting.

It can be easily adapted as a function of the intended application. In accordance with the present invention, the logometer includes guard 100 of the type shown in Figures 2 to 4. which comprises a peripheral annular skirt 110 centered on the axis of rotation 0-0 and terminated with an orthogonal disc-shaped wall 120. to the 0-0 axis. According to the invention, the annular peripheral skirt 110 has two planes of symmetry A and B that cut on the axis of rotation 0-0 of the equipment. The protector 100 is made of a soft magnetic metal. preferably stamped. More precisely, protector 100 is preferably made using a sheet of iron-nickel alloy, for example 64% iron and 36% nickel. The end wall 120 of the protector 100 may be provided with passages for bolts connected to the coils 10 and 20. However, it is preferable, as shown in figure 1 »that the coils 10 and 20 are electrically connected by bolts. 90. 91"and 92" connected to the ends of the coils 10 and 20 and supported on a protrusion 59 extending from the projection 57 »this protrusion 59 is disposed on the outer side of the shield 100. near the external line of its opening. In the particular embodiment of the protector 100 shown in FIGS. 2 to 4, the peripheral annular skirt 110 of the protector 100 comprises two diametrically opposed cylindrical sectors 112 and 114 centered on the 0-0 axis and interconnected by two planes 116 and 118 which they are parallel to each other and to the axis 0-0. and that are also diametrically opposed to their surroundings. The planes 116 and 118 are parallel to the plane of symmetry A and perpendicular to the plane of symmetry B. The angular extent of the sectors 112 and 114 is conveniently around 150 °. The radius of the cylindrical sectors 112 and 114 is complementary to the radius of the cylindrical caps 70. 72 and 74. Furthermore, the distance between the planes 116 or 118 and the axis 0-0 is complementary to the distance between the planes 76 or 7B formed on the frame 50 and the same axis 0-0. The person skilled in the art will thus understand that the protector 100 can easily be fixed to the frame 50, for example, by means of adhesive, ultrasonic bonding, hot tackling, etc. or by using any equivalent means that prevents deformation of the protector 100. It will be observed what. in accordance with another advantageous feature of the invention, the axes 12 and 52 of the coils 10 and 20 are not orthogonal to the planes 116 and 118 of the protector. By way of non-limiting example, the axes 12 and 22 of the coils 10 and 20 are inclined approximately 35 ° in relation to the plane of symmetry 80, B perpendicular to the planes 116 and 118 of the protector. This characteristic makes it possible to obtain a pivotal angle for the mobile equipment about the axis 0-0 which is greater than the angle that could be obtained only by controlling the field generated by the coil 10 and 20 in the presence of the protector 100 which is circularly cylindrical.

A) Yes. when the coil 10 is activated in the presence of the circular cylindrical protector 100 »the magnet of the mobile equipment normally aligns itself on the axis 12 of said coil 10. However» due to the presence of the planes 116 and 118 of the protector 100. The axis of the magnet held by the mobile equipment tends to take a position that is intermediate between the axis 12 of the coil 10 and the axis 80 which is orthogonal to the planes 116 and 118. This produces delay in the left-handed direction for the position of the mobile equipment in relation to the control imparted by the coil 10 on itself. The opposite effect is obtained when the coil 20 is activated. In the presence of a circular cylindrical protector, the axis of the magnet of the mobile device normally aligns itself on the axis 22 of the coil 20 when the coil is activated, while with the protector 100 of the invention, the axis of the magnet of the equipment The mobile takes a position that is intermediate between said axis 22 of the coil 20 and the plane 80 mentioned above, orthogonal to the planes 116 and 118 of the protector. This thus provides an advance in the left-handed direction for the mobile equipment in relation to the axis 22 of the coil 20 on itself. Figure 5 also shows a ball 220 placed in a central chamber at the end of the frame 50 to serve as a support for an end of the arrow 210 secured to the magnet 200. and an arrow support 230 adapted to be fixed on the frame 50 to guide the other end of the arrow 210. The general operation of the logometer shown in the attached figures is as follows: The coils 10 and 20 are activated by conventional signals that take into account the geometry of the coils. and more precisely, the inclination relative to each other and the reluctance of the protector 100. Together, the two coils 10 and 20 create a field that imparts a torque if the magnet 200 is moved away from its position. The protector 100 also creates a torque because it is not circularly symmetrical. The stable positions of these two torques do not match.

At an angle occupied by the magnet 200 is the angle corresponding to the sum of the two torques that are zero. When the power supply is stopped »due to the variable reluctance of protector 100 due to its lack of circular symmetry» the magnet of the mobile equipment tends to align itself on the plane of symmetry 80 which is orthogonal to planes 116 and 11B . and so it comes to hold without rebound on the mechanical splice provided in the logometer. The logometer of the present invention provides numerous advantages over previously known devices. First, it will be noted that the logometer of the present invention is completely symmetrical about the plane 80. Consequently, it can be driven without difficulty in any of two opposite directions of rotation, and this can be done with the same response angle curve as a control signal function »regardless of the direction of rotation. This constitutes a major advantage over the prior art logometers, providing return by means of a magnet or by means of a spiral spring, since they have asymmetric response curves depending on the direction of rotation. Furthermore, the logometer of the present invention makes it possible to increase the pivotal amplitude of the mobile equipment compared to that which originates only from the control by means of the coils 10 and 20. Finally, the logometer of the present invention is simple to manufacture and assemble. and does not require any fundamental changes in the manufacturing or installation lines. Naturally, the present invention is not limited to the particular embodiment described above, but extends to any variant within the spirit of the invention. As mentioned above, more generally, the protector 100 of the present invention comprises a generally circular cylindrical annular skirt 110 having at least one reentrant shape (for example a plane or some other shape) in relation to said circular cylinder. It can have two reentrant forms that are optionally diametrically opposed. In another variant, protector 100 may have a section that is generally elliptical in shape.

Claims (14)

NOVELTY OF THE INVENTION REIViNPICACIQNES

1. - An electromagnetically controlled drive device, in particular a logometer of the type comprising: a group of control coils (10. 20); a frame (50) supporting the group of coils (10. 20); equipment that includes a magnet suitable to be moved pivotally by the group of control coils (10, 20); and magnetic shield (100) surrounding the group of coils (10, 20) and the support frame. at least in part; the device is characterized by the fact that the protector (100). which is done by stamping a sheet of a soft magnetic metal. it comprises an annular skirt (110) that is not a circular cylinder.

2. A device in accordance with the rei indication 1. characterized in that the protector (100) comprises an annular skirt (110) which is a cylinder generally circular, but having at least a reentrant form (116. 118) that is reentrant in relation to the circular cylinder.

3. A device according to claim 2 »characterized in that the protector (100) has two reentrant forms (116. 118) that are reentrant in relation to the circular cylinder.

4. - A device according to claim 3 »characterized in that the reentrant forms (116. 118) are formed by planes.

5. A device according to claim 3 or 4. characterized in that the two reentrant forms (116. 118) are diametrically opposed around the axis of the device.

6. A device according to claim 3 or 4, characterized in that the two reentrant forms (116. 118) are not diametrically opposed around the axis of the device.

7. A device according to any of claims 1 to 6. characterized in that the protector (100) comprises an annular skirt (110) that is not a circular cylinder and has two orthogonal planes of symmetry (A B) that cut on the axis of rotation 0-0 of the equipment.

8. A device according to any of claims 1 to 5 and 7. characterized in that the annular skirt (110) comprises two diametrically opposed sectors (112. 114) of a circular cylinder interconnected by two parallel planes ( 116. 118).

9. A device according to any of claims 1 to 8. characterized in that the axes (12. 22) of the coils (10. 20) are not orthogonal to the planes (116. 118) of the protector (110).

10. - A device according to any of the rei indications 1 to 9. characterized by the fact that the axes (12. 22) of the coils (10. 20) are inclined approximately 35 ° in relation to a plane of symmetry (80 ) perpendicular to the planes (116. 118) of the protector (100).

11. A device according to any of claims 1 to 10, characterized in that the coils (10, 20) are inclined, one relative to the other, approximately 110 °.

12. A device according to any of claims 1 to 11. characterized in that the protector (100) is made of soft steel.

13. A device according to any of claims 1 to 12. characterized in that the angular magnitude of each of the cylindrical sectors (112, 114) of the protector (100) is around 150 °.

14. A device according to any of the refs of 1 to 13. characterized in that the protector (100) comprises an annular skirt of section that is generally elliptical in shape.