Position detector for a spatial geared stepping motor

Abstract

The invention relates to a rotating device (1) comprising a fixed part (2) and a rotary part (4) rotatable about an axis of rotation with respect to the fixed part (2), the rotating device (1) comprising an angular position detector (6) detecting the angular position of the rotary part (4) with respect to the fixed part (2), the angular position detector (6) comprising: - a magnet (62) integral with the rotary part (4), capable of generating a magnetic flux along a radial axis (A2) of the rotary part (4), - a magnetic field binary detector integral with the fixed part (2), configured to switch from a so-called open state to a so-called closed state when the magnetic flux of the magnet (62) is passing through the magnetic field binary detector.

Description

DESCRIPTION Title of the invention: Position detector for a space stepper geared motor

[0001] The invention relates to the field of angular position detection of a rotating device included in an antenna. More particularly, the invention relates to angular position detection intended for the control of a permanent magnet stepper motor. The invention finds a particularly advantageous application in the field of antennas and space activities, for which the detection of the position of the rotating element must be precise, but is suitable for any system comprising a rotating part requiring the detection of its position relative to a fixed part or of the number of complete rotations made by said rotating part.

[0002] Traditionally, to detect the rotation angle of a rotating element, it is indicated to use an optical incremental wheel encoder that provides feedback for precise control of the speed and positioning of the rotating element. However, this type of component has the disadvantage of requiring significant processing electronics to provide feedback regarding the position of the rotating element. In addition, the need, related to space applications, to determine very precise angular positions also implies the use of only high-precision encoder models for which the financial cost is high.

[0003] As an alternative to this, it is possible to consider using a Hall effect position sensor. However, this type of sensor has a higher failure rate than the incremental encoder.

[0004] Additionally, it is also possible to consider using an absolute encoder, such as a potentiometer. However, this type of encoder also requires processing electronics and even an analog-to-digital converter. In addition, this type of encoder is more likely to fail due to wear and tear, particularly due to vibrations, which is a fact to be taken into account in an environment where mechanical conditions are often extreme with strong vibrations and high temperatures.

[0005] Finally, it is possible to consider using a capacitive sensor but, once again, the temperature and humidity coefficients that will be subjected to it make it an unconvincing alternative.

[0006] In addition, all of the solutions mentioned are active in nature and therefore require packaging electronics, increasing the overall volume of the system and the risk of failure due to the on-board electronics.

[0007] The invention aims to overcome all or part of the problems mentioned above by proposing an angular position detector based on a simple magnetic structure making it possible to trigger the bouncing-free switching of a set of reed switches making it possible to indicate the position of the rotary element of a stepper motor driven by a control signal. The angular position detector according to the invention has the advantage of being made up of a minimum of electronic components, these components being passive and suitable for systems intended for space activities.

[0008] To this end, the invention relates to a rotating device comprising a fixed part and a rotating part around an axis of rotation relative to the fixed part, the rotating device comprising an angular position detector of the rotating part relative to the fixed part, the angular position detector comprising: - A magnet secured to the rotating part, capable of generating a magnetic flux along a radial axis of the rotating part, - A binary magnetic field detector secured to the fixed part, configured to switch from a so-called open state to a so-called closed state when the binary magnetic field detector is crossed by the magnetic flux of the magnet.

[0009] According to one aspect of the invention, the binary magnetic field detector comprises a first reed switch, the first reed switch comprising two edges and being configured to switch from the so-called open state, in which the two edges are distant to the so-called closed state, in which the two edges are electrically connected when the first reed switch is crossed by the magnetic flux of the magnet.

[0010] According to one aspect of the invention, the binary magnetic field detector comprises a second reed switch secured to the fixed part, the second reed switch comprising two edges of the second reed switch and being configured to switch from the so-called open state to the closed state when the second reed switch is crossed by the magnetic flux of the magnet, the second reed switch being distant from the first reed switch by a predefined angle relative to the axis of rotation of the rotating part.

[0011] According to one aspect of the invention, the first reed switch and the second reed switch are electrically connected in series.

[0012] According to one aspect of the invention, the first reed switch and the second reed switch are spaced from the axis of rotation by a predefined length.

[0013] According to one aspect of the invention, the first reed switch and the second reed switch are configured to have a common detection range, the common detection range representing the angular range during which the switching from the open state to the closed state of the first reed switch and the second reed switch is effective.

[0014] According to one aspect of the invention, the first reed switch and the second reed switch are included in a second part obtained from a high-performance thermoplastic material.

[0015] According to one aspect of the invention, the rotating device comprises a device for adjusting the position of the first reed switch and the second reed switch relative to the fixed part.

[0016] According to one aspect of the invention, the magnet is included in a first part obtained from a high-performance thermoplastic material.

[0017] According to one aspect of the invention, the rotating device comprises at least one flux channeler configured to channel the magnetic flux of the magnet radially relative to the axis of rotation of the rotating part.

[0018] According to one aspect of the invention, the rotating device comprises a magnetic protection casing configured to isolate the rotating part and the fixed part from a flux coming from a medium external to the rotating device.

[0019] According to one aspect of the invention, the rotating device is a stepper motor.

[0020] The invention will be better understood and other advantages will appear on reading the detailed description of an embodiment given by way of example, a description illustrated by the attached drawing in which:

[0021] Figure 1 shows an exploded view of a rotating device comprising an angular position detector according to the invention;

[0022] Figure 2 shows a sectional view of the rotating device of Figure 1;

[0023] Figure 3 represents a schematic and sectional view of a variant of the rotating device of Figure 1;

[0024] Figure 4 shows a schematic sectional view of the rotating device comprising a bias magnet;

[0025] Figure 5 shows a graph of the activation state of the reed switches inducing the detection of the angular position of the rotating part.

[0026] For the sake of clarity, the same elements will have the same references in the different figures.

[0027] Figure 1 represents an exploded view of a rotating device 1 comprising a fixed part 2, or commonly called stator, and a rotating part, or commonly called rotor 4, movable in rotation around an axis of rotation A1 relative to the fixed part 2.

[0028] The rotating device 1 also comprises an angular position detector 6 of the rotating part 4 relative to the fixed part 2. The angular position detector 6 comprises a magnet 62 secured to the rotating part 4, capable of generating a magnetic flux along a radial axis A2 extending from the axis of rotation A1 of the rotating part 4. The magnet 62 is considered to be the rotor 620 of the angular position detector 6. This rotor 620 then undergoes a rotation identical to the rotating part 4. To do this, the rotating part 4 comprises a housing 42 in which the magnet 62 is inserted so that the magnetic poles of the magnet 62 are aligned with the radial axis A2. Thus, the magnet 62 generates a magnetic flux extending along the radial axis A2 and also undergoing the rotation of the rotating part 4.

[0029] As an indicative example, magnet 62 is a Sm2Co17 magnet. This type of magnet has the advantage of having a small footprint compared to other types of magnet. A Sm2Co17 magnet also has a high remanent induction, of the order of 1.1 Tesla, and a high volumetric energy, of the order of 240 kJ / m 3 The thermal variation coefficients of the remanent induction and the coercive field of this Sm2Co17 magnet are also advantageous for the thermal cycles that a satellite undergoes in orbit.

[0030] Alternatively, any type of magnetic structure for generating a magnetic flux extending along the radial axis A2 may be considered. As an indicative example, an electromagnet may be considered. A collector system for powering the electromagnet or an induction power supply system may be coupled with the electromagnet by on-board electronics. However, the use of an electromagnet, its power supply and the on-board electronics requires a larger volume compared to the magnet 62.

[0031] The magnet 62 and the rotor 620 of the angular position detector therefore undergo a rotation at the rate of the rotating part 4 and generate a variation of the magnetic field along the radial axis A2.

[0032] The angular position detector 6 comprises a binary magnetic field detector secured to the fixed part 2, configured to switch from a so-called open state to a so-called closed state when the binary magnetic field detector is crossed by the magnetic flux of the magnet 62. The binary magnetic field detector is, by way of indicative example, a sensor delivering binary information when the magnetic field varies.

[0033] The angular position detector 6 comprises for example a first flexible reed switch 64 secured to the fixed part 2. The first flexible reed switch 64 comprises two edges, or two contacts, and is configured to switch from a so-called open state, in which the two edges are distant to a so-called closed state, in which the two edges are electrically connected when the first flexible reed switch is crossed by the magnetic flux of the magnet 62 so to generate a pulse or change of state when the magnetic field exceeds a predefined value.

[0034] Indeed, a reed switch is a magnetic switch comprising two contacts. These two contacts, or edges, which are, as an indicative example, made of iron-nickel alloy, are magnetizable and elastic. Thus, in the presence of a magnetic field exceeding a predefined intensity, the contacts become magnetized by influence, and are attracted to each other. The contacts move closer until they touch, which is observable when establishing the passage of a current. When the magnetic field is reduced below the predefined value, the magnetization of the blades is no longer sufficient to establish contact between the blades, ending the electrical connection.

[0035] According to a variant, the magnet 62 is inserted into the housing 42 so as to generate the magnetic flux perpendicular to the radial axis A2. Therefore, although the magnetic flux is not directed directly in the direction of the first reed switch 64, the first reed switch detects a variation in the magnetic field making it possible to switch from the open state to the closed state and vice versa.

[0036] Normally, the two contacts are about ten micrometers apart, but under the effect of a strong magnetic field, they move closer together until the reed switch closes.

[0037] Now, for a defined position and orientation of the first reed switch 64 in the fixed part 2 as well as a defined trajectory of the passage of the magnet 62, and particularly of the magnetic field generated by the magnet 62 in the vicinity of the first reed switch 64, it is then possible to determine a range of the angular position of the magnet 62, of the rotor 62 and therefore of the rotating part 4 in which the first reed switch 64 switches into the closed state, i.e. the detection angle of the rotating part 4 relative to the fixed part 2.

[0038] Therefore, by detecting the binary signal that is turned on / off from the first reed switch 64, it becomes possible to detect the angular position of the rotor 620 and thus of the rotating part to which the magnet 62 is attached when the magnet 62, and particularly the magnetic field generated by the magnet 62, passes opposite the reed switch.

[0039] According to a preferred configuration, the rotating device 1 comprises a second reed switch 66 secured to the fixed part 2. The second reed switch 66 also comprises two edges or contacts of the second reed switch and is also configured to switch from the so-called open state to the closed state when the second reed switch 66 is crossed by the magnetic flux of the magnet 62. The first reed switch 64 and the second reed switch 66 can thus be considered as the stator 640 of the angular position detector, stationary relative to the rotor 620.

[0040] Furthermore, the second reed switch 66 is spaced from the first reed switch 64 by a predefined angle 2 oc relative to the rotation axis A1 of the rotating part 4, as shown in FIG. 2. In other words, the second reed switch 66 is angularly offset from the first reed switch 64 by a predefined angle 2 oc relative to the rotation axis A1 of the rotating part 4.

[0041] Indeed, since the magnet 62 operates at high temperatures, the magnetic field generated by the magnet 62 is affected. Therefore, it is necessary to bring the reed switch closer so that the latter becomes magnetized and detects the passage of the magnetic field and therefore the angular position of the rotating part 4. In other words, it becomes necessary to vary the position of the magnet 62, and to bring the reed switch closer to the magnet 62 along the radial axis A2. This allows an adjustment of the operation of the sensor, namely the reed switch.

[0042] However, this approach has disadvantages such as a reduction in the accuracy of detecting the precise passage of the magnetic field at the level of the reed switch or a significant impact of the temperature on the reed switch.

[0043] Therefore, the angular positioning of the first and second reed switches 64 and 66 has the advantage of increasing the accuracy of the detection of the angular position of the magnetic flux generated by the magnet 62 and therefore the angular position of the rotating part 4. Indeed, when the first reed switch 64 switches from the open state, in which the edges or contacts of the first switch 64 are distant, in the closed state in which the edges are magnetized and in contact with each other allowing the passage of an electric current but the second reed switch 66 remains in the open state, then the magnetic field generated by the magnet 62 only impacts the first reed switch 64 and the magnet 62, characterizing for example the angular position of the rotating part 4, is located upstream of the first reed switch 64 according to the direction of rotation of the rotating part 4.Conversely, when the second reed switch 66 switches from the open state, in which the edges or contacts of the second switch 66 are distant, to the closed state in which the edges are magnetized and in contact with each other allowing the passage of an electric current but the first reed switch 64 remains in the open state, then the magnetic field generated by the magnet 62 only impacts the second reed switch 66 and the magnet 62, characterizing for example the angular position of the rotating part 4, is located downstream of the second reed switch 66 according to the direction of rotation of the rotating part 4.

[0044] Therefore, when simultaneously the first reed switch 64 switches from the open state to the closed state and the second reed switch 66 switches from the open state to the closed state, then the first and second reed switches 64 and 66 are impacted by the magnetic field generated by the magnet 62. Thus, it is possible to detect that the angular position of the magnet 62 and the rotating part 4 is between the two angular positions of the first reed switch 64 and the second reed switch 66.

[0045] Indeed, each reed switch has its own detection angle or detection range. The first reed switch 64 therefore has a first detection range 64' linked to the known angular position of the first reed switch 64 and the second reed switch 66 also has a second detection range 66' linked to the known angular position of the second reed switch 66. These detection ranges represented by the first detection angle 64' and the second detection angle 66', by overlapping, give a common detection angle 65 or common angular detection range 65 which thus represents the angular position of the rotor 620 and therefore of the rotating part 4.

[0046] Another real disadvantage related to temperature variation is that the common detection angle 65 varies greatly compared to the two detection ranges specific to reed switches, namely the first detection range 64' of the first reed switch 64 and the second detection range 66' of the second reed switch 66.

[0047] For example, a 10% increase or decrease in the two detection ranges specific to the first and second reed switches 64 and 66 induces a 40% increase or decrease in the common angular detection range 65.

[0048] Therefore, the variations in the magnetic behaviors of the first and second reed switches 64 and 66 as well as of the magnet 62, of the order of a few percent, must be taken into consideration. It is therefore necessary to adjust the position of the magnet 62 so that the variations undergone by the common angular detection range 65 do not cause one of the following two fault cases: - In a first case, when the common detection angular range 65 is too wide, that is to say the common detection angle 65 is large, the detection can also occur on the two steps adjacent to the step targeted by the stator 640 during the damped oscillation of the rotor 620 when the rotor comes to position itself on one of these two adjacent steps. Therefore, the angular detection is imprecise. - In a second case, when the common detection angular range 65 is too narrow, that is to say the common detection angle 65 is small, the loss of detection during the damped oscillation of the rotor 620 when coming to position itself on the targeted pitch can be more frequent although the rotor 620 is positioned on the targeted pitch.

[0049] In the case of a proximity between the magnet 62 and the first and second reed switches 64 and 66, the impact is less significant because the ratio between the common detection angular range 65 and the detection angle of a single reed switch can be higher, reducing the uncertainty linked to the detection.

[0050] The term simultaneously is considered to be the state during which the first reed switch 64 and the second reed switch 66 are switched from the open state to the closed state, i.e. at the level of the common angular detection range 65 as described previously. However, it may be envisaged to also take into consideration the moment upstream of the moment when this simultaneous switching of the first and second reed switches 64 and 66 takes place during which only the first reed switch 64 switches from the open state to the closed state. Similarly, it may be envisaged to take into consideration the moment downstream of the moment when this simultaneous switching of the first and second reed switches 64 and 66 takes place during which only the second reed switch 66 switches from the open state to the closed state.Indeed, the magnetic flux generated by the magnet 62 being aligned with the radial axis and undergoing the rotation of the rotating part 4, the first and second reed switches 64 and 66 being distant from each other by a non-zero angle, it is logical that a reed switch is magnetized before the other reed switch. Furthermore, there is a delay during which the current is not established in a reed switch although the reed switch undergoes the magnetic flux inducing the rocking. This is the delay necessary for the two edges or contacts of the reed switch to magnetize, deform and make contact in order to allow a passage of the electric current in the reed switch.Therefore, it becomes important to take into consideration the moments upstream and downstream of the moment during which the switching of the first and second flexible reed switches 64 and 66 takes place in order to know precisely the angular position of the rotating part 4, represented for example by the magnet 62.

[0051] As an indicative example, it can be estimated that the magnet 62 is located at the center of the arc formed between the first reed switch 64 and the second reed switch 66, as shown in FIG. 2. However, the first and second reed switches 64 and 66 being separated by an angle 2 oc, the angular position of the magnet 62 and of the rotating part 4 is easily determined.

[0052] Alternatively, a reference mark determining the angular position of the rotating part 4 can be envisaged and the angular distance between this reference mark and the magnet 62 along the radial axis A2 is known.

[0053] As an indicative example, the predefined angle between the first reed switch 64 and the second reed switch 66 is an angle between 10° and 30°. Preferably, the predefined angle between the first reed switch 64 and the second reed switch 66 is an angle between 15° and 20° and in an ideal configuration, the predefined angle is 18°.

[0054] In order to detect the moment during which the switching of the first reed switch 64 and the second reed switch 66 is effective, that is to say the common angular detection range 65 shown in FIG. 2, the first reed switch 64 and the second reed switch 66 are electrically connected in series. This electrical connection has the advantage of isolating the overlap of the detection zones of each of the first and second reed switches 64 and 66 to obtain a reduced centered detection zone.

[0055] Stated another way, the first reed switch 64 and the second reed switch 66 are configured to have a common detection range 65 representing the angular range during which the switching from the open state to the closed state of the first reed switch 64 and the second reed switch 66 is effective.

[0056] According to a preferred configuration of the invention, the rotating device 1 is a stepping motor. Therefore, the rotation of the rotating part 4 is incremented according to a defined angle, namely the step. The rotor 620, and more particularly the magnet 62, of the position detector 6 is indexed to a step of the rotating part 4 of the stepping motor. The first reed switch 64 and the second reed switch 66, for their part, are positioned along the radial axis A2, on either side of the step, so that the step is positioned between the first reed switch 64 and the second reed switch 66 along an arc connecting the first and second reed switches 64 and 66. This indexing of the positioning of the rotor 620 and the stator 640, represented by the first reed switch 64 and the second reed switch 66, to a step of the stepping motor allows and that the magnetic field generated by the magnet 62 is stopped between the first reed switch 64 and the second reed switch 66 at one of the stable positions of the stepper motor.

[0057] Thus, with a series connection of the first reed switch 64 and the second reed switch 66, it has the advantage of highlighting that a signal in the high state, indicating that the first and second reed switches are in the closed state, indicates that the stepper motor has stopped on the targeted step, i.e. positioned between the first reed switch 64 and the second reed switch 66.

[0058] According to a variant, a second pair of reed switches is placed at 120° from the first pair of reed switches formed by the first reed switch 64 and the second reed switch 66, facing another stable position of the stepper motor, to ensure redundancy.

[0059] Any other angle between the first pair of reed switches and the second pair of reed switches can be considered as long as the second pair of reed switches is opposite another stable position of the stepper motor.

[0060] In another configuration, the rotating device is a rotating motor.

[0061] As stated previously, the distance along the radial axis A2 between the magnet 62, or the rotation axis A1, and the first and second reed switches 64 and 66 is an important factor. Indeed, too small a distance impairs the accuracy of the detection of the angular position of the magnet 62 and the rotating part 4 while too large a distance prevents any magnetization of the switches to the reed. Therefore, the first reed switch 64 and the second reed switch 66 are distant from the rotation axis A1 by a predefined length L, shown in FIG. 2. As an indicative example, the predefined length L is a length between 10 millimeters and 30 millimeters.According to a preferred configuration, the predefined length L between the rotation axis A1 and the first and second reed switches 64 and 66 is a length between 12 millimeters and 20 millimeters and ideally is a length of 16 millimeters.

[0062] Furthermore, it should be noted that the presence of heat around a reed switch can harm the magnetization of the edges or contacts. However, three heat sources can be identified as being able to interfere with the rotating device 1 for spatial activity: - Solar radiation passing through the rotating device, - The conduction of thermal losses from the stator 2 of the motor via the bearings then the rotor 2, - The transmitted and / or reflected radiation as well as the thermal conduction of the satellite structure.

[0063] In order to protect against the heat generated in particular by solar radiation, the magnet 62 is included in a first part 80 obtained from a high-performance thermoplastic material, as shown in FIG. 1. The first part 80 is, for example, made of polyetheretherketone (PEEK). Alternatively, any material having high heat resistance is considered.

[0064] In addition, the first reed switch 64 and the second reed switch 66 are included in a second part 82 obtained from a high-performance thermoplastic material integral with the fixed part 2. The second part 82 is, for example, made of polyetheretherketone (PEEK). Alternatively, any material having characteristics such as good electrical insulation, with an adequate degassing rate for a space environment and high resistance to thermal cycles is considered.

[0065] The second part 82 also has the advantage of improving the relative positioning of the first flexible blade switch 64 with respect to the second flexible blade switch 66.

[0066] In order to best protect the first reed switch 64 and the second reed switch 66, the second thermoplastic material part 82 may be composed of two parts 820 and 822 positioned so as to encompass each reed switch, as shown in FIG. 1.

[0067] According to a preferred variant, the first part 80 and the second part 82 are printed circuit boards (PCBs). The first part 80 and the second part 82 also have the advantage of allowing the first reed switch 64 and the second reed switch 66 to be held between the first part 80 and the second part 82 while placing the first reed switch 64 and the second reed switch 66 in series. The use of the second part 82 has the advantage of not having to bend the legs of the first reed switch 64 and the second reed switch 66.

[0068] In another configuration, the first reed switch 64 and the second reed switch 66 may be surface mounted components (SMDs) of the first part 80, as shown in FIG. 3.

[0069] The use of the first reed switch 64 and the second reed switch 66 as surface-mounted components thus has the advantage of being fixed directly to the first part 80 without requiring the use of the second part 82, thus limiting the axial size along the axis of rotation A1.

[0070] It may also be envisaged to use two or a multitude of magnets 62 or magnetic poles on the rotating part 4. The magnets 62 are then arranged in an equidistant manner. This configuration based on the use of several magnets 62 distributed equidistantly in the rotating part 4 makes it possible to generate several pulses per rotation of the rotating part 4. It can also be envisaged that the magnets 62 or the magnetic poles are directly positioned at the level of a step or an increment of the rotating part 4. This configuration then has the advantage of being able to identify the step taken by the rotating part 4 in the case of use, for example, of a stepper motor.

[0071] It may also be envisaged to use several pairs of reed switches identical to the first reed switch 64 and the second reed switch 66 in order to obtain a redundant measurement of the angular position of the magnet 62. Indeed, the main and redundant readings can allow an identical measurement by compensating for the angular offset in a predefined manner.

[0072] According to a variant, the rotating device 1 comprises at least one flux channeler 9 configured to channel the magnetic flux of the magnet 62 radially relative to the axis of rotation A1 of the rotating part 4 so as to align the magnetic flux along the radial axis A2. Alternatively, the at least one flux channeler 9 is bonded to the magnet 62 with a polymerized adhesive having good magnetic permeability. According to a preferred configuration, shown in FIG. 1, the rotating device 1 comprises two flux channelers 9 inserted into the housing 42 so that the magnet 62 is positioned between the two flux channelers 9 along the axis of rotation A1. The rotor 620 then comprises the magnet 62 and the two flux channelers 9.

[0073] The flux channeler 9 is, by way of illustrative example, a pole piece for channeling the magnetic flux. The flux channeler 9 is, by way of illustrative example, made of ferromagnetic material.

[0074] According to a variant, the rotating device 1 comprises at least one flux channeler 9, positioned opposite the first flexible reed switch 64 against the fixed part 2 so as to channel the magnetic flux generated by the magnet 62 at the level of the first flexible reed switch 64. Preferably, the rotating device 1 comprises two flux channelers 9 positioned near the first flexible reed switch 64 against the fixed part 2 so that the first flexible reed switch 64 is between two flux channelers 9.

[0075] And similarly, the rotating device 1 comprises at least one flux channeler 9, positioned near the second reed switch 66 against the fixed part 2 so as to channel the magnetic flux generated by the magnet 62 at the second reed switch 66. Preferably, the rotating device 1 comprises two flux channelers 9 positioned near the second reed switch 66 against the fixed part 2 so that the second reed switch 66 is between two flux channelers 9. Therefore, the stator 640 comprises the first and second reed switches 64 and 66 as well as the four flux channelers 9.

[0076] The rotating device 1 may also comprise a magnetic protection casing 10 configured to isolate the rotating part 4 and the fixed part 2 from a flow coming from a medium external to the rotating device 1. Thus, the protection casing magnetic 10 magnetically isolates the rotating device 1 from the external environment. Therefore, the first reed switch 64 and the second reed switch 66 are less sensitive, or even insensitive, to electromagnetic disturbances from other machines located nearby or from the external environment such as cosmic radiation. The magnetic protection casing 10 is fixed to the stator 2 by means of paramagnetic screws 100. The use of paramagnetic screws 100 has the advantage of absorbing a small portion of the magnetic flux near the latter and thus tends to reduce the size of the common detection range 65.

[0077] Alternatively, it may be envisaged to fix the magnetic protection casing 10 by means of screws.

[0078] According to another variant, the magnetic protection casing 10 is a paramagnetic casing.

[0079] The rotating device 1 may also comprise a device 11 for adjusting the position of the stator 640, and particularly of the first reed switch 64 and of the second reed switch 66, relative to the fixed part 2 so as to adjust the angular position of the stator 640 relative to the rotor 620 and to the rotating part 4. The device 11 for adjusting the stator 640 induces a rotation of the stator 640 relative to the fixed part 2 along the axis of rotation A1 so as to move the angular positions of the first reed switch 64 and of the second reed switch 66.

[0080] As an indicative example, the device for adjusting the position 11 of the stator 640 relative to the fixed part 2 comprises at least one gutter 110 extending, along the fixed part 2, perpendicularly relative to the axis of rotation A1 and radially relative to the direction of rotation of the rotary part 4 and an adjustment screw 111 introduced into the gutter 110 making it possible to block the stator 640 relative to the fixed part 2. This adjustment has the advantage of making it possible to center each pair of flexible reed switches on a step of the stepping motor.

[0081] Furthermore, position adjustment device 11 makes it possible to adjust the angular position of the fixed part 2 relative to the part on which the fixed part is mounted, which is in this case the rear flange of the motor.

[0082] It may also be envisaged, as shown in Figure 3, that the fixed part 2 directly comprises a flux channeler 9'. This variant makes it possible to dispense with the use of a flux channeler 9 added near the magnet 62 or the reed switches 64 or 66. The flux channeler 9' thus takes the form of a planar protrusion 90' perpendicular to the axis of rotation A1 projecting relative to the fixed part 2. The flux channeler 9' comprising this protrusion 90' thus makes it possible to redirect the magnetic flux towards the first and second reed switches 64 and 66.

[0083] It may also be envisaged to combine the flux channeler 9 positioned near the magnet 62 in the rotating part 4 and the flux channeler 9' included in the fixed part 2 in order to optimize the redirection of the magnetic flux from the poles of the magnet 62 to the first and second reed switches 64 and 66. In addition, in a preferred configuration, the flux channeler 9 positioned near the magnet 62 in the rotating part 4 and the flux channeler 9' included in the fixed part 2 form salient poles and teeth facing each other when the reluctance is minimal.

[0084] Furthermore, it may also be envisaged to work with a magnetic field saturating the flux ducts 9 and / or 9' rather than capturing magnetic field creepage lines. Operation in saturation of the flux ducts 9 and 9' thus has the advantage of obtaining detection that is less sensitive to external influences due to temperature or manufacturing dispersions for example.

[0085] According to a preferred configuration, the flow channels 9 and 9' are magnetic sheets.

[0086] It may also be envisaged, as shown in Figure 4, to position a bias magnet 7 located in the detection area of ​​the first reed switch 64, namely the first detection range 64', or in the detection area of ​​the second reed switch 66, namely the second detection range 66'. In other words, the bias magnet 7 is positioned close to the first reed switch 64 and / or the second reed switch 66. As an indicative example, the bias magnet 7 is aligned with the first reed switch 64 along the axis of rotation A1. The fixed part 2 may also comprise several bias magnets 7 arranged near each reed switch 64 and 66. Indeed, the bias magnet 7 makes it possible to generate a bias field which reduces the sensitivity of the first reed switch 64 and / or the second reed switch 66. Therefore, detection by the first reed switch 64 and the second reed switch 66 requires a stronger magnetic field compared to the bias magnetic field generated by the bias magnet 7, which has the advantage of reducing the risk of disturbances by external fields.

[0087] Figure 5 shows a graph of the respective activation state of the first reed switch 64 and the second reed switch 66 as well as a graph representing the angular position of the rotating part 4 according to the two activation states of the first and second reed switches 64 and 66.

[0088] For each of the graphs the abscissa represents the angular position of the rotating part 4 according to the direction of rotation of the rotating part 4 and the ordinate represents the activation state of the component.

[0089] Two activation states are considered: a low state which corresponds to the open state of each reed switch and a high state which corresponds to the closed state of each reed switch. Therefore, when the magnetic field generated by the magnet 62 comes into contact with the first reed switch 64, the first reed switch 64 switches from the low or open state to the high, or closed, state, as shown in Figure 5.

[0090] And, similarly, when the magnetic field generated by the magnet 62 contacts the second reed switch 66, the second reed switch 66 switches from the low or open state to the high, or closed state with a delay relative to the first reed switch 64 due to the angular position being offset by the predefined angle 2 oc relative to the angular position of the first reed switch 64.

[0091] Furthermore, as mentioned previously, there is a delay between the moment when the first reed switch 64 is swept by the magnetic flux and the switching from the open state to the closed state of the first reed switch 64 called magnetic hysteresis. Therefore, it is possible to dissociate an electrical angular position P1 from a mechanical angular position P2. The position electrical angular position P1 then represents the angular position of the rotary part 4 at which the first reed switch 64 is closed. As an indicative example, the electrical angular position P1 can be considered as the position centered with respect to the period during which the first reed switch 64 is in the up or closed state, as shown in Figure 5.

[0092] The mechanical angular position P2 then represents the angular position of the rotating part 4 for which the magnetic flux impacts the first flexible reed switch 64. Thus, knowing the delay linked to the magnetic hysteresis, the mechanical angular position P2 of the rotating part 4 can be determined relative to the electrical angular position P1. The mechanical angular position P2 is then upstream of the electrical angular position P1 according to the direction of rotation of the rotating part 4.

[0093] Similarly, it is possible to detect an electrical angular position P3 of the rotary part 4 and a mechanical angular position P4 of the rotary part relative to the second reed switch 66. The electrical angular position P3 then represents the angular position of the rotary part 4 at which the second reed switch 66 is closed. As an illustrative example, the electrical angular position P3 can be considered as the centered position relative to the period during which the second reed switch 66 is in the up or closed state.

[0094] The mechanical angular position P4 then represents the angular position of the rotating part 4 for which the magnetic flux impacts the second reed switch 66. Thus, knowing the delay linked to the magnetic hysteresis, the mechanical angular position P4 of the rotating part 4 can be determined relative to the electrical angular position P3. The mechanical angular position P4 is then upstream of the electrical angular position P3 according to the direction of rotation of the rotating part 4.

[0095] Furthermore, it is possible to check the angular distance between the first reed switch 64 and the second reed switch 66 since the electrical angular position P1 must then be distant from the electrical angular position P3 by an angle 2a and the mechanical angular position P2 must also be distant from the mechanical angular position P4 by the angle 2a.

[0096] Therefore, it is possible to detect the angular position of the rotary part 4 from the electrical angular position P1 measured from the first reed switch 64 and the electrical angular position P3 measured from the second reed switch 66. As an indicative example, the electrical angular position P5 of the rotary part 4 detected from the electrical angular position P1 and the electrical angular position P3 is a position centered between the electrical angular position P1 of the first reed switch 64 and the electrical angular position P3 of the second reed switch 66, equidistant from the electrical angular position P1 and the electrical angular position P3. This detection from the electrical angular position P1 and the electrical angular position P3 can be judged as acceptable although being subject to the inaccuracy due to magnetic hysteresis.

[0097] Alternatively, the detection of the mechanical angular position P6 of the rotary part 4 is done from the mechanical angular position P2 measured from the first reed switch 64 and the mechanical angular position P4 measured from the second reed switch 66. As an indicative example, the angular position of the rotary part 4 detected from the mechanical angular position P2 and the mechanical angular position P4 is a position centered between the mechanical angular position P2 of the first reed switch 64 and the mechanical angular position P4 of the second reed switch 66, equidistant from the mechanical angular position P2 and the mechanical angular position P4.

[0098] The angular position detection device according to the invention has the advantage of being able to emit a pulse or a slot which indicates the position of the rotating part controlled by a control signal while being robust with respect to mechanical disturbances during detection. The angular position detection device according to the invention also comprises a simple design since it consists of the minimum of passive electronic components, thus minimizing the need for expensive advanced processing electronics and is compatible with the quality requirements of current European standards for systems intended for space activities.

[0099] The angular position detector according to the invention is based on the use of a pair of reed switches connected in series. The series connection allows the overlap of the detection zones of each of the reed switches to be isolated to obtain a reduced detection zone.

Claims

CLAIMS 1. Rotating device (1) comprising a fixed part (2) and a rotating part (4) about an axis of rotation (A1) relative to the fixed part (2), the rotating device (1) comprising an angular position detector (6) of the rotating part (4) relative to the fixed part (2), the angular position detector (6) comprising: A magnet (62) secured to the rotating part (4), capable of generating a magnetic flux along a radial axis (A2) of the rotating part (4), A binary magnetic field detector secured to the fixed part (2), configured to switch from a so-called open state to a so-called closed state when the binary magnetic field detector is crossed by the magnetic flux of the magnet (62), the binary magnetic field detector comprising: - a first reed switch (64), the first reed switch (64) comprising two edges and being configured to switch from the so-called open state, in which the two edges are distant to the so-called closed state, in which the two edges are electrically connected when the first reed switch (64) is crossed by the magnetic flux of the magnet (62), - a second reed switch (66) secured to the fixed part (2), the second reed switch (66) comprising two edges of the second reed switch and being configured to switch from the so-called open state to the closed state when the second reed switch (66) is crossed by the magnetic flux of the magnet (62), the second reed switch (66) being distant from the first reed switch (64) by a predefined angle relative to the axis of rotation (A1) of the rotating part (4), the first reed switch (64) and the second reed switch (66) are included in a second part (82) obtained from a high-performance thermoplastic material with a low degassing rate.

2. A rotating device (1) according to claim 1, wherein the first reed switch (64) and the second reed switch (66) are electrically connected in series.

3. Rotating device (1) according to one of claims 1 to 2, wherein the first reed switch (64) and the second reed switch (66) are spaced from the axis of rotation (A1) by a predefined length.

4. A rotating device (1) according to one of claims 1 or 3, wherein the first reed switch (64) and the second reed switch (66) are configured to have a common detection range (65), the common detection range (65) representing the angular range during which the rocker from the open state to the closed state of the first reed switch (64) and the second reed switch (66) is effective.

5. Rotating device (1) according to one of claims 1 to 4, comprising a device (11) for adjusting the position of the first reed switch (64) and the second reed switch (66) relative to the fixed part (2).

6. Rotating device (1) according to one of claims 1 to 5, in which the magnet (62) is included in a first part (80) obtained from a high-performance thermoplastic material.

7. Rotating device (1) according to one of claims 1 to 6, comprising at least one flux channeler (9) configured to channel the magnetic flux of the magnet (62) radially relative to the axis of rotation (A1) of the rotating part (4).

8. Rotating device (1) according to one of claims 1 to 7, comprising a magnetic protection casing (10) configured to isolate the rotating part (4) and the fixed part (2) from a flow coming from a medium external to the rotating device (1).

9. Rotating device (1) according to any one of claims 1 to 8, the rotating device (1) being a stepping motor.

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