FR2995001A1 - ELECTROMECHANICAL ACTUATOR FOR DRIVING A DOMOTIC SCREEN - Google Patents

Abstract

This electromechanical actuator is intended for driving a home automation screen and comprises a motor, a gear and a brake itself comprising an input member (110), an output member (120) and a spring (130) provided with two folded tabs (132a, 132b). This spring brake (105) comprises a friction element (118) between the input member (110) and the output member (120). This friction element (118) is integral, in rotation, with a first member (110), among the input member and the output member. The second member (120), between the input member and the output member, rubs against the friction element in case of relative rotational movement between the input member and the output member around the a central axis (X100) of the actuator.

Description

ELECTROMECHANICAL ACTUATOR FOR DRIVING A DOMOTIC SCREEN Description of the state of the art: The invention relates to an electric actuator for driving a home-automation screen, such as a shutter, blind, curtain, grille, projection screen or garage door. The actuator according to the invention is provided with a spring brake. This type of brake is particularly suitable for tubular motors. The use of a coil spring brake in actuators for home automation screens is known, in particular in patent FR-B-2,610,668. In the material described in this document, a coil spring is mounted in a friction piece. At least one coil of the spring is radially constrained by a bore of the friction piece. Each end of the spring forms a tab extending radially inwardly of the spring. Each tab can be moved to cause the rotation of the spring relative to its axis. The input member, the output member and the spring are arranged specifically to obtain the following kinematics: an action of the input member located on one side of the first leg causes the rotation of the spring in a first direction . This movement releases the output member, i.e., it tends to decrease the diameter of the outer casing of the spring. Thus, the friction between the bore of the friction piece and the turns of the spring decreases, due to the decrease in the radial stress between the spring and the friction piece. Conversely, an action of the output member on the opposite side of the first leg causes the rotation of the spring in the second direction, that is to say, the opposite direction. This movement blocks the output member, that is to say, it tends to increase the diameter of the outer casing of the spring. The friction between the bore of the friction piece and the turns of the spring therefore increases. It is the same for the radial stress between the spring and the friction piece. On the other hand, the input member may also act on the second leg of the spring to cause the rotation of the spring in the second direction while releasing the output member. Furthermore, the output member may also act on the second leg of the spring to cause the rotation of the spring in the first direction. In this case, the output member is blocked or, at least, is braked by the friction of the spring against the friction piece. Consequently, the rotation of the input member allows the rotation of the spring and the output member, while the rotation of the output member immobilizes the spring which blocks the primed movement of the output member.

A similar brake is described in EP-B-2230415. This offers a spring brake with symmetrical operation, that is to say, with equivalent performance irrespective of the direction of rotation of the drive part. For this, the axial displacement of the coil spring is stopped, in both directions, by two parts forming lateral stop abutments continuously integral in rotation about the axis of the spring. By this configuration, the spring is always pressed against a lateral stop piece having the same speed differential with the spring, that the drive part rotates in one direction or the other. The actuator then makes it possible to move the domotic screen without the spring inducing parasitic friction, since the spring and the lateral stop piece have the same rotation speed continuously, at the axial stop, when the brake is released. However, it is noted that during downward movements, while the brake holds the load, and in particular at low load, between 0.3 and 0.5 times the nominal torque, noises occur, different from the no-load noise due to Friction torque of the spring brake.

These noises are more persistent when the temperature of the actuator increases, following the implementation of successive motorized movements and / or because of a rise in ambient temperature. Insofar as the brake is mounted upstream of at least one reduction stage, this reduction stage absorbs a part of the vibrations that could be produced due to an elastic behavior of the brake. However, these vibrations, which occur at a portion of the actuator having a high rotational speed, generate operating noise and decrease the acoustic quality of the actuator. It is this noise problem that the present invention intends to address more particularly. An object of the present invention is to improve the operation of a spring brake in all operating configurations, including in a driving load situation, while the speed of rotation of the load is greater than the exit speed of the load. the actuator, and thus that the brake is partially released. To this end, the invention relates to an electromechanical actuator for driving a home automation screen, this actuator comprising a motor, a gear and a brake comprising itself an input member, an output member and a spring provided with two folded tabs, characterized in that the spring brake comprises a friction element between the input member and the output member, in that said friction element is integral, in rotation, with a first member, among the input member and the output member, and in that the second member, among the input member and the output member, rubs against the friction element in case of relative rotational movement between the input member and the output member about a central axis of the actuator. Thanks to the friction element, a friction is created between the brake input member and the brake output member, these two members being in contact with the folded tabs of a spring, thus creating a damping between these two organs. This high speed friction makes it possible to reduce or even eliminate the noise observed. In particular, the load speed at the output of the brake and the engine speed are smoothed by this friction device. The damping of the angular movement can be achieved by an elastic friction system.

According to advantageous but non-compulsory aspects of the invention, such an electromechanical actuator may incorporate one or more of the following characteristics, taken in any technically permissible combination: the friction member is disposed upstream of at least one reduction stage; reducer. - The friction element is formed integrally with the input member or with the output member. Alternatively, the friction element is an insert on the input member or on the output member. - A first member, among the input member and the output member, comprises a plate provided with a peripheral collar, the friction element is disposed on a radial inner surface of the collar and the friction element. comes into direct or indirect contact with a part of the second organ. In this case, the friction element is advantageously formed by a local extra thickness of the flange. - The part of the output member in contact with the friction element is a tab inserted into the coil spring. - The portion of the output member in contact with the friction element is an outer radial surface of the output member. - The plate comprises a guide light of an axial pin disposed on the output member and the friction element is provided in this light and in contact with the axial pin. A first member, among the input member and the output member, comprises a first shaft engaged in a second hollow shaft of the second member, among the input member and the output member, whereas the friction element is arranged, radially with respect to the central axis of the actuator, between a radial outer surface of the first shaft and a radial inner surface of the second shaft, the friction element being integral in rotation with a of the two shafts and rubbing against the inner or outer radial surface of the other shaft. - The friction element is made of a metal having elastic properties substantially invariable over a temperature range between -20 ° C and 80 ° C.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of three embodiments of an actuator according to its principle, given by way of non-limiting example and with reference to the accompanying drawings in which: - Figure 1 is an axial sectional view of a motorized screen installation comprising an actuator according to the invention; FIG. 2 is a partial exploded perspective view of a spring brake belonging to the actuator shown in FIG. 1; FIG. 3 is an end view, on the output side, of the part of the brake visible in FIG. 2; FIG. 4 is a perspective view of the brake of FIGS. 2 and 3; - Figure 5 is a smaller scale section along the line V-V in Figure 3; FIG. 6 is a perspective view of a friction element belonging to an actuator according to a second embodiment of the invention and FIG. 7 is a perspective view similar to FIG. 6 for an actuator according to FIG. a third embodiment of the invention. FIG. 1 schematically represents a rotary tubular actuator 100 intended to drive in rotation a winding tube 1 on which may be more or less wound an apron 2 which defines a sun protection screen E. The tube 1 is driven by the actuator 100 rotating about an axis of revolution XX which is disposed horizontally in the upper part of an opening, for example an opening in the walls of a building. The actuator 100, the tube 1 and the apron 2 then form a motorized screen. The actuator 100 comprises a fixed cylindrical casing 101 in which is mounted a geared motor 102 comprising an electric motor 103, a spring brake 105, an epicyclic reduction gear 106 and an output shaft 107 which projects at an end 101A of the tube 101 and causes, in rotation about the axis XX, a wheel-crown 3 integral in rotation with the tube 1. Other types of gear units may be used in an actuator according to the invention, with one or more reduction stages. The brake 105 is arranged upstream, that is to say on the motor side 103, relative to the gearbox 106. When the gearbox comprises several reduction stages, the brake 105 is arranged upstream of at least one stage of reduction of the reducer. X100 is the central axis of the actuator 100, this axis coinciding with the X-X axis in the configuration of use of the motorized screen.

The winding tube 1 rotates about the X-X axis and the fixed tube 101 through two pivot links. A crown-bearing 4, mounted on the outer periphery of the housing 101 near its end 101B opposite the end 101A, provides the first pivot connection. The second pivot link is installed at the other end of the tube 1 and is not shown.

The actuator 100 also comprises a fastener 109, projecting from the end 101B and making it possible to fix the actuator 100 on a frame 5. This fastener 109 is, in addition, intended to close the casing 101, as well as it has to support an electronic module 108 for controlling the power supply of the motor 103. This control module is powered by a power supply cable 6. Other embodiments can be envisaged, such as, for example, the power supply of the motor. the actuator 100 by an autonomous device of the battery or battery type, or the training of cords or laces maintaining a screen, itself not windable, or the maintenance of an actuator in a polygonal section rail. During the operation of the tubular actuator 100, the geared motor 102 rotates the shaft 107 which, in turn, rotates the tube 1 via the wheel-crown 3. As a result, the rotation of the shaft 103 causes the opening and, alternately, the closing of the screen E constituting the load. Figures 2 to 5 illustrate more particularly the structure of the spring brake 105 according to a first embodiment of the invention.

The spring brake 105 comprises a drum 150 in which are housed its main components: a brake spring 130 mounted on an input member 110 of the brake 105. This input member 110 is sometimes referred to as a "butterfly tray" and also supports an output member 120, sometimes called "butterfly". For clarity of the drawing, the drum 150 is not shown in Figure 2. It is however visible in Figures 4 and 5. The construction of the spring brake is generally as explained in EP-B-2267330 patents and EP-B-2230415. In the embodiment of actuator described above, the spring brake 105 is located upstream of the epicyclic reduction gear 106. The brake spring 130 is in the form of a helical spring 130 whose turns are centered on an axis X130 coincides with the axis X100 of the actuator when the brake 105 is in place as shown in Fig.1. This spring is mounted tightly within the drum 150, which tends to frictionally fasten the spring 130 and the drum 150 when the spring is at rest. The drum 150 is itself fixedly fixed, in translation and in rotation relative to the axis X100 in the casing 101 of the actuator. To do this, the outer radial surface of the drum 150 is provided with ridges 152 which serve to lock the drum in rotation inside the housing 101. X105 is noted the central axis of the brake 105, this axis coinciding with the axes XX, X100 and X130 in mounted configuration of the motorized screen. Parts 110 and 120 are centered on axis X105. Each end of the spring 130 forms a tab 132a, 132b extending radially towards the axis X130 and towards the inside of the spring, from its turns. The input member 110 comprises a first plate 111 itself comprising a drive tooth 113a adapted to be in contact with a tab 132a or 132b of the spring 130, in the direction of rotation provided by the motor. The brake spring 130 and the butterfly 120 are held axially between the first plate 111 and a second plate 115 which also belongs to the input member 110. A spacer 113b mounted on the first plate 111 diametrically opposite the drive tooth 113a, relative to the axis X105 makes it possible to maintain the distance between the two plates 111 and 115. Alternatively, the spacer 113b may be provided on the second plate 115.

The first 111 and the second plate 115 each comprise an axial peripheral collar 114, 116 disposed opposite each other along the axis, so as to delimit, between the first and the second plate, a receiving space of the butterfly 120, the drive tooth 113a and the spring 130. The plates 111 and 115 are integral in rotation about the axis X105. The input member 110 is thus constituted by the assembly of the trays 111 and 115, on either side of the spring 130 along the axis X105. The trays 111 and 115 can be held integral in rotation about the axis X105 by simple interlocking, for example by cooperation of a not shown pin extending axially from the tab 113a and 115a 115a of the plate 115 As a variant, the plates 111 and 115 are integral in rotation around the axis X105 via an element such as a screw or a rivet 119 represented by its center line in FIGS. the two trays, at the orifice 115a or any other orifice not shown. A rotation of the throttle plate 110 causes, depending on the direction of this rotation, an action by the tooth 113a on the tab 132a, or on the tab 132b, tending to release the brake 105, that is to say, to cause in rotation the tab 132a or 132b in a direction such that the radial stress between the outer casing 131 of the spring 130 and the inner radial surface 151 of the drum 150 decreases, thus reducing the contact force between the spring and the internal radial surface of the drum 150. The brake 105 being released, the movement of the motor can be transmitted from the input member or throttle plate 110 to the output member or throttle 120. The throttle 120 is supported by the plate 111, that it comprises a hollow shaft 112 centered on the axis X105 and on which is threaded the butterfly 120, axially and free to rotate about the axis X105. For this, the butterfly 120 is guided by a central pin 122 which is itself centered on the axis X105 in the shaft 112 of the input member. However, the rotational movement of the butterfly 120 is limited to a game in rotation, in particular because of the presence of the folded spring tabs 132a and 132b, the drive tooth 113a and the spacer 113b. The butterfly 120 is in the form of a hollow shaft 123 provided with two lugs 121a, 121b, inserted inside the helical spring 130. Each lug 121a, 121b comprises a surface 124a, 124b capable of coming into contact with a tab 132a, 132b, in particular in the case of a rotation of the throttle 120, with respect to the throttle plate 110 in particular under the effect of the load due to the weight of the deck 2. Such a rotation tends to bring the tabs 132a closer together and 132b, which has the effect of radially expanding the turns of the spring 130 relative to the X axis 130 and increasing the contact force between the spring 130 and the friction surface 151 of the drum 150. This amounts to actuate the brake 105, that is to say, to slow the rotation of the spring 130 relative to the inner surface 151 of the drum 150. Thus, the radial stress between the outer casing 131 of the coil spring and the inner surface 151 drum 150 increases. This is the case for example when the weight of the load exerts a torque leading to the output member 120, for example to the descent of the screen E or the shutter or to the stop of the actuator. The second plate 115 comprises a guide slot 117, in which can be inserted a not shown axial pin disposed on one of the ears 121a, 121b of the butterfly and extending parallel to the axis X105. Alternatively, the light 117 can only be used for the manufacture of the second plate and a pad mentioned below. According to a first embodiment, a pad 118 forming a friction element is provided inside the guiding light 117. This pad is able to be in contact with a portion of the butterfly 120, in the example directly in contact. with an ear 121a of the butterfly, as shown in Figure 5 where the friction pad is in contact with the outer radial surface 121c of the ear 121a. Alternatively, the pad 118 is in contact with the guide pin mentioned above.

This friction pad is therefore active to slow down the rotation of the output member 120 vis-à-vis the input member 110, when such a rotation occurs within the limit of the rotation clearance of limited amplitude mentioned above. According to the embodiment shown, the friction pad 118 is disposed on the inner radial surface 116i of the axial flange 116 of the second plate 115. It is in the form of a local extra thickness of the collar 116. Its dimensions, in particular its width measured parallel to the axis X105 and its thickness measured radially to this axis, are such that it slows the displacement of the output member 120 relative to the input member 110, without blocking this displacement in the limit of the game in rotation of limited amplitude between these two parts.

The friction pad 118 can be made integrally with the second plate as in the example of the figures or be reported thereon by various known means, for example by welding or gluing. The friction pad 118 is subjected to few mechanical stresses during the life of the actuator 100, insofar as it is only used during the load-carrying and load-driven driving passages. driving charge, or during reversals of meaning. In the second and third embodiments of the invention, which are partially shown in FIGS. 6 and 7 by their friction elements 118, the overall architecture of the actuator 100 and the brake 105 is comparable to that of the first embodiment. of realization. In particular, the brake 105 comprises an input element 110, an output element 120 and a spiral spring 130 similar to those of the first embodiment. In the second embodiment, the friction element 118 is constituted by a split ring provided with four tabs 118a obtained by localized cutting of the ring 118. The dimensions and the constituent material of the ring 118 are chosen so that it can be mounted tight around the central shaft 112 of the plate 111 of the input member 110. Thus, the elements 110 and 118 are integral in rotation about the axes X100 and X105. In particular, the ring 118 can be made of zamak or sintered steel. When the output member 120 is mounted in the brake 105, the hollow shaft 123 of the outlet member 120 caps the shaft 112, whereas the split ring 118 is interposed radially with respect to the axes X100 and X105, between the outer radial surface of the shaft 112 and the inner radial surface of the shaft 123. The lugs 118A are thus bearing against the radial inner surface of the shaft 123. In the embodiment of FIG. 7, the friction element 118 comprises an annular and flat portion 118b provided with a central opening 118c of suitable dimensions to allow its tight fitting around the shaft 112 of the input member 110, these elements being then secured in rotation around the X100 and X105 axes. The element 118 also comprises three tabs 118a which then bear against the internal radial surface of the hollow shaft 123 of the throttle valve or outlet member 120 when this member is mounted on the member 110 by capping the shaft 112 with the hollow shaft 123. The second and third embodiments have the advantage of distributing the friction over a greater distance than in the first embodiment, namely over at least half of the axial overlap distance between the organs. input and output, with a suitable conformation of the tabs 118a. In the second and third embodiments, the friction element 118 operates under a radial elastic stress. Alternatively, the friction pad 118 may be integral with or integral with the input member 110, including its flange 114 in the first embodiment or its shaft 112 in the second and third embodiments. An advantage of the invention lies in the use, for the realization of the friction pad 118, of a part provided for this purpose, whose mechanical, thermal, elastic properties can be chosen as needed, in particular when this pad is reported on the first plate 111, on the second plate 115 or on the shaft 123. Thus, advantageously, the friction pad 118 is made of a metal having substantially constant elastic properties over a range of temperature between - 20 ° C and + 80 ° c. In the embodiments described above, the friction element 118 is integral in rotation with the input member 110 and the output member 120 rubs against this friction element. Alternatively, whatever the embodiment, the friction member 118 may be integral with the output member 120, while the input member 110 rubs against the friction element. Whatever the embodiment, as the friction pad 118 belongs to the brake 105, it is disposed upstream of at least one reduction stage of the gear reducer 106.

Claims (11)

CLAIMS1.- Electromechanical actuator (100) for driving a home automation screen (E), this actuator comprising a motor (103), a gear (106) and a brake (150) itself comprising an input member ( 110), an output member (120) and a spring (130) having two folded tabs (132a, 132b), characterized in that the spring brake (105) comprises a friction member (118) between the member input member (110) and the output member (120), in that said friction element (118) is integral, in rotation, with a first member (110), between the input member and the output member, and in that the second member (120), between the input member and the output member, rubs against the friction element in case of relative rotational movement between the member input and the output member, about a central axis (X100) of the actuator. 2. Electromechanical actuator according to claim 1, characterized in that the friction member (118) is arranged upstream of at least one reduction stage of the gear (106). 3. Electromechanical actuator according to one of claims 1 or 2, characterized in that the friction element (118) is an insert on the input member (110) or on the output member (120). ). 20 4. Electromechanical actuator according to one of claims 1 or 2, characterized in that the friction element (118) is formed integrally with the input member (110) or with the output member (120) . 5. Electromechanical actuator according to one of the preceding claims, characterized in that a first member (110), among the input member (110) and the output member (120) comprises a plate ( 115) provided with a peripheral flange (116), in that the friction element (118) is disposed on an inner radial surface (116i) of the flange and that the friction element comes into direct contact or indirectly with a portion (121a, 121b) of the second member (120). 6. Electromechanical actuator according to claims 3 and 5, characterized in that the friction element (118) is formed by a local extra thickness of the flange (116). 7. Electromechanical actuator according to one of claims 5 or 6, characterized in that the portion of the output member in contact with the friction element is an ear (121a, 121b) inserted inside the spring (130) which is helical. 8. Electromechanical actuator according to one of claims 5 to 7, characterized in that the portion of the output member in contact with the friction element is an outer radial surface (121c) of the output member ( 120). 9. Electromechanical actuator according to one of claims 5 to 7, characterized in that the plate (115) comprises a slot (117) for guiding an axial pin disposed on an ear (121a, 121b) of the organ. outlet (120) and in that the friction element (118) is provided in this slot and in contact with the axial pin. 10. Actuator according to one of claims 1 to 3, characterized in that a first member (110), among the input member (110) and the output member (120), comprises a first shaft (112) engaged in a second hollow shaft (123) of the second member (120), among the input member (110) and the output member (120), in that the friction element ( 118) is arranged, radially with respect to the central axis (X100) of the actuator (100), between an outer radial surface of the first shaft (112) and an inner radial surface of the second shaft (123), in that the friction element is integral in rotation with one (112) of the two shafts and bears against the radial inner or outer surface of the other shaft (123). 11. Electromechanical actuator according to one of the preceding claims, characterized in that the friction element (118) is made of a metal having elastic properties substantially invariable over a temperature range between -20 ° C and 80 ° vs.