MXPA96005814A - Mechanism of electrically controlled gear coupling integrated with a magnetic hysteresis sliding underlock - Google Patents

Abstract

The present invention relates to an electrically controlled torque transfer mechanism for selectively transferring the torque between a first arrow mounted for rotation on a housing, through a magnetic hysteresis sliding clutch towards a second gear mounted for the rotation on the housing, such a sliding clutch comprising a magnetized armature mounted on the first arrow and fixed thereto, and a hysteresis layer within a cylindrical cup surrounding the magnetized member and in a torque / transfer ratio thereto. , the cup mounted to rotate about its axis with respect to the housing, wherein the improvement is characterized in that it comprises means for mounting the cup to allow axial translation of the cup between a first and second positions, a first gear concentric with the first arrow and fixed to the cup for axial translation with it and taken with the driving gear, when the cup is in its first axial position and out of engagement with the second gear when the cup is in its second axial position, the cup including a magnetic member externally attached thereto, and the transfer mechanism of Torque further comprises in juxtaposition to the magnetic member, an electromagnet that generates magnetic flux flowing through a flow path when activated, the electromagnet is positioned to include in its flow path the external magnetic member, the magnetic flux pushing the cup to one of the first and second axial positions when the electromagnet is active

Description

ELECTROMAGNETICALLY CONTROLLED GEAR COUPLING MECHANISM INTEGRATED WITH A SLIDING CLUTCH OF MAGNETIC HYSTERESIS DESCRIPTION Mechanical actuators are used in a variety of applications to operate devices, such as valves, dampers, doors, etc. Such actuators are used in applications that require a high level of force whether torsional or linear. The actuators can be designed to provide their output in any form, which can then be converted to the other by means of different mechanisms such as an arm or crank support and a pinion. Internally, these actuators typically include a small electric motor that drives a reduction gear train to provide a high torque or force output needed. The typical reduction gear train ratios may be of the order of 1000: 1 Frequently it is required to limit or control the torque or output force, and one way by which is achieved by placing a slip clutch torque limiter or null, on the output shaft of the motor.

When a load requires more torque or force than the value of the clutch design, the clutch simply slides. In many cases, it is important to limit the force applied to the controlled device to prevent it from being damaged. A type of sliding clutch that is usually used in low torque situations, such as a torque limiting coupling between first and second coaxial arrows, such as an engine arrow and the gear train input shaft. an actuator, is the so-called magnetic hysteresis clutch. Such a clutch has a cylindrical armature formed of material with high magnetic remanence and in which an alternating magnetic pattern, north-south, is permanently formed around its periphery. The armor is mounted to rotate on a first arrow. A cup, which is mounted to rotate on a second arrow coaxial with the first arrow, fits tightly around the periphery of the armature. A special magnetic hysteresis layer is present on the inner cylindrical surface of the cup. As the magnet rotates, it creates a magnetic field in the hysteresis layer, which opposes that of the armature. The opposing magnetic fields transfer the torque in any direction through the clutch. By properly selecting the strength of the magnetic field of the armature and the physical dimensions of the cup and the armature, the maximum torque that the clutch can transfer can be controlled relative and accurately. In the application of the drive, the torque is transferred by the clutch from the motor to the input gear of the gear train. An additional requirement in some actuator designs is the ability to return the controlled device to a preselected position, when an electrical power interruption occurs. For example, if the device is a fuel valve, when the power is lost, the valve should be closed immediately to prevent the fuel escaping in an uncontrolled manner. A common means for this power return function is a strong coil spring, which is wound or kept wound when the output element moves away from the preselected position, and is then released when an interruption of power occurs to provide an alternating source of torque for the gear train. The torque generated by the spring is then applied to the gear train to return the actuator output element to the preselected position. Certain types of motors usually used in these actuators have a spike and groove torque, which resists the torque applied to the motor shaft from an external source. When a coil spring is used to drive the return of torque for an actuator that uses the motor, it is necessary to disconnect the gear train motor during the spring-loaded return. If coupled to the gear train inlet during the return operation, the motor provides a resistive torque to the input shaft of the gear train, which prevents a spring from returning to the output element to its preselected position . Even if the motor does not have a spike and groove torque, its position on the gear drive input shaft will provide sufficient mechanical drag that requires a much larger spring than would otherwise be necessary. Accordingly, it is necessary in some designs to provide means for disconnecting the drive motors from the input shafts of the gear train of the actuators of which they are a part. At present there are several types of clutches operated by power, in which you can perform this function. However, these devices are relatively complex and expensive, so that an inexpensive and simple type of disconnecting appearance for the gear motor motor shaft in the actuator could be advantageous. The subject matter of the invention allows electrical control of torque transfer between a first arrow mounted for rotation on a housing, through a magnetic hysteresis sliding clutch towards a second gear mounted to rotate on the housing. As explained above, the sliding clutch comprises a magnetized armature mounted on the first arrow and fixed thereto, and a hysteresis layer within a cylindrical cup surrounding the magnetized member and in a relationship therewith of torque transfer of torsion. The cup is mounted to rotate about its axis with respect to the housing. The invention is an improvement to this conventional arrangement, and comprises means for mounting the cup to allow axial translation of the cup between a first and second positions. A concentric first gear with the first arrow is fixed to the cup for axial translation with it, being taken with the drive gear when the cup is in a first axial position and out of take with the second gear when the cup is in its second axial position. The cup includes a magnetic member externally attached thereto. An electromagnet in juxtaposition to the magnetic member when it is actuated, generates a magnetic flux which flows through a flow path that includes the external magnetic member. The magnetic flux pushes the cup into one of the first and second axial positions when the electromagnet is driven.

It is preferred that the electromagnet is positioned with respect to the magnetic member, so that when the electromagnet is activated, the cup is pushed towards its first position, with the first gear in engagement with the second gear and the armature partially withdrawn from the cup. The armature, being magnetic exerts a magnetic force on the magnetic member, extracting the cup to its second position, which places the armature more completely inside the cup, and the first gear out of take with the second gear. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a sectional view of a part of an actuator incorporating the invention, and showing the gear train coupled with the motor. Figure 2 is a sectional view similar to that of Figure 1, of a part of a drive embodying the invention, and showing the gear train decoupled from the engine. Figure 3 is a sectional view at right angles to that of Figures 1 and 2, and shows the spatial relationship of the armature and the cup. Figure 4 is an alternative arrangement for assembling the armature and cup assembly. Figure 1 shows the details of the invention as applied to an actuator 10. The elements of the actuator 10 are mounted on and within a housing 21, which comprises an upper stage 23, a side wall 24, and a lower stage 25. The torque for operating the actuator 10 and rotating a load, not shown, is supplied by a motor 12. The motor 12 is mounted by brackets 14 and 15 forming a part of the motor case 12. The brackets 14 and 15 are attached to an external surface of the housing 21 on the upper stage 23 by machine screws and bolts 19 and 20. The motor 12 has an arrow 16 that extends through an opening in the upper platen 23. The arrow 16 has fixed thereto a cylindrical armature 18 formed of a magnetic material of high remanence, which is magnetized in order to create alternating poles, north and south, around its periphery. The armature 18 together with the hysteresis cup 43 form a magnetic hysteresis sliding clutch, which allows the transfer of a precisely limited amount of the torque from the armature 18 to the cup 43. The cup 43 has an outer part and a inner part circularly cylindrical, with its inner diameter slightly exceeding the diameter of the armature 18. The part of the cup 43, which produces its shape and stiffness, is formed of a non-magnetic material such as high-strength plastic. The cylindrical interior of the cup 43 conventionally comprises a hysteresis layer 44. The layer 44 is formed of a magnetic hysteresis material, in which a magnetic pattern is created under the influence of an external magnetic field varying in strength and polarity. The magnetic hysteresis material, in which the pattern is formed, is attracted to the field generator as the generator moves with respect to the hysteresis material. A known type of the hysteresis material is an FeCrCo alloy, formed according to the owner's procedure and currently available under the name "Arnokrome III" from Arnold Engineering Co., Marengo, IL 60152. An additional aspect of the cup 43 is an outer cylindrical layer, which comprises a piece of pole or member 41 formed of a low reluctance magnetic material, such as soft iron. The pole piece 41 has a predetermined axial dimension, and is axially placed on the outside of the cup 43 in a position that will be explained later in more detail. The cup 43 has a bottom, which includes a mass portion 51 mounted for rotation on an arrow 49 fixed to the bottom platen 25. The cup 43 can also be slid axially on the arrow 49 between a first position, where the 43 glass occupies, as shown in Fig. 1, and a second position as shown in Fig. 2. The dough portion 51 also includes a first integral gear 46 formed in the adjacent mass portion and external to the enclosed volume of the cup 43. In the first position of the cup 43 shown in Fig. 1, the gear 46 is completely in engagement with a relatively larger second gear 58, which forms the first gear of a gear train which reduces the speed and increases the torque of the engine 12 to a level that allows the actuator 10 to operate at a relatively heavy load. In the second position of the cup 43 shown in Fig. 2, the first gear 46 is completely out of engagement with the second gear 58. The second gear 58 is concentric with and is fixed to a third gear relatively smaller, both of which are mounted for rotation on an arrow 65, which is fixed to the lower platen 25. The gear 60 simultaneously takes with a relatively larger gear 72, which is concentric with and is fixed to a gear 55 relatively smaller. The gears 55 and 72 are mounted for rotation on an arrow 53, which is fixed to the platen 25. The gear 55 is taken with a gear 70, which continues the gear train through an appropriate number of stages for provide the necessary torque amplification for the design of the particular actuator involved. The last gear in the gear train is mounted on the output shaft (not shown) of the actuator 10. The device to be placed is attached to the output shaft. A toroidal electromagnet 30 concentrically surrounds the cup 43 and comprises a winding 31 and an external core 33. The electromagnet 30 is fixedly mounted between an end 24 of the housing 21 and an internal fitting 27. Since the electromagnet 30 is shown in cross section in Figs. 1 and 2, the following explanation will refer to the elements as their real three-dimensional forms. The core 33 has a U-shaped cross section, as can be seen in Figs. 1 and 2, and has a base comprising a ring 34 concentric with the armature 18. The ring 34 has upper and lower edges, wherein the upper and lower annular flanges, which extend at approximately right angles from the top and bottom edges, are joined. ring 34 towards the cup 43. The inner edges of the upper and lower flanges are adjacent to and face towards the cup 43 and form pole faces 36 and 35 respectively, each pole face in three dimensions, in reality, comprising a separate concentric ring . The pole face 36 is visible on the edge in Fig. 3. The flow of current through the individual turns of the winding 31 generates a magnetic flux, which flows radially through the upper and lower flanges of the core 33, and axially through the base section 34.

The position in which the electromagnet 30 is mounted, must be selected so that when the cup 43 is in its first position (as shown in Fig. 1), the upper and lower edges of the pole piece 41 are close to each other. juxtaposed, respectively, to the pole faces 35 and 36, and form annular flow voids between each pole face 35 or 36, and the adjacent edge of the pole piece 41. The annular flow gap 39 is defined between the face of pole 36 and the pole piece 41. When the cup 43 is in its second position, the pole face 35 adjacent the flow gap is dramatically elongated, and very little flow can be directed into this gap due to its length. The operation of the actuator 10 is mediated by a controller 72, which receives operating power for itself and the mechanical elements of a power connection 75. The external apparatus of the actuator 10 forms a part, which provides a position signal of a trajectory 80, which specifies the desired position for the output arrow of the actuator 10 in a particular case. The controller 72 then provides a driving current to the motor 12 on the paths 78, which causes the motor 12 to rotate, with the polarity or phase of the driving current controlling the direction in the motor 12, and consequently the arrow of exit tour.

The controller 72 also provides DC power to the winding 31 of the electromagnet 30. When the winding 31 receives power, the magnetic flux flows through the core 33, attracting the pole piece 41 and pushing the cup 43 towards its first position, the minimum position of reluctance for the magnetic circuit comprising the core 33 and the pole piece 41. The winding 31 generates a sufficient flow to overcome the axially directed attraction of the magnetic armature 18 for the cup 44, and draws the cup 43 towards its first position. For a more efficient operation, the pole piece 41 must have an axial length approximately equal to the space between the upper and lower flanges of the core 33. When the pole piece 41 has an axial length absolutely equal to the space between the upper and lower flanges of the core 33, the minimum reluctance position for the magnetic circuit is achieved only when the cup 43 is in its first position. There are a number of design choices, which will ensure that when power is applied to the winding 31, the cup 43 is reliably driven to its first position, where the gear 46 is fully in engagement with the second gear 58, and then maintained. in this position. For example, a mechanical stop for the cup 43 can be provided, and which prevents the cup 43 from shifting to the minimum reluctance position. Rather, such a mechanism will simply provide that the first position of the cup 43 provides a reluctance in the magnetic circuit, which is much less than that present when the cup 43 is in its second position. In general, during normal operation, the controller 72 will maintain a continuous power to the winding 31, keeping the cup 43 in its first position and the first gear 46 in engagement with the second gear 58. This allows the motor 12 to serve as a brake, which prevents movement of the output shaft even if a dynamic torque load is present on the output shaft. An example of such loading may be an air duct cushion having blades, which will fall within the force of gravity towards the closed position when the torque is absent from its control arrow. Another type of load may be the return spring that forms a part of certain actuator designs. The return spring attachment of some actuators is in fact the motivation of this invention. As explained above, when power is lost, it is necessary to return many loads of the actuator to a preferred position. Nevertheless, certain types of motors have spindle torque and notch, and resist the torque applied to their arrows. If a return spring is used to provide the return torque for the output shaft, the motor 12 will resist its return torque. However, the actuators embodying this invention avoid this problem. When the power is lost to the controller 72, the power is no longer provided to the winding 31, and the cup 43 is no longer brought to its first position, where the gear 46 is in engagement with the gear 58. Rather, the axially directed magnetic attraction between the armature 18 and the layer 44 pushes the cup 43 towards its second position, where the gear 46 is out of engagement with the gear 58, allowing the gear train to return as freely as possible to the friction inherent in it that is allowed when the torque is applied to the output shaft. Figure 3 shows the relative shapes and positions of the coupling elements within the engine 12 and the gear 58 in a cross-sectional view taken parallel to the axis of the arrow 16. The circular shape of the armature 18 can be seen around which periphery alternating north and south magnetic poles are present. A small gap separates the outer surface of the armature 18 from the hysteresis layer 44. The non-magnetic cup 43 and the magnetic pole piece 41 form successive rings outside the layer 44. The magnetic flux gap 39 separates the piece of pole 41 of the pole face 36 of the upper flange of the core 33.

Fig. 4 shows a slightly different arrangement for a support cup 43. In this embodiment, the arrows 16 and 49 of Figures 1 and 2 are replaced with a single arrow 76, which extends from the upper stage 23 towards the lower platen 25. A bearing 48 supports the end of the arrow 76 for rotation on the platen 25. The cup 43 is carried on the arrow 76 for both the translation between its first and second positions for rotation. This design avoids the cantilever arrangement for the arrow 16 shown in Figs. 1 and 2, which can lead to higher loads on their bearings. The presence of the bearing 48 at the end of the arrow 76 minimizes the radial movement which can affect the separations in the clutch and the positioning of the gear 46 with respect to the gear 58. In addition, the speed of rotation of the cup 43 with relation to the arrow, which carries it, is substantially reduced in this mode, since the motor arrow will rotate in the same direction as the cup, the relative rotation will be equal only to the speed of spillage in the clutch, which can be 0 when the clutch (and actuator 10) is not overloaded.

Claims (14)

1. CLAIMS 1. An electrically controlled torque transfer mechanism for selectively transferring the torque between a first arrow mounted for rotation on a housing, through a magnetic hysteresis sliding clutch towards a second gear mounted for rotation on the housing, such sliding clutch comprising a magnetized armature mounted on the first arrow and fixed thereto, and a hysteresis layer within a cylindrical cup surrounding the magnetized member and in a torque / transfer ratio thereto, the cup mounted to rotate about its axis with respect to the housing, wherein the improvement is characterized in that it comprises means for mounting the cup to allow axial translation of the cup between a first and second positions, a first gear concentric with the first arrow and fixed to the cup for axial translation with it and taken with the gear of impulse, when the cup is in its first axial position and out of engagement with the second gear when the cup is in its second axial position, the cup including a magnetic member externally fixed thereto, and the torque transfer mechanism of The torsion also comprises in juxtaposition to the magnetic member, an electromagnet that generates magnetic flux that flows through a flow path when activated, the electromagnet is positioned to include in its flow path the external magnetic member, the magnetic flux pushing the cup to one of the first and second axial positions when the electromagnet is activated.
2. 2. The torque transfer mechanism according to claim 1, characterized in that the electromagnet is axially positioned to provide a magnetic flux that pushes the drive cup to its first axial position.
3. 3. The torque transfer mechanism according to claim 2, characterized in that the magnetic member concentrically surrounds the outside of the cup.
4. 4. The torque transfer transfer mechanism according to claim 3, characterized in that the electromagnet concentrically surrounds the magnetic member.
5. 5. The torque transfer mechanism according to claim 4, characterized in that the electromagnet includes a pole piece having an annular flow gap, the electromagnet axially positioned to position the flow gap adjacent to the magnetic member when the Cup is in its first axial position.
6. 6. The torque transfer mechanism according to claim 5, characterized in that the electromagnet is toroidally configured and includes a winding with circumferential turns, and the pole piece has a toroidal shape surrounding the winding with its flow gap looking into.
7. The torque transfer mechanism according to claim 6, characterized in that the flow path created by the pole piece and the magnetic member has an air gap between the pole piece and the magnetic member, and in where the length of the air gap is greater when the cup is in its second position than when it is in its first position.
8. 8. The torque transfer mechanism according to claim 1, characterized in that the electromagnet concentrically surrounds the cup.
9. The torque transfer mechanism according to claim 7, characterized in that the electromagnet includes a pole piece having an annular flow gap, the electromagnet axially positioned to position the flow gap adjacent to the magnetic member when the Cup is in its first axial position.
10. 10. The torque transfer mechanism according to claim 8, characterized in that the electromagnet is toroidally configured and includes a winding with circumferential turns., and the pole piece has a toroidal shape that surrounds the winding with its flow gap facing the first arrow.
11. The torque transfer mechanism according to claim 1, characterized in that the magnetic member is positioned relative to the armature for magnetic attraction thereto, pushing the cup to its second position and the electromagnet is positioned to , when activated, provide a magnetic flux attracting the magnetic member and pushing the cup to its first position.
12. 12. The torque transfer mechanism according to claim 10, characterized in that the magnetic member magnetically pushes the cup to its second position with a preselected force when the cup is in its first position, and where the weight of the cup and the elements attached to it is smaller than the preselected force. The torque transfer mechanism according to claim 1, characterized in that the first arrow carries the cup, and the first gear for relative rotation with respect thereto. The torque transfer mechanism according to claim 12, characterized in that the first arrow has a first end mounted for rotation adjacent to a first panel of the housing and a second end mounted for rotation in a second separate panel. of the first panel.