• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
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  • 法律状态
  • 优先权
    • 专利摘要:
    Elastic device with variable stiffness, actuator with variable stiffness and coupling with variable stiffness. The invention relates to an elastic device (10) comprising a first spiral spring (20a), connected to a casing (22) and a shaft (21), and a second spiral spring (20b), connected to a casing (22) and to a shaft (21), where: the shaft (21) or, alternatively, the casing (22), is common to both springs (20a, 20b); the stiffness of the spring (20a) depends on the relative position between the shaft (21) and the casing (22) to which said spring (20a) is attached; The stiffness of the spring (20b) depends on the relative position between the shaft (21) and the casing (22) to which said spring (20b) is attached and where the turns of the spring (20a) run in the opposite direction to the turns of the spring (20b). (Machine-translation by Google Translate, not legally binding)
    公开号:ES2785676A1
    申请号:ES202030135
    申请日:2020-02-18
    公开日:2020-10-07
    发明作者:Guijosa Juan Manuel Munoz；Cabello Enrique Navarro；Tanarro Enrique Chacon；Lantada Andres Diaz
    申请人:Universidad Politecnica de Madrid；
    IPC主号:
    专利说明:

    [0004] Object of the invention
    [0006] The present invention belongs, among others, to the technical field of mechanical connections and is useful in many different sectors, such as, for example and without limitation, robotics, exoskeletons, vehicle suspensions, rehabilitation machines, bodybuilding machines, as well as structural systems.
    [0008] More particularly, the present invention has for its object an elastic device with variable stiffness. Said elastic device can be adjusted at will so that - when subjected to the action of a torque - the angular deflection generated in said device as a consequence of the action of said torque, is of greater or lesser magnitude.
    [0010] Likewise, the invention also relates to an actuator with variable stiffness comprising at least one of the elastic devices with variable stiffness mentioned above.
    [0012] Finally, the invention also relates to a coupling with variable stiffness comprising at least one of the elastic devices with variable stiffness mentioned above.
    [0014] Technical problem to solve and background of the invention
    [0016] In mechanical and structural terms, the stiffness of an element is the relationship between the force applied to said element and the deflection that said element experiences due to the action of said force.
    [0018] Thus, for example, the torsional stiffness Kt is the relationship between the torque dM applied to an element and the angular deflection d0 obtained in it:
    [0020] dM
    [0021] K t =
    [0022] ~ d6
    [0023] The stiffness of an element is also related to its ability to transmit mechanical stresses, limiting its transmission to increases in force or torque as long as a greater deflection is not achieved in the element.
    [0025] Many engineering systems can see their characteristics improved if they have elements with adjustable stiffness.
    [0027] Thus, for example, the stiffnesses of the elements that constitute a structural system influence the natural frequencies of vibration or critical rotational speeds of said system. The structural design has, among other objectives, to determine the stiffness of the different elements that make up a structural system so that their natural frequencies or critical rotational speeds are far from the frequencies at which the stresses act on the system. The incorporation of elements of variable stiffness to structural systems would therefore be beneficial, since it would make it possible to increase the versatility of said structural systems since it is possible to vary their stiffness, depending on the frequencies at which the stresses act.
    [0029] In the same way, the use of joints with adjustable stiffness in robots would make said robot, as in the case of humans, able to improve positioning and gripping operations, reducing the effect that disturbances in the movements have on its structure. external requests.
    [0031] On the other hand, an adjustable stiffness joint in a robot that works in collaborative environments, capable of reducing its stiffness before one of the connecting elements hits a worker, would reduce the severity of the impact and therefore its consequences. Under normal operating conditions, the joint will have a higher stiffness, so that the effective transmission of forces and mechanical torques between the elements it connects is possible, which would allow the robot to perform its work properly.
    [0033] Another application that benefits from adjustable rigidity connections is robotic exoskeletons. Different biomechanical studies on human gait have shown that the hip, knee and ankle joints allow a different turn when facing the same pair depending on the position of the leg, calf and foot. This stiffness, which varies depending on the position of the joint, also makes it possible to regulate the energy stored in the muscles responsible for walking, so that the excess energy in some phases is recovered in others. The same goes for the shoulder, elbow and wrist or neck joints. The execution of the gait or of other movements or sequences of body movements by means of exoskeletons would be, consequently, more realistic, ergonomic and efficient if connections of variable stiffness are used between the different elements of the exoskeleton.
    [0035] Due to the aforementioned non-linearity of the joints, in training, gym or rehabilitation machines it is also necessary to adjust the rigidity of the system on which the subject to be trained must make an effort, so the incorporation of elements of rigidity variable, it would be beneficial.
    [0037] The possibility of varying the stiffness at will is also useful in many different machines, for example in machines provided with several transmission shafts connected to each other by means of couplings. In nominal working conditions, a high rigidity is necessary in the coupling, so that efficient transmission of torque between the connecting shafts is possible, simultaneously absorbing radial and angular misalignments between them. However, in the event of a sudden rise in the resistive torque, a substantial reduction in stiffness is beneficial, so that the connected elements are protected from mechanical overloads, thanks to a greater angular deflection in the coupling. This stress limitation can also be used in, for example, torque wrenches, so that the tightening torque obtainable with the wrench can be adjusted.
    [0039] Vehicles, machines and structures can also benefit from a suspension with adjustable stiffness. For example, in automobile and railway vehicles a suspension with high stiffness at high speeds is necessary so that it is possible to meet the requirements of dynamic stability. However, at low speeds, -for example, in sections with curves with a small radius of curvature, or with bumps- it is important that the stiffness of the suspension is lower, so that the transmission of efforts and accelerations to the driver or passengers can be limited. , as well as the suspended structure. features Similar requirements are required in rail and motor vehicle torsion bars. In the same way, regulating the rigidity of the suspension of a machine can significantly reduce the transmission of vibrations towards its support if the rigidity of said suspension changes due to changes in the frequency of the forces generated in the machine. Similarly, it is possible to isolate a structure from excitations from its support by modifying the stiffness of the suspension that joins the structure to the support, so that the natural frequencies of the structure are far from the frequencies of the excitation through the support. .
    [0041] Different methods are currently known to obtain a variable stiffness. For example, patent application WO2014 / 001585 presents a system based on the preload of a rectilinear spring. However, the stiffness of the connection is very high up to the value of the spring preload. If the force exerted exceeds this value, the stiffness of the connection drops to that of the spring.
    [0043] Applications US2016082603 and TW201350095 present a connection of variable torsional stiffness, the variable stiffness being achieved by varying the free length of a beam on the center of which a torque is applied.
    [0045] Application US2015123417 obtains a joint with variable stiffness by modifying the shape of a beam by means of buckling it. Application US9366323 obtains a variable stiffness by modifying the useful length of an elastic element. Applications WO2013025510 and KR20160033340 obtain a connection of variable torsional stiffness by modifying the lever arm on which springs are acted. The application EP1731336A1 presents an element with variable torsional stiffness through the variation of the flexural inertia of a beam, by modifying its axes of inertia with respect to the torsion plane. Application WO2014033603A1 presents an adjustable stiffness system by preloading two non-linear elastic systems, in turn composed of springs with linear behavior.
    [0047] Some of the already known variable stiffness devices mentioned above achieve torsional stiffness by using rectilinear elastic elements. However, in such devices it is necessary to employ means for the conversion of a linear motion in a turning motion. Said means involve an increase in weight, size and cost.
    [0049] Other of the aforementioned variable stiffness devices achieve variable stiffness using elastic elements with constant stiffness, which also implies the need for means to modify the apparent stiffness of said constant stiffness springs, such as cables, pulleys, tensioners, cams, levers. variable arm, etc., or a combination of these. This also means additional weight, size and cost. The weight gain associated with the use of these peripheral systems may also imply a worsening of the dynamic response of the system and reaction time. The increase in size is especially problematic in systems such as robots, exoskeletons or cars. On the other hand, the increase in the number of components of the system reduces its reliability and raises the cost of maintenance.
    [0051] Description of the invention
    [0053] The present invention seeks to remedy or reduce the problems and disadvantages of the prior art, mentioned above.
    [0055] To this end, a first object of the present invention refers to an elastic device with variable stiffness, comprising:
    [0057] - A first torsion spring, with a spiral shape, which defines a plurality of turns, said first spring being joined at one of its ends to a casing and being joined by its opposite end to a rotation shaft, said shaft being configured in a such that it can rotate and vary its position relative to the casing to subject said first spring to a preload;
    [0058] - A second torsion spring, with a spiral shape, defining a plurality of turns, said second spring being joined at one of its ends to a casing and being joined by its opposite end to a rotation shaft, said shaft being configured in a such that it can rotate and vary its relative position with respect to the housing to subject said second spring to a preload;
    [0060] characterized by what
    [0061] - the first spring is non-linear, that is, the first spring is configured in such a way that its torsional stiffness can be varied by modifying the relative position between the rotary shaft and the housing to which said first spring is attached;
    [0063] - the second spring is not linear, that is, the second spring is configured in such a way that its torsional stiffness can be varied by modifying the relative position between the rotating shaft and the housing to which said second spring is attached;
    [0065] - the first and second torsion springs are coupled to each other in an antagonistic configuration, that is, they are attached to the same common shaft or, alternatively, they are attached to the same common housing, the springs also being arranged so that the coils of the first spring run in the opposite direction to the turns of the second spring; Y
    [0067] - the device has locking means configured to retain the shaft (or shafts) and the casing (or casings) in their relative positions, once the first and second torsion springs have been subjected to a preload.
    [0069] Thanks to the use of spiral torsion springs whose response is not linear and to the configuration described above, the element according to the present invention is capable of varying its stiffness - that is, the magnitude of the relative rotation between shaft (s) and housing ( s) for the same drive torque - without the need to use auxiliary elements, which reduces its size, weight, cost and complexity, and increases its reliability.
    [0071] Likewise, by imposing a certain preload on each of the spiral torsion springs, given the opposing configuration, an equilibrium position will be reached in which the preload torques of each spring are compensated and in which, in addition, the stiffness of Each spring is the one corresponding to the equilibrium point in each torque-angular deflection curve. In this way, it is possible to adjust the torsional stiffness of the device according to the present invention to the desired value. Furthermore, and contrary to what happens in devices provided with a single spiral spring, the device according to the present invention can be operated in both directions of rotation and it is not necessary for the torque exerted on the springs to exceed a certain minimum value (or threshold ), to achieve an angular deflection in said device.
    [0072] To achieve the variable bending stiffness mentioned in the previous paragraph, the first and / or second spring must have a geometry such that part of its length is wound around the turning shaft or around the casing as required. acts on the spring (whereby the useful length decreases and, therefore, the stiffness increases), or a geometry such that part of the length is initially wound around the casing or around the turning shaft, and that progressively unwind as the spring is acted upon (thereby increasing the useful length and, therefore, reducing its rigidity).
    [0074] Furthermore, in order to achieve a more pronounced non-linear behavior, the first spring may optionally have a flexural stiffness that varies along its length. Also, the second spring may optionally have a flexural stiffness that varies along its length. This is achieved, for example, by a width that varies along its length, a thickness that varies along its length, a cross section that varies along its length, a chemical composition that varies along its length. of its length, or any combination of these magnitudes (width, thickness, cross-section and / or chemical composition) that varies along its length.
    [0076] Likewise, the first and / or second springs can be made from a composite material, or through an additive manufacturing process, which also allows said springs to have a variable stiffness along their length if desired. .
    [0078] In a possible embodiment of the invention, the opposing configuration is obtained by joining the first spring and the second spring to the same common rotation shaft, the first spring being connected to a first casing and the second spring being connected to a second casing. , (the first housing and the second housing being different from each other).
    [0080] In another possible embodiment of the invention, alternative to that described in the previous paragraph, the opposing configuration is achieved by joining the first spring and the second spring to the same housing, the first spring being also connected to a first rotation shaft and being the second spring attached to a second rotation shaft, different from the first rotation shaft.
    [0081] The present invention contemplates the possibility that both the first spring, as well as the casing and the rotation shaft to which said first spring is attached, are independent pieces from each other.
    [0083] On the other hand, the present invention also expressly contemplates all the following possibilities:
    [0085] - That the first spring and the casing to which said first spring is attached, are made in one piece;
    [0086] - That the first spring and the rotation shaft to which said first spring is attached, are made in one piece; Y
    [0087] - That the first spring, the casing and the rotation shaft to which said first spring is attached, are made in one piece.
    [0089] The invention also contemplates all the possibilities mentioned in the previous paragraphs in relation to the second spring, the casing and the rotation shaft to which said second spring is attached.
    [0091] The elastic device with variable stiffness, according to any of the embodiments described above, can optionally be made by an additive manufacturing process, such as three-dimensional printing.
    [0093] A second object of the present invention refers to an actuator with variable stiffness useful, without limitation, in robots, exoskeletons, weight training machines, rehabilitation machines or suspensions of vehicles and machines.
    [0095] Said actuator with variable stiffness comprises at least one elastic device with variable stiffness, according to any of the embodiments described above, and two actuating means, configured to fix at will the relative positions between the casing (or alternatively, the casings) and the shaft. (or, alternatively, the trees). The variable stiffness actuator connects two contiguous members of the same kinematic chain, the first member connected to the casing (s) and the second member connected to the shaft (s).
    [0097] Preferably, the actuator with variable stiffness is provided with at least one elastic device with two identical non-linear spiral springs, the first spring of the device being attached to a first housing and the second spring being attached to a second housing, different from the first, but both springs being attached to the same rotation shaft. The actuating means, which in turn also serve as locking means, may comprise, without limitation, electric motors, linear actuators, pneumatic and hydraulic actuators, etc. In order to increase the driving torque, the driving means can have transmission means such as, without limitation, worm gear, Harmonic Drive, etc.
    [0099] By producing, by means of the actuating means, an equal and opposite rotation between the casings, the relative position of the latter with respect to the common shaft is modified without movement of the latter and, therefore, a modification of the spring preloads is achieved and, consequently , of the torsional stiffness of the elastic device. On the other hand, by producing, by means of the drive means, the same relative rotation between the casings and the shaft, the transmission of the torque between the two elements of the kinematic chain connecting the actuator is achieved.
    [0101] In a possible embodiment of an actuator according to the present invention, the shaft of at least one elastic device is connected to a corresponding element of a kinematic chain by means of a coupling. Preferably, said coupling is a non-permanent coupling, operable at will.
    [0103] A third aspect of the present invention refers to a coupling with variable stiffness useful, without limitation, in rehabilitation machines, bodybuilding machines, vehicle and machine suspension systems, or couplings between transmission shafts.
    [0104] The variable stiffness coupling comprises at least one elastic device with variable stiffness, according to any of the embodiments described above, and a single actuating means configured to fix at will the relative positions between the casing (or alternatively, the casings) and the shaft. (or, alternatively, the trees). The driving means may be, for example and without limitation, an electric motor, or a linear, pneumatic, hydraulic actuator, etc., which allows the relative position between the housings to be set at will (in the event of different housings and shaft unique) or between the trees (in case of different trees and unique carcass). The coupling can also be provided with locking means, such as, without limitation, reversible freewheels.
    [0106] Preferably, the actuator with variable stiffness is provided with at least one elastic device, the first spring of the device being attached to a first housing and the second spring being attached to a second housing, different from the first, but both springs being attached to the same shaft. rotation. By fixing the actuating means to one of the casings, and allowing said actuating means to act on the other casing, the relative position of the latter with respect to the common shaft is modified without movement of the latter and, therefore, a modification is achieved. spring preloads and, consequently, the torsional stiffness of the elastic device and the coupling.
    [0108] Description of the figures
    [0110] To complement the present description and in order to help a better understanding of the technical characteristics of the invention, according to preferred examples of practical embodiments thereof, a set of drawings is attached as an integral part of said description where, For illustrative and non-limiting purposes, the following has been represented:
    [0112] Fig. 1A.- Is a perspective view of a spiral torsion spring attached at its inner end to a rotation shaft;
    [0114] Fig. 1B.- Is a perspective view of the spiral torsion spring of Fig. 1A, which is also joined at its outer end to a casing;
    [0116] Figs. 2A and 2B.- These are plan views that schematically illustrate the effect of different preloads on the spiral spring of Fig. 1B;
    [0118] Fig. 3A.- It is a perspective view that graphically illustrates how a torque M applied to a rotation shaft produces an angular deflection 0;
    [0120] Fig. 3B.- It is a graph that shows the relationship between the torque applied to a non-linear spiral spring similar to those represented in Figs. 1A and 1B, in which, for increasing torque, firstly there is a reduction of the useful length and subsequently an increase in it, and the angular deflection that occurs in it, as well as the torsional stiffness obtained;
    [0122] Fig. 4.- Shows, in three different graphs, how the stiffness of a spiral spring like the one in Fig. 2A varies, for three different values of the torque applied to said spring and of the angular deflection that occurs in it;
    [0124] Fig. 5a.- Is an exploded view of a first embodiment of an elastic device according to the present invention;
    [0126] Fig. 5b.- Is an exploded view of a second embodiment of an elastic device according to the present invention;
    [0128] Fig. 6.- Is a perspective view of an actuator with variable stiffness, according to a first embodiment of the present invention, which comprises an elastic device with variable stiffness;
    [0130] Fig. 7.- Is a perspective view of an actuator with variable rigidity, according to a second embodiment of the present invention;
    [0132] Fig. 8.- Is a perspective view of a variable stiffness coupling, according to a third embodiment of the present invention; Y
    [0134] Fig. 9.- Is a perspective view of a variable stiffness actuator, according to a fourth embodiment of the present invention.
    [0136] Numerical references of the figures
    [0137] (10) Elastic device of the invention;
    [0138] (20a) First coil spring;
    [0139] (20b) Second coil spring;
    [0140] (21) Shaft of the first and second springs;
    [0141] (22) Housing of the first spring and / or the second spring;
    [0142] (24a) Top of the first spring;
    [0143] (24b) Stopper of the second spring;
    [0144] (25) Length of spring locked around shaft of rotation; (26) Length of spring locked around housing;
    [0145] (27a) Key of the first coil spring;
    [0146] (27b) Key of the second coil spring;
    [0147] (28) Keyway;
    [0148] (71) Fastening element;
    [0149] (72) Swing motor worm;
    [0150] (73) Swing motor;
    [0151] (74) Fixed support;
    [0152] (75) Stiffness variation motor worm;
    [0153] (76) Stiffness variation motor;
    [0154] (79) Link member coupling;
    [0155] (80) Locking system;
    [0156] (100) Variable stiffness actuator;
    [0157] (200) Variable stiffness coupling;
    [0158] (221, 222) Casing sprocket crowns;
    [0159] (M) Torque;
    [0160] (0) angular deflection;
    [0161] (K t ) Torsional stiffness.
    [0163] Description of an embodiment of the invention
    [0165] A detailed description of a preferred embodiment of the present invention is provided below with the aid of the attached Figures 1A to 9.
    [0167] Throughout the present description, as well as in the attached figures, elements with the same or similar functions will be designated with the same reference numbers.
    [0169] Fig. 1A shows a spiral spring 20a attached at its inner end to a rotation shaft 21.
    [0171] In Fig. 1B. Coiled spring 20a of Fig. 1a is shown which is further attached at its outer end to a housing 22.
    [0173] Figs. 2A and 2B schematically show the effect of subjecting a spiral spring, such as the one shown in Fig. 1B, to a torque M. Thus, as can be seen in the lower part of Fig. 2A, when applying a torque M some turns 25 of spring 20a are locked around shaft 21.
    [0175] This effect occurs because the curvature of said turns 25 due to the applied parapet is, in theory, greater than the maximum possible when they are wound around shaft 21. As a consequence, the free length of spring 20a decreases, thereby increasing its stiffness.
    [0177] On the other hand and as shown in the upper part of Fig. 2B in this case, by applying a torque M, some coils 26 of the spring 20a, which were initially locked around the casing 22, are unlocked from it.
    [0179] This effect is produced because the initial curvature of said turns 26 is less than the minimum possible when they are wound around the casing 22. The application of a torque as indicated in the figure causes said turns to unblock and therefore an increase in the free length of the spring 20a, whereby its stiffness decreases.
    [0181] Fig. 3A graphically illustrates how, by applying a torque M to the rotation shaft 21, it is produces 0 angular deflection.
    [0183] In Fig. 3B a curve is shown illustrating how the angular deflection 0 varies, as a function of the torque M applied. The tangent (tg a) to the curve M against 0, at any point on said curve, is precisely the value of the torsional stiffness K t corresponding to said point.
    [0185] Several M vs. 0 curves are shown in Fig. 4, similar to Fig. 3b. In each one of them it is shown what is the specific value of the stiffness (K1, K2, and K3), corresponding to a certain angular deflection (01 , 02 , 03 ) when a minimum torque Mo is applied.
    [0187] In Fig. 5a a first embodiment of an elastic device 10 with variable stiffness according to the present invention is shown. In this particular embodiment illustrated in said figure, the first spiral spring 20a and the second spiral spring 20b are attached to the same common rotation shaft 21. Furthermore, the first spring 20a is attached to a first housing 22 and the second spring 20b is attached to a second housing 22, different from the previous one.
    [0189] However, and according to the aforementioned, the present invention also contemplates the possibility - although it is not expressly illustrated in the figures - that the first spring 20a and the second spring 20b are joined to the same casing 22, the first spring also being joined to a first rotation shaft 21a and the second spring being attached to a different second rotation shaft 21b.
    [0191] In the embodiment shown in Fig. 5a, and according to the view shown in the figure, the turns of the first spring 20a run, in this particular embodiment of the invention and without limitation, in a clockwise direction from the shaft towards the casing. On the contrary, the turns of the second spring 20b run counterclockwise from the shaft towards the housing.
    [0193] Restriction of unwanted movements of springs and shaft can be achieved by threaded elements and bearings or thrust bearings.
    [0194] Each of the housings 22 and 22 is provided with means 24a, 24b to lock the relative position between them.
    [0196] In Fig. 5b a variant of the first embodiment of the elastic device 10 of Fig. 5a is shown, in which -in addition- the first spiral spring 20a is provided with an elongated key 27a and the second spiral spring 20b is provided with an elongated key 27b. Said keys 27a and 27b are intended to be inserted into a keyway 28 provided in each of the housings 22. If the keyway has a suitable width, it can allow obtaining zero stiffness by allowing free rotation, in an angular range defined by the width of the keyway, between the spring and the housing. Zero stiffness can also be achieved if temporary decoupling means are provided between the springs and / or their housings or shafts.
    [0198] Fig. 6 shows a first variable stiffness actuator 100, according to the present invention, comprising an elastic device 10 of variable stiffness.
    [0200] The variable stiffness actuator 100 can be used, for example and without limitation, in robots or exoskeletons, in car or machine suspensions, as a variable stiffness torsion bar, or for weight training machines or rehabilitation machines.
    [0202] Said actuator 100 allows, depending on the specific case, the transmission of a variable torque to an articulation member, the modification of the height of the vehicle or machine, or the modification of the rigidity of the actuator or the suspension.
    [0204] The actuator 100 is provided with an elastic device 10 of variable stiffness, as shown in Fig. 5 in which - preferably - both coil springs have the same torque-angular deflection curve.
    [0206] The casing of the elastic device 10 is connected to the first member 74 of the connecting kinematic chain, by means of two clamping elements 71. Said clamping elements 71 comprise a bearing, bearing or other similar means, which allows the rotation of the elastic device 10 and simultaneously prevents other turns, as well as their axial or radial displacement.
    [0208] In the embodiment shown, the housings of the elastic device 10 have toothed rings 221, 222. The toothed ring 221 is driven by an endless 72 by a rotation motor 73, and there may be a transmission system between the auger and the rotation motor , for example, by gears, belts, or some other means. The stator of the swing motor 73, like the brackets 71, are attached to the first member 74 of the connecting kinematic chain. Obviously, the connection between the elastic device 10 and the rotation motor 73 can be made by means of other types of configurations, such as Harmonic Drive geared motors, linear actuators, or hydraulic or pneumatic systems.
    [0210] The other ring gear 222 is driven by means of a worm 75 by a stiffness variation motor 76. The stator of the stiffness variation motor 76 is attached to the casing opposite the one with the ring gear 222. Both the shaft and each motor They also have an encoder, or an equivalent system that makes it possible to measure the angular position of the casings of the elastic devices and the common inner shaft 21. The shaft 21 may also have a torque sensor for measuring the drive torque of the system.
    [0212] The shaft 21 has, at least at one of its ends, a coupling 79 for the connection of the second member of the kinematic chain that connects - not shown in the figure - at one or both ends.
    [0214] In those applications where the actuator 100 is used in a robot joint, the first member 74 of the kinematic chain connecting the actuator 100 is the first joint member and the common inner shaft 21 is connected by a coupling 79 to the joint. second member of the joint. In those cases where the actuator 100 is used as a variable stiffness suspension, the common inner shaft 21 is connected to the unsprung mass of the vehicle and the element 74 represents the suspended mass. In those cases where the actuator 100 is used as a variable stiffness torsion bar, the common inner shaft 21 is connected to one wheel and the element 74 to the other. Lastly, in those cases where the actuator 100 is used in weight training or rehabilitation machines, the common inner shaft 21 is connected through the coupling 79 and, possibly, other transmission elements -not represented in the figure- to the flange operated by the user, and element 74 represents a fixed point of the machine.
    [0216] The present invention also contemplates that the coupling of the actuator 100 with the second member of the joint may be through a non-permanent coupling 79, actuable at will. In this case, means are provided to temporarily and voluntarily decouple said coupling, achieving zero stiffness while it is deactivated. Alternatively, zero stiffness can also be achieved if means - not represented in the figure - are available to temporarily and voluntarily uncouple any of the ends of the springs of the elastic device 10 from the shaft 21 or, alternatively, from the housings 22, as appropriate. .
    [0218] By driving the rotation motor 73 in the desired direction without actuating the motor 76, depending on the specific application in question, the relative rotation between the members of the joint or, alternatively, the raising or lowering of the vehicle chassis is achieved. relative to the ground.
    [0220] By driving the stiffness variation motor 76 in the appropriate direction, it is possible, depending on the specific application in question, to modify the relative position of a casing with respect to the other and with respect to the common inner shaft 21 and, therefore, the preload of the springs, so that the rigidity of the system is modified. Note that in order to modify the position of the casings without modifying the position of the inner shaft, it is necessary to simultaneously operate the rotation motor 73, since said motor also acts as a means of blocking the rotation of the elastic device 10. It can be used, optionally , an automatic regulation system that varies the speed of the rotation motor 73 as a function of the speed of the stiffness regulation motor 76, in order to minimize the rotation of the inner shaft 21.
    [0222] Obviously, the present invention contemplates that the drive of the casings can be carried out by any other means, in addition to by means of motors and worm gear.
    [0223] Figure 7 shows a second embodiment of a variable stiffness actuator 100 according to the invention. Said embodiment is similar to the embodiment shown in Figure 6, with the difference that now there is no stiffness variation motor 76, but rather two rotation motors 73, each one being coupled by means of an endless 72 to the corresponding teeth of each Case. The motors also serve as means of blocking the rotation of the elastic device. The relative rotation of the first member of the robotic joint with respect to the second member, or the variation in the height of the vehicle chassis with respect to the ground, is achieved by operating both motors 73 simultaneously, at the same speed and in the same direction of rotation. The rigidity variation is achieved by driving each motor 73 in the opposite direction. In the same way as in the embodiment shown in Figure 6, it is possible to modify the stiffness without obtaining movement of the common inner shaft 21, by means of an automatic regulation system that regulates the speed difference of each motor, measured by means of the encoders or corresponding speed or position measurement systems, so that the rotational speed of the inner shaft is minimized, also measured with the corresponding encoder or equivalent system.
    [0225] Figure 8 shows a first embodiment of an elastic coupling of variable stiffness 200 according to the invention, for use, for example and without limitation, in vehicle and machine suspensions, torsion bars, bodybuilding or rehabilitation machines, or couplings between trees.
    [0227] In the embodiment shown in Figure 8, there are no rotation motors, there is only a stiffness variation motor 76 mounted in one of the casings of the elastic element 10, which acts by means of the endless 75 on the other casing through its crown. toothed 222. The shaft 21 of the elastic device is connected, at one or both ends, to the suspension arm (in suspension applications), to one of the wheels (in torsion bar application), to the flange that actuates the user (in the applications of weight training and rehabilitation machines) or one of the shafts to be coupled (in the application of coupling between shafts). The housings 22a and 22b are connected, -through some fastening elements 71, which, in addition to the elements necessary to guarantee the rotation of the elastic system 10 around its axial axis, preventing movements along or around any other axis, include 80 locking elements such as wheels reversible free - to unsprung mass (in suspension applications), to the other wheel (in torsion bar application), to a fixed point on the machine (in strength and rehabilitation machine applications), or to the other tree (in the inter-tree coupling application). As the stiffness variation motor 76 is acting on one of the casings and joined to the other, due to the action and reaction principle there will be no movement of the inner shaft 21 when acting on the stiffness variation motor 76 to modify the relative position of the casings and, therefore, the preload of the springs. The freewheels should be configured in such a way that the desired movement of each casing is allowed, but the opposite movement is prevented. Elements can be arranged to balance the centrifugal force produced by the stiffness variation motor and its peripheral elements.
    [0229] Note that, in the application of coupling between shafts, this type of coupling can absorb angular and radial misalignments in the position of one of the shafts with respect to the other, due to the small angular and radial mobility that can be achieved, if desired, between the housings.
    [0231] Figure 9 shows an embodiment of an elastic coupling 200 of variable stiffness according to the invention for use, for example and without limitation, in couplings between trees or weight-training or rehabilitation machines. This particular embodiment of the elastic coupling 200 allows the rigidity to be adjusted manually, or by means of some stress amplification system such as a lever, screw, pulley or the like. In order to be able to modify the relative position of the shells of the elastic devices 10, it is necessary to allow some axial mobility between them. The shells of the elastic device 10 are connected to a first shaft of the coupling or to a fixed support 74 through connection elements 71, which include locking means 80 as reversible freewheels, and the shaft 21 of the elastic system 10 is connected, by means of the coupling 79, to the second shaft of the coupling or to the flange of the bodybuilding or rehabilitation machine operated by the user. In the case of coupling between shafts, even without adjustment of the stiffness of the coupling by means of the variation of the preload of the springs through the rotation of the casings, the non-linearity of the springs can achieve a reduction in the stiffness of the coupling at the cost of an increase in its torsional deflection, protecting the elements it connects.
    [0232] The present invention is not limited, in any way, to the embodiments disclosed herein. Other possible embodiments of this invention will be apparent to the person skilled in the art in light of the present disclosure. Consequently, the scope of protection of the present invention is defined exclusively by the claims that follow.
    权利要求:
    Claims (17)
    [1]
    1. Elastic device (10) with variable stiffness, comprising:
    - A first torsion spring (20a), with a spiral shape, defining a plurality of turns, said first spring (20a) being joined at one of its ends to a casing (22) and being joined by its opposite end to a shaft of rotation (21), said shaft (21) being configured in such a way that it can rotate and vary its position relative to the casing (22) to subject said first spring (20a) to a preload;
    - A second torsion spring (20b), with a spiral shape, defining a plurality of turns, said second spring (20b) being joined at one of its ends to a casing (22) and being joined at its opposite end to a shaft of rotation (21), said shaft (21) being configured in such a way that it can rotate and vary its position relative to the casing (22) to subject said second spring (20b) to a preload;
    characterized by what
    - the first spring (20a) is configured such that its torsional stiffness can be varied by modifying the relative position between the rotation shaft (21) and the housing (22) to which said first spring (20a) is attached;
    - the second spring (20b) is configured in such a way that its torsional stiffness can be varied by modifying the relative position between the rotation shaft (21) and the casing (22) to which said second spring (20b) is attached;
    - the first spring (20a) and the second torsion spring (20b) are attached to the same common shaft (21) or, alternatively, they are attached to the same common casing (22), said springs (20a, 20b) so that the turns of the first spring (20a) run in the opposite direction to the turns of the second spring (20b); Y
    - Locking means (24a, 24b) are provided, configured to retain the shaft or shafts (21) and the casing or casings (22) in their relative positions, once the first spring (20a) and the second spring (20b ) torsion have been subjected to a preload.
    [2]
    Elastic device (10) according to any one of the preceding claims, in which the first spring (20a) has a stiffness that varies along its length.
    [3]
    Elastic device (10) according to any one of the preceding claims, in which the second spring (20b) has a stiffness that varies along its length.
    [4]
    Elastic device (10) according to any of claims 2 or 3, wherein the width; The spesor; the cross section, chemical composition, or any combination of these quantities varies along the length of the first spring (20a), the second spring (20b), or both springs (20a, 20b).
    [5]
    Elastic device (10) according to any of the preceding claims, in which the first spring (20a) and the second spring (20b) are attached to the same common shaft (21) being, in addition, the first spring (20a) attached to a first housing (22) and the second spring (20b) being attached to a different second housing (22).
    [6]
    Elastic device (1) according to any of the preceding claims, in which the housings have keyways that allow, under the appropriate circumstances, to obtain zero rigidity.
    [7]
    Elastic device (1) according to any of the preceding claims, in which there are means for temporarily decoupling the springs from their housings and / or from their rotation shafts, thus making it possible to obtain zero stiffness.
    [8]
    8. Elastic device (10) with variable stiffness, according to any of claims 1 to 6, characterized in that it is made by means of an additive manufacturing process.
    [9]
    9. Elastic device (10) with variable stiffness, according to claim 6, characterized in that the additive manufacturing process is three-dimensional printing.
    [10]
    10. Variable stiffness actuator (100), characterized in that it comprises at least one elastic device (10) with variable stiffness, according to any of claims 1 to 7 and two actuating means (72, 73, 75, 76), being the actuating means (72, 73, 75, 76) configured to fix at will the positions of the shaft or shafts (21) and the casing or casings (22).
    [11]
    A variable stiffness actuator (100) according to claim 8, wherein the actuation means comprises electric motors (73, 76), linear actuators, pneumatic actuators, or hydraulic actuators.
    [12]
    Variable stiffness actuator (100) according to any one of claims 8 and 9, in which the actuating means are provided with transmission means (72, 75).
    [13]
    Variable stiffness actuator (100) according to any one of claims 8 to 10, wherein the shaft (21) of at least one elastic device (10) is connected to an element of a kinematic chain by means of a coupling (79) .
    [14]
    Variable stiffness actuator (100) according to claim 11, in which the coupling (79) is a non-permanent coupling and can be actuated at will.
    [15]
    15. Coupling (200) with variable stiffness, characterized in that it comprises at least one elastic device (10) with variable stiffness, according to any of claims 1 to 7; a single actuating means (72, 73, 75, 76), said actuating means being configured (72, 73, 75, 76) to fix at will the relative positions of the shaft or shafts (21) and the casing or casings ( 22); and a blocking means (80) to avoid turns opposite to those in the desired direction.
    [16]
    Use of at least one variable stiffness actuator (100) according to any one of claims 9 to 14, in a suspension of a vehicle or a machine, a torsion bar, an exoskeleton, a robot, a torque wrench, a machine bodybuilding machine or a rehab machine.
    [17]
    Use of at least one variable stiffness coupling (200) according to any one of claims 9 to 14, in a suspension of a vehicle or a machine, a torsion bar, an exoskeleton, a robot, a torque wrench, a machine bodybuilding machine or a rehab machine.
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    同族专利:
    公开号 | 公开日
    ES2785676B2|2021-02-19|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    GB1189800A|1969-02-24|1970-04-29|John Robert Ramsey|Drum Beater Device.|
    US20130075966A1|2011-09-23|2013-03-28|Adicep Technologies, Inc.|Non-linear torsion spring assembly|
    DE102012112084A1|2012-12-11|2014-06-12|Dorma Gmbh & Co. Kg|Door fastener for operating door leaf of door, has spring unit that is formed from several spiral springs which are extended in respective planes around door shaft|
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    ES202030135A|ES2785676B2|2020-02-18|2020-02-18|ELASTIC DEVICE WITH VARIABLE RIGIDITY, ACTUATOR WITH VARIABLE RIGIDITY AND COUPLING WITH VARIABLE RIGIDITY|ES202030135A| ES2785676B2|2020-02-18|2020-02-18|ELASTIC DEVICE WITH VARIABLE RIGIDITY, ACTUATOR WITH VARIABLE RIGIDITY AND COUPLING WITH VARIABLE RIGIDITY|
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