Apparatus for producing reciprocating rotational motion

Abstract

An apparatus for generating rotary reciprocating motion has an input shaft driven in one direction of rotation and an output shaft for providing reciprocating rotary motion. A first magnetic or ferromagnetic ring is disposed about an axis of rotation fixed to the input shaft, and a second magnetic or ferromagnetic ring is disposed about an axis of rotation fixed to the output shaft. At least one of the rings is formed as an array of permanent magnets. The first and second rings are disposed inside each other about the axis of rotation. Magnetic coupling between the rings, combined with the effect of an output load, produces the desired reciprocating motion of the output shaft.

Description

[Technical field]

[0001] The present invention relates to an apparatus for generating reciprocating rotational motion, for use in producing vibratory motion, such as for use in chest compression systems or body manipulation (eg massage) systems. [Background technology]

[0002] There are many cases in which we are interested in reciprocating rotary motion, which means rotation back and forth, usually with less than one revolution in each direction.

[0003] Examples where such movement is of interest include toothbrush actuators, interdental flossing devices, skin care appliances and massage appliances, such as cardiac massage devices. Summary of the Invention [Problem to be solved by the invention]

[0004] What is needed is a system capable of producing reciprocating rotational motion that can be implemented at low cost and / or in a compact size. [Means for solving the problem]

[0005] The invention is defined by the claims.

[0006] According to an example according to one aspect of the present invention, there is provided an apparatus for generating a rotary reciprocating motion, the apparatus comprising: an input shaft having a rotating axis; a drive motor for providing unidirectional rotation of said input shaft about said axis of rotation; an output shaft for providing reciprocating rotational motion about said axis of rotation, said output shaft for coupling to a load that limits rotation of said output shaft, thereby preventing unidirectional rotation of said output shaft; a first magnetic or ferromagnetic ring disposed about the axis of rotation and rotationally fixed to the input shaft; and a second magnetic or ferromagnetic ring disposed about the axis of rotation and rotationally fixed to the output shaft; the first and second rings being disposed one inside the other about the axis of rotation, and at least one of the first and second rings having an annular sequence of permanent magnet elements. An apparatus is provided.

[0007] The device converts the continuous rotational motion of the input shaft into reciprocating rotational motion of the output shaft. The alignment between the two magnets or ferromagnetic rings changes as the input and output shafts assume different relative angular positions. In this way, the resisting force depends on the relative angular orientation. This can be used to make the output shaft induced to oscillate with the rotation of the input shaft. This provides a compact design consisting essentially of two concentric magnets or ferromagnetic rings. This design can be easily scaled to the forces and torques required.

[0008] The load driven by the output shaft forms part of a oscillating mechanical circuit, preventing the two rings from simply rotating in unison.

[0009] The or each annular sequence of permanent magnet elements comprises, for example, a annular sequence of alternating magnetic poles, i.e. a sequence of N and S poles, however, other configurations with different magnetic field distributions, but not necessarily opposite magnetic poles, are also possible.

[0010] The first and second rings may each have an annular sequence of permanent magnet elements, or one of the first and second rings may have an annular sequence of permanent magnet elements and the other of the first and second rings may have a sequence of ferromagnetic poles. With permanent magnet elements in only one ring, a magnetic field is induced in the opposing ring, which has a ferromagnetic ring with a series of magnetic poles (e.g. formed as protruding teeth).

[0011] In one example, there are two magnet rings, each with four pole pairs, hence eight magnets. There is then a 45 degree offset between the maximum (attractive) and minimum (repulsive) magnetic coupling between these two magnet rings.

[0012] The relative axial alignment between the first and second rings along the axis of rotation is adjustable to a desired relative alignment to set the output torque level.

[0013] In this way a single design of the device can be set for different torque levels. The alignment of the axes sets the overlap area between the first and second rings, and therefore the attractive and repulsive forces between the magnetic rings, or between the magnetic and ferromagnetic rings.

[0014] The relative axial alignment between the first and second rings along the axis of rotation may alternatively be set to a relative alignment along the axis of rotation to set the output force level. The relative alignment between the two rings also changes the axial force at the output shaft. Thus, both reciprocating rotational motion and cyclic axial forces can be generated.

[0015] The device may further include a third magnetic or ferromagnetic ring, where the second and third magnet rings are both disposed within or around the first magnet ring, and where the first and second magnet rings define a coupling that is in phase opposite to the coupling defined by the first and third magnet rings.

[0016] In this way, the torque required to drive the input shaft to separate the magnets of the first and second rings is countered by the attractive force between the first and third rings, and therefore the torque required to drive the input shaft becomes more uniform over time and is also reduced by having the two magnetic couplings cancel each other out.

[0017] A second output shaft can be provided, wherein the third ring is disposed about the axis of rotation and rotationally fixed to the second output shaft. The first and second output shafts are for coupling to a load that limits rotation of the first and second output shafts, thereby preventing unidirectional rotation of the first and second output shafts.

[0018] The load driven by the output shaft thus again forms part of an oscillating mechanical circuit and acts on both of the pair of rings. The first and second output shafts may, for example, be coupled by a further load.

[0019] The present invention relates to An apparatus as defined above, and a chest compression belt connected at both ends to the output shaft for positioning around the subject's chest; A chest compression device having a

[0020] The apparatus provides a compact configuration for the chest compression device, e.g., since the chest compression device is placed directly on the chest, there is no need for a separate base station. The device can be lightweight, compact, and energy efficient. The device can be, e.g., battery operated.

[0021] The device allows for operation at a wider range of frequencies, for example higher frequencies.The device is also programmable to generate a particular desired pressure pulse profile based on the drive arrangement of the motor.

[0022] The apparatus may further comprise a further output shaft for providing a second reciprocating rotational motion about the axis of rotation, the chest compression device then further comprising a second belt connected at both ends to the further output shaft, this allowing the second belt to be driven by incorporating a further output shaft (but the same output shaft).

[0023] The friction reducing device is, for example, between the belt and the subject.

[0024] The present invention also provides a body manipulation device, the body manipulation device comprising: A set of devices as defined above, and a set of force applicators for applying a force to the subject, each driven by an associated one of the devices; with each force applicator having a pair of spring loads connected to radially opposed locations on the output shaft.

[0025] Each output shaft drives two spring loads which induce a reciprocating motion and then an angular position which causes the spring loads to project towards the subject, for example to apply a massage force.

[0026] A belt is provided around the set of devices and the force applicator.

[0027] The present invention also provides a method of generating a rotary reciprocating motion, the method comprising: driving an input shaft in unidirectional rotation about an axis of rotation, thereby rotating a first magnet or ferromagnetic ring disposed about said axis of rotation; inducing rotation of a second magnet or ferromagnetic ring disposed about the axis of rotation by magnetic coupling with the first magnet ring, at least one of the first and second rings having an annular sequence of permanent magnet elements; and providing a reciprocating rotational motion of an output shaft about the axis of rotation coupled to the rotation of the second magnet ring; has.

[0028] The output shaft is preferably coupled to a load that limits rotation of the output shaft, thereby preventing unidirectional rotation of the output shaft.

[0029] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter. [Brief description of the drawings]

[0030] For a better understanding of the present invention, and to show more clearly how the same may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which: [Figure 1] FIG. 1 shows an apparatus for generating a rotary reciprocating motion. [Diagram 2] FIG. 2 shows the set of relative rotational positions of the two magnet rings caused by one revolution of the input shaft. [Diagram 3] FIG. 3 shows that a simple DC motor is used to drive the device. [Figure 4] FIG. 4 shows the output shaft connected to an output load. [Diagram 5] FIG. 5 shows how the output torque is regulated. [Figure 6] FIG. 6 shows how both the reciprocating rotational motion and the periodic axial force are generated. [Figure 7] FIG. 7 shows a variant using a third magnet ring. [Figure 8] FIG. 8 shows how the arrangement of FIG. 7 is coupled to an output load. [Figure 9] FIG. 9 illustrates different periods during the operation of the device of FIG. [Figure 10A] FIG. 10A shows a concentric ring design using one magnetic ring and one ferromagnetic ring. [Figure 10B] FIG. 10B shows a concentric ring design using one magnetic ring and one ferromagnetic ring. [Figure 11] FIG. 11 shows a chest compression device having the apparatus of FIG. [Figure 12] FIG. 12 shows an example with an additional output shaft for providing a second reciprocating rotational motion about the axis of rotation for a second chest compression belt. [Figure 13] FIG. 13 shows an interface for attachment between the belt and the body. [Figure 14] FIG. 14 shows a different design of the actuator. [Figure 15] FIG. 15 shows an example of a body manipulation device comprising a set of four of the actuators of FIG. 14 surrounded by a belt. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] The present invention will now be described with reference to the drawings.

[0032] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the devices, systems and methods, are for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects and advantages of the devices, systems and methods of the present invention will become better understood from the following description, appended claims and accompanying drawings. It should be understood that the drawings are merely schematic and are not drawn to scale. It should be understood that the same reference numerals are used throughout the drawings to indicate the same or similar parts.

[0033] The present invention provides an apparatus for generating rotary reciprocating motion, the apparatus having an input shaft driven in unidirectional rotation and an output shaft providing reciprocating rotary motion. A first magnetic or ferromagnetic ring is disposed about an axis of rotation fixed to the input shaft and a second magnetic or ferromagnetic ring is disposed about the axis of rotation fixed to the output shaft. The first and second rings are disposed one inside the other about the axis of rotation, at least one of which is formed as an array of permanent magnets. Magnetic coupling between the rings, in combination with the effect of an output load, results in the desired reciprocating motion of the output shaft.

[0034] The present invention relates generally to an apparatus for generating a reciprocating rotational motion, however one aspect of the invention relates specifically to the use of such an apparatus in a high frequency chest compression device for treating patients suffering from cystic fibrosis, COPD, bronchitis or bronchiectasis and therefore experiencing respiratory distress.

[0035] In chronic bronchitis, the bronchi are constantly inflamed. This leads to excess mucus production, making breathing difficult. In cystic fibrosis, the mucus is harder and cannot carry waste products and enzymes. This leads to the accumulation of this hard mucus, which causes serious problems for the patient.

[0036] Moving mucus out of the airways is essential to the health of these types of patients.

[0037] The traditional treatment for this problem is percussion massage, which involves gently tapping the patient with cupped hands. In recent years, high frequency chest compression (HFCC) devices have been developed. Compared to manual therapy, HFCC vests achieve much better results and significantly change the life expectancy of cystic fibrosis patients.

[0038] When a patient wears the vest, air inflates the vest, which creates a pocket of air around the chest, some of which is then released, creating a pulsating motion, for example around 5-15 Hz.

[0039] The air pulsating within the vest compresses the lungs, forcing air in and out of the lungs. This air movement causes the cilia to move the mucus out. In addition to this air movement, the vibration of the lung tissue by the HFCC vest benefits the patient. This vibration loosens the bonds in the mucus so that it can flow more easily.

[0040] The study concluded that airflow appears to be more dominant than vibrating tissue.

[0041] Since actuation of the vest is achieved via airflow, the device is typically quite large. A pump is in a separate base station, for example to deliver air, which is connected to the vest via a large hose. This base station is connected to a power source. As a result, the device is stored in a large suitcase on wheels for transport, and is therefore not a truly portable solution. The operating frequency of this device is also limited by the characteristics of the airflow, and the shape of the pressure pulse is not easily accommodated.

[0042] This aspect of the invention is therefore based on the concept that reciprocating rotary motion can be used to tighten and loosen belts for use in HFCC systems.

[0043] Returning to the more general concept of an apparatus for generating a reciprocating motion, Figure 1 shows an apparatus 10 for generating a rotary reciprocating motion. The arrangement is shown in end view on the left and in cross section on the right.

[0044] The device has an input shaft 12 having an axis of rotation 14. A drive motor, not shown in Figure 1, is used to provide unidirectional rotation of the input shaft 12 about the axis of rotation.

[0045] An output shaft 16 is provided for providing reciprocating rotational motion about the axis of rotation 14 .

[0046] The input shaft and the output shaft are coupled by a magnetic mechanism formed of two concentric magnetic or ferromagnetic rings, where at least one ring is magnetic (i.e. formed as a magnet ring of permanent magnets). If only one ring is formed as a magnet ring then the other is a ferromagnetic ring and formed as a series of ferromagnetic poles.

[0047] An embodiment is first presented based on the use of two concentric rings of permanent magnets.

[0048] A first magnet ring 18 is disposed about the axis of rotation and is rotationally fixed to the input shaft 12. This first magnet ring has a first annular sequence of alternating magnetic poles, e.g., dark areas are north poles and light areas are south poles. A second magnet ring 20 is disposed about the axis of rotation but is rotationally fixed to the output shaft 16. This second magnet ring has a second annular sequence of alternating magnetic poles, shown with the same designation.

[0049] In the example shown, the first magnet ring is concentrically mounted on the outer periphery of the input shaft, and the second magnet ring is concentrically mounted on the inner surface of an annular housing 22 that is connected to the output shaft 16.

[0050] Thus, the first magnet ring 18 and the second magnet ring 20 are arranged one inside the other around the axis of rotation and, in the example shown, are perfectly aligned along the axis of rotation and therefore perfectly overlapping.

[0051] Since the magnet rings can have the same number of magnets, the magnet rings can be perfectly rotationally aligned with all the north poles of one magnet ring radially aligned with the south poles of the other magnet ring. This is a stable arrangement, and the stable arrangement is maintained in the absence of an external force to impart relative rotation (as described below). This stable state is shown in Figure 1.

[0052] The example of Figure 1 has four pole pairs in each magnet ring. Of course, there may be a different number of magnets in the two magnet rings. Furthermore, there may be a different number of magnets in one magnet ring compared to the other. The relationship between the poles in one magnet ring and the poles in the other magnet ring affects the resulting torque curve delivered to the output shaft 16.

[0053] If, instead, the same magnetic poles are aligned, an unstable state is reached whereby the magnetic forces tend to impart a relative rotation that tends to return to a stable state.

[0054] The device converts continuous rotational motion of an input shaft into reciprocating rotational motion of an output shaft based on slippage between two magnet rings. In particular, the output shaft is subjected to an external load. As a result, the alignment between two magnet rings changes as the input shaft rotates. A resistive force changes depending on the relative angular position. This varying resistive force causes the output shaft to undergo oscillations induced by the rotation of the input shaft. Because a motor drives the input shaft continuously, the motor can be relatively small and lightweight.

[0055] The output shaft is coupled to a load which limits rotation of the output shaft, thus preventing rotation of the output shaft in one direction. The load forms part of an oscillatory mechanical circuit which prevents the two magnet rings from simply rotating in unison.

[0056] Figure 2 shows the relative rotational positions of the two magnet rings in series, resulting from rotation of the input shaft alone. Figure 2 also shows the resulting torque curve, torque versus rotor angular position.

[0057] The first image, at the top left, shows the steady state described above: no torque is produced.

[0058] The first (inner, input side) magnet ring then rotates 45 degrees counterclockwise to provide the second orientation shown. A force is applied to the second magnet ring that causes the first magnet ring to rotate counterclockwise to return to the stable state. This is shown as a negative torque. The force reaches a maximum when the overlap is 50%.

[0059] Further rotation of the input shaft reduces the magnitude of the torque back to zero. In the third orientation, an unstable condition is reached. The torque is again zero because the force is axial rather than radial.

[0060] Further rotation of the input shaft will result in a fourth orientation, indicated by a positive torque. The second magnet ring will attempt to rotate clockwise to its nearest stable state. Thus, there are four periods in the torque curve.

[0061] Thus, the points where the torque is zero define stable points when the gradient is negative and unstable points when the gradient is positive. Between these points, positive or negative torques can be produced.

[0062] Figure 3 shows a simple DC motor 30 connected to the input shaft, and hence to a first magnet ring. The second magnet ring, and hence to the output shaft, is connected to a load 32 which prevents the output shaft from rotating fully. In this way, a pulsating torque is supplied to the load 32.

[0063] 4 shows the output shaft (specifically the annular housing 22) connected to an output load 40 in the form of a spring which connects to mechanical ground 42. Four successive positions of the output shaft produced by rotation of the input shaft are shown.

[0064] The top image shows the starting state, in which the torque is zero and the spring 40 is undeformed.

[0065] The motor then rotates the input shaft, and therefore the first magnet ring, and the second magnet ring, and therefore the output shaft, tries to follow as best it can, but is prevented by the spring, as can be seen in the second image.

[0066] At some point, the coupling between the magnet rings reaches an unstable state, as shown in the third image. At this point, the device cannot provide any torque, but the spring provides a return force. This means that a high negative torque is generated and the output shaft and the second magnet ring are thrown backwards (clockwise).

[0067] In the fourth image, the output shaft and the second magnet ring are in a flyback position: the output shaft angle is negative and the spring exerts an opposing restoring force (i.e. pushing the output shaft counterclockwise).

[0068] The outer magnet ring is caught up by the inner magnet ring (with a new north to south pole alignment) and the cycle repeats.

[0069] In this example, the outer magnet ring only reaches the first instability point. However, a flyback mechanism could be arranged to force the second magnet ring past two or more instability points. This depends on the nature of the restoring force generated by the load, i.e. the spring in this example.

[0070] It is noted that the spring may itself be the load that drives the reciprocating motion, however, said spring may simply serve to create the reciprocating motion and the load driven by the output shaft may be separate, for example a light load that does not create enough resistance to induce said reciprocating motion, this applies to all examples.

[0071] The rotational frequency of the reciprocating output can be easily varied by the rotational speed of the drive motor 30. However, in the drive train of Figure 3, the amplitude of the torque pulses is fixed.

[0072] However, the torque can be varied by varying the axial position of the second magnet ring relative to the first magnet ring, as shown in FIG.

[0073] The top image shows the two magnet rings completely overlapping, thus generating maximum magnetic torque, when the rotational orientation is away from the stable point.

[0074] The second image shows an adjustment of the relative axial position (along the axis of rotation) which reduces the overlap area between the magnetic rings, thereby giving a reduced magnetic torque. The bottom image shows a further reduced overlap area.

[0075] In this way the torque can be adapted to the load: a single design of the device can be set to different torque levels.

[0076] The relative axial alignment between the first and second magnet rings along the axis of rotation may alternatively be set to a relative alignment along the axis of rotation to set the output force level. The relative alignment between the two magnet rings also varies the axial force at the output shaft. Thus, both reciprocating rotational motion and cyclic axial forces can be generated.

[0077] This concept is illustrated in Figure 6. Axial misalignment means that there is a force depending on the relative angular position, indicated by arrow 60, that either pulls in or pushes out the first magnet ring. In a stable state, the first magnet ring is pulled in, whereas in an unstable state, the first magnet ring is pushed out.

[0078] This results in a dual motion actuator that delivers both vibration torque and force. This dual motion is of interest in a variety of applications, for example abrasive tools that provide rotational torque as well as axial force. One example is dental flossing.

[0079] The above example utilizes a single first magnet ring (acting as the input rotor) and a single second magnet ring (acting as the output rotor).

[0080] As shown in Figure 7, the apparatus further comprises a third magnet ring 70. The second magnet ring 20 and the third magnet ring 70 are both positioned around the first magnet ring 18. The third magnet ring again comprises an annular sequence of alternating magnetic poles.

[0081] There are then two annular housings 22a, 22b (which act as two output shafts).

[0082] The magnetic coupling formed by the first magnet ring 18 and the second magnet ring 20 is in antiphase with the magnetic coupling defined by the first magnet ring 18 and the third magnet ring 70. To maintain this relationship, a coupling is provided between the two annular housings, such that when one is in a stable state (as shown for the second magnet ring 20), the other is in an unstable state (as shown for the third magnet ring 70). Furthermore, the directions of rotation of the two annular housings, and therefore the two output shafts, are opposite. Thus, the two output shafts can be arranged to provide equal and opposite rotating torques.

[0083] The advantage of this is that the torque required to drive the input shaft to separate the magnets of the first and second magnet rings is offset by the attractive force between the first and third magnet rings, and therefore the torque required to drive the input shaft becomes more uniform over time and is also reduced by the two magnetic couplings cancelling each other out.

[0084] FIG. 8 shows how the arrangement of FIG. 7 is coupled to an output load, and also provides the required coupling between the annular housings to maintain the desired phase relationship.

[0085] The output load provides a first connection 80 between the first output shaft and mechanical ground, a second connection 82 between the second output shaft and mechanical ground, and a third connection 84 between the first output shaft and the second output shaft. In Figure 8, these connections are shown as springs.

[0086] Thus, both the first output shaft and the second output shaft are intended to be coupled to a load that limits rotation of the first output shaft and the second output shaft, thereby preventing unidirectional rotation of the first output shaft and the second output shaft.

[0087] FIG. 9 illustrates different periods during the operation of the device of FIG.

[0088] FIG. 9 shows the two output shafts 22a, 22b rotating in opposite directions, first stretching the third link 84 apart as shown in the top two images, and then rotating together, thus drawing the first and second links 80, 82 together as shown in the bottom image.

[0089] The output shafts exert a torque on the spring system tending to their preferred magnetic positions, and the symmetry of the spring system maintains the desired phase relationship between the rotation of the two annular housings.

[0090] All of the above examples utilize concentric magnet rings. As noted above, ferromagnetic rings could be used so that each concentric magnet ring pair (in any of the above examples) could have one ring of permanent magnets and one ring of ferromagnetic poles.

[0091] Figures 10A and 10B show two examples, in each case the inner ring is formed as a sequence of magnets with alternating poles and the outer ring is formed as a ferromagnetic ring with protruding teeth that define the ferromagnetic poles.

[0092] FIG. 10A shows narrow teeth and FIG. 10B shows wide teeth. The tooth design and air gap size affect the resulting torque curve. For pairs of magnet rings, the magnetic field induced in the ferromagnetic rings results in preferred initial positions, and as the inner ring rotates, a bias is created toward these initial positions. The design of these rings may be used to select the number of initial positions and the amplitude of the rotary oscillation. These design options will be apparent to those skilled in the art of motor design.

[0093] Of course, the magnetic ring may be the outer ring and the ferromagnetic ring may be the inner ring.

[0094] All the above examples show that the angular spacing of the magnetic poles in the two rings is the same (or a multiple) so that there is a position where all magnets in the magnet ring are simultaneously in a zero torque position. However, this is not required and there may be a different number of poles in the two rings (with no common denominators). The design may also be adapted to produce a torque pattern as a function of angular position rather than a regular sinusoidal torque pattern as shown in Figure 2.

[0095] As mentioned above, one application of the present invention is to provide a chest compression device.

[0096] Figure 11 shows a chest compression device 100 comprising the apparatus 10 of figure 3, where the load is in the form of a chest compression belt 102 for attaching the apparatus as defined above around the chest of a patient. The belt 102 is connected at both ends to an output shaft, in particular to the annular housing 22. This belt is used to generate pressure pulses in the body. A drive system creates a pulsating tension in said belt.

[0097] Both ends of the belt can be wound on a single rotor as shown in figure 10. However, it is also possible to use a double rotor magnetic coupling, where each of the two output shafts (in particular the annular housings) receives one end of the belt.

[0098] The device for generating a reciprocating motion first winds up the belt until it tightens around the chest. At this stage, since there is no counterforce from the chest, the outer magnet follows the motor together with the inner magnet. At the next stage, the belt is tightened around the chest, which makes the outer magnet slip and thus creates a pulsating tension in the belt. This not only vibrates the lung tissue, but also obtains a pulsating airflow in the airways. This vibration is necessary to loosen the mucus bonds and the airflow is necessary to carry it towards the mouth.

[0099] It allows for a compact configuration for the chest compression device, and since the device can be placed directly on the chest, it avoids the need for a separate base station. The device is lightweight, small and energy efficient. The device can be, for example, battery operated.

[0100] 12 shows an example with a further output shaft 120 for providing a second reciprocating rotational motion about an axis of rotation, where the chest compression device further comprises a second belt 112 connected at either end to the further output shaft 120. This incorporates a further output shaft but allows the second belt to be driven by sharing the same input shaft.

[0101] A better compensation for the chest shape is obtained when two belts are used: the belts are automatically wrapped around the chest and then operate at different diameters.

[0102] When there are two belts, the tightening force of each belt can be adjusted, which can be of great benefit to women, for example when setting the upper belt that covers the woman's chest to a looser tightening.

[0103] Where friction between the body and the belt is an issue, the belt may provide a "belt-body" interface.

[0104] Figure 13 shows an example of a possible belt-body interface in the form of soft pads 130 that touch the body. These are used to eliminate peaks in the force pulse. A ring 132 is provided over which the belt can easily slide.

[0105] These interfaces can be placed in specific locations selected by the user, or wherever they are expected to have the most effect. The interfaces guide the belt using plain bearings as shown in the figure. Other bearing designs (e.g. ball bearings, roller bearings, etc.) can also be applied. The reason for reducing friction is to prevent the skin from getting pinched, and another advantage is that all interfaces work with equal effectiveness.

[0106] The properties of the interface 130 can be tailored in various ways, using different geometries and materials (for damping, stiffness or other properties), In particular, a shear viscous material can be used, which adapts itself for optimal mechanical coupling to the body, but ensures a stiff interface for optimal transmission of high frequency force pulses.

[0107] The examples described above use the tightening or loosening of a belt to induce pulsating vibrations.

[0108] Instead, an alternative design utilizes localized actuators around the belt. This configuration can be thought of as a body manipulation device.

[0109] 14 shows one such actuator 140. The actuator includes the apparatus 10 as described above, where the load includes a pair of spring loads 142 connected to diametrically opposed locations on the output shaft, and in particular the annular housing 22.

[0110] The spring load 142 acts as a force applicator to apply a force to the subject. This set of actuators can be formed around a belt or within a vest.

[0111] The spring is, for example, a leaf spring that is wound (and thereby reduces its outer diameter) by the rotation of the motor. When the second magnet ring slips, the spring is released (and thereby increases its outer diameter) and the spring generates a force towards the body.

[0112] FIG. 15 shows an example of a body manipulation device 150 with a set of four actuators 140 surrounded by a tightening belt 152 to ensure that the set of four actuators 140 directs force towards the chest and does not bounce up and down on the chest.

[0113] Every actuator in this case has its own motor. If there are two belts, actuators for different belts in the same location can share a motor.

[0114] This configuration allows for local selection of force strength for each actuator, where the first embodiment distributes the actuator force evenly across the body or interface.

[0115] The various examples above share a common method of operation that includes driving an input shaft in unidirectional rotation about an axis of rotation, thereby rotating a first magnet ring having a first annular sequence of alternating magnetic poles arranged about said axis of rotation. Rotation of a second magnet ring having a second annular sequence of alternating magnetic poles arranged about said axis of rotation is induced by magnetic coupling with the first magnet ring. Reciprocating rotational motion is then output about said axis of rotation by an output shaft coupled to the rotation of the second magnet ring.

[0116] The apparatus can be used in many devices, not just the chest compression device shown: examples are toothbrush actuators, dental floss devices, e.g. pumps for generating jets of liquid or air, skin care appliances, kitchen appliances, massage appliances, e.g. cardiac massage devices.

[0117] The output shaft provides reciprocating rotary motion about an axis of rotation. The angular range of this motion can range from a very small (e.g., less than 1 degree) arc to a significant (e.g., 90 degrees or more) arc. When very small amplitude vibrations are generated, the torque transmitted is relatively large, whereas when large amplitude vibrations are generated, the torque transmitted is relatively small. Thus, the "rotary motion" generated can have a very small amplitude and the design can be optimized for motion or torque delivery.

[0118] In describing the chest compression device, reference is made to a belt, which can have any cross-sectional shape and hence can be a loop of any shape, either circular (like a rope or cord) or wide and flat.

[0119] The above examples utilize magnet rings formed as an alternating sequence of north and south poles. However, each annular sequence of magnets can generate more complex magnetic field patterns, where the magnetic field direction and strength for each magnet is designed to achieve desired characteristics of the resulting reciprocating motion. By tailoring the magnetic field and air gap characteristics, the torque function may be modified to provide desired operating characteristics in response to a known load.

[0120] The above-described systems utilize a drive motor to provide unidirectional rotation of an input shaft about an axis of rotation, meaning that during use of the device, the rotation is in only one direction, and the rotation does not necessarily have to be at a constant speed, or even continuous in nature, in examples the rotation is pulsed.

[0121] Variations to the disclosed embodiments can be understood and implemented by those skilled in the art in implementing the principles and techniques described herein, from a study of the drawings, the disclosure, and the appended claims. In the claims, the term "comprising" does not exclude other elements or steps, nor does a recitation of a plurality of elements exclude a plurality of the elements. A single processor or other unit may perform the functions of several items recited in the claims. The mere fact that certain methods are recited in mutually different dependent claims does not indicate that a combination of these methods cannot be advantageously used. Where a computer program is described above, the computer program may be stored / distributed on a suitable medium, such as an optical storage medium or a solid-state medium, provided together with or as part of other hardware, but may also be provided in other forms, such as the Internet or other wired or wireless telecommunication systems. When the term "adapted for" is used in the claims or the specification, the term "adapted for" is meant to be equivalent to the term "configured for". Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. an input shaft having a rotating axis; a drive motor for providing unidirectional rotation of said input shaft about said axis of rotation; an output shaft for providing reciprocating rotational motion about said axis of rotation, said output shaft for coupling to a load that limits rotation of said output shaft, thereby preventing unidirectional rotation of said output shaft; a first magnetic or ferromagnetic ring disposed about the axis of rotation and rotationally fixed to the input shaft; and a second magnetic or ferromagnetic ring disposed about the axis of rotation and rotationally fixed to the output shaft; the first and second rings being disposed inside one another about the axis of rotation, at least one of the first and second rings comprising an annular sequence of permanent magnet elements; a relative axial alignment between the first ring and the second ring along the axis of rotation is adjustable to a desired relative alignment to set an output torque level; A device for producing rotary reciprocating motion.

2. The apparatus described in claim 1, wherein one or both of the first and second rings have a circular sequence of alternating magnetic poles.

3. the first and second rings each comprise an annular sequence of permanent magnet elements; or 3. Apparatus according to claim 1 or 2, wherein one of the first and second rings comprises an annular sequence of permanent magnet elements and the other of the first and second rings comprises a sequence of ferromagnetic poles.

4. a third magnetic or ferromagnetic ring; the second and third rings are both arranged side by side within or around the first ring along the axial direction of the rotation shaft, the first and second rings define a coupling that is in anti-phase with a coupling defined by the first and third rings; 4. Apparatus according to any one of claims 1 to 3.

5. a second output shaft; the third ring is disposed about the rotation axis and is rotationally fixed to the second output shaft; and the first and second output shafts are for coupling to a load that limits rotation of the first and second output shafts and prevents unidirectional rotation of the first and second output shafts.

5. The apparatus of claim 4.

6. The apparatus of claim 5 , wherein the first and second output shafts are coupled by an additional load.

7. A device according to any one of claims 1 to 6, and a chest compression belt connected at both ends to the output shaft for positioning around the subject's chest; A chest compression device comprising:

8. the apparatus further comprising a further output shaft for providing a second reciprocating rotational motion about the axis of rotation; The chest compression device further includes a second belt connected at both ends to the further output shaft. The chest compression device of claim 7.

9. a friction reducing device between the chest compression belt and the subject.

9. A chest compression device according to claim 7 or 8.

10. A set of devices according to any one of claims 1 to 6, and A set of force applicators for applying force to a subject each force applicator is driven by an associated one of said devices, each force applicator having a pair of spring loads connected to diametrically opposed positions on said output shaft. Body manipulation device.

11. The body manipulation device of claim 10 , further comprising a belt around the set of apparatus and the force applicator.

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