Motion conversion device

Abstract

An apparatus for converting between motion in one direction and motion in another direction is disclosed, the apparatus comprising: a magnetic protrusion or patch attached to a first movable element and having a surface; and a track attached to a further movable element and having a predetermined magnetic property, the track defining a path along which the magnetic protrusion or patch is attracted by a magnetic force, the magnetic force being: The movable element is constrained from movement and the magnetic protrusions or patches are adapted to move in a direction along the magnetic track in response to relative movement between the first element and the further element.

Description

Technical Field

[0001] The field of the present invention relates to an apparatus for converting motion in one direction into motion in another direction.

Background Art

[0002] Mechanisms for converting motion in one direction into motion in another direction, such as a Scotch Yoke for converting rotational motion into linear motion, are known. These mechanisms include a pin extending from a wheel within a linear slot extending perpendicular to a rod. Rotation of the wheel moves the pin up and down within the slot and pushes the slot left and right, resulting in a reciprocating linear motion of the rod. A drawback of such mechanisms is due to friction and wear between relatively moving parts such as the pin and slot of the Scotch Yoke.

Summary of the Invention

Means for Solving the Problems

[0003] One aspect provides an apparatus for converting between motion in one direction and motion in another direction, the apparatus comprising a magnetic protrusion or patch attached to a first movable element and having a surface, and a track attached to a further movable element and having predetermined magnetic properties, the track defining a path along which the magnetic protrusion or patch is attracted by a magnetic force, the magnetic force constraining movement of the movable element, and the magnetic protrusion or patch being adapted to move in a direction along the magnetic track in response to relative movement between the first element and the further element, the surface of the magnetic protrusion or patch having a width dimension that aligns with the width of the track and differs from it by less than 30%, and a length dimension that is substantially shorter than the length dimension of the track and is less than 30% of the length dimension of the track, the length dimension being perpendicular to the width dimension.

[0004] Devices that convert between motion in different directions, particularly between linear and rotational motion, are crucial in many industrial fields. These devices suffer from wear and friction at the points where surfaces come into contact with each other. This not only leads to damage and failure of the devices but also to operational inefficiencies. This invention attempts to address these problems by using magnetic force instead of mechanical force to constrain movement, thereby reducing friction and wear. Accordingly, the previous arrangement of slots and pins is replaced with magnetic protrusions or patches and tracks having predetermined magnetic properties that act to attract the magnetic protrusions or patches. The predetermined magnetic properties can be magnets of opposite polarity or magnetic materials with higher permeability than the surrounding material.

[0005] In some embodiments, the patch or projection has dimensions similar to the width of the track, and the length of the track is several times its width, so that it is held within the track and moves from one end to the other.

[0006] In some embodiments, the surface of the magnetic projection or patch is flat, the track is straight, and the surface of the patch or projection facing the track is on a plane parallel to the plane of the track surface.

[0007] In some embodiments, the surface of the magnetic patch or projection is substantially circular. The width and length of the magnetic patch or projection are the diameter of the circle.

[0008] In some embodiments, the width and length of the surface of the magnetic patch or projection are substantially similar, and are within 30%, preferably within 20%, of each other.

[0009] In some embodiments, the width of the patch or protrusion is within 10% of the width of the track.

[0010] In some embodiments, the motion in one direction includes rotational motion, and the motion in the other direction includes translational motion.

[0011] In some embodiments, the movement of the further movable element includes reciprocating motion.

[0012] In some embodiments, one of the movable elements is configured to be driven externally.

[0013] In some embodiments, the magnetic projection or patch may have a single magnetic pole, while in other embodiments, the magnetic projection or patch may have at least two magnetic poles facing the track.

[0014] If the magnetic projection or patch has at least two magnetic poles facing the track, the magnetic field extending from the magnetic projection or patch can preferentially reside within the track, extending within the track and returning to the other magnetic pole of the magnet, thereby confining it to some extent, reducing inefficiencies that may arise from eddy currents and magnetic hysteresis losses that may occur if the magnetic field is not confined in this manner.

[0015] In some embodiments, the magnetic projection or patch has an axis perpendicular to the surface, and the magnetic projection or patch is mounted so as to be symmetrical with respect to the axis or rotatable with respect to the axis.

[0016] To maintain an aligned magnetic field when a magnetic patch or projection moves along a track and has multiple magnetic poles, the magnetic patch or projection can be symmetrical with respect to an axis perpendicular to its surface, and in some cases, rotationally symmetrical, or, if not, can be mounted on a rotary joint to maintain alignment.

[0017] In some embodiments, the magnetic projection or patch includes a horseshoe-shaped magnet, which is mounted to extend perpendicular to the surface and rotate around an axis located between the two magnetic poles.

[0018] As mentioned above, if the magnetic patch or protrusion is not symmetrical with respect to the axis, rotational mounting of the magnet can be used to maintain alignment during different relative motions between the magnet and the track.

[0019] In some embodiments, the track comprises at least two tracks such that each magnetic pole of the at least two magnetic poles of the magnets faces the respective track.

[0020] If the magnetic patch or protrusion is a multi-pole magnet, it may be advantageous to have multiple tracks, each facing a different pole.

[0021] In some embodiments, the magnetic patch or projection includes a permanent magnet, and in other embodiments, the magnetic patch or projection includes at least one electromagnet or at least one permanent electromagnet.

[0022] A permanent magnet can be used, and a permanent electromagnet can be used in which the magnetic properties can be switched on and off by the use of electric current. Alternatively, the electromagnet can be used as a magnetic projection.

[0023] Both permanent electromagnets and regular electromagnets have the advantage of being controllable, but they have the disadvantage of requiring electrical circuits and, in some cases, associated control circuits. Therefore, the choice of magnet type depends on the application.

[0024] In some embodiments, the apparatus includes a plurality of electromagnets or permanent magnets attached at different positions on the first movable element, and the apparatus includes a control circuit configured to activate one of the plurality of electromagnets or permanent magnets at any given time, and the selection of one of the plurality of electromagnets to activate defines a trajectory of one of the movable elements.

[0025] One advantageous use of an electromagnet or a permanent magnet is that it can provide an adaptable device that offers the possibility of different trajectories depending on which magnet is activated at which point in time.

[0026] In some embodiments, the first movable element includes a rotating disk, and the plurality of electromagnets or permanent magnets are attached at different radial positions on the rotating disk.

[0027] When the first movable element is a rotating disk, by attaching different electromagnets at different radial positions, the translational length received by a further movable element can be changed.

[0028] In some embodiments, the at least one track having a predetermined magnetic property is formed by lithographically patterning a high-permeability material on a low-permeability substrate.

[0029] Providing a track having a predetermined magnetic property can be done using lithographic printing of a high-permeability material onto a low-permeability substrate, thereby providing a low-cost device that can easily customize the shape and length of the track according to requirements.

[0030] Furthermore, a low-permeability substrate can be used as a circuit board, and if there are multiple intersecting tracks, switching and control elements can be mounted parallel to the high-permeability tracks. Along a predetermined direction of travel, during its motion, the patch or protrusion will approach various intersections of the multiple tracks. The high-permeability track material at any exit point can be driven to a saturated state by a control circuit mounted next to it. If all but one exit is saturated, the patch or protrusion will be guided to the unsaturated exit as the most energetically favorable option. Switching can be used to control the saturation of the tracks, and switching between paths can be enabled based on the saturation of the tracks, which can be controlled by a control circuit with conductive switching.

[0031] In some embodiments, the at least one track having predetermined magnetic properties has a thickness of less than 3 mm.

[0032] Thin tracks offer low manufacturing costs and can provide suitable properties. For example, when lithographic printing tracks, thin tracks with appropriate properties can be easily produced.

[0033] In some embodiments, the device comprises a sliding joint, a cam follower in some embodiments, and a Scotch yoke in other embodiments.

[0034] In some embodiments, the device comprises an additional movable element corresponding to the first movable element, the additional movable element including a magnetic patch or projection corresponding to the magnetic patch or projection of the first movable element, and the additional movable element is mounted on the opposite side of the first movable element from the additional movable element.

[0035] In some cases, it may be advantageous to have a movable element corresponding to the first movable element and mounted on the opposite side of the further movable element, so that the further movable element has a corresponding force that pulls it not only toward the first movable element but also in the opposite direction, so that the two forces substantially cancel each other out and there is no force, or a minimal force, acting perpendicular to the direction of movement along the track.

[0036] In some embodiments, the apparatus further includes an airtight seal between the first element and the further element.

[0037] One advantage of non-contact fittings is the ability to place an airtight seal between two elements, which can be particularly advantageous in certain applications. For example, when equipment is used in environments with pressure differences, such as in vacuum pump applications, or when handling hazardous materials. Non-contact fittings allow two elements that may interact with different parts of a system to be isolated from each other by the use of a sealed enclosure between them.

[0038] Further embodiments include a cryocooler in which rotational motion from a motor is converted into reciprocating motion by an apparatus according to one embodiment. In some embodiments, the reciprocating motion drives a piston in a Gifford-McMahon type cycle process. In some embodiments, the cryocooler forms part of a cryopump.

[0039] Further specific preferred embodiments are described in the attached independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate and in combinations other than those expressly described in the claims.

[0040] When a feature of a device is described as being capable of operating to produce a certain function, it should be understood that this includes features of the device that produce that function, or that are adapted or configured to produce that function.

[0041] Herein, embodiments of the present invention will be further described with reference to the accompanying drawings. [Brief explanation of the drawing]

[0042] [Figure 1] A Scotch yoke according to one embodiment is shown. [Figure 2] Figure 1 shows a view of the Scotch yoke from above. [Figure 3] This diagram schematically illustrates the magnetic field generated by a magnet that is opposite the pole piece and has a magnetic pole at the end opposite the magnet. [Figure 4] This diagram schematically illustrates the magnetic field generated by a magnet having two magnetic poles at the same end. [Figure 5A] This diagram schematically illustrates the magnetic field generated by a horseshoe-shaped magnet facing a pole piece of a single track. [Figure 5B] This diagram schematically illustrates the magnetic field generated by a horseshoe-shaped magnet facing the pole piece of a dual-track system. [Figure 6] Another embodiment of the Scotch yoke is shown. [Figure 7] Additional mechanical devices suitable for adaptation to form the apparatus according to the embodiment are shown. [Modes for carrying out the invention]

[0043] Before describing the embodiments in more detail, let's first give an overview.

[0044] Since James Watt's invention, the efficient conversion between rotational and linear motion has been a crucial area of ​​industrial development. While many inventions and developments have naturally been made on such an important topic, the simple Scotch yoke remains a commonly chosen solution due to its simplicity and robustness, and is indeed used as a key component in some refrigeration vacuum pumps. A conventional Scotch yoke drives a well-formed sliding joint with contact points mounted on a rotary drive wheel. In particular, the motion path taken by the slider can be adjusted by changing the slots, which can be used, for example, to adjust the residence time at both ends of the sliding motion.

[0045] While conventional Scotch yokes have many advantages, they also have drawbacks due to wear and friction. Embodiments seek to reduce or eliminate friction between contacting moving parts by using magnetic force as the force used to convert motion. Utilizing the strong interaction between magnetic poles instead of direct mechanical contact significantly reduces friction and wear and makes the device more robust against damage.

[0046] The embodiment provides a non-contact magnetoresistive mechanism for efficient conversion between rotational and linear motion.

[0047] Figure 1 shows a Scotch yoke according to an embodiment, in which the rod 10 reciprocates as the wheel 20 rotates. The wheel 20 has a permanent magnet "pin" 12. The rod 10 has a high-permeability pole piece 22, which corresponds to the "slot" of a conventional Scotch yoke. In this case, the high permeability of the pole piece 22 is energetically advantageous for the magnet pin 12 to remain centered on the pole piece 22, and the movement along the long axis of the pole piece is energetically neutral until the magnet reaches either end.

[0048] Any losses in such non-contact joints may take the form of eddy current dissipation or magnetic hysteresis loss. Fortunately, methods to mitigate these effects are well known. Since the power lost due to eddy current generation varies in proportion to the resistivity of the material from which the current is generated, it can be advantageous to form the device portion where eddy currents are a problem with a high-resistivity material. When high permeability and high resistance are required, a high-resistivity material such as silicon iron can be selected. Further reductions in eddy current losses can be achieved by switching to one of the many high-permeability sintered powders developed for transformers. It is also possible to reduce eddy currents by forming the core by laminating multiple thin high-permeability layers, as is done in transformers.

[0049] Magnetic hysteresis loss occurs when the local direction of the magnetic field generated by individual domains of a magnet changes. Such losses are large in magnetically "hard" materials where the domains are less prone to change, and small in magnetically "soft" materials. For this reason, transformer cores typically use "soft" materials to minimize such losses, and non-contact couplings should be the same. It should also be noted that losses generally worsen when the direction of the magnetic field is completely reversed, as in transformers. In magnetic sliding couplings, the external magnetic field acting on a particular point on the slider does not completely reverse; it simply rises to a peak value and then declines as the magnetic "pin" moves across it.

[0050] Therefore, directly integrating such a magnetic sliding coupling into a Scotch yoke is effective and simple. At the midpoint of the yoke's rotation, the force from the rotating member is transmitted to the slider by the natural tendency of the pole piece to keep its center on the permanent magnet "pin". At either end of the yoke's rotation, the pin 12 can move freely along the length of the slider 22. This is because, as long as the pin is completely covered by the pole piece, the accumulated magnetic energy is minimized. In between, there is a combination of force transmission in the linear motion direction and free sliding in the vertical direction, as seen in conventional Scotch yokes, except for reduced friction and the absence of contact.

[0051] Figure 2 is a top view of the Scotch yoke from Figure 1, showing a gap between the pin 12 and the slider 22. This gap allows for the placement of an airtight seal (not shown) between the two movable elements. There are applications where it is highly desirable to be able to separate both ends of the joint, and having a non-contact joint means that there is a gap between the two elements, providing space for an airtight seal.

[0052] One of the potential problems with this design, schematically shown in Figure 3, stems from the lack of a clearly defined method for routing the magnetic field to the opposite pole after crossing the high-permeability track. Excessive stray magnetic fields can cause eddy current losses in nearby metal components, potentially leading to interference as other components change. Furthermore, poor routing in such magnetic circuits reduces the effective connection force between the "pins" and "sliders."

[0053] The embodiment attempts to address this by using coaxially divided magnetic poles instead of a single magnetic pole, as shown in Figure 4. This results in a circularly symmetrical closed circuit for the magnetic flux, and the stray magnetic field is almost eliminated or at least reduced. Circular symmetry is essential in this case because, in the case of a fixed "pin" point, each rotation of the drive wheel results in a rotation of the pin's relative orientation to the slider.

[0054] Another possible variation involves using a “horseshoe” magnet with both its north and south poles facing the high-permeability slider; see Figure 5A. This has the advantage of directly completing the overall magnetic circuit, thereby minimizing or at least reducing the stray magnetic field spreading from the mechanism, but requires housing the magnetic pin in a free-rotating coupling, such as one provided by a ball bearing.

[0055] In the magnetic field generated by such a horseshoe-shaped magnet, the receiving pole can also be divided into multiple tracks or equivalent receiving "teeth" (see Figure 5B). This alternating arrangement of high and low magnetic field regions generates a large connection force between the pin and the slider, as any lateral displacement of the pin relative to the slider results in greater energy loss than in the case of a single magnetic pole. This multi-tooth or multi-track scenario can be extended to three or more teeth or tracks using a layered stack of multi-pole pins and sliders.

[0056] Another interesting feature of the Scotch yoke is that the relative stroke length can be changed by adjusting the radial position of the pin. Normally, this involves mechanical complexity, requiring a dial to adjust the pin's position inward or outward. This feature can be incorporated very easily into a non-contact magnetic Scotch yoke.

[0057] The simplest option is to replace the permanent magnets with electromagnets and incorporate other electromagnets at different distances along the same radius. Then, when the yoke is at the midpoint, the drive electromagnet can be switched off and the coils of different radii can be energized to take over driving the slider. Compared to the simple permanent magnet solution, this modification requires incorporating multiple electromagnets or permanent electromagnets into the drive wheel, as well as the drive circuit and associated rotating electrical connections. However, this is far simpler than a mechanically variable Scotch yoke and can be switched more quickly, even during a single rotation of the drive wheel.

[0058] Figure 6 shows an alternative embodiment of the Scotch yoke, which has an additional wheel 24 corresponding to wheel 20 and a corresponding magnetic pin. Wheel 24 works to reduce the resulting perpendicular force on the slider 22 caused by the magnetic attraction between the magnetic projection of wheel 22 and the slider by acting its own force in the opposite direction. Wheel 20 can be a driving wheel, and the additional wheel 24 can be a driven wheel.

[0059] Figure 7 shows several conventional devices with mechanical sliding joints, and to manufacture the devices according to the embodiments, pins can be replaced with magnetic patches or protrusions, and slots can be replaced with high-permeability tracks. Thus, Figure 7A shows a Geneva wheel mechanism that functions as a kind of gear that converts continuous rotational motion into intermittent rotational motion in the opposite direction. Figures 7B and 7C show a 6-bar sliding mechanism and a 5-bar slot mechanism, respectively, and Figure 7D shows a cam follower.

[0060] While exemplary embodiments of the present invention have been disclosed in detail with reference to the accompanying drawings, it will be understood that the present invention is not limited to the exact embodiments and that various changes and modifications can be made by those skilled in the art without departing from the concept of the invention as defined by the accompanying claims and equivalents. [Explanation of symbols]

[0061] 10 Rods or further movable elements 20 Wheel or first movable element 12 Magnetic patch or protrusion 22 Tracks or Sliders 30 swivel joint 24 additional wheels

Claims

1. A device for converting between motion in one direction and motion in another direction, A magnetic projection or patch having a surface is attached to the first movable element, A track attached to a further movable element and having predetermined magnetic properties, Equipped with, The track defines a path through which the magnetic protrusion or patch is attracted by magnetic force, the magnetic force restricts the movement of the movable element, and the magnetic protrusion or patch moves along the track in response to the relative movement between the first movable element and the further movable element. The surface of the magnetic projection or patch has a shape having a width dimension aligned with the width of the track and differing by less than 30%, and a length dimension perpendicular to the width dimension, which is substantially shorter than the length dimension of the track and less than 30% of the length dimension of the track. An apparatus wherein the surface of the magnetic projection or patch is flat, the track is straight, and the surface of the magnetic projection or patch facing the track is on a plane parallel to the plane of the track's surface.

2. The apparatus according to claim 1, wherein the motion in one direction includes rotational motion, and the motion in the other direction includes translational motion.

3. The apparatus according to claim 1, wherein the magnetic projection or patch includes a magnet having at least two magnetic poles facing the track.

4. The apparatus according to claim 1, wherein the magnetic projection or patch has an axis perpendicular to the surface, and the magnetic projection or patch is mounted so as to be symmetrical with respect to the axis or so as to be rotatable with respect to the axis.

5. The apparatus according to claim 3, wherein the magnetic projection or patch includes a horseshoe-shaped magnet, the horseshoe-shaped magnet is mounted to extend perpendicularly to the surface of the horseshoe-shaped magnet facing the track and to rotate around an axis located between the two magnetic poles.

6. The apparatus according to claim 3, wherein the track comprises at least two tracks such that each magnetic pole of the at least two magnetic poles of the magnets faces the respective track.

7. The apparatus according to claim 1, wherein the magnetic protrusion or patch includes a permanent magnet.

8. The apparatus according to claim 1, wherein the magnetic projection includes at least one electromagnet or at least one permanent electromagnet.

9. The apparatus according to claim 8, comprising a plurality of electromagnets or permanent electromagnets mounted at different positions on the first movable element, wherein the apparatus comprises a control circuit configured to activate one of the plurality of electromagnets or permanent electromagnets at any time, and the selection of one of the plurality of electromagnets to be activated defines the trajectory of one of the movable elements.

10. The apparatus according to claim 9, wherein the first movable element includes a rotating disk, and the plurality of electromagnets or permanent electromagnets are mounted at different radial positions on the rotating disk.

11. The apparatus according to claim 1, wherein the track having predetermined magnetic properties is formed by lithographic printing a high-permeability material onto a low-permeability substrate.

12. The apparatus according to claim 1, wherein the track having the predetermined magnetic properties has a thickness of less than 3 mm.

13. The apparatus according to claim 1, wherein the further movable element includes a plurality of tracks, the plurality of tracks defining different relative trajectories between the movable elements.

14. The apparatus according to claim 1, comprising one of a cam follower or a Scotch yoke.

15. The apparatus according to claim 1, further comprising an additional movable element corresponding to the first movable element, wherein the additional movable element includes a magnetic projection or patch corresponding to the magnetic projection or patch of the first movable element, and the additional movable element is mounted on the opposite side of the first movable element from the further movable element.

16. The apparatus according to claim 1, further comprising an airtight seal between the first movable element and the further movable element.

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