Magnetic coupling device for magnetically coupling with ferromagnetic workpieces

Abstract

A magnetic coupling device for magnetically coupling with a ferromagnetic workpiece, comprising: a plurality of pole portions and a plurality of permanent magnets, the plurality of permanent magnets including: a first permanent magnet located between a first and a second pole portion and positioned to be vertically offset from the workpiece contact interfaces of the first and second pole portions, and a second permanent magnet located between at least two pole portions and positioned to be vertically offset from its workpiece contact interface; a plurality of electrical windings wound around the first permanent magnet, extending above its top and below its bottom, and positioned between the first and second pole portions; and an electronic controller operatively coupled to the plurality of electrical windings and controlling the magnetic path through the ferromagnetic workpiece at the workpiece contact interfaces of the plurality of pole portions, wherein the electronic controller establishes a first state of the magnetic path through the ferromagnetic workpiece at the workpiece contact interfaces of the plurality of pole portions in a first configuration having a plurality of permanent magnets, and establishes a second state at the workpiece contact interfaces in a second configuration.

Description

[0001] This application is a divisional application of a Chinese national phase patent application with the application number 201880038210.6, which entered the Chinese national phase on December 9, 2019, from a PCT application with the international application number PCT / US2018 / 036734, an international filing date of June 8, 2018, and an invention title of "Switchable Permanent Magnet Unit for Magnetic Coupling with Ferromagnetic Workpieces and Method of Manufacturing the Same".

[0002] Cross - reference to related applications

[0003] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 517,057, filed on June 8, 2017, titled "Electromagnetically Switchable Permanent Magnet Apparatus", the entire disclosure of which is hereby expressly incorporated by reference. Technical field

[0004] The present disclosure relates to magnetic devices. More particularly, the present disclosure relates to switchable magnetic devices that can be switched between a magnetically attractive "on" state and a non - magnetically attractive "off" state, and more particularly to magnetic coupling devices for magnetic coupling with ferromagnetic workpieces. Background art

[0005] Switchable magnetic devices can be used to magnetically couple a magnetic device to one or more ferromagnetic workpieces. A switchable magnetic device can include one or more magnets that are rotatable relative to one or more fixed magnets to generate a magnetic field and a shunt magnetic field. By switching the magnet device between an "on" state and an "off" state, the switchable magnet device can be removably attached to a ferromagnetic object (workpiece), such as for lifting operations, material handling, material holding, magnetic locking, or coupling objects to each other in numerous application fields. Summary of the invention

[0006] Example embodiments provided by the present disclosure include the following.

[0007] In an exemplary embodiment of the present disclosure, a switchable permanent magnet unit for magnetic coupling with a ferromagnetic workpiece is provided. The magnetic unit includes: a housing; a first permanent magnet mounted within the housing and having an active N-S pole pair; a second permanent magnet rotatably mounted within the housing in a stacked relationship with the first permanent magnet and having an active N-S pole pair, the second permanent magnet being rotatable between a first position and a second position, when the second permanent magnet is in the first position, the switchable permanent magnet unit has a first level of magnetic flux available for the ferromagnetic workpiece at the workpiece contact interface of the switchable permanent magnet unit; when the second permanent magnet is in the second position, the switchable permanent magnet unit has a second level of magnetic flux available for the ferromagnetic workpiece at the workpiece contact interface, the second level being greater than the first level; and at least one conductive coil disposed around the second permanent magnet and configured to generate a magnetic field in response to current being passed through the at least one conductive coil, wherein when the second permanent magnet is in the first position, the magnetic field component of the conductive coil points from S to N along the active N-S pole pair of the second permanent magnet.

[0008] In an example thereof, the switchable permanent magnet unit further includes means for holding the second permanent magnet in the second position.

[0009] In a variant of the example thereof, the switchable permanent magnet unit includes a rotation limiter configured to hold the second permanent magnet in the second position.

[0010] In another variant of the example thereof, at least one conductive coil is disposed around the first permanent magnet and the second permanent magnet.

[0011] In yet another variant of the example thereof, the conductive coil is disposed around the outer surface of the housing.

[0012] In yet another variant of the example thereof, the conductive coil is disposed within the housing and around the outer surface of the second permanent magnet.

[0013] In yet another variant of the example thereof, the active N-S pole pair of the first permanent magnet includes a plurality of active N-S pole pairs, and the active N-S pole pair of the second permanent magnet includes a plurality of active N-S pole pairs.

[0014] In another example thereof, the switchable permanent magnet unit includes a power source configured to supply current to the conductive coil to generate the magnetic field of the conductive coil.

[0015] In another example thereof, the component pointing from S to N along the N-S pole pair of the second permanent magnet includes the magnetic fields of all the conductive coils.

[0016] In yet another example thereof, the housing is a two-piece housing.

[0017] In another example thereof, the housing is a one-piece housing.

[0018] In another exemplary embodiment of the present disclosure, a method for manufacturing a switchable permanent magnet unit is provided. The switchable permanent magnet unit is configured to be magnetically coupled to a ferromagnetic workpiece at a workpiece contact interface of the switchable permanent magnet unit. The method includes: mounting a first permanent magnet in a housing, the first permanent magnet having an active N-S pole pair; mounting a second permanent magnet in the housing in a stacked relationship with the first permanent magnet, the second permanent magnet having an active N-S pole pair, the second permanent magnet being rotatable relative to the first permanent magnet between a first position and a second position; when the second permanent magnet is in the first position, the switchable permanent magnet has a first level of magnetic flux available for the ferromagnetic workpiece at the workpiece contact interface, and when the second permanent magnet is in the second position, the switchable permanent magnet has a second level of magnetic flux available for the ferromagnetic workpiece at the workpiece contact interface, the second level being greater than the first level; and arranging at least one conductive coil around the second permanent magnet, the at least one conductive coil being configured to generate a magnetic field in response to a current passing through the conductive coil, when the second permanent magnet is in the first position, a component of the magnetic field points from S to N along the active N-S pole pair of the second permanent magnet.

[0019] In an example thereof, the at least one conductive coil is arranged around an outer surface of the housing.

[0020] In a variant of the example thereof, the at least one conductive coil is arranged inside the housing and around an outer surface of the second permanent magnet.

[0021] In yet another variant of the example thereof, the at least one conductive coil is arranged around the first permanent magnet and the second permanent magnet.

[0022] In yet another variant of the example thereof, the method further includes means configured to hold the second permanent magnet in the second position.

[0023] In a variant of the example thereof, the method further includes a rotation limiter configured to limit rotation of the second permanent magnet relative to the first permanent magnet within a set rotation range.

[0024] In yet another variant of the example thereof, at least one of the first permanent magnet and the second permanent magnet includes a plurality of permanent magnets.

[0025] In yet another variant of the example thereof, the method further includes coupling a power supply to the conductive coil, the power supply being configured to supply current to the conductive coil to induce the magnetic field of the conductive coil.

[0026] In another example thereof, the housing is a two-piece housing.

[0027] In yet another example thereof, the housing is a one-piece housing.

[0028] Other aspects of the present invention, as well as optional and / or preferred features, will become apparent from the following description of the preferred embodiments provided with reference to the accompanying drawings. Description of the Drawings

[0029] Figure 1 is a schematic exploded view of an electrically switchable permanent magnet device according to an embodiment of the present disclosure.

[0030] Figure 2 is an isometric view of the device according to an embodiment of the present disclosure in an assembled state Figure 1 of the device.

[0031] Figure 3A is a front cross-sectional view of the device depicted in Figure 1 and Figure 2 and the magnetic circuit generated when the device is in the "off" position.

[0032] Figure 3B is a top view of the device depicted in Figure 3B and includes the B-field generated by the top magnet when the device is in the "off" position.

[0033] Figure 3C is a partial top cross-sectional view of the device depicted in Figure 3A and Figure 3B and includes the top magnet when the device is in the "off" position.

[0034] Figures 4A - 4E to Figures 8A - 8E are top views of the device according to an embodiment of the present disclosure in Figure 1 and Figure 2 sequentially switching from the "off" position to the "on" position.

[0035] Figure 9A is a front cross-sectional view of the device depicted in Figure 1 and Figure 2 and the magnetic circuit generated when the device is in the "on" position.

[0036] Figures 9B to 9C is a top view of the device according to an embodiment of the present disclosure in Figure 1 and Figure 2 and the B-field generated by the top magnet when the device is in the "on" position.

[0037] Figure 10A is a side view of another embodiment of an electro-switchable permanent magnet device according to an embodiment of the present disclosure.

[0038] Figure 10B is in Figure 10A a side view of the electro-switchable permanent magnet device depicted in, where the cap structure and the solenoid coil body are removed from the device.

[0039] Figure 10C is in Figure 10A and Figure 10B a side cross-sectional view of the electro-switchable permanent magnet device depicted in.

[0040] Figure 11 shows a robotic system including a switchable magnetic device according to an embodiment of the present disclosure.

[0041] Although the disclosed subject matter may be subject to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. However, the intention is not to limit the present disclosure to the specific embodiments described. On the contrary, the present disclosure is intended to cover all modifications, equivalents, and alternatives falling within the scope of the present disclosure as defined by the appended claims. Detailed Description

[0042] It should be understood that the terms and adjectives "vertical", "horizontal", "upper", "lower", "top", "bottom", "lateral", "transverse", "width direction", etc. are used in this description and the specification only for providing a reference description for facilitating the understanding of the drawings and the relationship between the components.

[0043] The switchable magnetic device can be actuated using manual actuation, pneumatic or hydraulic actuation, and / or electro-actuation. Manual actuation is to directly rotate or linearly move one or more magnets or magnetic units relative to one or more fixed magnets or magnetic units through a handle or a manual actuator. The embodiments provided herein relate to switchable magnetic devices. Exemplary manually switchable magnetic devices are disclosed in the following patent documents: U.S. Patent No. 7,012,495 titled "Switchable Permanent Magnet Device" (referred to as the '495 patent); U.S. Provisional Patent Application No. 62 / 248,804 titled "Magnetically Coupled Device with a Rotary Actuation System" filed on October 30, 2015, with docket number MTI-0007-01-US-E; and U.S. Provisional Patent Application No. 62 / 252,435 titled "Magnetically Coupled Device with a Linear Actuation System" filed on November 7, 2015, with docket number MTI-0006-01-US-E, the entire disclosures of which are expressly incorporated herein by reference.

[0044] Pneumatic or hydraulic actuation drives one or more movable magnets or magnet units in a switchable core device through a pneumatic or hydraulic fluid actuator.

[0045] Electrical actuation generally falls into one of two categories. The first category includes “electromechanical permanent magnet” (or EPM) devices that have two (or more) fixed permanent magnets that cooperate with a ferromagnetic armature and a conductive coil (e.g., a solenoid coil) suitably surrounding the armature or the magnets. These two magnets have different magnetization strengths and coercivity characteristics, and the conductive coil is rated to temporarily cancel the magnetic field of one of the magnets by superimposing an electromagnetic field, thereby switching the device from an active state to a deactivated state in a bistable manner. In an embodiment, the magnetic field generated by the conductive coil may not affect the other fixed magnet. These devices typically rely on permanent magnetic members with high coercivity (which are not easily demagnetized by external magnetization) and a second magnetic element composed of magnetic elements with medium or low coercivity, which is positioned to cooperate with the conductive coil and thus can be magnetized by the magnetic field of the coil so that its magnetization vector aligns or anti-aligns with the high coercivity magnet present in the magnetic circuit.

[0046] The second category of electrical actuation includes permanent magnet devices similar to those mentioned above, where a motor is used to apply torque to a movable magnet using a shaft or other type of transmission mechanism coupled to the output shaft of the motor.

[0047] Due to the lack of moving parts and the increased efficiency of directly magnetizing medium or low coercivity elements compared to using a separate drive motor, the first category is the more commonly used method for electrically switching magnets between an on state and an off state.

[0048] The electrical actuation of a switchable magnet system has several advantages over manual and pneumatic actuation systems. Due to the widespread availability of electrical control systems and power systems, and due to the development of electromagnetic switching technology in consumer products that themselves require power to operate, it is much more convenient to use electricity for switching than to use a hydraulic actuator or a pneumatic actuator, which requires a source of working fluid that is usually not available outside of industrial and manufacturing plant settings.

[0049] Despite their advantages, existing EPM devices have many disadvantages. The more common AlNiCo / NdFeB EPM devices use AlNiCo as the working material for switching between magnetization states. See, for example, the thesis by Ara Nerses Knaian at: http: / / cba.mit.edu / docs / theses / 10.06.knaian.pdf. Although AlNiCo is a powerful magnetic material with a relatively high residual induction and the highest non-rare-earth magnetic energy product, it is characterized by an extremely low coercivity. While this low coercivity enables the EPM technology to function properly, it also degrades the performance of the EPM device.

[0050] If an EPM device is used in a magnetic circuit with a full large cross-section, the total magnetic flux density output should be equal to that of NdFeB of the same volume. However, if this technology is used in a poor or heavily loaded magnetic circuit, due to the low coercivity of AlNiCo, the unfavorable magnetization curve of AlNiCo will result in a significant reduction in the available (tractive) force of the system. This limits the application range of most EPM units to cases where they will be fully saturated.

[0051] In addition, since solenoid electromagnets require a large amount of current to fully saturate a piece of permanent magnetic material relative to the opposite magnetic field, EPM devices require a relatively large power consumption to switch the system between the on state and the off state. Even for units with a small magnetic range, this requires a high-power processing circuit and control device, thus limiting the portability and flexibility of the setup of these systems.

[0052] On the other hand, motor-driven actuation systems have the advantage of having an extremely wide operating range in terms of torque - because even in the presence of an external magnetic circuit, the torque variation required to actuate the switchable permanent magnet throughout the cycle is large.

[0053] When a motor is used with a switchable permanent magnet device, it is difficult to "tune" the motor to the ideal operating point because the operating conditions of the motor must vary over a wide range to adapt to the various applications and situations of the applied magnet units. In addition, the need for mechanical coupling elements and possibly a gearbox increases the weight, complexity, and associated losses, which means that the efficiency of motor-driven magnets is significantly lower than that of the directly magnetized EPM method described above. The large number of moving parts and the high stress on these parts also shorten the service life of the parts and prevent miniaturization and size minimization, which are almost effective for any EPM unit.

[0054] An object of the present disclosure is to improve existing EPM devices by providing a design that allows the use of permanent magnets having similar coercivity characteristics while reducing the amount of power required to switch the device between magnetization states. Another object of the present disclosure is to provide a modified permanent magnet switchable device in which activation and deactivation of the device is achieved by relative movement of permanent magnets included in the switchable device, by providing an alternative way of applying a torque (or force) on a movable magnet to change its relative position with respect to a fixed magnet so that the device switches between on and off magnetization states.

[0055] Embodiments of the present disclosure were initially conceived to facilitate, improve, or provide a different mechanism for actuating (turning on and off) a switchable permanent magnet device (such as the magnet device disclosed in the '495 patent). Embodiments of the present disclosure may utilize some of the basic concepts of the '495 patent, but as will be immediately appreciated by those skilled in the art from the following description, embodiments of the present disclosure are not limited to devices similar to those described in the '495 patent. For example, while the '495 patent uses two integral, cylindrical, diametrically magnetized rare earth permanent magnets as a source of magnetic flux, embodiments of the present disclosure may be implemented in other types of devices, such as those described in U.S. Patent No. 8,878,639, U.S. Patent No. 7,161,451, German Utility Model DE202016006696U1, and U.S. Provisional Patent Application No. 62 / 248,804, filed October 30, 2015, entitled "Magnetically Coupled Device with a Rotary Actuation System" (Docket No. MOT-0007-01-US-E), the entire disclosure of which is expressly incorporated herein by reference.

[0056] Those skilled in the art will note that the term "magnet" as it appears in the description must be understood in context. That is, the term "magnet" may refer to a permanent magnet, for example, a cylindrical single dipole of a single type of rare earth magnet material (such as NdFeB or SmCo), or a composite including a magnetic core of such rare earth material to which pole extensions of a low magnetic resistance material (commonly referred to as ferromagnetic passive pole pieces) are fixed, etc. Additionally, strictly speaking, the term "magnet" may also refer to an electromagnet and a conductive coil (such as a solenoid coil) with or without a ferromagnetic core element.

[0057] In an embodiment, a pair of identical, diametrically magnetized cylindrical bipolar permanent magnets are arranged in a dedicatedly designed ferromagnetic two-piece housing in an active shunt arrangement, and a pair of passive ferromagnetic pole elements (also referred to as 'pole shoes') are fixed to the housing. A ferromagnetic workpiece can be coupled to the magnets via the pole shoes. Such devices can be incorporated into many different apparatuses in which magnetic attraction is used to temporarily hold ferromagnetic bodies on tools, such as lifting devices, coupling devices, end-of-arm robotic workpiece handling devices, latches, and the like.

[0058] For a description of the basic concept behind such a switchable permanent magnet device, reference should be made to the '495 patent, the content of which is incorporated herein for all purposes.

[0059] Turning to the first embodiment shown in Figure 1 and Figure 2 Device 10 includes a central housing 12 composed of two ferromagnetic (e.g., steel) housing parts 28, 30, which can be joined by a pair of ferromagnetic passive pole extensions 32, 34. Although pole extensions 32, 34 are depicted in the illustrated embodiment, device 10 can operate in other embodiments without pole extensions 32, 34. Two cylindrical and radially magnetized magnets 14, 16 can be received within upper housing part 28 and lower housing part 30, respectively. In an embodiment, magnets 14, 16 can be NdFeB magnets. In an embodiment, the active magnetic mass and magnetic properties of magnets 14, 16 can be equal and / or equal within achievable manufacturing tolerances and permanent magnet magnetization techniques. Magnet 14 can be referred to herein as upper magnet 14 and / or second magnet 14, and magnet 16 can be referred to herein as lower magnet 16 and / or first magnet 16. Although it is discussed herein that upper magnet 14 can rotate within upper housing part 28 and lower magnet 16 is fixed within lower housing part 30, in other embodiments, upper magnet 14 can be fixed within upper housing part 28 and lower magnet 16 can rotate within lower housing part 30.

[0060] In an embodiment, a thin disk 18 of ferromagnetic material can close an opening at the lower end of a cylindrical cavity 38 that extends through lower housing part 30. A multi-component support and spacer structure 20 can be located between upper magnet 14 and lower magnet 16. A non-magnetizable (e.g., aluminum) cap structure 22 can be mounted to upper housing portion 28 to cover an open upper end of a cylindrical cavity 36 that extends through upper housing part 28.

[0061] In embodiments where the upper magnet 14 is rotatable, the solenoid coil body 24 can be made of enameled wire and can surround the upper housing portion 28 and the cap structure / member 22. In another embodiment, the solenoid coil body 24 can surround only the upper housing portion 28, in which case the cap member 22 can be modified by having a downwardly extending foot portion at the widthwise ends of the cap member 22, the foot portion enabling the cap to be attached to the housing portion while accommodating the thickness of the coil between the housing portion and the cap member. In another embodiment, the solenoid coil body 24 can be within the upper housing portion 28 and surround the upper magnet 14. In this embodiment, the upper housing portion 28 can be modified to accommodate the thickness of the solenoid coil body 24. Additionally, the solenoid coil body 24 can include enough wire to provide slack for the upper magnet 14 to rotate, and / or slip rings that can be used to maintain the electrical connection between the solenoid coil body 24 and the power source 82. In another embodiment, the solenoid coil body 24 can surround both the upper magnet 14 and the lower magnet 16. In these embodiments, the solenoid coil body 24 can surround the lower housing member 30 of the lower magnet 16 or be disposed within the lower housing member 30 and surround the lower magnet 16. Although only one solenoid coil body 24 is depicted, in other embodiments, the solenoid coil body 24 can include multiple solenoid bodies. The purpose of the solenoid coil body 24 is discussed in more detail below.

[0062] In embodiments where the lower magnet 16 is rotatable, the solenoid coil body 24 can surround the lower housing member 30 and the cap structure 18. In another embodiment, the solenoid coil body 24 can surround only the lower housing member 30, in which case the cap member 18 can be modified by having a downwardly extending foot portion at the widthwise ends of the cap member 18, the foot portion enabling the cover to be attached to the housing portion while accommodating the thickness of the coil between the housing portion and the cap member. In another embodiment, the solenoid coil body 24 can be within the lower housing member 30 and surround the lower magnet 16. In this embodiment, the lower housing member 30 can be modified to accommodate the thickness of the solenoid coil body 24. Additionally, the solenoid coil body 24 can include enough wire to provide slack for the lower magnet 16 to rotate, and / or include slip rings for maintaining the electrical connection between the solenoid coil body 24 and the power source 82.

[0063] In an embodiment, the two housing members 28, 30 can be identical and consist of rectangular parallelepiped blocks of a low magnetic reluctance ferromagnetic material, with centrally located cylindrical cavities 36, 38 extending perpendicularly to the upper and lower axial end faces (only the top surfaces 42, 44 are visible in Figure 1 ) through their respective blocks to receive the upper magnet 14 and the lower magnet 16, respectively.

[0064] The diameters of the cavities 36, 38 can be such that the blocks 28, 30 have only small web materials 37′, 37″ at the diametrically opposite vertical sides 40. However, the wall portions 39′, 39″ at the other two parallel vertical side surfaces 43 and 45 of the blocks 28, 30 can have sufficient and defined thicknesses such that the magnetic flux generated by the permanent magnets 14, 16 is contained and redirected within these ferromagnetic wall sections or regions 39. The thin webs at 37′ and 37″ can magnetically isolate the two housing regions 39′ and 39″ from each other substantially, such that the housing regions 39′ and 39″ can be magnetized with opposite N and S magnetic poles by the magnets 14, 16 received in the housing blocks 28, 30 respectively, and as described below, no flux short - circuiting will occur. In the illustrated embodiment, the thin web portions 37 and the thick wall sections 39 are identified only with reference to the lower housing block 30.

[0065] The cylindrical cavity 36 of the upper housing block 28 can have a smooth wall surface, and its diameter allows the upper magnet 14 to be received therein such that the upper magnet 14 can rotate with minimal friction and preferably maintain a minimal air gap. In an embodiment, a friction - reducing coating can be applied to the surface of the cylindrical cavity 36.

[0066] In an embodiment, the cylindrical cavity 38 in the lower housing block 30 can have a rough wall surface and a diameter selected to provide an interference fit with the lower magnet 16 such that when the magnet 16 is installed in the cavity 38, the magnet 16 maintains its rotational orientation and prevents axial and rotational displacement under the operating conditions of the device 10. Additionally or alternatively, other mechanisms, such as adhesives or additional cooperating shaped mating parts (not shown), can be used to fix the magnet 16 within the cavity 38 to prevent displacement.

[0067] As will be noted from Figure 1 Further noted, a pair of parallel - spaced threaded holes 46, 47 can be cut into the opposite vertical outer surfaces 43, 45 of the ferromagnetic wall sections 39′, 39″ of the two housing blocks 28, 30. The holes 46, 47 can extend perpendicular to the axis A of the central cavities 36, 38 and are for providing anchorage for (not - shown) fastening screws or bolts by which the pole - piece extensions 32, 34 are removably fixed to the two central housing blocks. In an embodiment, since the housing wall sections 39″ of the upper housing block 28 and the lower housing block 30 have cross - sections sufficient to carry all of the magnetic flux from the magnets 14, 16 without significant leakage within the ferromagnetic confines, there may be no or only minimal air gaps at the pole shoes 32, 34 and the housing wall sections, whereby the stacked wall portions 39″ on one side of the upper housing block 28 and the lower housing block 30 have opposite magnetic poles, as is the case with the wall section 39′.

[0068] The pole extension blocks 32 and 34 may be identical in construction and made of a low-reluctance ferromagnetic material, such as that used in the manufacture of passive magnetized pole elements. Although the pole extension blocks 32, 34 are depicted as having a parallelepiped plate-like shape, the pole extension blocks may have other shapes, which may be based on the shape of the workpiece of the attachment device 10. Additional pole extension block devices are disclosed in U.S. Provisional Patent Application No. 62 / 623,407, filed on January 29, 2018, titled "Magnetic Levitation Device with Pole Shoes Having Spacing Projections" (Docket No. MTI-0015-01-US), the entire disclosure of which is expressly incorporated herein by reference.

[0069] Although the illustrated embodiment depicts the pole extension blocks 32, 34, in other embodiments, the device 10 may not include the pole extension blocks 32, 34.

[0070] The vertical side surfaces 33, 35 of the blocks 32, 34 may mate with the vertical side surfaces 43, 45 of the central housing blocks 28, 30, which have surface finishes and shapes on the outer surfaces 43, 45 of the side walls 39′, 39″ of the two housing blocks 28, 30 that achieve a gapless and flush surface fit. The surfaces 33, 35 are sized to completely cover the surfaces 43 and 45 of the two housing blocks 28, 30.

[0071] Each plate-like pole extension block 32 and 34 may include a pair of counterbored through-holes 54 and 56, whose lateral spacing is equal to the lateral spacing of the threaded hole pairs 44, 46 on the housing blocks 28, 30, and whose spacing along the cavity axis A is such that the housing blocks 28, 30 are fixed in a spaced-apart manner by fastening bolts (not shown) that extend through the holes 54, 56 and are fixed in the threaded holes 46, 47 of the housing blocks 28, 30. Thus, the two housing blocks 28 and 30 may be connected via the lateral pole extension blocks 32, 34 in such a way as to provide a substantially gapless, low-reluctance magnetic path between the thick-walled sections 39′, 39″ of the two housing blocks 28, 30 and the respective magnets 14, 16 received therein, whereby the cavities 36 and 38 and the cylindrical magnets 14, 16 are coaxially aligned and concentric about the axis A, and the vertical surfaces of each housing block 28, 30 are pairwise coplanar.

[0072] In an embodiment, a lower cylindrical magnet 16 magnetized in a diametrical direction is received and fixed against rotation in a cavity 38 of a lower housing block 30 such that the N-S pole separation line (as shown by the diametrical line D on the top surface of the magnet 16) extends across relatively positioned thin-wall webs 37′ and 37″ of the block 30. In other words, the N-S axis of the permanent magnet 16, which is perpendicular to the separation line and is shown by the arrow ML, is oriented such that the opposing housing sidewalls 39′ and 39″ (and the respectively associated pole extension blocks 32, 34) are magnetized according to the active magnetic poles beside them. In Figure 1 this case, the wall portion 39″ is thus magnetized as an S pole, while the wall portion 39′ becomes an N pole.

[0073] Conversely, since in the absence of the pole extension blocks 32, 34, an upper cylindrical magnet 14 within the top housing block 28 rotates about an axis A and is free to rotate relative to the lower housing block 30 having the fixed magnet 14, the magnetic poles of the sidewalls 39′ and 39″ will be determined by the relative rotational position and orientation of the N-S axis MU of the upper magnet, as Figure 1 schematically shown in

[0074] In an embodiment, the upper magnet 14 is configured to be rotatable 180 degrees from the orientation shown in Figure 1 to a rotational position in which its N pole coincides with the N pole of the lower magnet 16 and, conversely, the S poles overlap each other (and the N-S axes MU and ML are oriented parallel). When the N-S axes MU and ML are oriented parallel, the two sidewalls 39′ of the upper housing block 28 and the lower housing block 30 will be magnetized by the same N magnetic poles, and the same applies to the adjacent pole extension blocks 32. Further, the other (opposing) sidewalls 39″ will be magnetized by the same but opposite S magnetic poles, and the same will apply to the adjacent pole extension blocks 34. This reorientation of the upper magnet 14 will create an “effective” working air gap at the lower axial end surfaces 50, 52 of the pole extension blocks 32, 34, enabling the formation of a closed magnetic circuit with a low magnetic resistance that starts and ends at the magnets 14, 16 and passes through the housing block walls 39′, 39″, the pole extension blocks 32, 34, and ferromagnetic workpieces that may contact the two lower axial end faces 50, 52 of the pole extension blocks 32, 34. Thus, the pole extension blocks 32, 34 form the workpiece contact interface of the device 10. That is, the pole extension block 34 forms the N-pole portion of the workpiece contact interface of the device 10, while the pole extension block 32 forms the S-pole portion of the workpiece contact interface of the device 10. In other embodiments, one or more other portions of the housing block 30 may form the workpiece contact interface of the device 10. This state is referred to herein as the device 10 being in an “on” state, and / or may be referred to as the upper magnet 14 being in a second position ( Figures 9A to 9C as shown in Figure 9Ais a front view cross-section of the device 10, and Figures 9B to 9C is a top view of the device 10). Conversely, the state in which MU and ML are oriented in reverse parallel and form a closed magnetic circuit within the device 10 is referred to as the device 10 being in the "off" state, and / or the upper magnet 14 being in the first position (shown in Figure 1 and Figures 3A to 3C wherein, Figure 3A is a front view cross-section of the device 10, Figure 3B is the top view of the device depicted in Figure 3B and Figure 3C is the partial top view cross-section of the device depicted in Figures 3A to 3B and includes the top magnet when the device is in the "off" position.).

[0075] In an embodiment, the thin ferromagnetic chassis 18 can be press-fitted or otherwise fixed so as to enclose the lower open end of the closed cylindrical cavity 38 in order to seal the cavity 38 and the magnets 16 received therein from contamination at the working face of the magnet device 10. The ferromagnetic properties of the disc 18 can assist in completing the magnetic circuit by providing additional magnetizable material between the magnetic poles of the housing block such that the magnetic field of the lower permanent magnet 16 couples exclusively with the magnetic material provided in the housing block 28 and the pole extension blocks 32, 34 so as to form a magnetic circuit in the on or off position. This also allows the device 10 to operate with a greater holding force when on, and to cancel any holding force when off.

[0076] As described above, the apparatus 10 further includes a multi-component support and spacing structure 20 located between the upper magnet 14 and the lower magnet 16, which is designed to support the upper magnet 14 within the cylindrical wall of the cavity 36 of the upper housing block 28 and maintain a set axial distance between the lower circular surface of the upper magnet 14 within the lower housing block 30 and the upper circular surface of the lower magnet 16. In an embodiment, the support and spacing structure 20 may include a circular base plate 60 of non-magnetizable metal material, a rotary bearing 62, and a base member 64 including a circular non-magnetic plate 63, the upper surface of the circular non-magnetic plate 63 being preferably coated with a PTFE coating to facilitate sliding and its lower surface having a boss or shaft (not shown) integrally formed therewith. The base plate 60 rests on the upper surface of the lower magnet 16 and closes the upper open end of the cylindrical cavity 38 by preferably a press fit into the lower magnet 16. A ball bearing or other type of bearing 62 may be seated in a suitably sized cylindrical recess (or seat) 61 in the upper surface of the base plate 60. The shaft of the base may be seated within the inner race bearing portion of the bearing 62. The diameter of the non-magnetic circular plate 63 is such that it can rotate within the lower terminal axial end of the cavity 36 of the upper housing block 28, i.e., the non-magnetic circular plate 63 has a diameter similar to that of the upper magnet 14, the lower axial end face of which upper magnet 14 is seated on the non-magnetic circular plate 63.

[0077] To maintain the upper magnet 14 coaxially centered within the cylindrical cavity 36 of the upper housing block 28, centering may be effected by a top cap 22 that covers the upper axial end face 42 of the upper housing block 28. A through-hole 66 may extend along the central axis A of the upper cylindrical magnet 14, terminating at opposite axial end faces of the magnet 14 in correspondingly diameter-increased counterbores into which non-magnetic bearings (not shown) flush with the axial end faces of the cylindrical magnet 14 are press-fitted. The combination of the through-hole 66 and the bearings at either axial end of the magnet 14 allows the provision of a shaft 69 that is rotatably supported in or fixed to the cap member 22 to be received within the upper magnet 14, thereby rotatably centering the magnet within the top housing block 28.

[0078] The support structure 20 may be replaced by different types of arrangements, in which the upper magnet 14 is fixed to the shaft 69 by a retaining snap ring (not shown) to prevent axial displacement while allowing its free rotation, and the retaining snap ring may be fixed to an annular groove near the terminal lower end of the shaft 69, which annular groove will project slightly beyond the opening 66.

[0079] The non-magnetizable cap member 22 is in Figure 1 and Figure 2The illustrated embodiment includes a simple rectangular plate 84 with an arcuate window 85 as described below, and a non-magnetizable cap member 22 can be fastened to the housing block itself. To fasten the non-magnetizable cap member 22 to the housing block, four threaded holes can extend vertically at the corners of the upper axial end face 42 of the upper housing block 28. Fastening bolts (not shown) can extend through holes in the cap member 22. Alternatively, the cap member 22 can be fixed to the pole extension blocks 32, 34 via bolts or other fasteners or press-fitted over the upper part of the entire housing assembly.

[0080] In an embodiment, the cap member 22 can include a part of a stop, a pin, and / or a latch mechanism 83 that operates to hold the rotational state of the upper magnet 14 within its housing block 28 and thus also fix the relative rotational position relative to the fixed lower magnet 16. Additionally or alternatively, the stop, pin, and / or latch mechanism 83 can limit and / or provide end points for the rotation of the upper magnet 14. Additionally or alternatively, the stop, pin, and / or latch mechanism 83 can be included in the housing block 28 or another part of the device 10. The stop, pin, and / or latch mechanism 83 can be a retractable pin as described in U.S. Patent Application No. 15 / 965,582, titled "Variable Field Magnetic Couplers and Methods for Engaging Ferromagnetic Workpieces," filed on April 27, 2018, the entire disclosure of which is expressly incorporated herein by reference.

[0081] The cap member 22 can further be configured to support / accommodate various electronic control and power components associated with the solenoid coil body 24 and that are required to supply current to the solenoid coil body 24, as will be described below. Alternatively, the cap member 22 can include contact leads for connection to a power source (not shown) that supplies current to the solenoid coil body 24.

[0082] As described above, the shaft 69 penetrates through the through-hole 66 in the upper magnet 14 such that the upper magnet 14 can rotate coaxially about the shaft 69. In the illustrated embodiment, the shaft 69 is a cylindrical pin that is welded or otherwise fixed to the central hub portion 86 of the cap member 22. Alternatively, a rotatable shaft may be employed that extends through the bottom of the cap member 22 via the through-hole, and bearings will surround the through-hole and the shaft to seat it centrally and facilitate the rotation of the upper magnet 14 about the shaft 69. Above the portion of the bearing shaft 66 and other mechanical components of the cap member 22, a second portion (not shown) of the cap member 22 may be integral with or assembled to it and may be allocated for accommodating electronic components not shown. This portion is isolated from the mechanical portion of the assembly to prevent mechanical damage to the circuitry; however, the shaft 69 may extend into the electronic housing section to allow a feedback device such as an encoder or limit switch to be attached to the shaft, thereby allowing the control circuit to detect the angular displacement of the upper magnet 14 relative to the lower magnet 16 and / or a set reference point.

[0083] As Figure 1 shown, the non-magnetic plate 84 of the cap member 22 can be machined to have a shape similar to that of the housing blocks 28, 30, i.e., rectangular, with a central arcuate window 85, the outer diameter of which corresponds to the outer diameter of the central cavity 36 of the upper housing block 28. The center of curvature of the arcuate window 85 can coincide with and be coaxial with the axis A of the cylindrical cavity 36. The central web portion 86 defines the radial inner boundary of the arcuate window 85 and carries the aforementioned support shaft 69 for centering the upper magnet 14 within the upper housing block 28. The opposite ends 87, 88 of the arcuate window 85 provide "hard stops" for preventing rotation of the member 89 fixed to the upper surface of the magnet 14 such that the rotation of the magnet 14 can travel within the slot 85 during the switching operation of the device 10. As will be explained below, the hard stops 87, 88 and the anti-rotation block 89 can cooperate to limit the rotation of the upper magnet 14 within the cavity 36 between two end positions that define the on and off positions of the device.

[0084] The fixed shaft 69 projects perpendicularly to the hub defined by the central web portion 86 such that the positioning of the shaft 69 by the mounting of the cap member 22 mates with the upper magnet 14 to ensure its concentric rotation within the cylindrical cavity of the upper housing block 28.

[0085] As Figure 2As shown, the solenoid coil body 24 may include an enamel-coated copper wire winding that surrounds (or is otherwise placed) around the upper housing block 28. However, as described above, the solenoid coil body 24 may also surround or otherwise be placed around the upper magnet 14. The solenoid coil body 24 may be placed such that the vertical extension sections 72, 76 of the solenoid coil body 24 extend along the paired vertical side surfaces 43, 45 of the upper housing block 28, and the horizontal extension sections 75, 77 are parallel to the lower axial end face of the (invisible) housing block 28 and parallel to one of the upper axial end face 42 of the upper housing block 28 or the upper surface of the plate 84 of the cap member 22.

[0086] In an embodiment, the solenoid coil body 24 may include a plurality of solenoid coil bodies. For example, the solenoid coil body 24 may include two solenoid coil bodies that are electrically isolated from each other and extend diagonally from one corner of the housing block 28, along the top surface 42 of the upper housing block 28, to the opposite corner of the housing block 28 located below the top housing block 28. The corresponding coils may be wound around the upper housing block 28 and the cap member 22 on opposite diagonals, one coil wound on top of the other, such that they form an "X" shaped winding when viewed in a top plan view of the housing block 28. In Figure 1 the embodiment, the windings may be guided on the horizontal extension section below the upper housing block 28 to define a through hole 79 around the axis A (as Figure 1 can be seen) to allow the upper magnet 14 to pass downward through the support rod 62 of the base 64 of the support structure 20 in such a way that the upper magnet 14 is rested on the lower magnet 16 via the support rod 62.

[0087] In an embodiment where the solenoid coil body 24 surrounds the upper housing block 28 before the cap member 22 is fixed to the upper housing block 28, the horizontal extension sections 75, 77 above the upper housing block 28 may be guided to define a through hole (not shown) around the axis A to allow a centering shaft or pin 69 to pass through. The centering shaft or pin 69 extends downward from the cap member 22 into the upper rotatable magnet 14 to center its coaxial rotation within the cylindrical cavity 36 of the upper housing block 28.

[0088] In an embodiment, a power supply 82 may be connected to the solenoid coil body 24 via a suitable control circuit to supply current to the solenoid coil body 24 to induce an H field on the upper magnet 14, thereby assisting the upper magnet 14 to rotate from the off position to the on position.

[0089] Specifically, Figure 4A 、 Figure 5A 、 Figure 6A 、 Figure 7A and Figure 8ADepicts a top view of the device 10 as it transitions from the off position to the on position, and more specifically, Figure 4A , Figure 5A , Figure 6A , Figure 7A and Figure 8A depicts a top view of the B-field generated by the magnets 14, 16 on the housing block 28. Figure 4B , Figure 5B , Figure 6B , Figure 7B , Figure 8B shows the direction of the current flowing through the electromagnetic solenoid body 24. Figure 4C , Figure 5C , Figure 6C , Figure 7C , Figure 8C shows the H-field generated by the current flowing through the solenoid coil body 24. Figure 4D , Figure 5D , Figure 6D , Figure 7D , Figure 8D shows the net magnetization state of the upper housing block 28 due to the reorientation of the rotatable upper magnet 14 and the superimposed H-field. And, Figure 4E , Figure 5E , Figure 6E , Figure 7E , Figure 8E shows the rotational position of the upper magnet 14 and its N-S pole axis MU starting from the "off" state and sequentially to the "on" state.

[0090] As Figures 4A to 8E depicted therein, the solenoid coil body 24 can induce an H-field in order to change the magnetization pattern experienced by the upper housing block 28 according to the rotational position of the upper magnet 14 received therein. That is, by applying a voltage to the windings of the solenoid coil body 24 and thus causing a current to flow, a magnetic field H-field will be generated within the perimeter of the coil. The H-field is perpendicular to the current direction and its N-S orientation vector will be determined by the direction of the current circulation within the solenoid coil body 24. It can also be understood that a distinction can be made between the H-field and the B-field. The H-field is defined as the magnetic field intensity and is alternatively referred to as the magnetization field, and will be used to represent the effect of the solenoid coil body 24 acting on the housing block 28. The B-field is the magnetic flux and is essentially a combination of an electrical or permanent magnetic field source and the magnetization intensity of the medium. Since the B-field is typically considered when calculating the mechanical torque applied to a magnetic dipole, the B-field will be used when referring to the rotation of the upper magnet 14 and the switching operation of the device as described below.

[0091] The H-field generated by the solenoid coil body 24 will depend on the number of turns of the coil winding, the cross-section of the coil, and the current within the solenoid coil body 24. When the upper magnet 14 is in the first position (e.g., as shown in Figure 1 , Figures 4A to 4E ), at least one component of the H-field generated by the solenoid coil body 24 will point from S to N along the active N-S pole pair of the upper magnet 14. Since the H-field is generated by applying a voltage across the solenoid coil body 24 and thereby generating a current, depending on the relative permeability of the ferromagnetic material including the housing block 28, the upper housing block 28 will be magnetized to a certain extent. In at least one example, when the upper magnet 14 rotates from the off position to the on position, the intensity of the H-field generated by the solenoid coil body 24 can be constant. In another example, when the upper magnet 14 rotates from the off position to the on position, by changing the current flowing through the solenoid coil body 24, the intensity of the H-field generated by the solenoid coil body 24 can be changed. Additionally or alternatively, when the upper magnet 14 rotates from the off position to the on position, by changing the direction of the current flowing through the solenoid coil body 24, the direction of the H-field generated by the solenoid coil body 24 can be changed to facilitate providing a braking function and / or to assist the upper magnet in rotating from the on position to the off position.

[0092] In at least some embodiments, the H-field generated by the solenoid coil body 24 can be oriented at an angle relative to the B-field generated by the upper magnet 14 (shown in Figures 4A to 4E ). In these embodiments, the magnetization of the housing block 28 in turn generates a B-field within the volume of the housing block 28, which can apply a mechanical torque to the upper magnet 14.

[0093] As depicted in Figures 4A to 8E , the device 10 can be switched from an "off" state ( Figures 4A to 4E ) to an "on" state ( Figures 8A - 8E ), in which in the "off" state, even when in contact with the lower surfaces 50, 52 of the passive pole blocks 32, 34, there is no or relatively little magnetic field available for ferromagnetic workpieces, and in the "on" state, the passive pole blocks 32, 34 are magnetized with opposite magnetic poles, and by bringing the passive pole blocks 32, 34 into contact with a ferromagnetic workpiece, an external flux exchange path can be created, thereby magnetically attaching the device 10 to the workpiece.

[0094] In the "off" switching position of the device 10, the upper permanent magnet 14 in the top housing block 28 and the lower magnet 16 in the bottom housing block 30 are rotationally arranged such that when viewed in a top view of the device 10, such as Figure 1 and Figure 4AAs shown, the N pole of the upper magnet is approximately aligned with the S pole of the lower magnet 16, and the S pole of the upper magnet 14 is approximately aligned with the N pole of the lower magnet 16. That is, the magnetic N-S axes MU and ML of the upper and lower magnets are aligned parallel to each other in opposite directions. In this off state of the device 10, there is a closed magnetic circuit via the thick-walled sections 39′, 39″ between the magnets 14, 16 and the housing blocks 28, 30 around the cavity that houses the magnets 14, 16 and a pair of pole extension blocks 32, 34 to provide a low magnetic resistance flux path between the upper housing block 28 and the lower housing block 30, thereby effectively shunting the circuit within the device 10.

[0095] To turn the device 10 to the "on" position, where the pole shoes and / or the pole extension blocks 32 and 34 at the lower ends of the wall sections 39′, 39″ present opposite magnetic poles, current can be supplied to the solenoid coil body 24, as Figure 4B 、 Figure 5B 、 Figure 6B 、 Figure 7B 、 Figure 8B depicted. When the solenoid coil body 24 is activated, the induced magnetic field depicted in Figure 4C 、 Figure 5C 、 Figure 6C 、 Figure 7C 、 Figure 8C changes the direction and net magnitude of the generated B-field vector (provided by the vectors of the permanent magnet and the coil magnet). When the upper magnet 14 rotates from the off position to the on position (as depicted in Figure 4E 、 Figure 5E 、 Figure 6E 、 Figure 7E 、 Figure 8E ), the direction and net magnitude of the B-field vector magnetize the upper housing block 28 (as depicted in Figure 4D 、 Figure 5D 、 Figure 6D 、 Figure 7D 、 Figure 8D ).

[0096] An electrically generated magnetic field can be selected to influence and change the magnetic circuit formed between the two permanent magnets 14, 16 and the adjacent housing wall sections 39', 39". With sufficient current, the magnetic field component in the top housing block 28 generated by the fixed lower magnet 16 in the bottom housing block 30 via the wall sections 39', 39" and / or the connecting pole extension blocks 32, 34 can be eliminated, thus canceling the magnetic influence of the lower magnet 16 on the upper magnet 14. Then, in addition to the rotatable magnet 14 itself, the magnetic field generated by the solenoid coil body 24 will remain as the main magnetic field source in the top housing block 28. As a result, it will require less torque to rotate the upper magnet 14 from the first position to the second position to switch the switchable magnet device to the "on" position. In some exemplary embodiments, when the upper magnet 14 is in the first position (as shown in Figure 4B , Figure 5B , Figure 6B , Figure 7B and Figure 8B ), the solenoid coil body 24 can be oriented at an angle relative to the upper magnet 14, which will apply a torque on the upper magnet 14.

[0097] In at least one example, the solenoid coil body 24 can include more than one coil oriented in different directions. If the coils of the solenoid coil body 24 are supplied with current in a certain direction, assuming that the magnetic field generated by the solenoid coil body 24 rotates away from the inherent magnetic field generated by the upper magnet 14 in its off position and at least one component of the H field is not parallel to the inherent magnetic field generated by the upper magnet 14, a torque is generated because as the upper magnet 14 attempts to realign the N-S axis MU onto the magnetizable wall sections 39', 39" of the top housing block 28 to follow the induced B magnetic field axis and the magnetic poles induced by the solenoid coil body 24, it will rotate within the top housing block 28 without being affected by other external influences.

[0098] Assuming that the induced B field due to the magnetization of the housing block 28 applies sufficient torque to the magnet 14, the upper magnet 14 can rotate until the corresponding N and S poles of the upper magnet 14 are aligned with the corresponding N and S poles of the lower magnet 16, such that the unit 10 is in the "on" state. At this time, the solenoid coil body 24 can be deactivated. As shown in Figures 9A to 9CAs shown, in the case where both permanent magnets 14, 16 have parallel N-S axes oriented in the same direction, the thick-walled sections 39' and 39'' of the housing blocks 28, 30 and / or the pole extension blocks 32, 34 are magnetized by opposite magnetic poles. As a result, the device 10 effectively forms a permanent dipole magnet which, when in contact with the active pole extension tracks or "boots" 32, 34, can form a closed magnetic circuit with an external ferromagnetic workpiece without continuously applying power to the solenoid coil body 24. Additionally or alternatively, a stop, pin and / or latch mechanism 83 may be included in the housing block 28 or another part of the device 10 to substantially hold the upper magnet 14 in the second position.

[0099] The "on" position of the device is a stable but labile position, i.e., a point at the top of a saddle-shaped magnetic potential curve defined by two interacting permanent magnetic fields, where a small external force, magnetic imbalance, or deviation of the N-S axes of the magnets from true parallelism between the permanent magnets 14, 16 of the device 10 will create a magnetic field between the two magnets 14, 16 in the housings 28, 30 to naturally apply a small torque which may be sufficient to return the upper magnet 14 to the off position, i.e., to enter a magnetically stable low potential state by itself. Thus, and as elaborated above, for practical reasons and to accommodate manufacturing tolerances, the device 10 may include a stop, pin and / or latch mechanism 83 to selectively hold the upper magnet 14 in the "on" position of the device and release the upper magnet when appropriate. As described above, this may be a simple hard stop arrangement. By way of example, this may include an arm member and two detent blocks, the arm member being attached to a shaft 69 rotatably coupled to the upper magnet 14, the two detent blocks being mounted on the top cap member 22 at positions about the axis of rotation of the shaft 69 about the shaft 69, indicating the "on" and "off" positions of the device 10.

[0100] Preferably, the stop, pin and / or latch mechanism 83 may be included in an arcuate slot 85 of the cap member 22, in particular the terminating, radially extending ends 87, 88 of the slot 85, and a non-magnetic material detent block 89 which is fixed to prevent it from protruding upwardly from the top surface of the upper magnet 14 and which is shaped (in plan view) to mate within and travel in the arcuate slot 85 as the upper magnet 14 rotates between the end stops. In other words, the length of the arcuate slot is at least 180 degrees to allow the upper rotatable magnet 14 to reach an orientation where its N-S axis MU is parallel or anti-parallel to the N-S axis ML of the fixed magnet 16.

[0101] Preferably, the arcuate slot 85 will extend over an arc greater than 180 degrees to provide a hard stop 88 against which the block 89 is fixed to the upper magnet 14 for rotation therewith, the hard stop 88 staying where the upper magnet 14 has rotated slightly beyond the "fully on" position. At this "over-rotated" position, the B-field of the lower magnet 16 exerts a large enough torque on the upper magnet 14 to bias the upper magnet 16 to hold the stop position at the hard stop 88.

[0102] By correctly sequencing a set of isolated biasing coils included in the solenoid coil body 24 (in the embodiment, a plurality of solenoid coils included in the solenoid coil body 24), then, the upper magnet 14 can rotate 180 degrees from a starting position where the reference line indicating the off position of the indicating device 10 is 0 degrees (see Figures 4A to 4E ) to the fully on position of the device 10, and a little further between 180 degrees and 185 degrees, to strike the hard stop, as shown in Figures 8A to 8E . As a result, the upper magnet 14 remains close to being fully aligned with the lower magnet 16, but is locked in position against the hard stop, thus allowing the device to remain "on" in a fault-free state.

[0103] A stop, pin, and / or latch mechanism 83 can be used to stop the upper magnet 14 before it rotates 180 degrees. In one of these intermediate states, the field strength (or level) of the device 10 at the workpiece contact interface is greater than the field strength (or level) when the device 10 is in the "off" state and less than the field strength (or level) when the device 10 is in the "on" state. As a result of being in one of these intermediate states, the device 10 can be configured to produce a variable magnetic field. Additional details regarding an exemplary variable magnetic field system are provided in U.S. Patent Application No. 15 / 965,582, filed on April 23, 2018, titled "Variable Magnetic Field Magnetic Coupler and Method for Engaging Ferromagnetic Workpieces" (Docket No. MTI-0016-02-US), the disclosure of which is hereby expressly incorporated by reference.

[0104] By briefly reversing the order of energy supply to a set of isolated, biased coils in the solenoid coil body 24, the upper magnet 14 can be "pulled" out of the hard stop by the B-field induced in the coil and rotated more than 180 degrees in the opposite direction of "on" rotation; once past the fully on point, due to the B-field of the lower magnet 16, the upper magnet 14 will naturally attempt to return to the off position, allowing the device 10 to effectively switch itself to the "off" state beyond the current pulse that would otherwise be required to achieve a torque sufficient to counteract the stop bias torque. Once off, the pole extensions 32, 34 and / or workpiece coupled to the device 10 can be demagnetized. In an embodiment, the device 10 can include a mechanism to lock the upper magnet 14 in the first position while demagnetizing the pole extensions 32, 34 and / or workpiece coupled to the device 10. Additional details regarding a system that provides a demagnetization function are provided in U.S. Patent Application No. 15 / 964,884, filed Apr. 27, 2018, titled "Magnetically Coupled Device Having at Least One Sensor Arrangement and Demagnetization Function" (Docket No. MTI-0013-02-US), the entire disclosure of which is expressly incorporated herein by reference.

[0105] In addition, this turn-off process can be used to advantage for the coil drive electronics. As the upper magnet 14 rotates back to the off position, the orientation of the magnetic field of the rotating upper magnet 14 changes with respect to the plane normal of the coils included in the solenoid coil body 24, i.e., a B-field rotating through a stationary current conductor, i.e., the coil windings. This induces a voltage in the coils included in the solenoid coil body 24, and thus an induced coil current. Appropriate drive and control circuitry with an energy storage device (capacitor, battery) can be provided at the cap member 22 to capture the power and return it to the coil drive circuitry, thereby recovering some of the energy lost in the process of applying torque (magnetic) to the upper magnet 14 to switch the device 10 from the off state to the on state.

[0106] Due to this cycling and design of the device 10 and the possibility of energy recovery, the preferred embodiments of the present invention represent a significant improvement over the prior art. Unlike existing electro-permanent magnet systems that require a large current to be applied to a magnetization coil to actuate and deactivate the device, the embodiments of the present invention described above require power only for a short time during half of the switching cycle and, during the deactivation half of the switching cycle, can recover most of the power invested in switching the device 10 from its off state to its on state. This can significantly improve efficiency compared to existing electro-permanent magnet systems with fixed magnets.

[0107] Additionally, under certain conditions, an electro-permanent magnet system is inherently limited in its ability to form a magnetic circuit. Although the magnetic flux output of AlNiCo magnets, which are commonly used as switchable magnets in electro-permanent magnet systems, can be as high as that of modern rare-earth magnets, the coercivity of AlNiCo is significantly lower than that of rare-earth magnetic substrates. In a "loaded" magnetic circuit where there are multiple air gaps or materials with relatively low magnetic permeability, AlNiCo will not be able to maintain a large magnetization, greatly affecting the overall strength of the generated magnetic field.

[0108] In a preferred embodiment of the present invention, the permanent magnet elements are all composed of the same rare-earth magnetic material and thus all have the same high coercivity. Therefore, even in an extremely unfavorable magnetic circuit, the device 10 according to the present invention can maintain a magnetic field strength greater than that of a corresponding electro-permanent magnet unit and active magnetic material of comparable size. This greatly expands the flexibility of the electro-actuated switchable permanent magnet system.

[0109] Figure 10A is a side view of another embodiment of the electro-switchable permanent magnet device 10'; Figure 10B is in Figure 10A a side view of the electro-switchable permanent magnet device depicted in, where the cap structure 22 and the solenoid coil body 24 are removed from the device; and, Figure 10C is in Figure 10A and Figure 10B a side cross-sectional view of the electro-switchable permanent magnet device depicted in. Like reference numerals represent corresponding like parts.

[0110] The function of the device 10' is similar to that of the device 10, but the device 10' includes a one-piece housing 31 instead of the two-piece housing included in the device 10. To accommodate the solenoid coil body 24 and the upper magnet 14, the housing 10' includes a cutout 90 for receiving the solenoid coil body 24. Similar to the device 10, the upper magnet 14 of the device 10' is disposed within the solenoid coil body 24. And, the lower magnet 16 is disposed within the bottom of the housing 31 ( Figure 10C shown in). Once the lower magnet 16 and the solenoid coil body 24 are disposed within the cutout 90 of the housing 10', the cap structure 22 is fixed to the top of the housing 31.

[0111] In an exemplary embodiment, the devices 10, 10' can be incorporated into a robotic system. Referring to Figure 11 , an exemplary robotic system 700 is shown. Although the robotic system 700 is depicted in Figure 11 , the embodiments described with respect to it can be applied to other types of machines (e.g., cranes, pick-and-place machines, etc.).

[0112] The robotic system 700 includes an electronic controller 770. The electronic controller 770 includes additional logic stored in an associated memory 774 for execution by a processor 772. A robotic motion module 702 is included, which controls the movement of a robotic arm 704. In the illustrated embodiment, the robotic arm 704 includes a first arm segment 706 that is rotatable relative to a base about a vertical axis. The first arm segment 706 is movably coupled to a second arm segment 708 by a first joint 710, at which the second arm segment 708 can rotate relative to the first arm segment 706 in a first direction. The second arm segment 708 is movably coupled to a third arm segment 711 by a second joint 712, at which the third arm segment 711 can rotate relative to the second arm segment 708 in a second direction. The third arm segment 711 is movably coupled to a fourth arm segment 714 by a third joint 716, at which the fourth arm segment 714 can rotate relative to the third arm segment 711 in a third direction and on a rotary joint 718, whereby the orientation of the fourth arm segment 714 relative to the third arm segment 711 can be changed. A magnetic coupling device 10 is schematically shown as being secured to the end of the robotic arm 704. The magnetic coupling device 10 is used to couple a workpiece 27 (not shown) to the robotic arm 704. Although the magnetic coupling device 10 is shown, any one and any number of the magnetic coupling devices described herein can be used with the robotic system 700.

[0113] In one embodiment, the electronic controller 770, by executing the robotic motion module 702 with the processor 772, moves the robotic arm 704 to a first pose at which the magnetic coupling device 100 contacts the workpiece at a first location. The electronic processor 770, by executing the magnetic coupler status module 776 with the processor 772, instructs the magnetic device 10 to move the upper magnet 12 relative to the lower magnet 14 to place the magnetic coupling device 10 in an on state for coupling the workpiece to the robotic system 700. The electronic controller 770, by executing the robotic motion module 702 with the processor 772, moves the workpiece from the first location to a second desired spaced location. Once the workpiece is in the second desired location, the electronic controller 770, by executing the magnetic coupler status module 776 with the processor 772, instructs the magnetic device 10 to move the upper magnet 12 relative to the lower magnet 14 to place the magnetic coupling device 10 in an off state for decoupling the workpiece from the robotic system 700. The electronic controller 770 then repeats the process to couple, move, and decouple another workpiece.

[0114] In one embodiment, the disclosed magnetic device includes one or more sensors to determine characteristics of a magnetic circuit present between the magnetic device and a workpiece to be coupled to the magnetic device. More details of an exemplary sensor system are provided in U.S. Patent Application No. 15 / 964,884, filed Apr. 27, 2018, entitled “Magnetic Coupling Device with at Least One Sensor Arrangement and Demagnetization Capability” (Docket No. MTI-0013-02-US), the entire disclosure of which is expressly incorporated herein by reference.

[0115] Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the invention. For example, although the embodiments described above relate to specific features, the scope of the invention also includes embodiments having different combinations of features and embodiments not including all of the described features. Accordingly, the scope of the invention is intended to cover all such alternatives, modifications, and variations falling within the scope of the claims and all equivalents thereof.

Claims

1. A magnetic coupling device for magnetically coupling with a ferromagnetic workpiece, comprising: A plurality of magnetic pole portions, the plurality of magnetic pole portions being arranged in parallel at intervals along a first horizontal axis, and each magnetic pole portion of the plurality of magnetic pole portions having a workpiece contact interface; A plurality of permanent magnets, the plurality of permanent magnets being positioned relative to the plurality of magnetic pole portions, the plurality of permanent magnets including: A first permanent magnet of the plurality of permanent magnets, which is located between a first magnetic pole portion and a second magnetic pole portion of the plurality of magnetic pole portions and is positioned to be vertically offset from the workpiece contact interfaces of the first magnetic pole portion and the second magnetic pole portion, and A second permanent magnet, which is located between at least two magnetic pole portions of the plurality of magnetic pole portions and is positioned to be vertically offset from the workpiece contact interfaces of at least two magnetic pole portions of the plurality of magnetic pole portions, and Wherein each of the first permanent magnet and the second permanent magnet is vertically spaced apart and fixed along a vertical axis perpendicular to the horizontal axis; A plurality of electrical windings, the plurality of electrical windings being wound around the first permanent magnet, extending above the top and below the bottom of the first permanent magnet, and the plurality of electrical windings being positioned between the first magnetic pole portion and the second magnetic pole portion of the plurality of magnetic pole portions; And An electronic controller, the electronic controller being operatively coupled to the plurality of electrical windings and controlling the magnetic circuit through the ferromagnetic workpiece at the workpiece contact interfaces of the plurality of magnetic pole portions, Wherein the electronic controller establishes a first state of the magnetic circuit through the ferromagnetic workpiece at the workpiece contact interfaces of the plurality of magnetic pole portions in a first configuration having the plurality of permanent magnets, and establishes a second state of the magnetic circuit through the ferromagnetic workpiece at the workpiece contact interfaces of the plurality of magnetic pole portions in a second configuration having the plurality of permanent magnets.

2. The magnetic coupling device according to claim 1, wherein, The electronic controller causes the magnetic circuit to transition between the first state and the second state by controlling the current passing through the plurality of electrical windings.

3. The magnetic coupling device according to claim 2, wherein when the magnetic circuit is in the first state, the first state is maintained without current passing through the electrical windings.

4. The magnetic coupling device according to claim 1, wherein When the magnetic circuit is in the first state, the first state is maintained without current passing through the electrical windings.

5. The magnetic coupling device according to claim 1, wherein, The plurality of electrical windings are positioned to be vertically offset from the workpiece contact interfaces of the first magnetic pole portion and the second magnetic pole portion.

6. The magnetic coupling device according to claim 1, wherein, The first permanent magnet is vertically positioned between the lower surface and the upper surface of the first magnetic pole portion.

7. The magnetic coupling device according to claim 1, wherein, In the first state, when the ferromagnetic workpiece contacts the workpiece contact interfaces of the plurality of magnetic pole portions, a first horizontal magnetic field is available for the ferromagnetic workpiece.

8. The magnetic coupling device according to claim 7, wherein, In the second state, when the ferromagnetic workpiece contacts the workpiece contact interfaces of the plurality of magnetic pole portions, a second horizontal magnetic field is available for the ferromagnetic workpiece, and the second horizontal is greater than the first horizontal.

9. The magnetic coupling device according to claim 1, wherein, The first permanent magnet is a rare earth magnet.

10. The magnetic coupling device according to claim 1, wherein, The second permanent magnet is a rare earth magnet.

11. The magnetic coupling device according to claim 1, wherein, The first permanent magnet can move relative to the second permanent magnet.

12. The magnetic coupling device according to claim 1, wherein, At least two of the plurality of pole portions are the first pole portion and the second pole portion.

13. A magnetic coupling device for magnetically coupling to a ferromagnetic workpiece, comprising: A housing having an upper portion and a lower portion, the upper portion including a recess between a first pole portion of the housing and a second pole portion of the housing, the first pole portion being magnetically coupled to a first workpiece contact interface supported by the housing, and the second pole portion being magnetically coupled to a second workpiece contact interface supported by the housing; A plurality of permanent magnets positioned relative to the first pole portion of the housing and the second pole portion of the housing, the plurality of permanent magnets including: A first permanent magnet of the plurality of permanent magnets, which is located between the first pole portion of the housing and the second pole portion of the housing and is within the upper portion of the housing, and A second permanent magnet, which is located between the first pole portion of the housing and the second pole portion of the housing and is positioned to be vertically offset from the first permanent magnet within the lower portion of the housing, Wherein each of the first permanent magnet and the second permanent magnet is fixed along a vertical axis extending through the first permanent magnet and the second permanent magnet; A plurality of electrical windings wound around the first permanent magnet, the plurality of electrical windings being positioned between the first pole portion of the housing and the second pole portion of the housing; and An electronic controller operatively coupled to the plurality of electrical windings and controlling the magnetic path through the ferromagnetic workpiece at the first workpiece contact interface and the second workpiece contact interface Wherein the electronic controller establishes a first state of the magnetic path through the ferromagnetic workpiece at the first workpiece contact interface and the second workpiece contact interface in a first configuration having the plurality of permanent magnets, and establishes a second state of the magnetic path through the ferromagnetic workpiece at the first workpiece contact interface and the second workpiece contact interface in a second configuration having the plurality of permanent magnets.

14. The magnetic coupling device according to claim 13, further comprising a top cap structure fixed to the housing to cover the recess.

15. The magnetic coupling device according to claim 14, wherein, The electronic controller causes the magnetic path to transition between the first state and the second state by controlling the current through the plurality of electrical windings.

16. The magnetic coupling device according to claim 15, wherein when the magnetic path is in the first state, the first state is maintained without current passing through the electrical windings.

17. The magnetic coupling device according to claim 13, wherein when the magnetic path is in the first state, the first state is maintained without current passing through the electrical windings.

18. The magnetic coupling device according to claim 13, wherein, The plurality of electrical windings are positioned to be vertically offset from the first workpiece contact interface and the second workpiece contact interface.

19. The magnetic coupling device according to claim 13 further includes a first magnetic pole extension portion coupled to the housing and a second magnetic pole extension portion coupled to the housing, the first magnetic pole extension portion defining the first workpiece contact interface, and the second magnetic pole extension portion defining the second workpiece contact interface.

20. The magnetic coupling device according to claim 13, wherein in the first state, when the ferromagnetic workpiece contacts the workpiece contact interface of the plurality of magnetic pole portions, a first horizontal magnetic field is available for the ferromagnetic workpiece.

21. The magnetic coupling device according to claim 20, wherein in the second state, when the ferromagnetic workpiece contacts the workpiece contact interface of the plurality of magnetic pole portions, a second horizontal magnetic field is available for the ferromagnetic workpiece, and the second horizontal is greater than the first horizontal.

22. The magnetic coupling device according to claim 21, wherein, The electronic controller establishes a third state of a magnetic path through the ferromagnetic workpiece at the first workpiece contact interface and the second workpiece contact interface at a third level in a third configuration having the plurality of permanent magnets, the third level being greater than the first level and less than the second level.

23. The magnetic coupling device according to claim 13, wherein, The first permanent magnet is a rare earth magnet.

24. The magnetic coupling device according to claim 13, wherein, The second permanent magnet is a rare earth magnet.

25. The magnetic coupling device according to claim 13, wherein The first permanent magnet is movable relative to the second permanent magnet.

26. The magnetic coupling device according to claim 13, wherein, The first permanent magnet and the plurality of electrical windings wound around the first permanent magnet are positioned entirely above the second permanent magnet.

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