An electromagnetic mooring system (MMS) that includes a first object and a second object, at least one of which includes an electronic coupler configured to connect the first object with the second object. The electronic coupler comprises a pair of magnets, at least one of which is an electro permanent magnet (EPM), having a flux path. When the electronic coupler is in the ON states, the flux path moves towards the first or second object transferring heat from the first or second object to the second or first object, and when the electronic coupler is in the OFF state, the flux paths moves towards the EPM.

FIELD

The present invention relates to a magnetic coupler, and more particularly, to a thermo-mechanical magnetic coupler to move adjacent small satellites or CubeSats.

BACKGROUND

Hard physical mounting systems consisting of either fasteners or pins, which are used to connect adjacent satellites to form a lattice. These mounting systems allow for the formation of large lattices as well as provide high contact forces required for good thermal conductivity.

This mounting system, however, does not lend itself to autonomous assembly or adaptive reconfiguration. Further, this mounting system requires a complex mechanism to install and torque mechanical fasteners or pins autonomously. The mounting system also requires the use of multiple electromechanical devices with large numbers of moving parts, which otherwise lowers the reliability of the mounting system. For example, if the mechanical system fails for any reason, the satellites within the lattice become non-function.

Thus, an alternative mounting system may be more beneficial.

SUMMARY

Certain embodiments of the present invention may provide solutions to the problems and needs in the art that have not yet been fully identified, appreciated, or solved by current mounting systems for satellite lattices. For example, some embodiments generally pertain to thermo-mechanical magnetic coupler (the “magnetic coupler”).

In an embodiment, a magnetic coupler for an electromagnetic mooring system (MMS) includes at least two magnets, of which at least one is an electro permanent magnet (EPM). Depending on the polarity of the at least two magnets, a heat path may flow between the at least two magnets or flow outwards from the at least two magnets.

In another embodiment, an electromagnetic mooring system (MMS) includes a first object and a second object, at least one of which comprises an electronic coupler that connects the first object and the second object together. The electronic coupler includes a pair of magnets, at least one of which is an EPM, having a reversible flux path. When the electronic coupler is in the ON state, the flux path moves towards the first or second object facilitating the transferring of heat from the first or second object to the second or first object, and when the electronic coupler is in the OFF state, the flux paths moves towards the EPM and the heat transfer is inhibited.

In yet another embodiment, an MMS configured to align a pin and cup thermal and electric interface between a pair of objects. The MMS includes a first object and a second object. The first object includes a female connecting member, which includes liquid, and the second object includes a male connecting member. The male connecting member electrically connects with the female connecting member by way of the liquid.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention generally pertain to a thermo-mechanical magnetic coupler (the “magnetic coupler”). In some embodiments, the magnetic coupler is configured to achieve sufficient mooring forces to maintain the position of individual satellites within a lattice of satellites. The magnetic coupler is further configured to provide a thermal conduction path to facilitate thermal management of the lattice. For example, with a lattice, the sun-side satellites tend to overheat, and the shaded-side satellites tend to overcool. To prevent overheating or overcooling, a thermal conduction path formed by the magnetic couplers transfer the heat from the sun-side (or hot-side) satellites to the shaded-side (or cold-side) satellites.

The magnetic coupler also utilizes an electro permanent magnetic effect found in magnetic material with low magnetic coercivity. Coercivity is the measure of how easily a magnet can be affected by a nearby magnetic field. Materials that can take on the properties of nearby fields are said to have low coercivity. These low coercivity materials are the basis for this magnetic coupler. For example, the magnetic coupler uses a reversible coil to switch the polarity of a low coercivity material (e.g., Alnico) that effectively nulls a high coercivity material (e.g., Neodymium). The ability to null the stronger magnet is the process by which the magnetic coupler connects and disconnects adjacent satellites. It should be appreciated that both states are electrically powered off states. The “ON” state and “OFF” state are in regard to the magnetic flux path. The “ON” state has external magnetic poles, and with the OFF state, all the flux is contained, and has no external magnetic poles.

In another embodiment, an electronic processor may be used to switch the magnetic coupler from an OFF state to an ON state or vice versa. Based on the desired coupling state of the satellite, an electronics controller (not shown) either directly or indirectly through a lower level processor or processors commands the mooring system (e.g., the magnetic coupler) to change states. The state change is accomplished by applying a pulse of current through a coil in the direction that causes an external magnetic field that permanently switches the magnetic polarity of the low coercivity magnet. The pulse of current is controlled by the electronics controller using additional electronics.

The magnetic coupler may include contact pads that are configured to press against contact pads of an adjacent magnetic coupler. In some embodiments, thermal interface material is applied to these contact pads. When the magnetic coupler is switched ON, the magnetic coupler is configured to generate magnetic forces to squeeze the thermal interface material between the contact pads. The squeezing of the thermal interface material increases the real contact area, allowing for thermal conductance of the interface to be maximized. The real contact area may be defined as the surface area over which the two bodies of an interface are in molecular contact. In some embodiments, this is necessary for direct conduction of heat across the interface. Because of mechanical misalignments and/or microscopic surface variation, the entire apparent area of thermal contact pad may not be active in conducting heat. As the pressure is increased, more of the thermal material is forced to comply with the mating contact pad, increasing the real contact area. In other words, without the thermal interface material, transfer of heat between the contact pads by conduction is restricted.

By incorporating the magnetic coupler into satellites, the satellites' operation cost remains low. For example, the magnetic coupler does not require moving parts, nor does the magnetic coupler require power during static operation. This is important in space in the terms of longevity and reliability. For example, cold welding does not affect the magnetic coupler. Further, the magnetic couplers allow the satellites to dock and undock. The docking and undocking of the satellites allows for different lattice formations.

FIG.1is a diagram illustrating a magnetic coupler100, according to an embodiment of the present invention. In some embodiments, magnetic coupler100may be composed of iron (Fe). In other embodiments, magnetic coupler100may be composed of: carbon steel, ferrite, stainless steel, electrical steel (SiFe), mu-metal (NiFe), or other material with high relative magnetic permeability. Magnetic coupler100may also include thermal material104that is applied on contact pads102of magnetic coupler100.

It should be appreciated that thermal material104prevents a cold welding event from occurring. Cold welding occurs when two clean metallic materials are held in contact in a vacuum. The clean metallic materials form a bond across the surfaces of the contact pads effectively joining them into a single piece of material. The thermal material prevents this contact from occurring.

Magnetic coupler100may include a neodymium (NEO) magnet106and an EPM108. In this embodiment, NEO magnet106is attracted to another opposite facing magnet depending on the polarity of magnetic coupler100. It should be appreciated, however, that the embodiments are not limited to NEO magnets, and any magnet may be used so long as the magnet is paired with an EPM.

In certain embodiments, an opposite facing magnetic coupler may be positioned to interface with magnetic coupler100.FIG.2is a diagram illustrating an electromagnetic mooring system (MMS)200, according to an embodiment of the present invention. In this embodiment, MMS200shows a first magnetic coupler2021and a second magnetic coupler2022, both of which are pressed against each other. As discussed above, magnetic couplers2021,2022have two states—attracting (or ON) state and OFF state. To connect, either magnetic couplers2021,2022may be in the ON state. In the ON state, when first magnetic coupler2021is pressed against second magnetic coupler2022, thermal material2041,2042between the surface of magnetic couplers2021,2022are also pressed. This form a high thermal conductance path. More specifically, the pressing of thermal material2041,2042allows for heat to transfer by way of magnetic couplers2021,2022and into the other satellite (not shown).

For heat to transfer, the heat flows through what is called a heat path with very low pressure (e.g., ˜2.5 to 5 pounds of force or 30 psi).FIG.2, for example, shows a heat path2061,2062. In this example, heat on the hot-side satellite routes through the frame of magnetic coupler2021and into the interface (i.e., thermal material2041). The heat then crosses over into magnetic coupler2022from thermal material2042and into the cold-side satellite, for example.

In another embodiment, magnetic couplers2021,2022are not used as the heat path; rather, a separate heat path may surround magnetic couplers2021,2022.FIG.3is a diagram illustrating MMS300with a separate heat path3061for magnetic coupler2021and a separate heat path3062for magnetic coupler2022. It should be appreciated that this embodiment uses the magnetic force to provide for the mechanical coupling of magnetic couplers2021,2022with a thermal interface separated from magnetic couplers2021,2022but on the same plane. For example, in this embodiment, thermal material3041,3042is located within heat paths3061,3062to enable transfer of heat when magnetic couplers2021,2022connect to one another. An air gap, as shown described below with respect toFIG.4, is maintained between the magnetic couplers to prevent a cold-welding event and maximize the force applied to the thermal interface material.

Either embodiment allows heat to transfer from one satellite to another, i.e., from the hot-side satellite to the cold-side satellite. In other words, the magnetic couplers (or magnets) establish a thermal path for heat transfer.

Returning toFIG.2, in some embodiments, when first magnetic coupler2021and second magnetic coupler2022are coupled together in the ON state, magnetic couplers2021,2022draw zero current. For example, to draw zero current, the current to reverse the polarity is provided via a pulse waveform. The pulse of the current is maintained for the minimum amount of time to generate the magnetic field in coil2081,2082, which permanently reverses the magnetic polarity in the EPM. Once the EPM has reversed polarity, all current can be removed from coil2081,2082without effecting the EPM. In the associated electrical controller, there may be some minor current draw.

UsingFIG.2as an example, it is assumed that magnetic coupler2021is the first magnet and magnetic coupler2022is the second magnet. Now, with magnetic coupler2021, each side may have a north pole and a south pole. When the polarity is switch from north to south, for example, the flux is conducted internally, and the external polarity in magnetic coupler2021changes to an OFF state.

Continuing with this example, if magnetic coupler2022is at an OFF state, then magnetic coupler2022will not couple to magnetic coupler2021. If, however, magnetic coupler2022is in an ON state or the poles are north and south, then magnetic coupler2022couples to magnetic coupler2021. Because magnetic couplers2021,2022are coated with thermal material2041,2042, magnetic couplers2021,2022retain thermal material2041,2042when magnetic couplers2021,2022decouple. It should be appreciated that magnetic couplers2021,2022may face in any orientation, and as long as there is a return path to negate the flux, magnetic couplers2021,2022may connect and disconnect.

FIG.4Ais a diagram illustrating a flux path, andFIG.4Bis a diagram illustrating a mooring force, in a magnetic coupler400, according to an embodiment of the present invention. InFIG.4A, magnetic flux path402flows from the north poles of the magnets, across the airgaps404, and returns to the south poles of the magnets. The pull force is determined by the magnetic field density, area of the airgap, and the separation distance of the magnetic surfaces. As shown inFIG.4B, a positive pull or mooring force is generated when the magnetic circuit is established as described inFIG.4Aabove.

FIG.5is a diagram illustrating a switchable magnetic coupler500, according to an embodiment of the present invention. Typically, there are two types of magnets—permanent magnets and electromagnets. However, a third type of magnet—the electro permanent magnet (EPM)—has also been used. EPMs are a type of permanent magnet with the capability of having its internal magnetic field reversed or realigned by a sufficiently strong externally applied field. The external field can be induced by either a permanent magnet or a coil by applying pulse of currents. These magnets are made from low coercivity or “soft” material. For example, Alnico is an example of a low coercivity or “soft” material. A NEO magnet, however, is an example of a high coercivity or “hard” material.

EPMs may be used with other types of magnets to form compound magnets, which can be switched “OFF”, “ON”, or have their poles reversed. InFIG.5, magnetic coupler500is shown in the OFF state and the ON state. Magnetic coupler500includes a NEO magnet504and an EPM506. When magnetic coupler500is in the ON state and a strong holding force is desired, the magnetic flux moves towards the opposite facing magnetic coupler (not shown). When magnetic coupler500is switched to an OFF state, EPM506shorts the path, moving the magnetic flux from NEO magnet504to EPM506. By having a switchable magnet and a thermal interface (e.g., as shown inFIG.2), not only does the two magnetic couplers couple to one another, but heat transfer from one satellite to another is possible.

In embodiments that utilize a coil to switch polarity, the coil (not shown) generates an external magnetic field that sets the polarity of EPM506. EPM506is a combination of “soft” magnetic material and the coil. The coil may have current flowing in both directions. The current then generates magnetic fields in both polarities with sufficient strength to “hard” flip the polarity in the “soft” magnetic material. Once EPM506is “hard” flipped, EPM506maintains the new polarity indefinitely. The coil currents are controlled by an electronic controller in some embodiments. The controller may use a circuit in certain embodiment. For example, the circuit is an H-bridge that controls the direction and amount of current within the coil. In certain embodiments, the controller is a single device controlling all EPMs or a distributed system were multiple devices are used.

FIG.6is a diagram illustrating a satellite lattice600, according to an embodiment of the present invention. Satellite lattice600shows that the magnetic couplers can achieve the necessary amount of heat transfer needed between satellites to mitigate the extremes of temperature. For example,FIG.6shows heat flow path P moving through satellite lattice600via magnetic couplers.

FIG.7Ais a diagram illustrating a magnetic coupler700, andFIG.7Bis a diagram illustrating a cross-sectional view of magnetic coupler700, according to an embodiment of the present invention. In this embodiment, magnetic coupler includes an inner material702and outer material (or ring)704. Inner material702may be composed of iron, carbon steel, ferrite, stainless steel, electrical steel (SiFe), mu-metal (NiFe), or other material with high relative magnetic permeability. Outer material704may be composed of iron, carbon steel, ferrite, stainless steel, electrical steel (SiFe), mu-metal (NiFe), or other material with high relative magnetic permeability. A plurality of connecting members706,708are configured to connect inner material702and outer material704. For example, in this embodiment, a pair of connecting members706are NEOs and another pair of connecting member708are EPMs. It should be appreciated that the embodiments are not limited to a pair of connecting members. For example, the embodiments may include at least two connecting members, of which at least one connecting member is an EPM.

Magnetic coupler700is planar in the sense that the thickness is less than its diameter. The planar arraignment is beneficial for use on satellite designs as it allows for the maximum use of the internal volume of the satellite for other payloads. The planar arraignment also allows for stronger magnets increasing the available pull forces.

For purposes of explanation, inner material702may be the south pole and outer material704may be the north pole. When in the “OFF” state, the flux flows internally in inner material702and outer material704. The flux leaves the north pole of the NEO magnets flows around outer material704to the south poles of an EPM. From there, the flux flows through the EPM exiting out the EPM's north pole and back to the NEO south pole through the inner material.

When in the “ON” case, the flux flows perpendicular to the “OFF” case. The flux leaves outer material704crossing outer airgap710to adjacent ferromagnetic material714. The flux returns to inner material702via inner airgap712. The flux then flows through inner material702to the south poles of each magnet. The magnetic circuit is then completed when the flux flows through the magnets to the north poles.

In some embodiments, rather than using a pair of NEOs and a pair of EPMs, magnetic coupler700may have four EPMs. By using four EPMs, magnetic coupler700becomes a tri-state device, i.e., a magnet having switchable polarity, with two ON states and one OFF state. This tri-state device may then reject (or push) an adjacent satellite, essentially launching the adjacent satellite. For example, if two satellites are moored, with one satellite being in an inner south configuration and the other being an inner north configuration, the satellites would attract each other and would be described as having a positive mooring force. If one satellite switched, such that both satellites were in an inner south configuration, the satellites would repel each other and would be described as having a negative mooring force. A negative mooring force would push the satellites apart.

FIG.8is a diagram illustrating a pin and cup thermal and electrical interface aligned by an MMS800, according to an embodiment of the present invention. In this embodiment, an adjacent device (partially shown) may have a female connecting member802. Female connecting member802may include liquid (or fluid)804such as mercury or liquid metal, for example. The other device (also partially shown) may include a male connecting member806. In some embodiments, liquid804is attracted to both male connecting member806and female connecting member802, and the resulting mechanical coupling causes heat (discussed below) to flow freely between female connecting member802and male connecting member806.

With this system, geometric alignment is required rather than a clamping mechanism. In this embodiment, liquid804is constrained by the geometry of female connecting member802and male connecting member806, which enters female connecting member802. Since male connecting member806is composed of copper, iron, or any thermally conductive material, male connecting member806becomes electrically connected with female connecting member802by way of liquid804. Additionally, transfer of heat may also be achieved by way of liquid804.

In some embodiments, pin and cup configuration shown inFIG.8are coarsely aligned via a blind mate. For example, a moving satellite is positioned over MMS800, and when MMS800is switched “ON”, mooring forces male connecting member806(e.g., the pin) into female connecting member802(e.g., the cup). The female connecting member802is tolerant of misalignments and guides male connecting member802into the center of female connecting member802. A heat path is established via liquid804in female connecting member802. Since liquid804contact acts as a high contact force, mechanical coupling heat will flow freely across female connecting member802and male connecting member806connection. In a pin and cup arrangement that utilizes an electrically conductive liquid, such as mercury, an electrical power bus may be established by electrically isolating the female connecting member802and male connecting member806. Additionally, in some embodiments, data is transmitted over the connection in a traditional serial protocol or as using a data over power method.

Some embodiments generally pertain to holding one or more objects, such as satellites, together with a reconfigurable mooring system. Additionally, some embodiments pertain to the transfer of heat from one object to another by way of the reconfigurable mooring system. It should be appreciated that the embodiments are not limited to holding satellites together with the reconfigurable mooring system. One of ordinary skill in the art would appreciate that the reconfigurable mooring system may be used to connect other objects together such as a laptop to a docking station or a phone charging module. Another example would be to use the reconfigurable mooring system for on-orbit replenishment, e.g., connecting a fuel pack to a space vehicle.

Depending on the embodiment, the reconfigurable mooring system uses little to no power, and has a high thermal conductance. For example, the reconfigurable mooring system uses small or low current pools for very short periods of time (e.g., in milliseconds) to reconfigure objects. More specifically, certain embodiments use a low current system to charge up a circuit that would release a larger current pulse than would otherwise be provided. In some embodiments, a pulse may be used to switch the reconfigurable mooring system from an ON state to an OFF state or vice versa. Furthermore, the high thermal conductance is achieved by the reconfigurable mooring system at low pressure. This system provides sufficient, reconfigurable heat transfer without consuming significant energy. For example, if an instrument package on a drone were generating excessive heat, the heat may be rerouted by the reconfigurable mooring system to radiators on the drone. In other words, the reconfigurable mooring system provides alternatives for heat management.

MMS may also be used for rapid noncontact (inductive) recharging of a wireless device such as an iPhone or laptop. The excess heat generated by the rapid recharging may be routed from the device to the recharger via the MMS.

In certain embodiments, MMS may be utilized with docking remote modules to a power and thermal backplane. In these embodiments, the MMS may hold the system in place as well as provide a thermal and power interface to the subsystem. This may be a terrestrial (computer docking station) or space system (instrument docking station).

In certain embodiments, attaching remote modules to existing space assets, externally or to provided internal attachment points, may provide on-orbit upgrades, replenishment, or orbital maintenance that would extend the life of the space asset.

In some embodiments, when gravity cannot be used as a separating force, the reconfigurable mooring system may be used to provide an initial separating force. The initial force can only be generated by the tri-state configuration of the MMS.

In some embodiments, satellites that are connected to one another by way of magnetic couplers may form an electro-optical communication link.FIG.9is a diagram illustrating a face-to-face communication system900using one or more magnetic couplers, according to an embodiment of the present invention. In this embodiment, each magnetic coupler, as shown inFIG.10, may include a sensor for data communication.

FIG.10is a diagram of a magnetic coupler1000embedded within a satellite, according to an embodiment of the present invention. In this embodiment, each side of magnetic coupler1000may include a sensor1010. Sensor1010may include radio frequency (RF) technology, infrared (IR) technology, or any other technology that would facilitate communication between adjacent satellites. Magnetic coupler1000may be lined up with a magnetic coupler of an adjacent satellite allowing data to be transmitted from one satellite to the other. In other words, magnetic coupler1000is not only used to make a structural connection between adjacent satellites, but also used to align interfaces (e.g., thermal interface, optical interface, etc.) of adjacent satellites.

Returning toFIG.9, each satellite902,904,906within the lattice of satellites may communicate with one another. Further, since each side of satellite902,904,906includes a magnetic coupler, each satellite902,904,906may communicate data with one or more adjacent satellites. This configuration allows data to flow through each satellite, and in any desired direction. Although three satellites are shown inFIG.9, the embodiments may include any number of satellites in any configuration.

In this embodiment, satellite902may initiate communication to satellite906with satellite904acting as a router to send messages to satellite906. Satellite906responds to message from satellite902with satellite904acting as a router to send messages to satellite902. To initiate communication, a communication link is established by way of wireless technology, such as light emitting diodes (LEDs), laser, radio frequency (RF), or any other hardware that passes data and does not require physical contact. This is an example of point-to-point protocol.

In some embodiments, satellite904may broadcast a message from all of its ports (e.g., transmit port Tx), when the message is for general distribution. In some further embodiments, satellite902may interrogate satellite904to determine the state. For example, an identification and location of the connected satellite may be determined in certain embodiments.

In the embodiment shown inFIG.9, each satellite902,904, and906may receive signals via Rx port and transmit signals via Tx port. Each satellite902,904, and906may have multiple Rx ports and Tx ports. In other embodiments, each satellite may use a single port to transmit and receive signals.