FOR A FOLDABLE ELECTRONIC DEVICE

TECHNICAL FIELD

The present invention relates to a thermally conducting hinge arrangement for a foldable electronic device.

BACKGROUND

In the field of foldable electronic devices, e.g. laptops, main trends are: decreasing sizes, thickness and weight, increasing computing power and heat dissipation, as well as construction of laptops with detachable screens, which means that a screen can be detached from a keyboard and can work in a wireless mode. In such conditions, it is not possible to use traditional methods for cooling, like large heat sinks, cooling supported by fans, or liquid cooling. For such foldable devices, a main way of cooling is dissipation of heat from all available surface of the foldable device by nature convection and radiation to the surrounding air. Typically, a source of heat is located in a small area of the foldable device, for example in a CPU. The heat must be transferred from the heat source and distributed through all available outer surface of the foldable device, which is in contact with the surrounding cool air. For such a transferring process, materials and devices with a high thermal conductivity are used, e.g. heat pipes, vapor chambers, large metallic plates, or graphite or graphene sheets.

However, these heat transferring materials are not able to distribute heat between rotatable or detachable parts like the screen and the keyboard. Usually, the screen is mechanically connected to the keyboard by a hinge. Conventional hinges are designed for mechanical connection and have a large thermal resistance, because there are many contacting parts with a small overall contacting surface.

A thermally improved design of such hinges (which require to be thermal connectors) with low thermal resistance is required to allow for transferring heat from one part to another part of the foldable device.

Conventional portable computers of the kind have a main body (i.e. keyboard) and a cover (i.e. a screen) thermally coupled by a hinge which also allows for rotation. Heat transfer may be obtained by a working fluid in a chamber, for instance in the screen connected to a part of the hinge. ^'

SUMMARY

The idea of the present disclosure is based on the observation that conventional heat dissipating solutions cannot work in different orientations (due to an influence of gravity), because after condensation of the working fluid inside the chamber, the condensate only can flow in a direction from the screen to the hinge elements (i.e. the axel). If the screen is oriented under the hinge or if a direction of heat transfer is from the screen to the hinge (e.g. if the heat source is located in the screen), the thermal hinge will not work as a heat transferring unit.

Further, conventional portable computers using thermal hinges have big visible parts on the keyboard (i.e. the tube) and the screen (i.e. the axel), which disturbs an operating experience of the portable computer.

Further, to improve heat transfer and movement of the detachable parts, there is located grease on them, which can be lost during an attachment or detachment process. In such a case, thickness of the grease will decrease, and the air gap between contacting surfaces of the hinge will increase, thereby causing an increase of the thermal resistance. This results in a gain of total thermal resistance of the thermal hinge and decrease possible amount of heat for transferring.

Further, conventional solutions allow for a maximum angle of rotation that is less than 360 degree. Consequently, that both parts of a foldable device (i.e. the screen and the keyboard) cannot be operated according to a desire of a user, e.g. they cannot be planar folded when both totally opening and closing the foldable device.

In view of the above-mentioned problems and disadvantages, the present invention aims to improve the conventional apparatus. The present invention has the object to provide a thermally conducting hinge arrangement for a foldable electronic device, which allows for heat transfer between a first part, (e.g. a screen) and a second part, (e.g. a keyboard) of the foldable electronic device (e.g. a laptop), which is able to rotate by 360 degrees, with the possibility to detach the first part from the second part of the foldable electronic device, with high reliability and low thermal resistance. The object of the present invention is achieved by the solution provided in the enclosed independent claim. Advantageous implementations of the present invention are further defined in the dependent claims.

A first aspect of the present invention provides a thermally conducting hinge arrangement for a foldable electronic device, the hinge arrangement including a first fastening member with a first cavity, the first fastening member being configured to be detachably connectable to a first part of the foldable electronic device, a second fastening member with a second cavity, the second fastening member being configured to be detachably connectable to a second part of the foldable electronic device, and a coupling member comprising a first axel element and a second axel element, wherein the first axel element is rotatably arranged in the first cavity, and the second axel element is rotatably arranged in the second cavity, wherein the first fastening member is configured to thermally couple to the first axel element, and the second fastening member is configured to thermally couple to the second axel element.

As the thermally conducting hinge arrangement does not include thermal interface material (e.g. thermally conductive grease) between contacting surfaces, but good thermal contact between this surfaces is achieved due to contact pressure and preselected materials with good conductive properties, thermal conduction of the hinge arrangement can be improved and be provided reliably. So, the thermally conducting hinge arrangement does not have the problem of loss of thermal interface material (i.e. grease) and loosing good thermal contact between contacting surfaces.

A distance between the first axel element and the second axel element, of the coupling member allows for rotating a first part that is fixed to the first fastening member by more than 360 degrees, relative to a second part that is fixed to the second fastening member.

The design of the thermally conducting hinge arrangement allows for an easy attaching/detaching process with good thermal contact, mechanical reliability, low force required for attaching/detaching and the possibility of rotation by 360 degrees.

Further, layers of material with high hardness and low friction coefficient on contacting surfaces of all components of the hinge arrangement can be used, which simultaneously allow for good thermal contact (e.g. supported by contact pressure applied to the surfaces) and a quick detaching/attaching process with low friction force between surfaces. In an implementation form of the first aspect, the first axel element is detachably arranged in the first cavity, and/or the second axel element is detachably arranged in the second cavity. Arranging the first or second axle element in the first, respectively second cavity, allows for improved handling of an electronic device comprising the thermally conductive hinge arrangement, since parts of the electronic device can be fastened and unfastened to each other in various comfortable ways. In a further implementation form of the first aspect, the first fastening member is configured to exert friction force onto the first axel element and thereby thermally couple to the first axel element, and/or the second fastening member is configured to exert friction force onto the second axel element and thereby thermally couple to the second axel element. Configuring the shape of the fastening members, the cavities and the respective axel elements to exert friction forces allows for improved thermal and mechanical coupling of parts of the electronics device using the hinge arrangement.

In a further implementation form of the first aspect, the coupling member further includes a coupling potion connecting the first axel element and the second axel element.

The coupling portion allows to include materials or elements which improve thermal or mechanical coupling of the first axel element or the second axel element.

In a further implementation form of the first aspect, the first axel element, and/or the second axel element, and/or the coupling portion comprise at least one heat pipe.

Including a heat pipe in the coupling member, in particular in the first axel element, and/or the second axel element, and/or the coupling portion, improves thermal coupling of the coupling member. Further, since the coupling member, the first axel element, the second axel element, or the coupling portion are typically made of durable, hard metal materials, the heat pipe (which is typically made of copper, which is less durable) is protected against mechanical damage.

In a further implementation form of the first aspect, the first axel element is of a conic shape and the first cavity is of a corresponding conic shape, and/or the second axel element is of a conic shape and the second cavity is of a corresponding conic shape. This allow to easily and quickly attach or detach one of the axle elements to a fastening member in order to realize easy and quick attaching or detaching of a keyboard to the screen of portable electronic device. The conic shape supports form fit, frictional fit or snap fit coupling.

In a further implementation form of the first aspect, the second fastening member is resting against and/or is integrally formed with a thermally transferring portion of the second part of the electronic device. This allows to fasten the thermally conducting hinge arrangement to a foldable electronic device.

In a further implementation form of the first aspect, the thermally conducting hinge arrangement further comprises a third fastening member, wherein in a fastening state, the first fastening member is configured to be detachably connected to the third fastening member thereby implementing thermal coupling, and the third fastening member is configured to be mounted to a thermally transferring portion of the first part of the electronic device.

This allows for even further improving operating flexibility of the hinge arrangement. Two parts of a foldable electronic device can be fastened to or unfastened from each other either by removing one of the fastening members from a corresponding axle element, and/or by attaching or detaching the third fastening member to or from the first fastening member.

In a further implementation form of the first aspect, the third fastening member further comprises at least one third cavity, the first fastening member further comprises a protrusion, and in the fastening state of the first fastening member and the third fastening member, the protrusion is arranged in the third cavity, and the third fastening member is configured to exert a pressure onto the protrusion to establish a detachable connection with the first fastening member.

The construction of the protrusion and the third cavity enable to form contact surfaces which are non-parallel to an inserting direction of the protrusion into the cavity, in order to implement a minimum gap between a surface of the protrusion and a surface of the third cavity. This allows for easy and quick attaching/detaching with low thermal resistance. This in particular ensures, that no thermally conductive grease is required on the surface of the protrusion and on the surface of the third fastening member, which allows to provide a maintenance free way of detaching and attaching. In a further implementation form of the first aspect, the protrusion is integrally formed with the first fastening member.

This allows for improved mechanical and thermal coupling of the protrusion and the first fastening member.

In a further implementation form of the first aspect, the detachable connection is a clamp connection.

This ensures that additional friction force (e.g. contact pressure) can be exerted from the third fastening member to the protrusion, resulting in additional mechanical and/or thermal coupling. Also, a detachment or attachment process is improved. Further, the clamp connection contributes to the freedom from maintenance, since no grease is required on the surfaces for thermal connection.

In a further implementation form of the first aspect, in the fastening state of the first fastening member and the third fastening member, a fastening portion of the protrusion is configured to engage with a fastening portion of the third cavity to exert friction force by the protrusion into the direction of the third fastening member to establish a detachable connection of the first fastening member and the third fastening member, and to implement thermal coupling.

The additional fastening portions allow for additional friction force being applied to the contact surfaces of the third fastening member and the protrusion, resulting in further improved mechanical and/or thermal coupling.

In a further implementation form of the first aspect, the third fastening member comprises a first friction section and a second friction section, wherein the first friction section and the second friction section form the third cavity.

The first and second friction sections allow for further increasing a contact surface of the third fastening member and protrusion, on which force can be applied to improve mechanical and/or thermal coupling. In a further implementation form of the first aspect, the thermally conducting hinge arrangement further comprises at least one spring configured to preload the first friction section or the second friction section to exert a friction force by the third fastening member. This ensures that additional contact pressure can be applied to the friction sections, which results in increased frictional forces being applied from the third fastening member to the protrusion.

In a further implementation form of the first aspect, the protrusion is arranged in parallel with the longitudinal extension of the first cavity, and the first friction section and the second friction section are preloaded into a direction perpendicular to a longitudinal extension of the protrusion by the at least one spring.

This allows for easily inserting the protrusion into the cavity formed by the first and second friction section.

In a further implementation form of the first aspect, the protrusion is arranged transverse with respect to the longitudinal extension of the first cavity and the first friction section and the second friction section are preloaded into a direction parallel to a longitudinal extension of the protrusion by the at least one spring.

The transverse arrangement of the protrusion leads to increased contact surface between protrusion and the friction sections, which further improves thermal and mechanical coupling.

It has to be noted that all devices, elements, units and means described in the present application could be implemented in the software or hardware elements or any kind of combination thereof.

All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof.

BRIEF DESCRIPTION OF DRAWINGS The above-described aspects and implementation forms of the present invention will be explained in the following description of specific embodiments in relation to the enclosed drawings, in which

FIG. 1 shows perspective views of a hinge arrangement according to an embodiment of the present invention.

FIG. 2 shows perspective views of a hinge arrangement according to an embodiment of the present invention in more detail.

FIG. 3 shows perspective views of components of a hinge arrangement according to an embodiment of the present invention.

FIG. 4 shows perspective views of components of a hinge arrangement according to an embodiment of the present invention.

FIG. 5 shows perspective views of components of a hinge arrangement according to an embodiment of the present invention.

FIG. 6 shows perspective views of components of a hinge arrangement according to an embodiment of the present invention.

FIG. 7 shows perspective views of a hinge arrangement according to an embodiment of the present invention.

FIG. 8 shows perspective views of a hinge arrangement according to an embodiment of the present invention.

FIG. 9 shows perspective views of a hinge arrangement according to an embodiment of the present invention.

FIG. 10 shows tabulations regarding materials and properties of a hinge arrangement according to an embodiment of the present invention. FIG. 11 shows a perspective view of a hinge arrangement according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows, in FIG. 1 A to FIG. ID, perspective views of a hinge arrangement 100 according to an embodiment of the present invention.

The hinge arrangement 100 is a thermally conducting hinge arrangement 100 and can be used for a foldable electronic device, e.g. to couple a first part of the electronic device (e.g. a screen, including a processor and memory) to a second part of the electronic device (e.g. a keyboard, including a heat sink).

The hinge arrangement 100 includes a first fastening member 101 that can be connected to, or be part of the first part of the electronic device. The first fastening member further includes a first cavity 102. The hinge arrangement 100 further includes a second fastening member 103 that can be connected to, or be part of the second part of the electronic device. The first fastening member further includes a second cavity 102.

The hinge arrangement 100 further includes a coupling member 105 comprising a first axel element 106 and a second axel element 107. Optionally, the first axel element 106 is rotatably and/or detachably arranged in the first cavity 102, and the second axel element 107 is rotatably and/or detachable arranged in the second cavity 104. Thus, the first fastening member 101 allows detachably connecting the first part of the foldable electronic device, to the first axel element 106, and the second fastening member 103 allows detachably connecting the second part of the foldable electronic device, to the second axel element 107.

By means of friction force, e.g. contact pressure, the first fastening member 101 is configured to thermally couple to the first axel element 106, and the second fastening member 103 is configured to thermally couple to the second axel element 107.

In particular, the first fastening member 101 is configured to exert friction force onto the first axel element 106 and thereby thermally couple to the first axel element 106. and/or, the second fastening member (103) is configured to exert friction force onto the second axel element 107 and thereby thermally couple to the second axel element 107. This is e.g. implemented by designing a shape of the first cavity 102 and the second cavity 104 according to a shape of the first axel element 106 and the second axel element 107, providing little to no air gap in between. This kind of thermal coupling allows for omitting thermally conductive grease on the first axel element 106 and/or the second axel element 107, resulting in a hinge arrangement free of maintenance, since the grease cannot get lost and would have to be replaced.

However, in case that the hinge arrangement is used as it is going to be described below in view of FIG. 2, grease can be provided on the first and second axel element 106, 107, since the detaching and attaching mechanism is going to be implemented in a different way (i.e. by means of further components), which does not lead to loss of grease on the first and second axel elements 106, 107.

To mechanically secure the first axel element 106 and the second axel element 107 against each other, the coupling member 105 further includes a coupling portion 108 connecting the first axel element 106 and the second axel element 107. The coupling portion is thermally conducting and allows for housing further elements that increase thermal coupling.

By means of the hinge arrangement, a heat sink in the keyboard part can be thermally coupled to a CPU in the screen part of the electronic device. That is, optionally the second fastening member 103 can be resting against and/or is integrally formed with a thermally transferring portion of the second part of the electronic device.

The hinge arrangement also allows for flexible movement of the first part of the electronic device (e.g. a screen, including a processor and memory) to the second part of the electronic device (e.g. the keyboard part). In particular, i.e. the first part can be rotated up to 360° with respect to the second part. Optionally, the first axel element 106 and the second axel element 107 can be arranged basically in parallel, to achieve a rotation into a predefined moving direction.

All parts of the hinge arrangement 100 in particular can be formed by durable, hard metals or metal alloys, to increase mechanical stability and thermal coupling (by means of providing reliable contact pressure). Further, all contact surfaces can be of a low friction coefficient (i.e. by means of polishing the surfaces, or coating them), to further improve their thermal conductance and minimize air gaps. FIG. 2 shows, in FIG. 2A to FIG. 2D, perspective views of a hinge arrangement 200 according to an embodiment of the present invention in more detail. The hinge arrangement 200 builds on the hinge arrangement 100 of FIG. 1 and includes all respective features. To this end, same features are labelled with same reference signs.

As it is indicated in FIG.2, the first axel element 106, and/or the second axel element 107, and/or the coupling portion 108 optionally can comprise at least one heat pipe 201. The heat pipe 201 can be flexible, e.g. made of copper, and connects to the inner surface of the first axel element 106 and/or the second axel element 107. In particular, one end of the heat pipe 201 is located inside the first axel element 106 and a second end of the heat pipe 201 is located inside the second axel element 107. On the inner surface of the heat pipe 201 there can be a wick structure, i.e. a porous material for transport of a working fluid inside the heat pipe 201 by capillary forces. Instead of a wick structure, a heat pipe 201 without a wick structure (thermo-siphon) can be used, which instead includes materials with high thermal conductivity (graphite, graphene). The purpose of this high conductive materials is to provide good heat transfer among the first and second axel elements 106, 107.

Instead of forming the first and second axel element 106, 107 from hard material that protects the heat pipe 201, a protective layer of hard material on the surface of the heat pipe 201 can be used in order to avoid deformation and crushing of the heat pipe 201 during rotation and/or an attaching/detaching process of the hinge arrangement 200.

Further, between the outer surface of the heat pipe 201 and the inner surface of the first axel element 106 and the inner surface of the second axel element 107, there can be located thermal interface material with high thermal conductivity, or the heat pipe 201 can be soldered to the inner surface of the first axel element 106 and the inner surface of the second axel element 107.

Inside the coupling member 105, and in particular inside the coupling portion 108, there can be two or numerous heat pipes 201, one side of each heat pipe is located inside the first axel element 106 of the coupling member 105, and a second side of each heat pipe 201 is located in the second axel element 107 of the coupling member 105.

In order to fix a first part on an electronic device relative to a second part of the electronic device, the hinge arrangement 200 according to the present invention can be combined with further mechanical hinges or connectors. The hinge arrangement 200 can also include parts for electrical connections and connections for information exchange between components in the different parts of the electronic device.

As it is now described in view of FIG. 3, further optionally, the first axel element 106 can be of a conic shape and the first cavity 102 can be of a corresponding conic shape, Also, the second axel element 107 can be of a conic shape and the second cavity 104 can be of a corresponding conic shape. Although only the first axel element 106 and the first cavity 102 are shown being conical in FIG. 3, also both, or only the second axel element 107 and the second cavity 104 can be conical. The outer diameter of the first or second axel element 106, 107 can be variable and be different from each other. Also the inner diameter of the first and second cavity 102, 104 can be variable and be different from each other.

To improve coupling of the axel elements 106, 107 to the fastening members 101, 103, the first and/or second axel element 106, 107 can have a circular protrusion 301, and the first and/or second cavity 102, 104 can have a circular opening, to establish a snap-fit coupling, providing contact pressure between the axel elements 106, 107 and the fastening members 101, 103. That is, thermally conductive material (e.g. grease) can be avoided on the axel elements 106, 107, if desired (e.g. if attaching and detaching is implemented by means of the third fastening member 202 and the protrusion as described below 204).

Turning back to FIG. 2, it is now described that the hinge arrangement 200 can also comprise a third fastening member 202 that can be detachably connected to the first fastening member 101. In particular, in a fastening state, the first fastening member 101 is configured to be detachably connected to the third fastening member 202 thereby implementing thermal coupling to enable thermal heat transfer in the electronic device, the third fastening member 202 is configured to be mounted to a thermally transferring portion of the first part of the electronic device.

The fastening member 202 can be detachably connected to the fastening member 101 either directly, or by means of the following manner:

As it is shown in FIG. 2, in a possible implementation, the third fastening member 202 can further comprise at least one third cavity or slit with a tapered section 203, and the first fastening member 101 can further comprise a protrusion 204. Due to its shape, the protrusion may also be called“fin”, see FIG. 2. The shape of the protrusion 204 can also be more complex, for example include not only one big fin but several small fins, fins with non-plane surface, can be used, or a fin with a plate shape.

In a fastening state of the first fastening member 101 and the third fastening member 202, the protrusion 204 is arranged in the third cavity 203, and the third fastening member 202 is configured to exert a pressure onto the protrusion 204 to establish a detachable connection with the first fastening member 101. This e.g. results in a press fit, clamp fit, form fit, or frictional connection between the third cavity 203 of the third fastening member and the protrusion 204. In case of a clamp fit connection, the third fastening member 202 can be regarded a clamp.

In a further implementation, the contacting surfaces of the protrusion 204 and the third cavity 203 are not parallel to the moving direction of protrusion 204 during insertion into the third cavity 203. This allows achieving high contacting pressure on the contacting surfaces, resulting in a small detaching force. The protrusion 204 is held in the cavity 203 due to friction, in particular between fastening portions of the third fastening member 202 and the protrusion 204, e.g. guide- ways and grooves. The detaching force should be predefined have a value that it is equal or at least close to the friction force between contact surfaces during inserting process. This friction force is a product of a contacting force and a friction coefficient.

The contacting force can in particular be controlled by means of elastic elements, e.g. springs. A friction coefficient is a property of a material of the contacting surfaces. If a friction coefficient is low, contacting pressure can increase friction force, while at the same time increasing contacting force leads to decreasing thermal resistance between the contacting surfaces. Because the contacting surfaces are not parallel to the insertion direction of the protrusion 204 into the cavity 203, a gap between the protrusion 204 and the third fastening member 202 is decreased. With a low gap between contacting the surfaces, thermal resistance also is low. Thus, no thermal interface materials between the contacting surfaces are required, but good thermal contact between this surfaces is achieved due to high contact pressure between contacting parts.

To allow for improved mechanical stability and thermal coupling, the protrusion 204 can be integrally formed with the first fastening member 101.

As mentioned before, fastening portions can support fastening the third fastening member 202 to the protrusion 204. As it is now going to be described in view of FIG. 4, in the fastening state of the first fastening member 101 and the third fastening member 202, a fastening portion 401 of the protrusion 204, which can be considered a guideway, is configured to engage with a fastening portion 402 of the third cavity 203, which can be considered a groove, to exert friction force by the protrusion 204 into the direction of the third fastening member 202. Thereby a detachable connection of the first fastening member 101 and the third fastening member 202 is established, and thermal coupling is implemented.

As it is now going to be described in view of FIG. 5, in an embodiment, the contact surfaces of the third cavity 203 can also be regarded as friction sections. That is, the third fastening member 202 can comprises a first friction section 501 and a second friction section 502, wherein the first friction section 501 and the second friction section 502 form the third cavity 203. Optionally, the first friction section 501 and the second friction section 502 are arranged in a non-parallel manner.

Optionally, the thermally conducting hinge arrangement 200 further can comprise at least one elastic element, e.g. a spring 503 that is configured to preload the first friction section 501 or the second friction section 502 to exert a friction force by the third fastening member 202. The third fastening member 202 can also comprise a frame 504 that is configured to house the first and second friction section 501, 502. The spring 503 can rest against the frame 504 to preload the friction sections 501 , 502 against the protrusion 204. Due to using springs, contacting pressure between the contacting surfaces can be increased.

As it is also illustrated in FIG. 5, the protrusion 204 can be arranged in parallel with the longitudinal extension of the first cavity 102. In such case, the first friction section 501 and the second friction section 502 are preloaded into a direction perpendicular to a longitudinal extension of the protrusion 204 by the at least one spring 503.

As it is now described in view of FIG. 6, the protrusion 204 alternatively can also be arranged transverse with respect to the longitudinal extension of the first cavity 102. In that case, the first friction section 501 and the second friction section 502 are preloaded into a direction parallel to a longitudinal extension of the protrusion 204 by the at least one spring 503.

Although the thermally conducting hinge arrangement 200 is described implementing the third fastening member 202 and the protrusion 204 in FIG. 2 to FIG. 5, it can also work without the need for the third fastening member 202 and the protrusion 204, as it is described in view of FIG ^’ . 1. In this case, the thermally conducting hinge arrangement 100 has decreased thermal resistance, because less parts are involved in thermal transmission.

FIG. 7 shows perspective views of the hinge arrangement 200 according to an embodiment of the present invention. More specifically, FIG. 7 shows the process of attaching the third fastening member 202 to the protrusion 204, as well as the process of attaching the first axel element 106 to the first fastening member 101 and the second axel element 107 to the second fastening member 103. It is also shown how a heat pipe 201 can be inserted into the coupling member 105, e.g. during its manufacturing process.

FIG. 8 shows perspective views of the hinge arrangement 200 according to an embodiment of the present invention. FIG. 8 in particular shows different positions of parts of the hinge arrangement 200 when changing a rotation angle from 0 to 360 degrees. In particular the use of a first axel element 106 and a second axel element 107 allow for a rotation angle of for instance 360 degrees.

FIG. 9 shows perspective views of the hinge arrangement 200 according to an embodiment of the present invention. FIG. 9 in particular shows different positions of the third fastening member 202 when attaching it to the protrusion 204. Because surfaces of the protrusion 204 are non-parallel to each other, during insertion of the protrusion 204 an air gap decreases between the surface of the protrusion 204 and the fastening member 202. Because an attachment force is applied when attaching the protrusion 204 to the third fastening member 202, the contact surfaces are more close to each other in comparison with a case of parallel surfaces.

In the following specific embodiment, an operating principle of the thermally conduction hinge arrangement, as disclosed in FIG. 1 to FIG. 9, is described.

The thermally conduction hinge arrangement is able to transfer heat in two directions: from the third fastening member 202 to the second fastening member 103 (i.e. from the screen to the keyboard of the foldable electronic device), and from the second fastening member 103 to the third fastening member 202 (i.e. from the keyboard to the screen).

If the thermally conduction hinge arrangement is structured for heat transfer from the screen to the keyboard, the third fastening member 202 (or, if only the first fastening member 101 is present, the first fastening member directly) is connected to the heat source inside the screen, directly or by using materials and devices with high thermal conductivity (copper, aluminum, heat pipes, vapor chambers, graphite, graphene etc.). All heat from the heat source (or part of this heat) is transferred by the highly conductive material to the third fastening member 202 (or the first fastening member 101). By means of thermal conductivity, heat flows through the third fastening member 202 to the contacting surface between the third fastening member 202 and the protrusion 204 (or the first fastening member 101 directly). Because it is not reliable to use thermal interface materials between this surfaces, good thermal contact can be achieved only by applying of high normal force (contact force perpendicular to the contact surface) for creating high contact pressure. Between this contacting surfaces heat flows parallel through thin air layers and through areas with direct contact of materials of the contacting bodies. Under high pressure, surfaces of direct contact areas (with low thermal resistance) are bigger and areas with air (high thermal resistance) are smaller, that is, increasing pressure helps to decrease thermal resistance of contact and leads to transferring a larger amount of heat. In the thermally conducting hinge arrangement, the third fastening member 202 is able to provide the desired high contact pressure. The third fastening member 202 is made of highly conductive material, so that during attaching the protrusion 204 to the third fastening member 202, the cavity 203 of the third fastening member 202 will be extended according to the shape of the protrusion 204. In his case, a material of the third fastening member 202 will try to come back to a previous non-extended state and exert force on a surface of the protrusion 204, resulting in contact pressure. The value of this pressure depends on material parameters of the third fastening member 202. For higher contact pressure to be applied, additional force from an elastic element such as a spring can be used, which can be attached to the outer surface of the third fastening member 202, i.e. the friction surfaces 501, 502. This method of creating higher contact force is shown more detailed in FIG. 5 and FIG. 6. In FIG. 5, the third fastening member 202 consist two symmetrical parts (i.e. the first and second friction section 501, 502) which are connected by springs 503 to the frame 504, being part of the electronic device. If the protrusion 204 is inserted into the space between first and second friction section 501, 502, this parts will move in the direction of the spring 503, thereby compressing the spring 503. Contacting force is applied by the spring 503 and depends on mechanical parameters of the spring 503.

The third fastening member 202 shown in FIG. 6 works based on a similar principle, but during attaching of the protrusion 204 to the third fastening member 202, the first friction section 501 and the second friction section 502 move along a longitudinal extension of the protrusion 204. Such a construction can be applied when it is e.g. necessary to decrease thickness of a part of the electronic device.

The hinge arrangement of course can also be used without the protrusion 204 and the third fastening member 202, as e.g. shown in FIG. 1.

A high contact pressure applied by the third fastening member 202 allows for good thermal contact between the contacting surfaces of the third fastening member 202 and the protrusion 204, but however, under high contact pressure, friction force between this surfaces also will be high. This effect is negative for an attaching/detaching process, because an attaching/detaching force will be equal to a friction force, requiring the user to expend large forces to handle the hinge. In order to ensure a quick and easy process of attaching/detaching, this force should be as small as possible. In order to reach this requirement on the contacting surfaces, a protective layer of material with low friction coefficient is used on the surfaces. Normal (contact) force is connected with friction force by the equation F = k-N, where F is a friction force; k is a friction coefficient; N is a normal force. If the friction coefficient k will be low, for high normal forces N, friction force (i.e. the attaching/detaching force) also will be low. Additionally, in order to achieve good mechanical contact between the third fastening member 202 and the protrusion 204, a fastening portion 402 (i.e. grooves) on the third fastening member 202 and a fastening portion 401 (i.e. guide- ways) on the protrusion 204 is used.

After contacting the surfaces of the third fastening member 202 and the protrusion 204, heat flows by thermal conductivity trough the protrusion 204 to the inner surface of the first cavity 102 of the first fastening member 101. In order to decrease thermal resistance, the first fastening member 101 is made by a thermal conductive material, for example by copper.

After that, heat is transferred by thermal conductivity through a layer of thermal interface material between inner surface of the first cavity 102 and the outer surface of first axel element 106. Space between surface of the cavity 102 and the outer surface of the first axel element 106 is insulated from outside (for example by using sealing members) in order to avoid losses of the thermal interface material. Thermal interface material used in the above parts not only plays a thermal role, but also is used as a lubricant in order to decrease friction force at high contact force between the inner surface of the cavity 102 and the outer surface of first axel element 106.

After this, surface heat flows through the wall of first axel element 106 to the contacting inner surface of the first axel element 106, through the layer of thermal interface material between inner surface of the first axel element 106 and the outer surface of the heat pipe 201, from the outer surface of heat pipe 201 to the wick structure inside the heat pipe 201. On the wick structure of one end of the heat pipe 201 (i.e. the part of the heat pipe 201 inside the first axel element 106) an evaporation process of working fluid in the heat pipe 201 takes place. In this process, heat is used for evaporation. After this, vapor moves to the second end of the heat pipe 201 (the end of the heat pipe 201 that is located inside the second axel element 107). On this side, the vapor condenses on the wick structure, liquid working fluid after condensation flows to the first end of heat pipe 201 through the wick structure, due to capillary forces inside pores. Heat from the condensation process transfers trough the wall of the heat pipe 201 to the outer surface of the heat pipe 201, through the thermal interface material between the outer surface of the heat pipe 201, and the inner surface of the second axel element 107, through the wall of the second axel element 107 to the outer surface of the second axel element 107, through the layer of thermal interface material between the second axel element 108 and the second fastening member 103 to the inner surface of the cavity 104 of the second fastening member 103. Heat of the second fastening member 103 is transferred to the heat dissipation system (e.g. a heat sink) in e.g. a keyboard connected to the second fastening member 103. In this case the second fastening member 103 can be connected to the heat dissipation system directly or by using materials and devices with high thermal conductivity (copper, aluminum, heat pipes, vapor chambers, graphite, graphene etc.).

Thus, heat can be transferred from a screen to a keyboard of a foldable electronic device by using the thermally conducting hinge arrangement according to the present invention. The heat transfer process can be conducted in an analogue manner from a keyboard to a screen, so that the hinge arrangement can transfer heat in both directions: from the third fastening member 202 to the second fastening member 103 and from the second fastening member 103 to the third fastening member 202.

FIG. 10 shows tabulations regarding materials and properties of a hinge arrangement according to an embodiment of the present invention. As it is now described in view of FIG. 10, a main effect of this invention is low thermal resistance, especially less than l.6°C/W, which equals that such a device can transfer 5W heat for temperature difference of 8°C between the third fastening member 202 and the second fastening member 103. An estimation of this parameter was based on a simulation of heat transfer in the hinge arrangement according to the present invention. A geometry of a hinge arrangement that was used for the simulation is shown in FIG. 11. The following table gives an overview of materials and parameters used in simulation:

A thermal resistance between the third fastening member 202 and the protrusion 204 is calculated based on the following equation, in which k _a is air conductivity; R _zl , R _z2 are roughness of contacting materials; p is contact pressure; k _m is average conductivity of contacting materials (copper); OB i ultimate tensile strength (400MPa for copper). For calculation, a roughness of Ra = 0.3pm and Rz = 2.7pm for surface after polishing are used. FIG. 10A shows coefficients of friction of copper alloys. In the calculation, a friction coefficient between surface of the third fastening member 202 and the protrusion 204 of k = 0.5 is used. That is, on the surface of the protrusion 204, a layer of a material with low friction coefficient should be used. In calculation it is assumed that a detaching force is 2N. For a friction coefficient of 0.5 and a simulated geometry of protrusion 204, the maximum normal pressure between contacting surfaces is 8l.8kPa (cf. FIG. 10B). For a friction coefficient of k=T this pressure is by twice lower (also with low thermal resistance). In such a case, the calculated contact thermal resistance is 0.9163 · 10 ⁴ m ² K/W. Resistances of thermal interface layers were calculated like for heat transfer through a plane shaped layer. Based on this parameters, in ANSYS Fluent a temperature distribution in the thermal transferring hinge and an estimated thermal resistance are simulated. The results depend on a quality of manufacturing the gap between the first axel element 106 and the cavity 102, and between the second axel element 107 and the cavity 104. Based on the shown simulation model it is estimated that with a gap of 0.2mm between the mentioned surfaces, the hinge arrangement can meet requirements of thermal resistance l .6°C/W and will transfer 5W of heat for a temperature difference of 8°C.

FIG. 10C shows results of a calculation of selected thermal resistances of the hinge arrangement in case that the thickness of thermal interface material is 0.2mm. Thus, calculation results showed that the hinge arrangement can reach low thermal resistance of 1.6°C/W. Similar results of total thermal resistance are achieved for all of the described above configurations of hinge arrangements.

The present invention has been described in conjunction with various embodiments as examples as well as implementations. However, other variations can be understood and effected by those persons skilled in the art and practicing the claimed invention, from the studies of the drawings, this disclosure and the independent claims. In the claims as well as in the description the word “comprising” does not exclude other elements or steps and the indefinite article“a” or“an” does not exclude a plurality. A single element or other unit may fulfill the functions of several entities or items recited in the claims. The mere fact that certain measures are recited in the mutual different dependent claims does not indicate that a combination of these measures cannot be used in an advantageous implementation.