GB2433770A

GB2433770A - Hinge with clamped pin coated with hardness imparting component

Info

Publication number: GB2433770A
Application number: GB0526555A
Authority: GB
Inventors: Mike Tyrrell; Angus Hutley
Original assignee: Thales Holdings UK PLC
Current assignee: Thales Holdings UK PLC
Priority date: 2005-12-29
Filing date: 2005-12-29
Publication date: 2007-07-04
Also published as: GB2433770A8; GB0526555D0

Abstract

A hinge includes a pin 1 fitting in a housing 2, 4, and a clamping system 2, 3 preventing the pin from rotating by itself in the housing. The pin, the housing and the clamping system are made from the same first material, and the pin is coated with a second material having lubricating properties and being selected also for resistance to plastic deformation. The first material may be aluminium and the second material may be ceramic loaded PolyTetraFlouroEthylene. The clamping system may comprise a screw 3, and housing 2. The hinge may be used in a laptop computer comprising a screen leaf and keyboard leaf.

Description

The present invention relates to a hinge, and particularly to a hinge

capable of being used in variable temperature conditions, for example robotics or laptops.

Hinges are commonplace devices, used in a variety of mechanical applications where parts are to be pivotable relative to each other. One form of hinge comprises a cylindrical pin fitting closely in a housing, the pin rotatable in the housing. The assembly ensures both that parts assembled with the hinge are clamped together and do not move by themselves if not subjected to external effort, and further that assembled parts are joined by lubricated contact and are easily movable if external effort is applied.

Should the pin and the housing be made from the same materials, and the fit of the parts be selected appropriately, the hinge assembly would hold immobile in any position but would tend to bind, due to the material selection. Lubrication would thus be required.

On the other hand, should the pin and the housing be made from different materials to ensure lubricated contact, the fit of the hinge assembly could be temperature dependent, since different materials have different rates of thermal expansion. A tight, binding fit could be experienced at one temperature, while a loose, even sloppy fit could be experienced at another temperature.

Solutions to this problem that have been presented in the past, in an attempt to both clamp and lubricate the pin in its housing, were based on the use of different materials to ensure lubrication and the use of an additional clamping system.

Materials would be selected to minimize the difference in rates of thermal expansion.

A clamping system enables adjustment of the operating temperature range of the hinge, which is specified by manufacturer.

Considering a laptop as an example, the housing can be made from aluminium and the pin from a plastics material such as polycarbonate. Stainless steel clamping screws can be used to adjust the friction of the hinge, and thus the fit. Lubrication is ensured through the use of the polycarbonate pin. Unfortunately, the effort required to move the leaves of the laptop often remains high and can lead to jerky movement and creaking, which is undesirable.

Moreover, at low environmental temperatures, such as below -20 C, the fit in the hinge becomes loose and the screen cannot be maintained in a single position, thus rendering the laptop difficult to use. When heated up to 50 C, it is conceivable that the screen leaf will be rendered immobile, relative to the keyboard base leaf. Even with careful materials selection, the different thermal expansion rates of materials limits the temperature range of practical use of such a device.

A number of other solutions have been proposed, all of them having substantial drawbacks.

For example, the previously described clamping system can be a thumbwheel to tighten up the hinge as required by the user. But, if the hinge engages two relatively heavy parts together, loosening the thumbwheel might be hazardous. In such a case, the user would need to set the position of the hinge with one hand and to tighten up or loosen the wheel with the other hand. This may at least be inconvenient to a user.

Another possibility is to use a gas strut to maintain the hinge in a fully open or fully closed position. The hinge itself is designed in such a case to be a loose fit, thus not providing resistance against the gas strut. This is thus similar to the mechanism found in the boot (trunk) of a car. The properties of the hinge are in this case not temperature dependent. However, this is disadvantageous as it does not enable intermediary positions of the hinge to be set. Secondly, it will affect the outline of device and may be bulky.

Another possible solution is to use a worm and wheel gearbox. The user can easily set the position of the hinge by simply turning a wheel. The wheel controls a worm screw, and the worm screw itself controls the moving part of the hinge. For the same reason as for the gas strut solution, the efficiency of the hinge is no longer dependent on temperature. Furthermore, this design may not affect the outline of the device in which the hinge is incorporated. However, this arrangement may be very expensive.

The present invention aims to provide a hinge apparatus that may be used in a wide temperature range while avoiding the drawbacks mentioned above.

One aspect of the invention provides a hinge apparatus for use in a wide range of temperature. The apparatus includes a pin fitting in a housing and clamping means for restricting rotation of the pin by itself in the housing. The pin, the housing and the clamping means are made from the same first material. The pin is coated with a second material providing a lubricating interface with the first material.

Another aspect of the invention provides a hinge including a pin fitting in a housing, and a clamping system preventing the pin from rotating by itself in the housing. The pin, the housing and the clamping system are made from the same first material, and the pin is coated with a second material having lubricating properties and being selected also for resistance to plastic deformation.

Preferably, the first material is aluminium. Preferably, the second material is PolyTetraFluoroEthylene (PTFE) loaded with ceramic. The ceramic loading is provided to limit the extent of creep of the PTFE. It will be appreciated that any other material could be provided alongside the PTFE with a view to limiting creep.

Preferably the clamping system is at least one screw. This may be of the same material as the housing. The screw is preferably screwed in the housing to clamp the housing around the pin.

Thus, a key advantage provided by the present invention is its simplicity, in the sense that it does not imply any alteration in the layout of the hinged device, with respect to previous devices, both externally and internally. For example a laptop equipped with hinges according to the invention will be of similar appearance and outline as a laptop incorporating a previous hinge. As a consequence the hinge can be incorporated into any hinged device without major redesign.

A non-limiting example of the invention is described below with reference to the accompanying figures, which schematically illustrate an example of embodiment of a hinge apparatus according to the invention.

Figure 1 illustrates a longitudinal axial section of a hinge in accordance with the described specific embodiment; and Figure 2 illustrates a cross section of the same hinge.

The hinge is shown in an assembly of the pivoting screen of a laptop to its keyboard. In the figures, like reference signs are assigned to like items.

This specific embodiment of a hinge includes a cylindrical elongate pin 1, one of whose ends fits in a cooperating aperture of a housing 4, to which it is fixedly attached. Fixed attachment is achieved by use of a pin 8 radially across the aperture of the housing 4 and into a bore of the pin 1. Therefore, the pin I cannot rotate in housing 4.

The other end of pin 1 fits also in a cooperating bore of a second housing 2, for free rotation. To separate the housings 2, 4, pin 1 comprises a middle portion of larger radius than either end, but it will be appreciated that the invention could be delivered without this feature.

It will be appreciated that housing 2 is mounted on a keyboard 6 of a laptop and housing 4 supports a pivoting screen 5 of the laptop. That way, the hinge joins the screen to the keyboard of the laptop.

It will further be appreciated that one or more hinges may be provided to provide sufficient support of the screen on the keyboard.

The pin 1 and its housings 2 and 4 are made from the same material, and in this case aluminium, which ensures that all parts of the assembly, given that they will be at substantially the same temperature, expand and contract in the same proportions as temperature changes. Thus, whatever the temperature is, the pin I is able to rotate in the housing 2.

It will be understood that variations in the material as described herein may be made without departing from the scope of the present invention.

To enable a user to set the screen easily in any convenient position, the pin 1 is coated with a lubricating material, and in this example PolyTetraFluoroEthylene (PTFE).

PTFE, as with many plastics materials, presents lubricating properties facilitating sliding friction of pin I inside housing 2. Hereby, the user can set the screen in any convenient position by a single smooth pivoting movement.

It will be understood that an aluminium on aluminium loose fit engagement between the pin 1 and the housing 2 would be rough and could bind Sometimes, the user would not be able to set the screen as expected in a single trial, and he would then need to move the screen forth and back several times.

To ensure that the screen holds in any position set by user, two screws 3 and 7 are threadingly engaged in respective threaded bores in the housing 2. As illustrated in figure 2, the shape of the housing 2 is such that the bore in which the pin I is accommodated is defined by a leaf of the housing which loops over the pin and then returns to alongside a main body portion of the housing. The screws 3, 7 provide means for controlling the diameter of the bore so that the housing 2 clamps around the rotating pin 1. The screws 3, 7 are of the same material as the housing 2.

The lubricating properties of the PTFE coating of the pin 1 and the fact that to be assembled its diameter must be slightly less than the internal diameter of the housing 2 could lead the screen to pivot by itself due to its own weight. The screws 3 and 7 provide a clamping means to restrict movement unintended by the user. By tightening or loosening the screws 3 and 7, the manufacturer or user can adjust the effort to be applied by the user to set the angular position of the screen. It is to be understood that variations in the clamping arrangement as described herein may be made without departing from the scope of the present invention.

1-lowever, lubricating materials also present the drawback that they can creep (elastically or plastically) when subject to localised stress. Indeed, the housing 2 may slowly sink into the lubricating coating of pin 1, if screws 3 and 7 are set too tightly by the manufacturer. This may displace PTFE into the bore, and further tighten the fit of the pini in the housing 2. Over the long term, the pin 1 may cease to be rotatable in the housing 2 and the screen may get stuck.

To prevent the housing 2 creeping into the PTFE coated pin 1, the PTFE is in this specific embodiment therefore loaded with a harder material, and particularly a ceramics material. The hardness property of ceramics material combines with the lubricating properties of PTFE to provide a lubricating but hard mixture that both facilitates sliding friction of the pin 1 in the housing 2 while preventing the stress imposed by the housing 2 from causing creep. This enables adjustment of the screws 3 and 7 such that the screen is fully mobile but only on user actuation.

It will be understood that variations in the both lubricating and hard coating material as described herein may be made without departing from the scope of the present invention.

It is to be understood that variations to the examples described herein, such as would be apparent to the skilled addressee, may be made without departing from the scope of the present invention.

Claims

CLAIMS: 1. A hinge including a pin rotatable in a housing, and clamping

means for clamping said pin in said housing for restricting rotation of the pin in the housing, wherein the pin, the housing and the clamping means are of a first material, the pin (1) being coated with a second material being lubricating on interface with the first material and further incorporating a hardness imparting component to limit creep of said second material on clamping engagement of said pin in said housing.

2. A hinge according to claim I wherein the first material is aluminium.

3. A hinge according to claim 1 or claim 2 wherein the second material is ceramic loaded PolyTetraFluoroEthylene.

4. A hinge according to any preceding claim wherein the clamping means comprises at least one screw for threading engagement in the housing to clamp the housing around the pin.

5. A hinge according to claim 4 wherein the or each screw is of the same material as the housing.

6. A hinge according to any preceding claim and further comprising a second housing, wherein the pin is also fixedly attached to said second housing.

7. A laptop computer comprising a screen leaf and a keyboard leaf, and the hinge according to claim 6, the screen leaf being attached to one of the two housings and the keyboard leaf being attached to the other, for hinging engagement of the screen leaf and the keyboard leaf relative each other.

Amendments to the claims have been filed as follows CLAiMS: 1. A hinge for a laptop computer including a pin rotatable in a housing, and clamping means for clamping said pin in said housing for restricting rotation of the pin in the housing, wherein the pin, the housing and the clamping means are of a first material, the pin (1) being coated with a second material being lubricating on interface with the first material and further incorporating a hardness imparting component to limit creep of said second material on clamping engagement of said pin in said housing.

2. A hinge according to claim 1 wherein the first material is aluminium.

3. A hinge according to claim 1 or claim 2 wherein the second material is ceramic loaded PolyTetraFluoroEthylene.

4. A hinge according to any preceding claim wherein the clamping means comprises at least one screw for threading engagement in the housing to clamp the housing around the pin.

5. A hinge according to claim 4 wherein the or each screw is of the same material asthehousing. * .*

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* 6. A hinge according to any preceding claim and further comprising a second housing, wherein the pin is also fixedly attached to said second housing.

7. A laptop computer comprising a screen leaf and a keyboard leaf, and the hinge according to claim 6, the screen leaf being attached to one of the two housings and the keyboard leaf being attached to the other, for hinging engagement of the screen leaf and the keyboard leaf relative each other.