WO2012049518A1

WO2012049518A1 - Hinge having self centering means

Info

Publication number: WO2012049518A1
Application number: PCT/GB2011/051996
Authority: WO
Inventors: Chung Chow
Original assignee: Chung Chow
Priority date: 2010-10-14
Filing date: 2011-10-14
Publication date: 2012-04-19
Also published as: CN202659012U; CN102454326A; CN102454326B; TW201224266A

Abstract

A glass door hinge having an internal door stop arrangement comprises: a housing (1); a mount (2) for coupling the housing to a support member; a pair of clamps (5); an axial spindle (6); one or more biasing members (16, 27) arranged to engage the spindle to return the clamps to one of a plurality of positions selected from a closed position and one or more opened positions; wherein the spindle has one or more centering surfaces (11, 12); the or each biasing member being arranged to apply a force to a respective centering surface to centre the clamps in one or more of said positions.

Description

HINGE HAVING SELF CENTERING MEANS

This invention relates to a hinge for a door particularly a glass door, more particularly but not exclusively a frameless glass door.

Frameless glass doors require a door stop to locate the door in a closed position. Internal door stops have been disclosed, for example in US 6560821. WO2011/020630 discloses a glass door hinge having an internal door stop arrangement comprising; a housing; a mount for coupling the housing to a support member; a pair of clamps; an axial spindle; and plurality of biasing members arranged to engage the spindle to return the clamps to one of a plurality of positions selected from a closed position and one or more opened positions; wherein the spindle has a plurality of centering surfaces; each biasing member being arranged to apply a force to a respective centering surface to centre the clamps in one or more of said positions. The disclosure of this specification is incorporated by reference for all purposes into the disclosure of the present specification.

According to the present invention a door hinge having an internal door stop arrangement comprises:

a housing;

a mount for coupling the housing to a support member;

a pair of clamps;

an axial spindle; and

one or more biasing members arranged to engage the spindle to return the clamps to one of a plurality of positions selected from a closed position and one or more opened positions; wherein the spindle has one or more centering cam surfaces;

wherein the spindle includes one or more stop surfaces, the or each stop surface being angularly displaced relative to a main centering cam surface and extending parallel to the spindle axis;

the or each biasing member being arranged to apply a force to a respective centering cam surface to centre the clamps in one or more of said positions;

wherein the hinge includes a main biasing member and a main spring arranged to extend the main biasing member to engage the main centering surface to urge the clamps into a closed position; and

wherein the or each stop surface is arranged to engage the main biasing member to retain the spindle in a position. Preferably the biasing member when extended does not intersect the spindle axis.

The door is preferably a glass door, more preferably a frameless glass door. Movement of the clamps to an opened or closed position correspondingly moves the door to an opened or closed position. The centering surfaces, particularly the main centering surface act as cam surfaces as the biasing member is rotated during opening or closing of the door.

The or each stop surface may be arranged to engage the main biasing member to hold the clamps of the hinge in an opened position. Preferably the hinge is held in an opened position perpendicular to the closed position.

Preferably the or each stop surface is perpendicular to the main centering surface.

Preferably two parallel stop surfaces are provided. There are preferably two open positions perpendicular on either side of the closed position. In this arrangement the door may be held in an open position perpendicular on either side of the closed position. A door attached to the hinge may be held open in either direction unless a small closing force is applied to the door sufficient to overcome the force of the main spring. In the following description a direction towards the biasing member or piston is referred to as proximal and a direction away from the biasing member or piston towards the spindle is referred to as distal.

In a preferred embodiment the spindle is arranged so that when the main centering surface is facing proximally towards the biasing member, the or each stop surface extends perpendicularly relative to the centering surface, the stop surface having a proximal edge facing towards the biasing member and a distal edge facing away from the biasing member.

In this position the stop surface preferably extends from a location distally of the spindle axis either to a location proximally of the spindle axis, or to a location on the axis that is on the diameter of the spindle parallel to the main centering surface. In the latter arrangement, wherein the or both proximal edges are located on the spindle diameter in the closed position, the proximal edge is orthogonal to the spindle diameter, the or each stop surface preferably extends distally of the spindle axis. In this arrangement the hinge is prevented from angular rotation beyond the angle of the opened position, due to abutment between the biasing member and the stop surface. Rotation of the hinge towards the closed position is facilitated by the biasing member contacting the proximal edge of the stop surface before engagement with the main centering surface. In an alternative embodiment the proximal edge is located proximally of the spindle diameter. In this arrangement the stop surface preferably extends proximally by a sufficient distance to provide a restoring force to resist rotation of the hinge towards the closed position. The distance between the proximal edge and the diameter (or spindle axis) may be selected so that the biasing member provides a restoring force sufficient to allow a door secured to the hinge to be held in the opened position but with the force not being so large that a user would have difficulty in closing the door. The magnitude of the distance and consequently of the restoring force may depend on the width of the door, the weight of the door and the strength of an intended user. In preferred embodiments the main centering cam surface is located proximally of the spindle diameter. This confers several advantages. Closing of the hinge is facilitated. The length of the extension of the spring or other biasing member in use is reduced. This permits use of a more powerful but less expensive spring. The volume of lubricating oil displaced during rotation of the spindle is reduced. This provides a longer working life for the oil.

A further cam surface may be provided between the proximal edge of the stop surface and an adjacent edge of the main centering surface. The further cam surface may be rounded to facilitate smooth opening and closing of the hinge, reducing wear of the contact surface. This permits use of a lower grade of steel for manufacture of the spindle.

The clamps may be adapted to securely engage a glass door panel. The glass panel may have holes to receive bolts passing through the clamps. Alternatively or in addition the clamps may engage the glass panel by friction or by use of an adhesive.

The hinge preferably includes damping means for damping the opening and closing movements of the hinge. Preferably the biasing means includes a damping arrangement to limit the rate of rotation of the hinge particularly from the opened to the closed position. The damping means may also limit the rate of rotation from a partially opened position to a fully opened position. In a first preferred embodiment the hinge includes a secondary biasing member and a secondary spring arranged to engage one or more secondary centering surfaces to urge the door into one of two opened positions.

The or each secondary centering surface may be a planar or cylindrically concave surface.

Alternatively the secondary centering surface may comprise a cylindrical member parallel to and displaced from the spindle axis. Use of a cylindrical surface has the advantage that smooth damping is achieved with low wear of the moving parts. The cylindrical member preferably located within the circumference of the spindle.

In a second alternative preferred embodiment two hinge units include two biasing members, a first unit including a main biasing member and a second unit including a secondary biasing member. The two units may comprise the lower and upper hinges of a door.

In the first preferred embodiment, the main and secondary biasing members are preferably located in horizontal bores arranged in vertically spaced relation extending radially relative to the spindle axis.

Preferably the two biasing members are integral within a single unit and have a common spindle.

Preferably the two opened positions of the hinge are perpendicular to the closed position, and the two secondary centering surfaces are orthogonal to the main centering surface and are diametrically opposed to each other. That is the secondary surfaces may be arranged to face in opposite directions perpendicular to the main centering surface.

The force of the main spring is preferably greater than the force of the secondary spring. In this way the hinge moves to the closed position unless the door is at or adjacent either of the opened positions. The hinge therefore may comprise an overcentre arrangement wherein it moves either into the closed position or an open position when opened in either direction. The angular location of each centre point on each side of the closed position is preferably close to the opened position. The main spring may comprise a pair of concentric springs. The outer spring may be a relatively powerful spring to provide the closing force for the hinge. The inner spring may be relatively less powerful than the outer spring and is arranged to provide a closing force for a nonreturn valve in the face of the biasing member. The non return valve is described further below.

Each biasing member may comprise a piston mounted in a cylindrical bore for movement radially with respect to the spindle.

The piston preferably comprises a hollow cylindrical member having a head arranged to engage a respective centering surface, and having a cavity, a spring being located in the cavity within the cylindrical member to urge the piston outwardly of the bore.

The spindle may be mounted in a vertical guideway in the housing, the guideway communicating with one or more passageways within which the or each of the biasing members are located to allow circulation of hydraulic fluid or other oil during actuation of the hinge.

The spindle preferably includes an attachment adapted to engage to the clamps. An end of the spindle may include a head configured to engage a socket in one of the clamps so that the spindle and clamps are constrained to rotate together.

According to a second aspect of the present invention a glass door hinge spindle comprises an axial shaft including an attachment for engagement to a door so that the spindle and door are constrained to rotate together in use;

wherein the spindle further comprises:

a main centering surface parallel to the axis of the shaft and two secondary centering surfaces orthogonal to the main centering surface;

wherein the two secondary centering surfaces extend axially of the shaft in diametrically opposed relation; and

wherein the spindle includes one or more stop surfaces angularly displaced from the main centering surface, perpendicular to the main centering surface and parallel to the spindle axis.

The or each stop surface is preferably perpendicular to the main centering surface. Preferably the spindle further includes upper and lower bearing surfaces adapted to cooperate with bearings in the hinge body.

In a preferred embodiment in which the housing contains two biasing members the main centering surface is located below the secondary centering surfaces. Alternatively the main centering surface may be above the secondary surfaces.

The cavity within the housing containing the spindle and piston is preferably filled with hydraulic fluid, for example lubricating oil.

Preferably a cylindrical collar is disposed between the main and secondary centering surfaces, the surface of the cylindrical collar being arranged to cooperate with an internal cylindrical surface of the hinge body to prevent deformation of the spindle in use. The collar may also serve to prevent flow of oil between upper and lower parts of the bore.

Rotation of the spindle as the hinge is rotated causes retraction of one piston against the restoring force of the respective spring, but permits expansion of the other piston. Similarly when the hinge and door are approaching a closed or opened position, expansion of a piston under the action of its spring causes the door to continue rotation until it is fully centered in the opened or closed position.

The piston and cylindrical sleeve may each provide a damping arrangement. The piston and sleeve may be dimensioned to provide a sliding fit but substantially prevent escape of oil between their surfaces as the piston is compressed by rotation of the spindle. Therefore oil may be forced through a constricted channel to damp the movement of the hinge.

A channel may be provided to allow oil to pass from the piston cavity to a cavity within the housing as the piston is compressed into the cylindrical sleeve.

The channel may include an adjustable valve to regulate a maximum flow of oil. Adjustment of the valve allows the rate of closure of the hinge to be regulated so that the rotational movement of the hinge and door is damped in use. The valve may comprise a needle valve, having a screw thread. This may be provided to control the dimension of the passageway leading from the piston and cylinder into a passageway in the hinge housing. Oil passing through the needle valve may be allowed to flow to a cavity between the spindle and the head of the piston.

A permanent magnet may be located within the cavity within the or each sleeve or piston. The permanent magnet may serve to collect any metal particles which are formed by wear of the moving surfaces in use of the hinge. This prevents further damage to the hinge components during use. For example the spring seat may be magnetic.

In a preferred embodiment the piston of the or each biasing means includes a non-return valve arranged to permit a flow of oil into the cavity as the piston and cylinder expand. In this way oil is circulated from the cavity of the piston into a cavity between the piston and spindle and back into the piston cavity during the compression and expansion cycle of the piston. During this cycle the volume of the cavity available between the centering surface of the spindle and piston increases as the piston is compressed and decreases as the piston expands to fully engage the centering surface. This change in volume serves to pump oil through the non-return valve to cause circulation of the oil during opening and closing of the hinge and door. Circulation of the oil contributes to efficient damping of the hinge.

The main piston may be provided with one or more apertures to allow a flow of oil from the cavity during initial compression of the piston.

In a preferred embodiment the piston has a head and a cylindrical body dimensioned to be slidably received within a cylindrical bore of the sleeve, and one or more apertures provided at a predetermined axial distance from the head, the aperture or apertures being blocked by the sleeve after sliding of the body by a predetermined distance into the cylindrical sleeve. In this arrangement oil can flow easily from the piston cavity until the piston has retracted to a predetermined extent, after which flow of oil is impeded or prevented, thereby providing a two speed damping effect.

The main non-return valve may be urged distally into a closed position by the inner spring of the main biasing means. The length of the inner spring may be selected to provide an appropriate closing force to the valve. Preferably the inner spring has a greater length than the outer spring.

A cut-away portion may be provided at the distal end of the cylindrical body of the piston to allow a flow of oil into the piston cavity as the piston is fully extended. At this stage the non-return valve is in engagement with the centering surface of the spindle.

The cutaway portion may increase in cross sectional area from a location intermediate the head of the piston and the end of the sleeve, so that a flow of oil between the sleeve and the bore in which it is mounted may increase as the piston is extended towards a fully extended position. The cross sectional shape of the cutaway portion may be selected to provide a suitable damping profile. For example the cutaway portion may comprise a V-shaped or U-shaped slot. Alternatively the cutaway portion may comprise a flat surface formed by removal of a sector from the cylindrical sleeve. As a further alternative a parallel sided channel may be employed.

The hinge of this invention has several advantages. The opening and closing of the hinge are both damped by circulation of oil through the biasing means. This restricts slamming of a door during opening or closing. Such slamming may shatter a glass door or may cause injury. The extent of damping during closing can be controlled by adjustment of the valve in the secondary biasing means. Circulation of oil within the biasing means is promoted by the pumping action of rotation of the spindle.

In a preferred aspect of the present invention, the hinge further comprises:

a housing having a vertical bore;

the axial spindle being mounted within the bore;

a closing arrangement within the housing and adapted to engage the spindle to urge the hinge to a closed or centred position;

a damping arrangement within the housing and adapted to engage the spindle to damp movement of the hinge toward the closed position;

wherein the spindle has a vertical axis and first and second centering cam surfaces, the centering surfaces being arranged to urge the closing and damping arrangements alternately away from the axis as the housing rotates in relation to the spindle respectively away from or towards the closed position; wherein the closing arrangement comprises a pusher head having at least one closing contact surface and a spring, the spring being arranged to urge the contact surface into engagement with a first centering surface;

wherein the damping arrangement comprises working fluid and a piston, the piston comprising a piston head and a sleeve slidably mounted within a cylinder, a spring located within the cylinder, the piston having a projection with a damping contact surface, the damping contact surface being urged by the spring into engagement with a second centering surface of the spindle; the damping piston including a non-return valve;

wherein the closing and damping arrangements extend radially from the spindle axis in opposite directions;

wherein an interior surface of the damping piston, sleeve and cylinder form a first chamber and the exterior surface of the damping piston head, bore and spindle form a second chamber for working fluid;

working fluid disposed in the second chamber passing through the non-return valve in the damper piston as the damper piston moves towards the spindle axis in use, return flow through the non-return valve being prevented as the damper piston moves away from the spindle axis.

In particularly preferred embodiments an adjustable valve is located in the housing; a first duct communicating between the first chamber and the adjustable valve;

a second duct communicating between the second chamber and the adjustable valve; whereby adjustment of the valve controls flow of working fluid from the first chamber to the second chamber to damp movement of the hinge towards the closed or centred position. Use of a single adjustable valve is preferred. However, two or more adjustable valves may be used, if desired.

A hinge in accordance with this embodiment of the present invention confers several advantages. Use of two separate closing and damping arrangements allows each of them to be manufactured with a simple and robust construction so that the closing and damping forces and the damping profile may be selected to suit any particular application. For example, a stronger damping arrangement may be used for a heavy door or a large door which may be easily slammed during use. The location of the damping arrangement on the opposite side of the spindle to the closing arrangement provides a more balanced construction in comparison to hinges in which both closing and damping pistons are on the same side of the spindle axis. Wear of the bearings is reduced so that misalignment of the cam surfaces is less likely to occur after prolonged use. This is particularly important where there are relatively small secondary or intermediate cam surfaces (if present as described below), since the edges of these cam surfaces may become worn if the spindle is not accurately aligned.

The damping arrangement comprises a circuit for working fluid extending from the chamber in which the spring is located to the adjustable valve, and from the adjustable valve to the chamber in which the exterior front surface of the damping piston engages the cam or centering surface of the spindle. The moving parts are therefore maintained in a well lubricated condition. A single adjustable valve may be located on the exterior of the housing permitting simple and convenient adjustment.

The closing arrangement, located in a separate chamber within the housing, may be filled with oil or other fluid, although this is not essential. One or more apertures may be provided to permit circulation of the working fluid into the piston as the piston extends and retracts in use. The aperture may be dimensioned to restrict the flow of fluid in order to provide additional damping for the hinge. Alternatively, the aperture may be sufficiently large to permit a free flow. The first and second centering cam surfaces may have a similar or different configuration. In preferred embodiments, the surfaces are approximately semicircular in radial cross-section. Preferably the planar portions extend forwardly of the spindle axis so that the axis passes through the spindle and does not pass through the space in front of the planar surface. Secondary stop surfaces perpendicular to the planar surfaces may be provided. This permits the hinge to be stopped at an open position, for example 90° from the closed centred position. Such an arrangement is not feasible if the closing member extends beyond the spindle axis in the centred position. The closing member may comprise a piston slidably moveable within a cylinder, the piston comprising a piston head and a sleeve, preferably a cylindrical sleeve. The piston head may have a projection with one or more contact surfaces. A spring may be located within the sleeve and arranged to engage a rear surface of the piston head to urge the contact surface or surfaces into engagement with the centering surface of the spindle.

In a preferred embodiment, the spindle comprises an axially extending member having a closing cam surface and one or more damping cam surfaces disposed in axially spaced relation to the closing cam surface;

a barrier between the closing and damping cam surfaces extending towards the surface of the bore to substantially prevent fluid flow between the closing and damping cam surfaces in use.

The fluid flow is preferably prevented to a sufficient extent that an increase in fluid pressure on one side of the barrier does not cause a sufficient increase in fluid pressure on the other side of the barrier to reduce the closing force exerted by the piston of the closing member.

However, a sufficient separation between the barrier and the bore may be provided to allow for lubrication by the fluid.

The barrier may comprise a cylindrical collar extending radially from the spindle to a location adjacent the surface of the bore.

The closing or cam surface may be parallel to the contact surface of the piston in the fully extended position of the piston.

The diameter or width of the closing or centering surface is preferably less than the diameter of the cylindrical collar or other barrier. The diameter of the closing cam or centering surface may be from 70% to 98%, preferably from 80% to 98%, more preferably 85% to 95% of the diameter of the collar. Use of a smaller diameter or width reduces the extent of compression of the closing spring or springs. Consequently friction and wear of the closing surfaces is reduced.

One or more secondary surfaces may be provided. These may be angularly perpendicular to the first surface. These surfaces allow the hinge to remain in an opened position, for example at 90° to the closed or centred position. The diameter or width of the closing or centering surface is the distance between the secondary surfaces and may be reduced in order to prevent wear of the moving parts in use. One or more intermediate surfaces may be provided between the first and second surfaces, being located at an angle intermediate the first and second surfaces. The intermediate surfaces may be planar or convex and may serve to impede or prevent closure of the hinge at an intermediate angle. In such an arrangement, accidental slamming of a door may be prevented. The intermediate surfaces may be at an angle of 30°, 45° or 60° to the main closing centering cam surface. The engagement of the biasing member with the intermediate surfaces may reduce the rate of rotation of the door or may allow the door to be halted at the intermediate angle.

The body of the damping piston may comprise a sleeve with one or more cutaway portions providing one or more passageways extending along the exterior of the sleeve to a location at the end of the sleeve communicating with the internal cavity to provide differential damping dependent on the extension of the damping piston. The cross-sectional area of the passageway or passageways may vary along the length of the sleeve, for example, increasing away from the spindle so that a smaller cross-sectional area for fluid flow is provided as the sleeve and piston head are compressed away from the spindle axis. Fluid flow through the passageway or passageways may be prevented as the damping piston approaches a fully compressed position.

The contact surface of the projection may be concave or cylindrical to provide a shallow depression. This may serve to prevent adhesion to the cam surface of the spindle. Irregularities in the cam surface may form during prolonged use. The cam surface may be planar or curved. Use of a concave or cylindrical surface may be beneficial to ensure smooth and unimpeded contact between the surfaces as the hinge rotates. Excessive compression of the spring is avoided reducing frictional forces between the moving parts. Use of a concave area on the piston pushing head provides several advantages. The concave surface helps in damping when the door to which the hinge is mounted closes. Good contact with the spindle is ensured if the centre contact surface of the spindle has become rough or uneven due to wear. Further, the concave surface is used to release the compression of the closing spring. When the hinge opens, this reduces the friction when a door is opened to 75° to 85°. The concave area may provide a recess for any residue to accumulate such as may occur during long term use. The contact surface may comprise a central portion and two outer portions, the central portion being located axially in relation to the spindle axis, the length of the central portion from the piston head being longer or shorter than the length of the outer portions from the piston head.

In a first embodiment the central portion is longer extending further towards the spindle so that the contact surface is generally convex.

In an alternative embodiment the central portion is shorter so that the contact surface is generally concave or inwardly curved.

The central and outer portions may be independently either curved or planar and may form a continuous or discontinuous axially symmetrical contact surface. For example a smooth concave or convex surface may be provided. Alternatively a stepped configuration may be provided.

Selection of an appropriate profile for the contact surface in combination with the configuration of the centering cam surfaces allows control of the closing or damping forces applied during rotation of the hinge in use.

In alternative embodiments, the contact surface may be convex or extend cylindrically outwardly.

A convex or outwardly extending surface may be helpful to maintain the spring under compression to enable a door to withstand strong winds without being blown open.

This invention is further described by means of example but not in any limitative sense with reference to the accompanying drawings of which:

Figure 1 is a perspective view of a first hinge in accordance with this invention;

Figure 2 is an exploded view showing the components of the hinge;

Figure 3 is a cross-sectional view of the hinge in the opened position;

Figure 4 is several cross- sectional views of the hinge in the various positions;

Figure 5 comprises various views of the spindle;

Figure 6 comprises various cross- sectional views of an alternative spindle;

Figure 7 comprises various views of the spindle;

Figure 8 is a cross-sectional view of a further hinge unit;

Figure 9 is a cross-sectional view of the unit; Figure 10 comprises various views of the spindle;

Figure 11 is an exploded view of a further hinge unit;

Figure 12 is a cross sectional view of the unit;

Figure 13 comprises various views of the spindle;

Figure 14 comprises various views of a further spindle;

Figure 15 comprises various views of the piston of the hinge in accordance with this invention;

Figure 16 is a perspective view of an alternative hinge in accordance with this invention;

Figure 17 is a cross sectional view of the hinge shown in Figure 16;

Figure 18 is a perspective view showing the damping piston;

Figure 19 is a perspective view showing the closing piston;

Figure 20 is a perspective view of the spindle; and

Figures 21 to 29 show different configurations for the piston and pusher head.

In the description of the embodiments of the invention the same reference numerals are used to denote like components in each embodiment.

Figure 1 shows a perspective view of a hinge in accordance with this invention. A housing (1) is mounted on a mounting block (2) having an upright member (3) with apertures (4) for bolts, screws or other fixing means (not shown).

A pair of clamps (5) are pivotally attached to the housing (1). The clamps (5) provide an aperture dimensioned to receive a glass plate.

Figure 2 is an exploded view of a first embodiment of the invention. Figure 3 shows the hinge in cross sectional view.

A spindle (6) is received in a vertical bore (7) of the housing (1). The spindle is mounted on bearings (8, 9) sealed by gaskets (10) and a threaded sealing member (43) to allow rotation of the spindle in use.

The spindle is generally elongate and includes cut-away portions which define centering surfaces. A main centering surface (11) is located at a lower part of the spindle. Two diametrically opposed secondary centering surfaces (12) are disposed perpendicular to the main centering surface (11) and above the latter on the spindle. A cylindrical collar is located between the main and secondary centering surfaces. The surface of the collar cooperates with an internal cylindrical surface of the housing to maintain the spindle in alignment and to transmit the forces from the springs to the housing. This serves to prevent deformation of the spindle due to the forces applied by the pistons in use.

A rectangular head (13) allows coupling of the spindle to a correspondingly shaped rebate (23) in one of the clamping members so that the spindle and clamping members are constrained to rotate together in use.

Two biasing means are located in vertically spaced horizontal bores in the housing (1) arranged radially in respect to the axis of the spindle (6). A main biasing means is located in a lower bore (14) and a secondary biasing means is located in an upper bore (15). The main biasing means comprises a cylindrical piston (16) having a head (17) and an internal cavity (18) as shown in Figure 3. The centre of the head (17) has an aperture (19) communicating with the cavity (18). The aperture (19) is dimensioned to control the rate of oil flow in use of the hinge. A spring seat (24) carries a pair of springs (25, 25a). The distal ends of the springs remote from the spindle are received in a cylindrical sleeve (26). The pair of springs (25, 25a) exert an axial force to urge the piston (16) towards the centering surface (11) of the spindle. The pair of springs (25,25a) are selected to provide an even extension force over their operating range.

A secondary biasing means comprises a secondary piston (27) having a hollow cylindrical body and a head (28) and defining an internal cavity (29) as shown in Figure 3. A disc (30) having a central aperture (31) cooperates with a non -return valve member (32). The disc (30) is sealed by a gasket (33). The aperture (31) in the disc (30) serves to regulate flow of oil through aperture (35) in the head of the piston. A main outer helical spring (36) engages a spring seat (20) to urge the piston (27) in engagement with the spindle (6). A secondary inner spring (36a) has a length selected to urge the valve member (32) against the valve seat (20) and the disc (30) to close the valve.

In a similar way to the main biasing means, a sleeve (38) has a cylindrical bore to receive the cylindrical piston body (27) permitting sliding movement of the piston in a radial direction with respect to the spindle axis. The upper secondary piston arrangement serves to damp the closing motion of the hinge. A sleeve (38) has a cylindrical bore to receive piston (27). The piston (27) has a head (28) and internal cavity (29). A cut-away portion (21) is provided at the distal end of the cylindrical piston body remote from the head and the spindle. A spring (36) urges the piston towards the spindle. As rotation of the spindle causes retraction of the piston into the sleeve as shown in Figure 3, the non-return valve (32) closes the aperture (31) so that oil is driven from the distal end of the piston through the cut-away portion (21), and annular channel (45), past needle valve (47), allowing the oil to circulate into the cavity adjacent the spindle and particularly the cavity formed by centering surface (12). Adjustment of the needle valve (47) controls the maximum rate of flow of oil to provide a desired damping effect suitable for the weight of the glass door or other factors. Rotation of the spindle and centering surface (12) allows the piston to extend and simultaneously forces oil through the non-return valve into the piston cavity for another cycle.

As shown in Figure 15, the piston (27) of the secondary biasing member has a cut-away portion (21) on the exterior of the cylindrical body of the piston. This cut away portion communicates with the channel (39) and aperture (22) when the piston is extended towards the spindle so that the head (28) engages the secondary centering surface (12). In this position oil can flow from the internal cavity (29) of the piston (27) through the cut away portion (21), channel (39), aperture (22) and into the cavity (40) surrounding the head of the piston. When the piston (27) is retracted, flow through the cut-away portion (21) is restricted and then cut off entirely. During the centering of the spindle in the closed position, as piston (16) is extended by action of spring (25), oil contained in the cavity (40) of the spindle passes through the aperture (19) into the internal cavity (18) of the piston. During the return stroke as the piston is compressed into the sleeve (26), oil returns into the cavity (40), the volume of which increases as the spindle is rotated in use.

Figures 4 and 5 further illustrate the construction and function of a hinge in accordance with this invention. Figure 4 contains cross sectional views showing the stages in operation of the hinge unit. The construction of the spindle is shown in greater detail in Figure 5. The same reference numerals are used to denote the parts shown in Figures 1 to 3. The spindle shown in Figure 5 comprises a rectangular head (13) from which depends a shaft having an axis (53). The secondary centering surfaces (12) are parallel to each other and extend on opposite sides of the axis (53). The secondary centering surface has a tapered or pointed end (58) to facilitate engagement with the head of the piston (27) as shown in the cross sections A-A of Figure 4.

The main centering surface (11) is generally planar and is displaced proximally with relation to the piston (16) so that the piston (16) cannot extend beyond the axis (53) and at its greatest extent is not located beyond the axis (53). The rear surface (50) is cylindrical to cooperate with the corresponding cylindrical bore (7) of the housing (1). Cylindrical collar (54) forms an additional bearing surface between the two centering surfaces.

In the embodiment shown in Section B-B of Figure 5 the main centering surface (11) is planar and extends parallel to the axis (53). Two stop surfaces (51) are also planar and extend perpendicular to the main centering surface (11) parallel to the axis (53). Curved cam surfaces (52) extend between the leading proximal edge (55) of the stop surface (51) and the adjacent edge (57) of the main centering surface (11). The cam surface (52) provides smoother operation of the hinge unit and reduces wear on the edges (55, 57). The stop surface (51) extends between a proximal edge (55) and a distal edge (56) as shown in Section B-B of Figure 5.

In the embodiment shown the spindle has two opposed stop surfaces (51). In alternative embodiments only a single stop surface (51) may be employed for hinge units which are adapted to open in one direction. Section B"- B" of Figure 5 shows an alternative construction wherein the main centering surface (57) is concave in cross section and generally cylindrical. The concave surface (59) may cooperate with a correspondingly rounded piston head. Alternatively a planar disc shaped piston head may be used. The function of the hinge is illustrated in Figure 4. In the upper cross section B-B the hinge is shown slightly opened. In this position the piston is pushed proximally and the spring (25) partially compressed. As rotation continues as shown in the middle cross sectional view the door reaches a fully opened position. In this position the stop surface (51) is aligned with the head (17) of the piston (16). The spring (25) is fully compressed. The alignment of the planar stop surface (51) with the head of the piston prevents rotation of the spindle so that a user may release the door to leave the door in an opened position. Slight dislodgement of the door as shown in the lower section B-B allows the door to be opened more fully. However cooperation of the piston head (17) and the cylindrical rear surface (50) of the spindle has the effect that the door can rotate freely without being urged into an opened or closed position. On the other hand dislodgement towards the closed position as shown in the upper cross sectional view allows the piston to expand and urge the door towards the fully closed position wherein the piston face (17) is aligned with the centering surface (11). In this position the door comes to rest.

In a first embodiment the proximal edge (55) of the stop surface (51) is located on a diameter of the spindle parallel to the main centering surface (11). In this arrangement further opening of a door beyond the perpendicular position as shown in the lower cross section B-B requires apphcation of force to further compress the spring (25). However closing of the door to the position shown in the upper cross sectional view does not require application of additional force.

In an alternative embodiment the proximal edge (55) is located proximally of the axis (53). In this arrangement a small force is required to dislodge the door from the perpendicular opened position to commence the closing movement. A door including a hinge in accordance with this invention requires manual force to be opened from the closed position to a perpendicular position. Opening beyond the perpendicular position may require a small additional force but further compression of the spring does not occur due to the cylindrical shape of the distal surface (50) of the spindle. Thus the door may be moved freely beyond the perpendicular position but will automatically close when moved from the perpendicular position towards the closed position.

Figure 6 and 7 illustrate an alternative embodiment wherein the secondary centering surface (60) of the spindle is cylindrical and offset from the spindle axis (53). Preferably the cylindrical surface (60) is located circumferentially of the main spindle body so as to form a continuous surface with the collar (54). In this embodiment the secondary centering surface (60) precesses as the spindle is rotated causing compression or release of the secondary spring (36). The centering surface may be tangential to the spindle surface. This arrangement may be less prone to mechanical wear than the arrangement shown in Figures 4 and 5. Smoother damping is provided due to a lower flow of displaced oil. Figures 8 to 14 illustrate embodiments of the invention wherein the hinge unit is provided in two parts, a first part containing the main centering surface and the second part containing the secondary damping arrangement. Figures 8 to 10 show the main centering unit. This may be located for example at the bottom of a door. A base plate (61) is screwed to a housing (62) containing a pair of cylindrical bores (63). A pair of pistons (64) are located within the bores and urged distally by axial spring (65). A spindle (66) mounted in bearings (67, 68) is disposed within a vertical bore (69) within the housing (62). The construction of the spindle is shown in detail in Figure 10. The spindle (66) has rectangular heads (79, 70) with a single main centering surface (71) extending proximally of the axis (72) so that a piston (not shown) cannot extend as far as the axis in use of the hinge. Stop surfaces (73) have proximal (75) and distal (76) edges connected by cam surfaces (74) to adjacent edges (77) of the main centering surface (71). The main centering surface (71) is cylindrically concave as shown in section B-B of Figure 10.

In an alternative embodiment the main centering surface as shown in Section B"- B" of Figure 10 may be planar (78).

Figures 11 to 13 show a secondary damping unit in accordance with this invention. This may be located for example at a central or upper part of a door to provide efficient damping. The construction of the unit is similar to that shown in Figures 1 to 3 although a single piston (80) is located within housing (81). The construction of the spindle (82) is shown in greater detail in Figure 13. Opposed planar centering surfaces (83) are disposed on either side of the spindle axis. The region between the centering surfaces has a tapered or pointed projection (84) to provide a smooth wearing surface for contacting the piston head (85).

Figure 14 shows an alternative spindle having a cylindrical cam surface (90) disposed between the bearing collars (91, 92). The cylindrical cam surface (90) is offset from the spindle axis to lie adjacent the circumference of the spindle. Rotation of the spindle provides a smooth cylindrical surface (90) affording smooth application of the damping force as the door closes or opens.

Figure 15 shows the construction of the piston of the damping arrangement as described with reference to Figure 2. One or more, preferably two cut away portions (21) comprise flat or planar sections removed from the proximal ends of the cylindrical sleeve (27). Concave sections may be used.

Figure 16 shows a perspective view of an alternative hinge in accordance with this invention. A pair of clamps (101) mounted on housing (103) form a channel (104) within which a glass door panel (not shown) may be engaged.

A base plate (102) serves as a support member arranged to be secured to a floor or ground surface (not shown). A mount (105) may be secured within the base plate (102) as shown in Figure 6 permitting easy assembly of a door unit.

Figure 17 shows a cross-sectional view of the hinge. Spindle (106) extends axially, vertically within the hinge body. The spindle (106) is received within a blind bore (111) within the housing (103), the bore having a closed upper end (112). Gaskets (113) seal the spindle and bore, preventing leakage of working fluid in use. A square fixing lug (107) at the lower end of the spindle is received in a correspondingly shaped socket of the mounting (105), preventing rotation of the spindle in use. Bearings (109,110) permit rotation of the housing (103) around the spindle axis. A closing arrangement (114) is mounted in a generally cylindrical chamber (115) in the housing (103), extending radially from the bore (111). The chamber (115) is closed by a cylinder (116) having a threaded end cap. A closing piston comprising a cylindrical sleeve (117) and a piston head (118) is slidably received within the cylinder (116). The piston head (118) has a projection (119) extending radially through an aperture (120) from the chamber (115) into the bore (111). A pair of coiled springs (121,122) extend between the end cap of the cylinder (116) and the rear surface of piston head (118) to urge the contact surface (125) of the projection (119) into engagement with the spindle (106).

A cylindrical collar (131) extends radially from the spindle to a circumference adjacent the inner surface of the bore (111). The clearance between the collar (131) and bore (111) is sufficient to allow passage of lubricating fluid but sufficiently small to prevent fluid pressure from being transmitted from one side of the collar to the other during the period in which a door is opened or closed during normal use. The cavity between the spindle and the bore is therefore divided into two, upper and lower parts. The lower chamber (123) communicates via aperture (120) with the forward part of chamber (115) located radially inwardly of the piston head (118). Aperture (124) permits flow of working fluid past the piston head as the piston head moves radially inwardly in or outwardly during use. The upper chamber (130) similarly communicates with the cylindrical damping chamber within which the damping piston is housed, as described below.

The contact surface (125) of the projection (119) is received in a socket defined by the lower surface of collar (131), the upper surface of an additional lower collar (127) and a generally planar cam surface (126) of the spindle (106). The cam surface (126) extends parallel to the contact surface (125) of projection (119), radially outwardly of the spindle axis so that the contact surface does not extend beyond the axis during use.

Planar stop surfaces (128) extend vertically perpendicular to the cam surface (126) as shown in Figure 20. Two stop surfaces are preferably provided. These serve to hold a door open during use.

Opening of the door causes the hinge body to rotate relative to the spindle. Rotation from the closed centred position causes projection (119) to rotate relative to cam surface (126) urging the projection and piston radially outwardly to compress the springs (121,122). During the movement of the piston, working fluid within the chamber (115) flows radially inwardly through the aperture (124) in the piston head into the cavity in front of the piston head between the bore and spindle. When the door is opened to 90° the hinge will remain open due to engagement of the end of the projection with the perpendicular stop surface (128). A slight pressure on the door is sufficient to release the hinge, following which the springs urge the housing to rotate relative to the spindle, causing the door to return to a closed centred position without application of further manual effort.

One or more intermediate stop surfaces (153) may be provided, as shown in Figure 20. The intermediate stop surfaces located at an angle intermediate between the main cam surface (126) and perpendicular stop surface (128) cause a damping force to be exerted in the event that the door is closed quickly. The width or diameter of the planar cam surface (126) is less than the diameter of the collars (127) or (131). Preferably the diameter of each of the cam surfaces is less than the diameter of the collars (127), (131)or (149) to reduce the wear on the components in use. The diameter of the surface (126) may be 70% to 98%, preferably 80% to 98%, more preferably 85% to 95% of the diameter of the collar (127). The reduced diameter serves to reduce the distance between the secondary stop surfaces (128), consequently reducing the extent to which the closing springs (121,122) are compressed in the fully opened position of the hinge. The closing force exerted by the closing piston is reduced so that friction and long term wear between the contact surface (125) and the surfaces (128) are also reduced.

The damping arrangement is located in a damping chamber (129) extending radially in an opposite direction to the closing arrangement (114). The damping chamber may be axially offset in relation to the closing chamber. A piston comprising a piston head (132) and cylindrical sleeve (133) is mounted for slidable movement in a cylinder (134). A one-way, non-return valve comprises a seat (135) and a valve stop (136) located within the piston. An aperture (137) in the valve head allows passage of working fluid between the first chamber (138) within the piston and the second chamber (139) radially inwardly of the piston head (132). Fluid may flow from the second chamber (139) to the first chamber (138) through the valve (135,136); but flow from the first chamber (138) to the second chamber (139) is prevented by closure of the valve (135,136).

A projection (144) having a radially inwardly facing contact surface (145) extends from the piston head (132). The contact surface (145) may be planar, slightly concave or have a central cylindrical depression and is arranged to engage one of two planar cam surfaces (146) on the spindle. The cam surfaces (146) extend parallel on opposite sides of the spindle axis and are perpendicular to the closing cam surface (126) of the spindle. Stop surfaces (147) extend perpendicularly to the cam surface (146). Secondary stop surfaces (148) extend between the cam surfaces (146) and stop surfaces (147) at an intermediate angle, for example 60 degrees, 45 degrees or 30 degrees to the cam surfaces.

In an alternative embodiment, the contact surface may be convex or have an outwardly cylindrical depression. An upper collar (149) serves with the collar (131) and cam surfaces (146) to define a socket (150) to receive the projection (144) as the hinge is rotated. Rotation of the hinge housing around the spindle as a door is opened or closed causes the closing and damping pistons to be compressed or allowed to expand dependant on the orientation of the respective cam surfaces relative to the projections of the pistons. As the closing piston is compressed, the damping piston is allowed to expand to cause the working fluid to flow radially outwardly from the chamber (139) into the chamber (138) in which the fluid is in contact with the spring, so that the fluid is largely located within the piston. Cylinder (134) has an aperture (143) communicating with a first duct (141) extending from the chamber (129) to a first side of an adjustable screw valve (140) located in a bore in the exterior of the housing (103). A second duct (142) extends from a second side of the adjustable valve (140) to the second chamber (139). When the screw valve is opened working fluid may flow from the first chamber (138) to the second chamber. Partial closure of the valve restricts the fluid flow, damping the motion of the piston and preventing rapid closure of the door.

As the door is manually closed or is released to allow closure due to the force of the springs (121,122), the damping piston is compressed. The spring (151) has a weaker force than the springs (121,122). Spring (151) serves to damp the opening and closing movements of the hinge by restraining opening of the hinge by compression of the spring. During opening further damping may be provided by the frictional force of the spring. A pair of springs may be provided, a weaker spring having a longer extension to maintain the damping force over the entire range of movement of the piston. Fluid pressure within the first chamber (138) increases and the one-way valve (135,136) is closed preventing passage of fluid through the valve. Due to the increase in pressure, fluid is forced through the aperture (143) in the cylinder and into the duct (141) within the housing (103). Fluid passes through the duct (141) to a first side of the screw valve and into duct (142) which returns the fluid to the damping chamber (129) of the damping arrangement, radially inwardly of the piston head, in the vicinity of the spindle as shown in Figure 17. Adjustment of the aperture of the screw valve limits the maximum rate of fluid flow through the valve, so that increased pressure within the chamber (138) restricts the closing or centreing movement of the hinge. The outer surface of sleeve (133) is provided with a cutaway portion (152) to form a passageway allowing fluid flow from the first chamber (138) to the aperture (143) and valve (140). The cross-sectional area of the passageway may vary along the axial length of the sleeve, decreasing radially inwardly relative to the spindle so that a smaller cross-sectional area for fluid flow is provided as the sleeve (133) and piston head are compressed and move away from the spindle.

Fluid flow is restricted and may be prevented as the damping piston reaches a fully compressed position. In this way the damping force is increased as the hinge nears the fully closed or centred position. The closing movement of the hinge is reduced and may be halted as the fully closed or centred position is reached.

During opening of the hinge, an increase in fluid pressure in second chamber (139) is caused by the pressure of the spring (151) and the piston head (132). Fluid is prevented from flowing into the operating chamber of the closing arrangement due to the proximity of collar (131) to the interior surface of the bore (111).

In this way fluid is retained in the second chamber (139) and passes through the nonreturn valve (135,136). This ensures an adequate amount of fluid to create sufficient pressure in the first chamber (138) during the return stroke to force the fluid through the circuit defined by the adjustable valve (140) and ducts (141,142).

Figure 21 to 28 show various constructions of the biasing members comprising pistons with pusher heads.

Figure 21 shows piston of a biasing member comprising a piston head (180) having a rearward or proximally extending cylindrical sleeve (181) and a rear end (182). The rear end is open to receive the spring (not shown). A projection (183) offset from the axis of the cylindrical sleeve (181) extends forwardly from the piston head (180) and has a flat or planar contact surface (184) arranged to engage a centering cam surface of the spindle (not shown). In use the piston moves radially inwardly or outwardly with respect to the spindle axis due to engagement with the cam surface against the restoring force provided by the spring.

Figure 22 shows an alternative piston having a contact surface with a cylindrically concave axial portion (185) located between a pair of flat or planar outer portions (186). The cylindrically concave central portion (185) serves to reduce frictional forces due to compression of the spring (not shown), in order to reduce wear on the moving parts on prolonged use.

Figure 23 shows a further alternative embodiment wherein a flat or planar central portion (187) is located between two shoulders (189) and flat or planar outer portions (188). In this arrangement the central portion (187) extends from the piston head (190) by a shorter distance than the outer surfaces (188) in order to reduce frictional forces at the maximum compression of the spring. Figure 24 shows a further alternative embodiment wherein the cylindrically convex central portion (191) extends at a greater distance from the piston head (193) than two flat or planar outer portions (192).

Figure 25 a further embodiment is shown. A planar axial central portion (194) is located between two shoulders (195) and planar outer portions (196). The central portion (194) of the contact surface extends a greater distance from the piston head (197) than the outer portions (196).

Figure 26 shows a further embodiment in which a continuous cylindrically convex contact surface (198) extends across the entire width of the projection (199).

Figure 27 shows a piston similar to that shown in Figure 21 wherein a V-shaped slot (200) into sleeve (203) extends from an intermediate position (201) on the sleeve to a rearwardly opening end (202). The cross sectional area of the slot (200) increases from the forward point (201) towards the end (202) so that the flow of oil increases as the piston moves forwardly towards the spindle within the axial bore (not shown).

Figure 28 shows a further embodiment in which the sleeve (204) has a flat sector (205) removed therefrom to provide a channel from a forward point (206) to an opening at the rear end of the sleeve (207). The cross sectional area of the channel increases rearwardly from the point (206) to the end of the sleeve (207) allowing a greater flow of oil as the piston extends towards the spindle in use.

Figure 29 shows a further embodiment in which the sleeve (208) has a V-shaped slot (209) extending from an intermediate portion and to an opening at the rear end of the piston. The piston head (210) has a projection (211) extending forwardly to form a contact surface (212). The contact surface (212) has a central axial planar portion (213) with sloping portions

(214) on either side extending to outer planar portions (215) formed on the outer edges of the projection (211). In this way the contact surface extends to a maximum distance axially of the piston and radially of the spindle (not shown) and is formed with shorter projecting portions

(215) on each outer side.

Claims

1. A door hinge having an internal door stop arrangement comprising:

a housing;

a mount for coupling the housing to a support member;

a pair of clamps;

an axial spindle;

one or more biasing members arranged to engage the spindle to return the clamps to one of a plurality of positions selected from a closed position and one or more opened positions; wherein the spindle has one or more centering surfaces; and one or more stop surfaces, the or each stop surface being angularly displaced relative to the main centering surface and extending parallel to the spindle axis;

the or each biasing member being arranged to apply a force to a respective centering surface to centre the clamps in one or more of said positions;

wherein the hinge includes a main biasing member and a main spring arranged to extend the main biasing member to engage a main centering surface to urge the clamps into a closed position; and

wherein the or each stop surface is arranged to engage the main biasing member; to retain the spindle in a position.

2. A hinge as claimed in claim 1 wherein the or each stop surface is perpendicular to the main centering surface, and wherein the or each stop surface is arranged to engage the main biasing member to hold the hinge in an opened position perpendicular to the closed position.

3. A hinge as claimed in any preceding claim wherein there are two parallel stop surfaces.

4. A hinge as claimed in any preceding claim wherein the spindle is arranged so that when the main centering surface is facing towards the biasing member, the or each stop surface extends perpendicularly relative to the centering surface, the or each stop surface having a proximal edge facing towards the biasing member and a distal edge facing away from the biasing member.

5. A hinge as claimed in any preceding claim wherein the main centering surface is located proximally of the spindle diameter.

6. A hinge as claimed in claim 4 or 5 wherein the stop surface extends from a location distally of the spindle axis to a location proximally of the spindle axis relative to the biasing member.

7. A hinge as claimed in claim 6 wherein the stop surface extends from a location distally of the spindle axis to a location on a diameter of the spindle, the diameter extending parallel to the main centering surface.

8. A hinge as claimed in claim 6 or 7 wherein the proximal edge is transverse to the spindle diameter.

9. A hinge as claimed in any of claims 4 to 8 wherein the proximal edge is located proximally of the spindle diameter.

10. A hinge as claimed in claims 4 to 9 wherein a cam surface is provided between the proximal edge of the stop surface and adjacent edge of the main centering surface.

11. A hinge as claimed in any preceding claim including;

a secondary biasing member and a secondary spring arranged to engage one of two secondary centering surfaces to urge the door into one of two opened positions.

12. A hinge as claimed in claim 11 wherein the main and secondary biasing members are located in horizontal bores arranged in vertical spaced relation extending radially relative to the spindle axis.

13. A hinge as claimed in any preceding claim, further comprising

a housing having a vertical bore;

the axial spindle being mounted within the bore;

14. A hinge as claimed in any preceding claim, wherein each biasing member comprises a piston mounted in a cylindrical bore for movement radially with respect to the spindle.

15. A hinge as claimed in claim 14 wherein the piston comprises a hollow cylindrical body having a head arranged to engage a respective centering surface and having a cavity, a spring being located in the cavity to urge the piston outwardly of the bore.

16. A hinge as claimed in any preceding claim, wherein the spindle is mounted in a vertical guideway in the housing, the guideway communicating with passageways communicating with bores within which the biasing members are located to allow circulation of hydraulic fluid or other oil during actuation of the hinge.

17. A hinge as claimed in any of claims 11 to 16 wherein the configuration of the secondary centering surface is selected from: cylindrical, concave or convex and is offset from the spindle axis.

18. A hinge as claimed in claim 11 or any claim dependent on claim 16 wherein a channel is provided to allow oil to pass from the piston cavity to a cavity within the housing as the piston is compressed into the sleeve, and including an adjustable valve to regulate a maximum flow of oil.

19. A hinge as claimed in claim 11 or any claim dependent on claim 16 wherein a piston of a biasing means includes a non-return valve arranged to permit a flow of oil into the cavity as the piston and cylinder expand.

20. A hinge as claimed in claiml8, wherein the biasing means includes inner and outer helical springs, the outer spring engaging the piston to urge the piston towards the spindle, at the inner spring engaging the non-return valve to urge the valve into a closed position.

21. A hinge as claimed in claim 14 or any claim dependent on claim 18 wherein the piston has a head and a cylindrical body dimensioned to be slidably received within a cylindrical bore of a sleeve, and one or more apertures provided at a predetermined axial distance from the head, the aperture or apertures being blocked by the sleeve after sliding the body by a predetermined distance into the cylindrical sleeve.

22. A hinge as claimed in claim 20 wherein a cut-away portion is provided at the distal end of the cylindrical body.

23. A hinge as claimed in claims 19 or 20 wherein the cut away portion comprises one or more sectors removed from the outer wall of a proximal end of the cylindrical body.

24. A hinge as claimed in claim 14 or any claim dependent on claim 14 wherein a permanent magnet is located within the piston or sleeve.

25. A door hinge spindle comprises an axial shaft including an attachment for engagement to a door so that the spindle and door are constrained to rotate together in use;

wherein the spindle further comprises:

wherein the two centering surfaces extend axially of the shaft in diametrically opposed relation;

26. A hinge as claimed in claim 14 or any claim dependent on claim 14 wherein the piston has one or more cutaway portions at an end of the cylindrical sleeve.

27. A hinge as claimed in claim 26 wherein the or each cutaway portion comprises a planar sector removed from the end of the sleeve.

28. A hinge as claimed in any preceding claim wherein the biasing member when extended does not intersect the spindle axis.