GB2474627A

GB2474627A - Door closer

Info

Publication number: GB2474627A
Application number: GB0916512A
Authority: GB
Inventors: Timothy Bland; James Frost; David Williams; Lee Melville
Original assignee: Ingersoll Rand Security Technologies Ltd Great Britain
Current assignee: Allegion UK Ltd
Priority date: 2009-09-19
Filing date: 2009-09-19
Publication date: 2011-04-27
Also published as: GB0916512D0

Abstract

A door closer comprises a housing 11 with a spindle 10 which rotates in response to the door being moved between open and closed positions. A piston 12 is disposed for movement in the axial direction. A biasing member such as a spring 13 biases the piston and spindle to a first position. A cam associated with the piston converts rotational movement of the piston into axial movement; the cam may be a helical groove 30 which engages with ball bearing 31 located in the housing; a hydraulic damper may be provided and a one-way seal included between the piston and housing. In an alternative arrangement a door closer comprising two cams is provided wherein a second cam 28 may function to provide a stable position, e.g. when the door is closed. In an alternative arrangement the housing is of plastic and at least a portion of the housing in which the piston runs is received in a metal sleeve 34. In another arrangement the housing is plastic and moulded around at least one metal liner that defines either a hydraulic fluid passage, piston bearing surface, sealing surface or a threaded bore. In another arrangement a door closer is provided wherein the piston biasing force is adjustable by means of an adjustable retaining cap.

Description

A DOOR CLOSER

The present invention relates to a door closer of the kind that is used to control the movement of a door from an open position to a closed position.

Door closers are conventionally fitted to a door or a door frame and typically comprise a mechanism for storing energy such as, for example, a spring. Energy is stored during opening of the door and is released to effect automatic closure of the door.

In one common type of door closer a rotary spindle for coupling to the door rotates with opening movement of the door. The spindle is coupled a transmission mechanism that converts the rotational movement into rectilinear reciprocation of a piston in a first direction within an elongate door closer housing. The spring biases the piston in an opposite second direction to urge the door to the closed position and the speed of movement of the door between the open and closed positions is controlled by the flow of hydraulic fluid from one side of the piston to the other via passages for the restricted flow of fluid. In one example the transmission mechanism may be a pinion that rotates with the spindle and drives a rack in translation, the rack being connected to the piston. in other example, a cam is coupled to the spindle and acts directly or indirectly on part of the piston.

Door closers of the kind described are disposed such that rotary spindle is oriented with its rotational axis in the vertical direction so that the reciprocating movement of the piston occurs in the horizontal direction. The elongate housing I of the door closer thus extends in the horizontal direction on the door 2 (as shown in figures lA-I D) or the door frame 3.

The horizontal orientation of the elongate door closer housing is not always desirable. In particular, the upper surface of the housing provides a relatively large horizontal surface area that accumulates dust, dirt and potentially bacteria. This is undesirable in environments such as hospitals, laboratories and clean rooms.

Moreover, in some circumstances the size and orientation of the housing can limit the maximum opening angle of the door as illustrated in the two examples shown in figure 1. In the embodiment of figure 1C one end of the door closer abuts the door frame and the maximum opening angle, a, is limited to less than 900. In the embodiment of figure lD the other end of the door closer abuts a return wall or as part of the door frame so as to limit the maximum opening angle to c.

In order to close the door the rectilinear movement of the piston (under the force imparted by the spring) is translated into rotation of the spindle by the transmission mechanism which is often inherently inefficient as a result of friction losses associated with moving parts.

A significant cost associated with the manufacture of door closers is the machining costs of the components. For example, very small tolerances are necessary on the interfacing surfaces of the piston and housing to ensure accurate alignment with the transmission mechanism, to reduce the friction losses during reciprocation of the piston and to control the flow of hydraulic fluid through the passages. Moreover, the passages themselves have to be machined with precision and sealed effectively which adds to the cost.

When door closers of the kind described are used with fire doors they are often concealed by being housed in a rebate inside the door or the door frame.

Intumescent sealing for preventing or hindering the passage of fire between the door and door frame has to be removed in the area of the rebate which impairs the fire integrity of the door. It is therefore desirable to reduce the length of the rebate.

It is one object of the present invention to obviate or mitigate at least one of the aforesaid disadvantages. It is also an object of the present invention to provide for an improved or alternative door closer.

According to a first aspect of the present invention there is provided a door closer for coupling to a door and comprising a housing with a spindle having a rotational axis about which it is rotatable relative to the housing in response to the door being moved between open and closed positions, a piston disposed for movement relative to the spindle in the direction of the rotational axis in response to relative rotation of the spindle and housing, a biasing member for biasing the piston and spindle to a first position, a cam associated with the piston for converting the relative rotational movement into axial movement of the piston and vice versa.

The movement of the piston in the same direction as the axis of the spindle allows the biasing force applied by the biasing member to effect axial movement of the piston towards the first position. The cam converts this into relative rotation of the spindle and the housing, with the result that the door can be closed in an efficient manner.

When a force is applied to the door to open it, the spindle and housing rotate relative to one another causing the piston to move axially by virtue of the cam. The cam may be of any suitable form for translating the relative movement of the spindle and housing into axial movement of the piston, or vice versa. The cam may, for example, be operational between the piston and spindle or between the piston and another member that is fixed against axial movement relative to the piston. The axial movement is against the biasing force of the biasing member and so energy is stored in the biasing member in order to effect closure of the door automatically.

The door closer may, in use, be mounted on or in the door, on or in a door frame relative to which the door moves, or on or in a floor over which the door moves. In each case it will be coupled to the door in some way.

The relative rotation may be achieved by the spindle rotating within the housing or the housing rotating about the spindle. For example, the spindle may be coupled to a door or door frame and may rotate inside the housing. Alternatively, the spindle may be fixed (e.g. to the door frame or floor) and the door and housing rotate around the spindle.

The piston and spindle may be arrangedto rotate together in which case the cam operates between the piston and a fixed member. For example, the piston and spindle may be coupled for rotation together by inter-engaging features, such as, for example, flats that prevent substantial relative rotational movement but permit axial movement of the piston along the spindle. Alternatively the spindle may be rotatable relative to the piston in which case the cam operates between the piston and the spindle.

The piston and spindle may be substantially concentrically disposed. This provides for a compact arrangement and ensures the piston remain centrally disposed relative to the spindle. The piston may be slidably mounted on the spindle which again provides for a compact arrangement. The piston may be in the form of a hollow cylinder.

There may be a suitable low friction interface between the piston and spindle to allow for sliding relative movement. In one embodiment there is provided at least one ball bearing disposed between the piston and spindle. The at least one ball bearing may be disposed in a surface of the spindle or the piston.

The cam can take any suitable form. In one embodiment it comprises one or more cam grooves that extend in a direction that has both axial and angular components so as to provide for axial translation of the piston in response to relative rotation of the piston and spindle or in response to relative rotation of the piston and a fixed member. For example, each cam groove may be spiral, partially spiral or helical. Each groove is preferably elongate and may have a concave cross-section.

The (or each) groove may be defined on a circumferential surface of the piston, which may be an external surface or an internal surface. Alternatively the groove(s) may be defined on a wall of the door closer housing in which the piston is received.

As a further alternative the groove(s) may be defined in an external surface of the spindle. If there is a plurality of cam grooves they may be axially and/or angularly spaced. The cam may be provided by any appropriately defined surface, edge that provides a cam profile. For example, instead of cam grooves the profile may be provided by an edge on the piston that runs against a corresponding edge on the housing or spindle.

The gradient of the at least one groove (or other profile) may be substantially unchanged along the length of the groove or it may vary to provide a desired force profile for opening or closing the door.

At least one cam follower may be received in the at least one groove. The cam follower is preferably fixed against movement in the axial direction so that rotational movement of the piston causes the groove to move over the cam follower such that the piston translates axially. The cam follower may be in the form of a rolling bearing such as, for example, a ball bearing which is preferably arranged to rotate about itself so as to reduce the friction between it and the cam groove. The cam follower may be fixed in a wall of a housing of the door closer and more particularly in an aperture in the wall. The aperture may be closed by a closure member. Where the cam groove(s) is defined in the wall of the housing the cam follower may be disposed in the piston.

In an embodiment where the cam profile is provided by an edge, the rolling bearing may be arranged to run against that edge The piston may have a first end and a second end. The cam may comprise a first cam surface defined on one of the first and second ends for interaction with a second cam surface which may be defined by the housing. This cam may be provided in addition to, or instead of, the cam groove(s).

The piston and spindle are preferably supported in the housing. The spindle may be supported in the housing at each end for rotation. The housing may comprise a closure member, such as an end cap, at one end which closes a bore in which the piston and spindle are disposed. The second cam surface may be defined on the closure member. The second cam surface may comprise a pluralityof raised surfaces which may be received in recessed defined by the first cam surface when the piston is in the first position. The raised surfaces and/or the first cam surface may be ramped.

When the piston is moved (e.g. rotated) from the first position it may be initially moved in the axial direction by the second cam before being moved further in the axial direction by the at least one cam groove. In the first position the cam follower (e.g. a ball bearing) may occupy the respective axial recess of each cam groove and during the initial axial movement from the first position the cam follower preferably leaves the recess to travel along the rest of the cam groove.

The piston may be moveable rotationally and axially relative to the housing. It may take any suitable form. For example, it may be in the form of a piston rod with a piston head or one or other of those components The piston may be moveable inside a bore defined by an internal surface of the housing, and wherein there may be provided a sealing member between the piston and internal surface. The seal may divide the bore into first and second variable volume chambers for receipt of hydraulic fluid. The sealing member may be configured to seal against the internal surface when the piston moves in a first axial direction towards the first position such that hydraulic fluid is prevent from flowing across the seal between the first and second variable volume chambers, and the sealing member may be configured to allow hydraulic fluid to flow between the internal surface and the seal when the piston moves in a second axial direction away from the first position.

The sealing member may comprise a deflectable element that projects outwardly from the piston to the internal surface, the deflectable element being deflectable by hydraulic fluid pressure when the piston moves in the second axial direction, The deflectable element may extend outwardly of a main annulus that is supported on an external surface of the piston. The sealing member may be an umbrella type seal.

The piston may be moveable inside a bore defined by an internal surface of the housing. There may be provided an annular sealing member disposed between the piston and the internal surface, there being a radial clearance between the sealing member and the piston so as to accommodate eccentricity of the piston relative to the bore.

The piston is preferably moveable from the first position to a second position against the biasing force of the biasing member.

According to a second aspect of the present invention there is provided a door closer comprising for coupling to a door and comprising a housing with a spindle having a rotational axis about which it is rotatable relative to the housing in response to the door being moved between open and closed positions, a piston disposed for movement relative to the spindle in response to relative rotation of the spindle and housing, the piston having a first end and a second end, a biasing member for biasing the piston and spindle to a first position, a first cam associated with the piston for converting the relative rotational movement into movement of the piston and vice versa and a second cam comprising a first cam surface defined on one of the first and second ends for interaction with a second cam surface.

The provision of two cams affords the possibility of incorporating a latching or opening force profile that is independent of the force profile of the rest of the movement of the door.

The second cam surface may be defined by the housing including a bearing surface defined by a component that forms part of the housing.

According to a third aspect of the present invention there is provided a door closer comprising a housing with a spindle having a rotational axis about which it is rotatable relative to the housing in response to the door being moved between open and closed positions, a piston disposed for movement relative to the spindle in response to relative rotation of the spindle and housing, the piston being biased to a first position by a biasing member, the wherein the housing has a first portion in which the piston resides in the first position, at least the first portion of the housing being received in a metal sleeve, the housing being a plastics material.

The metal sleeve serves to react against the forces generated by the movement of the piston within the housing. There may be provided a cam for converting relative rotation of the spindle and housing into movement of the piston in which case the sleeve acts to react the forces generated at the cam profile. The provision of a separate sleeve to react (i.e. contain) the forces allow the remaining part of the housing to be made from a relatively lightweight plastics (e.g. polymer) material. The lighter weight of the closer allows it to be fitted without a supporting bracket. Moreover, in the event of a fire the plastics material will melt and prevent the build up of pressure in the closer which can be dangerous.

According to a fourth aspect of the present invention there is provided a door closer comprising a housing with a spindle having a rotational axis about which it is rotatable relative to the housing in response to the door being moved between open and closed positions, a piston disposed for movement relative to the spindle in response to relative rotation of the spindle and housing, the housing being made from a plastics material and moulded around at least one metal liner that defines one or more of the following: a hydraulic fluid passage for delivering fluid to the piston; a bearing surface for the piston; a sealing surface for the piston; or a threaded bore.

In one example, the housing is a polymer material the is moulded around an elongate small bore pipe that is design to convey hydraulic fluid to the piston, and more particularly to a bore in the housing in which the piston moves. In another example, the housing is moulded around one or more bearing or sealing surfaces for the piston. This inventive aspect eliminates the requirement for costly machining of a metal housing. The provision of a liner means that multiple machining operations to produce a single passage that extends in several directions are eliminated.

Moreover, it eliminates the cost associated with areas where fine tolerances are required e.g. bearing or sealing surfaces.

According to a fifth aspect of the present invention there is provided a door closer comprising a housing with a spindle having a rotational axis about which it is rotatable relative to the housing in response to the door being moved between open and closed positions, a piston disposed for movement relative to the spindle in response to relative rotation of the spindle and housing, a biasing member for biasing the piston to a first position in the housing, wherein the biasing member acts between the piston and a retainer, the position of the retainer being adjustable relative to the housing and the biasing member to vary the force applied by the biasing member to the piston.

The biasing member may take any form such as a resilient member. One example is a compression spring. The position of the retainer may be adjustable to vary the degree of compression of the spring.

The retainer may be threadedly engaged with the housing and its axial position in the housing may be adjusted by rotation. The adjustment may be performed by a gear mechanism that is drivable by an adjustment tool for insertion into the housing.

According to a further aspect of the present invention there is provided a door or door frame fitted with a door closer as defined in any of the inventive aspects above. In the first position of the piston the door is preferably substantially closed. In the second position the door is preferably fully open.

The door closer structure permits it to be arranged on the door such that its housing extends generally in a vertical direction. That is the length of the housing, which is longer that the depth or the width, may extend in a generally vertical direction, The length of the housing may be disposed in the same direction as the axis of rotation of the spindle and the direction of movement of the piston, which may be in the same direction as the axis of rotation of the door.

A specific embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1A is a schematic perspective view of an upper part of a door fitted

with a prior art door closer;

Figure lB is a plan view of the door and door closer of figure 1A, the door being hingedly connected to a door frame, and being in a closed position; Figure IC is a plan view of the door, door closer and frame of figure 1 B with the door being in a fully open position; Figure ID is a plan view of the door and door closer of figures IA-iC fitted to an alternative door frame with the door shown in a fully open position; Figure 2 is a sectioned side view of an embodiment of a door closer in accordance with the present invention; Figure 3 is an exploded perspective view of the door closer of figure 2; Figure 4 is a perspective view of the piston of the door closer of figures 2 and 3; Figures 5A-5C are schematic illustrations showing an embodiment of a sealing arrangement of the piston of the door closer of the present invention; Figure 6 is a schematic side view an alternative embodiment of a sealing arrangement of the piston; Figure 7A is a plan view of the sealing arrangement of figure 6, with the piston shown concentric with a bore; Figure 7B is a plan view corresponding to figure 7A but with the piston not concentric with the bore; Figure 8 is a perspective view of the door closer of figures 2 to 4, coupled to a track for connection to a door or door frame; Figures 9A-9D correspond to those of figures lA-iD but with the door and door frame fitted with a door closer according to the present invention; Figure 10 is a perspective view of the door closer of the present invention with a first embodiment of an adjustment mechanism; Figure 11 is a perspective view of the door closer of figure 10 with a plate present; Figure 12 is a perspective view of the door closer of the present invention with a second embodiment of an adjustment mechanism; Figure 13 is a sectioned view of the housing of the door closer of the present invention with internal components removed and illustrating metal liners; Figure 14 is a perspective view of an alternative embodiment of part of the spindle of the door closer; Figure 15 is a front view of the spindle of figure 14 with the piston mounted thereon; and Figure 16 is a section through the piston and spindle of figure 15 in a plane perpendicular to the spindle axis.

Referring now to figures 2 to 4 the drawings, the exemplary door closer has a vertical drive spindle 10 supported in a housing 11 of the door closer for rotation about its central longitudinal axis and a concentrically mounted hollow cylindrical piston 12 for reciprocation along the spindle 10 within the housing 11 against a biasing coil spring 13. As will be described below, the spindle 10 is coupled indirectly to one of the door or the door frame (neither of which is shown in figures 2 and 3) in such a manner that it rotates as the door moves between open and closed positions relative to the door frame.

The housing 11 is elongate in the direction of the longitudinal axis and comprises a generally cylindrical central body ha flanked at diametrically opposite locations by smaller cylindrical side portions 11 b. The central body 11 a defines a bore lic with upper and lower circular openings 14, 15, the upper opening 14 being closed by a rectangular plate 16 that extends over the upper opening 14 and is fixed to the housing 11 by screws, and the lower 15 being closed by a cap 17 that is received in the bore lic. A first end 18 of the drive spindle 10 projects through a central aperture 19 in the plate 16 and is connected to an end of a main arm 20 which is coupled to the door or door frame as will be described below. A second end 21 of the drive spindle 10 has a reduced diameter that projects through a central aperture 22 in the cap 17 and is retained in place by a circlip 23. An 0-ring type seal 24 is provided between the second end 21 and the cap 17.

The piston 12 is disposed concentrically over the spindle 10 in a lower half of the bore 11 c and has an annular upper end surface 25 against which one end of the coil spring 13 bears and an annular lower end surface 26 in which there is a plurality of first cam elements 27 for co-operation with corresponding ramped second cam elements 28 defined on the cap 17. The first cam elements 27 comprise projections interspersed by recesses designed to receive the second cam elements 28 on the cap 17. The outer circumferential surface of the piston 12 has a plurality of elongate cam grooves 30, each of which extends in a direction that has both the axial and circumferential components. The grooves have a concave cross-section and are designed to receive a respective ball bearing 31 mounted in an aperture 32 in the housing 11. The piston 12 is thus in the form of a barrel cam with the ball bearings being cam followers that are fixed against axial movement but free to rotate about themselves. In the specific embodiment depicted in the figures there are three pairs of such cam grooves 30 and three ball bearings 31, the balls 31 being disposed in apertures 32 that are angularly spaced around the axis of the drive spindle 10 and the cam grooves 30 being similarly angularly spaced around the outer surface of the piston 12. The interaction of the ball bearings 31 and cam grooves 30 is designed to guide movement of the piston 12 within the housing bore lic and it will be appreciated that the particular number of grooves 30 and balls 31 may be varied and can indeed be as little as one. The presence of three groove pairs and balls spaced about the longitudinal axis in this embodiment helps to spread the load.

As can be seen best in figure 4, in this particular embodiment the grooves 30 are arranged in three pairs that are axially spaced along the piston 12. Each pair has a first groove 30a that extends clockwise (when the piston is viewed in plan from its upper end 25) and in a direction downwards from the upper end 25 to the lower end 26 and a second groove 30b that extends in the same downwards direction but which extends anticlockwise. At the intersection of the first and second grooves 30a, 30b there is a small rebate 30c that extends in an upwards direction (only one such rebate is shown in figure 4, the others being hidden). The provision of groove pairs 30a, 30b allows the door closer to be used with doors that open in either direction relative to a door frame or indeed with a swing door that is capable of being opened in both directions.

Each of the apertures 32 in which a ball bearing 31 is resident is normally closed on the outside of the housing by a cover disc 33 as illustrated in figure 3 and a metallic sleeve 34 sits over the lower half of the central body 1 la.

The coil spring 13 is compressed in the housing bore lic between the upper end surface 25 of the piston 12 and an annular end fitting 35 disposed under the plate 16, such that it biases the piston 12 downwards on the spindle 10. In this position the second cam elements 28 on the cap 17 are received in the recesses of the first cam elements 27 on the lower end surface 26 of the piston 12. Travel of the piston 12 along the spindle 10 in the direction towards the plate 16 is thus resisted by the coil spring 13.

The drive spindle 10 has a radially outwards extending flange 40 adjacent to its first end 18 for abutment against an underside of the plate 16 and which is received in an annular groove 41 in the end fitting 35. This prevents the spindle being lifted out of the housing 11. The spindle 10 is also stepped inwardly towards its second end 21 to define an annular shoulder 42 immediately above which there is a plurality of angularly spaced flats 43 defined on the external surface of the spindle 10 for engagement with corresponding flats 44 defined on the interior surface of the hollow piston 12. The flats 43, 44 interact to prevent relative rotation of the spindle and piston 12 (ensuring they rotate together) but do not interfere with axial displacement of the piston 12 along the spindle 10.

In use, when the door is closed, the coil spring 13 biases the piston 12 downwardly such that the first and second cam elements 27, 28 of the piston 12 and cap 17 inter-engage as described above. In this position the ball bearings 31 occupy the recesses 30c of each of the cam groove pairs 30. When the door is opened the spindle 10 and the piston 12 rotate together about the longitudinal axis. In the initial stages of opening the first cam elements 27 on the lower end surface 26 of the piston 12 ride over the ramped second cam surfaces 28 on the cap 17 and serve to raise the piston 12 by a short distance. This action moves the recesses 30c relative to the respective ball bearings 31 such that either the first or the second cam groove 30a, 30b is brought smoothly into register with a respective ball bearing 31, depending on the direction of rotation. The interaction of the first and second cam elements 27, 28 at the interface of the piston 12 and cap 17 thus provides an initial opening movement of the door which, in the reverse closing movement, would serve to provide a latching action in which the ball bearings 31 enter their respective recesses 30c. Further opening of the door effects further co-rotation of the spindle and piston 12 such that the cam grooves 30 travel over the ball bearings 31 and serve to move the piston 12 upwards along the spindle 10 so as to compress the spring 13. The increasing spring force resists the movement of the piston 12 so that increasing torque is required to rotate the spindle 10 and piston 12. The gradient of the cam grooves 30 determines the relationship between the angular movement of the piston 12 and its length of axial travel which in turn determines the rate of increase in spring force resisting movement of the piston. The gradient of the grooves 30 thus determines the force profile required to move the door from the closed position to a fully open position. It will be appreciated that the gradient of a cam groove 30 may vary along its length to provide a variable force profile that is the rate of increase in the force varies as the spindle rotates. R will also be understood that the gradient of the grooves 30 can differ between applications and can be designed accordingly to achieve a desired force profile.

In the particular embodiment described herein the door is only designed to open in one direction and therefore in practice the ball bearings will only ride in one of each of the groove pairs -either in first grooves 30a or in second grooves 30b.

The piston is conveniently provided with the first and second cam grooves so that the same closer can be used with doors of differing opening directions. Alternatively it may be used with a swing door that is capable of being opened in both directions relative to the door frame.

The compression of the spring 13 allows energy to be stored so that when the force that opens the door is released the stored energy is released so as to urge the spindle and piston back to their rest positions and therefore the door to its closed position.

Hydraulic fluid, such as oil, is present in the housing 11 and is displaced from one end of the piston 12 to the other as the piston moves axially in the housing bore 1 ic. This provides a damping force particularly in one direction when the door moves towards the closed position. The flow of oil through the housing is afforded by a pair of elongate passages 45, one extending through each of the cylindrical side portions 11 b of the housing 11. The passages 45 extend in a direction that is predominantly parallel to the housing bore lic from a first end that is alongside the upper opening 14 in the housing to a second end that is approximately halfway between the upper and lower openings 14, 15. The first ends are each closed by needle valves 46 and a side passage 47 adjacent to each valve 46 provides fluid communication between the elongate passage 45 and the bore in the area above the piston 12, although the flow of fluid from the side passage 47 to the elongate passage 45 is throttled by the presence of the needle valve 46. An annular seal 49 is disposed in an annular groove 50 around the piston 12 towards its upper end 25 so as to divide the bore 11 c into upper and lower pressure chambers and is designed to permit the flow of oil across the seal depending on the direction of movement of the piston 12. Thus when the door is being opened the piston 12 will travel upwards on the spindle 10 and fluid above the seal 49 is forced from the upper pressure chamber into the side passages 47 from where it passes into the elongate passages 45, although the flow is restricted by the throttling effect of the needle valve 48, to the first end of the elongate passage 45 and back into the lower pressure chamber. In addition the compressed fluid is able to pass across the seal 49 between the pressure chambers of the bore 11 c. When the door is being closed the piston 12 moves downwards in the housing bore lic and fluid is prevented from passing across the seal 49 but is able to flow from the lower pressure chamber into the first end of the elongate passage 45 and via the needle valve throttle 46, the side passage 47 and into the upper pressure chamber. This restricted flow path serves to create a dampening effect during closing thereby controlling the speed and smoothness with which the door closes.

One example of the piston seal 49 is an umbrella type seal as illustrated in figures 5A-5C. The seal 49 is generally annular and has a deflectable skirt 51 that projects outwardly and downwardly to seal against the interior surface of the housing that defines the bore lic. When the piston 12 is moving upwardly (i.e. the door is opening) the increased pressure of the fluid in the upper pressure chamber P serves to deflect the skirt 51 downwardly such that oil can pass into the lower pressure chamber L. This is represented in figure 5B. In the reverse direction the skirt 51 is forced upwardly so as to bear against the housing 11 with a greater sealing force, as illustrated in figure 5C. This prevents, or at least severely restricts, fluid passing from the lower pressure chamber L to the upper pressure chamber P across the seal 49.

The adoption of a seal 49 of this kind permits the machining tolerances of the piston 12 and the surface of the housing that defines the bore lic to be relaxed thereby reducing the manufacturing costs.

An alternative embodiment of the piston seal 49 that affords a reduction in the manufacturing cost for the same reasons as presented above is illustrated in figure 6, 7A and 7B. For ease of understanding the piston 112 is represented in schematic form in a bore iii c defined by the central housing portion lila. The seal is provided by a piston ring 149 that is located in an annular recess 150 at the upper end of the piston 112. An inner surface 152 of the ring 149 has a diameter that is larger than the outside diameter of the recess 150 so that there is a radial clearance between the ring 149 and the piston 112 whereas the outer surface 153 of the piston ring 149 seals against the interior surface housing lila that defines the bore ilic.

The ring 149 is retained in the recess 150 by a cap 154 that is fitted to the upper end of the piston 112, the recess 150 having an axial dimension that is greater than the axial dimension of the piston ring 149 such that there is an axial clearance between the ring 149 and the cap 154 and/or the piston 112. This arrangement allows the piston ring 149 to seal against the wall of the bore lllc regardless of whether the piston 149 is concentric with the bore 11 ic. In figure 7A the piston 112 is shown concentric with the bore 111 c of the housing lila and the piston ring 149, whereas in figure 7B the piston 112 is not concentric with the bore ilic but the piston ring 149 still seals against the wall of the bore ilic as radial clearance between the piston ring 149 and the piston 112 accommodates the eccentricity.

Referring now to figure 8 and as described above, one end of the main arm is connected to the first end 18 of the drive spindle 10 and rotates therewith over the plate 16. The other end of the main arm 20 is captively disposed in a guide track such that is slidable therein. In practice the door closer may be fitted to the door with the track 60 secured to the door frame or vice versa. When the door is moved from the closed to the open position the angular displacement of the door causes the arm 20 to rotate aJong with the spindle 10 at one end and to slide in the guide track at the other end, The design of the piston 12 with the cam features 27, 28, 30 allows the piston 12 to move axially along the spindle 10 rather than laterally thereof as in prior designs. This enables the door closer to be packaged in a compact manner and with the elongate housing 11 extending with the longitudinal axis of the spindle 12 in a vertical direction with respect to the door as shown in figures 9A-9D which should be compared to those of figures lA-iD illustrating the prior art arrangement in which the closer housing extends in a generally horizontal direction. In these figures the housing 11 is represented for simplicity as a box shape and the spindle 10 by a dotted line (figure 9A only) that coincides with its axis of rotation. The box shape may in practice be the form of an outer casing or covering in which the housing 11 is disposed. The benefit of the vertical arrangement is illustrated particularly in figures 9C and 9D. In figure 9C the disposition of the closer housing 11 is such that the door D may be opened fully to an angle b which is greater than the corresponding angle a of figure IC. Similarly for the configuration of 9D the door closer housing ii allows the door D to be opened fully to an angle d which is greater than the angle c shown in figure 1 D. The vertical arrangement of the housing 11 also means that it affords a reduced surface area for the accumulation of dust and dirt etc. Moreover, the vertical orientation means that in relation to fire door applications the amount of intumescent sealing for preventing or hindering the passage of fire between the door and door frame that has to be removed in the area of the rebate is reduced compared to existing designs.

The cam arrangement described above is more efficient than those of prior art door closers. In particular, the losses associated with the moving parts that convert rectilinear movement to rotational movement (or vice versa) are reduced.

The arrangement allows the axis of drive spindle 10 to be disposed substantially in line with the direction of the closing force applied by the piston 12 and spring 13 combination and thus the need to translate a rectilinear closing force from the horizontal to a torque about a vertical axis is obviated. The drive spindle 10 serves to centralise the piston 12 in the bore ii c such that the dimensions of the piston and bore are less critical than in prior art designs and as a result manufacturing costs associated with producing fine tolerances can be reduced. This is particularly so by virtue of the piston seal designs 49, 149 described above.

As an alternative to the door closer being fixed to an outer surface of the door or the door frame, it may be mounted inside the door, in the door frame or in the floor.

Referring now to figures 10 and lithe axial length of the spring 13 may be adjusted by changing the position of the end fitting 35 that serves to retain the spring in position at one end. The adjustment is achieved by making the end fitting 35 (or a component to which it is connected or against which it bears) threaded for engagement with a corresponding thread in the housing 11. In the embodiment shown the end fitting 35 has an annular formation 35a at the upper opening 14, the formation is externally threaded for engagement with corresponding threads 14a in the housing 11 at the upper opening 14. The internal surface of the annular formation defines gear teeth 35b. The axial position of the end cap 35 and therefore the amount of compression of the spring 13 is adjusted by inserting an appropriate toothed key 55 and rotating the end cap 35 such that its threads travel in those 14a of the opening 14. Figure 10 shows the key 55 in position with the plate 16 removed purely for clarity. In practice the plate 16 would remain in place and the key 55 inserted through an appropriate opening as illustrated in figure 11.

Figure 12 shows an alternative adjustment mechanism (again as in figure 10 the plate 16 is removed from the upper end of the door closer for clarity). In this embodiment the end fitting 35 has an upper portion 35a with external teeth 35b so as to define a primary gear wheel for engagement with the teeth of a smaller secondary gear wheel 56 which is rotatable by a key 55. Rotation of the key 55 effects rotation of the secondary gear wheel 56, which, in turn, rotates the end fitting 35. The outer periphery of the end fitting 35 is threaded (under the upper portion 35a) and engaged with corresponding threads 14a defined in the upper opening 14 of the housing 11. Rotational of the upper portion 35a by the secondary gear 56 thus effects axially movement of the upper portion 35a to adjust the compression of the spring 13.

The design of the door closer is such that the housing 11 may be manufactured from a polymer such as, for example, a nylon-based plastics material.

Metallic inserts (not shown in the figures) may be provided in the polymer housing by, for example, moulding the polymer around suitable inserts to provide the bore 1 ic and the hydraulic passages 45, 47 where fine dimensional tolerances are required. These may also serve to add strength to the polymer housing in appropriate locations. In addition, or alternatively, there may be provided outer shell members for strength such as, for example, metal sleeve 34. This serves to react (contain) the forces generated by the cam.

An example of such a housing is illustrated in figure 13. In addition to the sleeve 34 this figure shows the polymer housing 11 having been moulded over the cap 17 which provides the cam elements 28 and is thus preferably made from metal.

The hydraulic passages 45, 47 are provided by small bore metal tubes 61, 62 over which the housing is moulded. Such tubes 61, 62 may be bent into the appropriate configuration rather than having to perform a complicated machining operation in the housing. Similar cylindrical metal inserts 63, 64 may also be provided in the bores that support the needle valves 46. Moreover, the housing 11 may be moulded over a steel liner 65 that provides a sealing surface for the piston 12. Finally a steel component 66 may be provided above the needle valves inserts 63, 64 and under the plate 16 to provide threaded bores to which the plate 16 and other components may be threadedly connected by means of screws.

The adoption of a polymer housing reduces the machining costs and weight of the housing. The reduced weight simplifies the assembly or installation process in that fixings and support brackets do not need to bear such a heavy weight as in prior art closers. Indeed, in some applications the support bracket may be eliminated. In the event of a fire the polymer would melt before the pressure of the hydraulic fluid (typically oil) reaches a dangerous level. This prevents the oil from being released as a jet as it would in prior art closers with metallic housings which tend to explode under the pressure generated by the oil. An appropriate additive may be added to the polymer during moulding which acts as a fire retardant to arrest the fire once the source has expired.

Figures 14 to 16 illustrate an embodiment of the door closer in which the interface between the spindle 10 and the piston 12 is configured to reduce the friction between them so as to facilitate the sliding movement of the piston relative to the spindle 10. The piston is the same design as that of figure 4 but in this particular embodiment the spindle 10 is provided with a plurality of embedded ball bearings 70 that project outwards of the outer surface of the spindle 10 and are free to rotate about their centres. The axial movement of the piston 12 relative to the spindle 10 thus occurs without large friction losses. Relative rotation of the piston and spindle is again prevented by suitable inter-engaging features (not shown).

It will be appreciated that numerous modifications to the above described design may be made without departing from the scope of the invention as defined in the appended claims. For example, the position of the cam grooves and the ball bearings may be interchanged e.g. the cam grooves could be provided on the internal surface of the housing and the balls accommodated in the piston. Moreover, cam features may be provided at the interface of the internal surface of the piston and the external surface of the spindle. In each case, the ball bearings may be replaced with any suitable cam feature such as rollers or fixed pins or other projections designed to locate in appropriately shaped cam grooves. The cam grooves themselves may take any suitable form including, for example, threads whose pitch determines the forces involved in opening or closing the door. It will be appreciated that the cam features between the lower end 26 of the piston and the cap 17 could be excluded or, alternatively, could be adapted to provide the full axial displacement of the piston 12 relative to the spring 13 instead of the grooves 30. It will also be appreciated that locations of the piston 12 and spring 13 may be interchanged in which case the cam features at the lower end 26 would be replaced by appropriate cam features at the upper end surface 25 of the piston 12 designed to interact with corresponding cam features on, for example, the end fitting 35.

The described and illustrated embodiments are to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the scope of the inventions as defined in the claims are desired to be protected. It should be understood that while the use of words such as "preferable", "preferably", "preferred" or "more preferred" in the description suggest that a feature so described may be desirable, it may nevertheless not be necessary and embodiments lacking such a feature may be contemplated as within the scope of the invention as defined in the appended claims. In relation to the claims, it is intended that when words such as "a," "an," "at least one," or "at least one portion" are used to preface a feature there is no intention to limit the claim to only one such feature unless specifically stated to the contrary in the claim. When the language "at least a portion" and/or "a portion" is used the item can include a portion and/or the entire item unless specifically stated to the contrary.

Claims

CLAIMS1. A door closer for coupling to a door and comprising a housing with a spindle having a rotational axis about which it is rotatable relative to the housing in response to the door being moved between open and closed positions, a piston disposed for movement relative to the spindle in the direction of the rotational axis in response to relative rotation of the spindle and housing, a biasing member for biasing the piston and spindle to a first position, a cam associated with the piston for converting the relative rotational movement into axial movement of the piston and vice versa.
2. A door closer according to claim 1, wherein the piston and spindle are arranged to rotate together relative to the housing.
3. A door closer according to claim 2, wherein the piston and spindle have inter-engaging features that prevent substantial relative rotationa' movement but permit axial movement of the piston along the spindle.
4. A door closer according to any one of claims 1 to 3, wherein the piston and spindle are substantially concentrically disposed.
5. A door closer according to any preceding claim, wherein the cam comprises at least one cam profile that extends in a direction that has both axial and angular components.
6. A door closer according to claim 5, wherein the at least one cam profile is defined in an external or internal circumferential surface of the piston.
7. A door closer according to claim 5 or 6, wherein the gradient of the at least one cam profile varies along the length of the profile.
8. A door closer according to any one of claims 5, 6 or 7, wherein at least one rolling bearing is arranged for bearing against the at least one cam profile, the rolling bearing being fixed against movement in the axial direction so that the relative rotational movement of the spindle causes the at least one profile to move over the rolling bearing such that the piston translates axially.
9. A door closer according to claim 8, wherein the at least one rolling bearing is a ball bearing.
10. A door closer according to any one of claims 5 to 9, wherein the at least one cam profile is a groove.
11. A door closer according to any one of claims 1 to 4, wherein the piston has a first end and a second end, and the cam comprises a first cam surface defined on one of the first and second ends for interaction with a second cam surface.
12. A door closer according to claim 11, the second cam surface being defined by the housing.
13. A door closer according to any one of claims 5 to 10, the piston having a first end and a second end and the closer further comprising a second cam comprising a first cam surface defined on one of the first and second ends for interaction with a second cam surface.
14. A door closer according to claim 13, wherein when the piston is moved from the first position it is initially moved in the axial direction by the second cam before being moved further in the axial direction by the at least one cam groove.
15. A door closer according any preceding claim, wherein the piston is moveable rotationally and axially relative to the housing.
16. A door closer according to any preceding claim, wherein the piston is moveable inside a bore defined by an internal surface of the housing, and wherein there is provided a sealing member between the piston and internal surface, the seal dividing the bore into first and second variable volume chambers for receipt of hydraulic fluid, the sealing member being configured to seal against the internal surface when the piston moves in a first axial direction towards the first position such that hydraulic fluid is prevent from flowing across the seal between the first and second variable volume chambers, the sealing member being configured to allow hydraulic fluid to flow between the internal surface and the seal when the piston moves in a second axial direction away from the first position.
17. A door closer according to claim 16, wherein the sealing member comprises a deflectable element that projects outwardly from the piston to the internal surface, the deflectable element being deflectable by hydraulic fluid pressure when the piston moves in the second axial direction.
18. A door closer according to any one of claims I to 15, wherein the piston is moveable inside a bore defined by an internal surface of the housing and wherein there is provided an annular sealing member disposed between the piston and the internal surface, there being a radial clearance between the sealing member and the piston so as to accommodate eccentricity of the piston relative to the bore.
19. A door closer according to any preceding claim, wherein the housing has a first portion in which the piston resides in the first position, at least the first portion of the housing being received in a metal sleeve, the housing being a plastics material.
20. A door closer according to any preceding claim, wherein the housing is a plastics material and is moulded around at least one metal liner that define at least one of the following: a hydraulic fluid passage for delivering hydraulic fluid for the piston; a bearing surface for the piston; a sealing surface for the piston; or a threaded bore.
21. A door closer according to any preceding claim, wherein the biasing member acts between the piston and a retainer, the position of the retainer being adjustable relative to the housing and the biasing member to vary the force applied by the biasing member to the piston
22. A door closer according to claim 21, wherein the biasing member is a compression spring and the position of the retainer is adjustable to vary the degree of compression of the spring.
23. A door closer according to claim 21 or 22, wherein the retainer is threadedly engaged with the housing and its axial position in the housing is adjusted by rotation.
24. A door closer comprising for coupling to a door and comprising a housing with a spindle having a rotational axis about which it is rotatable relative to the housing in response to the door being moved between open and closed positions, a piston disposed for movement relative to the spindle in response to relative rotation of the spindle and housing, the piston having a first end and a second end, a biasing member for biasing the piston and spindle to a first position, a first cam associated with the piston for converting the relative rotational movement into movement of the piston and vice versa and a second cam comprising a first cam surface defined on one of the first and second ends for interaction with a second cam surface.
25. A door closer according to claim 24, wherein the second cam surface is defined by the housing.
26. A door closer comprising a housing with a spindle having a rotational axis about which it is rotatable relative to the housing in response to the door being moved between open and closed positions, a piston disposed for movement relative to the spindle in response to relative rotation of the spindle and housing, the piston being biased to a first position by a biasing member, the wherein the housing has a first portion in which the piston resides in the first position, at least the first portion of the housing being received in a metal sleeve, the housing being a plastics material.
27. A door closer comprising a housing with a spindle having a rotational axis about which it is rotatable relative to the housing in response to the door being moved between open and closed positions, a piston disposed for movement relative to the spindle in response to relative rotation of the spindle and housing, the housing being made from a plastics material and rnoulded around at least one metal liner that defines one or more of the following: a hydraulic fluid passage for delivering fluid to the piston; a bearing surface for the piston; a sealing surface for the piston; or a threaded bore.
28. A door closer comprising a housing with a spindle having a rotational axis about which it is rotatable relative to the housing in response to the door being moved between open and closed positions, a piston disposed for movement relative to the spindle in response to relative rotation of the spindle and housing, a biasing member for biasing the piston to a first position in the housing, wherein the biasing member acts between the piston and a retainer, the position of the retainer being adjustable relative to the housing and the biasing member to vary the force applied by the biasing member to the piston.
29. A door closer according to claim 28, wherein the biasing member is a compression spring and the position of the retainer is adjustable to vary the degree of compression of the spring.
30. A door closer according to claim 28 or 29, wherein the retainer is threadedly engaged with the housing and its axial position in the housing is adjusted by rotation.
31. A door or door frame fitted with a door closer according to any preceding claim
32. A door or door frame according to claim 31, wherein in the first position of the piston the door is substantially closed.