Abstract:
A door closer components include a housing having a mounting plate, a tension member extending longitudinally within the central bore of the housing, a movable body within the housing connected to the tension member, a spring within the housing, and a hydraulic assembly for hydraulically controlling the longitudinal movement of the movable body. The hydraulic assembly is disposed within the central bore of the housing and includes a piston coupled to the housing and slidable in a fluid-filled chamber within the movable body, wherein the piston divides the chamber into two compartments. The piston has a valve mechanism which opens to permit relatively free movement of the fluid from one compartment to the other when the movable body is moved. The valve mechanism of the piston includes a boss fitted to a piston shaft and defining an annular sealing face and a longitudinally extending channel member integral with the boss.

Description:
BACKGROUND OF INVENTION 
       [0001]    This invention relates to a door closing device for urging an opened door towards its closed position relative to a doorframe. 
         [0002]    More particularly, the invention concerns improvements in a door closer, which is of the kind that usually acts between a door leaf and a doorframe. This type of door closer typically comprises a housing, a plunger movable along the housing, a biasing element disposed in the housing and biasing the plunger inwardly of the housing, and a tension member having one end connected to the plunger and another end, which extends to an anchor element. The housing is normally installed in a bore in the door leaf and the anchor element installed in the doorframe. However, the positions of the housing and the anchor element may be reversed. The biasing element comprises a spring, which operates to bias the plunger, and consequently the tension member, inwardly of the housing, for closing the door. The tension member comprises an articulated element so that the tension member can be bent around the opening angle of the door relative to the door frame. 
         [0003]    It is known to provide such concealed door closers with a hydraulic damping assembly, as disclosed for example in GB-A-2441893, GB-A-2441894, WO-A-2005/124079 and WO-A-2008/102115. The hydraulic damping assembly comprises a piston and cylinder assembly that can damp the movement of the plunger. The hydraulic damping assembly comprises circuit for the hydraulic fluid that incorporates an adjustable valve assembly. The valve can be adjusted to vary the damping force of the hydraulic damping assembly. 
         [0004]    Recently, a standard classifying controlled door closing devices has been established as BS EN 1154 1997, with Amendment A1 2003. Door closers intended for use on fire resisting doors and smoke control doors are covered by a Construction Products Directive mandate issued by the European Commission, and the Amendment A1 to the BS EN 1154 1997 harmonised the standard in compliance with the Directive and allows application of the CE mark. The standard sets minimum performance parameters for door closer operation, in particular with regard to closing moment (dependent on door size and mass) and closing time. 
         [0005]    While face fixed overhead closers can readily be constructed so as to comply with BS EN 1154 1997, because a bulky housing can be provided which merely needs to fit to the door face or the frame, in contrast concealed door closers of the type disclosed in EP-A-0016445 generally cannot, primarily as a result of the inherently low power characteristics of this construction, because the spring needs to be dimensioned to fit within the door leaf without compromising the structural integrity of the door, which is crucial for fire resisting doors, for example. 
         [0006]    There is a need in the art for concealed door closers that can comply with BS EN 1154 1997. 
         [0007]    There is also a general need for such concealed door closers to have a structure to enable them to be incorporated into a variety of different door constructions having a variety of different uses. For example, the British Standard BS.EN 1154, and its equivalent European Standard EN 1154, sets (among others) a technical criterion required to be met by door closers, concealed or not, which is that the door closer must have a minimum opening/closing efficiency—the closer must provide a minimum resistance force in an opening direction, to enable a person readily to be able to pull open the door, but must provide a maximum closing force, to enable the door reliably to be closed under the action of the door closer, overcoming any resistance from the door latch, in order to ensure that the door closer can properly and promptly act to close the door, which provides safety in the event of a fire. 
         [0008]    We have found that for concealed door closers incorporating a hydraulic damping assembly this demanding performance criterion is difficult to meet because the door closer can suffer from inadvertent jamming, and because it is necessary to ensure that the door closes completely, which means a reliable high closing force right at the end of the closing stroke to overcame any resistance to closing from the latch mechanism for the door. 
         [0009]    Even for non-concealed “up and over” door closers, the efficiency can be quite low, for example 60 to 70%. 
         [0010]    In addition, the fitting of concealed door closers even by professional workers such as builders, joiners, etc. can be rather problematic. The door closer incorporates a mechanical spring having a high spring constant, which applies a very high tensile restoring force to pull together the two parts of the door closer which are fitted to the door frame and to the door leaf These parts need to be separate during installation. Furthermore, sometimes the door closer maybe inadvertently fitted incorrectly, for example “inside out” with the tensioning member between the two parts having the edge that should be oriented on the radially inside side of the closing arc being located o the radially outside edge. Although a fitting tool is disclosed in WO-A-2008/102115 to assist installation, there is still a need for an “idiot proof” fitting tool to ensure that the door closer is correctly fitted in the required orientation. 
       SUMMARY OF THE INVENTION 
       [0011]    The present invention at least partially aims to overcome the problems of the known door closers described hereinabove. The present invention aims in particular to provide a concealed door closer having a high efficiency, and an improved fitting tool. 
         [0012]    Accordingly, the present invention provides a door closer comprising: (a) a housing for fitting into a door, the housing having a mounting plate with an opening adjacent to a central bore of the housing; (b) a tension member extending longitudinally within the central bore of the housing and extending outwardly of the housing through the opening to define an end thereof for fitting to a door frame; (c) a movable body within the housing and adapted for longitudinal movement within the central bore, the movable body being connected to the tension member; (d) a spring within the housing and biasing the movable body in a first direction away from the mounting plate so as to urge the tension member inwardly of the housing in a door closing motion; (e) a hydraulic assembly for hydraulically controlling the longitudinal movement of the movable body, the hydraulic assembly being disposed within the central bore of the housing; wherein the hydraulic assembly comprises a piston coupled to the housing and slidable in a fluid-filled chamber within the movable body, wherein the piston divides the chamber into two compartments, and the piston comprises a valve mechanism which opens to permit relatively free movement of the fluid from one compartment to the other when the movable body is moved relative to the piston in a second direction, opposite to the first direction, in response to movement of the tension member outwardly of the housing but closes to present resistance to movement of the movable body in the first direction, wherein the valve mechanism of the piston comprises a boss fitted to a piston shaft and defining an annular sealing face, a longitudinally extending channel member integral with the boss, the channel member having at least one longitudinal channel therein which terminates at a closed end near to but spaced from the annular sealing face, an annular seal member fitted around the channel member, the annular seal member being disposed for longitudinal sliding motion on the channel member, between sealed and unsealed positions, the at least one longitudinal channel extending between opposite sides of the annular seal member, the seal member having an annular end sealing surface facing the boss, and a circumferentially outer surface of the annular seal member providing a sealing engagement with the movable body. 
         [0013]    The door closer may further comprise an annular washer slidably fitted around the channel member between the boss and the annular seal member, the washer having a thickness greater than the distance of the closed end from the annular sealing face. 
         [0014]    Typically, in the sealed position the washer abuts the boss and the annular seal member abuts the washer, the washer covering the or each closed end to prevent fluid movement though the at least one channel. 
         [0015]    Typically, in the unsealed position the washer is spaced from the boss to expose the or each closed end to permit fluid movement though the at least one channel and through a central opening in the annular seal member. 
         [0016]    Preferably, the valve mechanism of the piston further comprises a disc having at least one fluid conduit extending longitudinally therethrough, the disc being fitted to the piston shaft adjacent to the annular seal member. 
         [0017]    Preferably, the annular sealing face of the boss is provided with at least one through-hole extending through the boss. 
         [0018]    Preferably, the fluid-filled chamber comprises an first elongate chamber within which the piston slides and a second elongate chamber in fluid communication therewith via an adjuster for adjusting a damping action of the hydraulic assembly in a door closing motion, the adjuster being located at one end of the fluid-filled chamber, and via at least one fluid return port, located at an opposite end of the fluid-filled chamber. 
         [0019]    More preferably, the second elongate chamber is annular and surrounds the first elongate chamber which is cylindrical. 
         [0020]    Optionally, the adjuster of the hydraulic assembly, for adjusting the damping rate of the longitudinal movement of the movable body at least in the first direction, comprises a rotatable threaded valve member of a fluid bypass valve located at an end of the hydraulic assembly which faces the opening in the mounting plate, and an end member for retaining the valve member captive in the adjuster. 
         [0021]    The present invention further provides a kit of parts for fitting a door closer, the kit comprising a door closer according to the present invention in combination with a fitting tool, the fitting tool comprise a U-shaped body with two parallel legs extending away from a base and with a central elongate linear slot, open at one end, between the two legs, and the rigid tension member is received in the slot to retain the rigid tension member partly out of the housing, and the fitting tool further comprises an orienting guide part extending orthogonally away from the base. 
         [0022]    Preferably, the orienting guide part is remote from the legs so that the fitting tool has an L-shape. 
         [0023]    Preferably, the rigid tension member is retained partly out of the housing to permit the housing and the mounting member of the door closer to be oriented at a desired angular relationship during installation of the door closer. 
         [0024]    Preferably, the central portion of the rigid tension member is received in the slot and an enlarged portion of the second end bears against an end face of the U-shaped body. 
         [0025]    Typically, the body comprises a rigid plate member having opposite parallel end faces which are orthogonal to the through-direction of the slot, and the orienting guide part is a rigid plate member integral with the body. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which: 
           [0027]      FIG. 1  is a partly cut-away perspective side view of a door closer according to an embodiment of the present invention in a closed configuration; 
           [0028]      FIG. 2  is a partly cut-away perspective side view of the door closer of  FIG. 1  in an open configuration; 
           [0029]      FIG. 3  shows an exploded perspective view of the plunger valve assembly of the door closer of  FIG. 1 ; 
           [0030]      FIG. 4  shows a side view of the plunger valve assembly of the door closer of  FIG. 1  in a first, closed, configuration; 
           [0031]      FIG. 5  shows a side view of the plunger valve assembly of the door closer of  FIG. 1  in a second, open, configuration; 
           [0032]      FIG. 6  shows a top view of the door closer of  FIG. 1  prior to installation between a door leaf and a door frame, the door closer being in combination with a fitting tool according to another embodiment of the present invention; and 
           [0033]      FIG. 7  shows a perspective side view of the fitting tool of  FIG. 6 . 
       
    
    
       [0034]      FIGS. 1 to 5  show a door closer according to the present invention that can be used for urging an opened door towards its closed position relative to a door frame; 
       DETAILED DESCRIPTION 
       [0035]    An elongate housing  2  in the form of a cylindrical tube comprises a biasing element  4  in the form of a helical compression spring  4 . In  FIGS. 1 and 2 , for clarity of illustration only the opposed ends of the helical compression spring  4  are shown and the central portion is not shown. A plunger  6  is disposed in and movable along the housing  2 . The plunger  6  is biased inwardly of the housing  2  by the biasing element  4 . The helical compression spring  4  annularly surrounds the plunger  6 . The housing  2  has a mounting plate  8  affixed thereto, the mounting plate  8  having holes  10  extending therethrough for receiving fixing screws. In use, the housing  2  is received in an elongate horizontal cavity in a door leaf (not shown), and the mounting plate  8  is rebated into the edge of the door leaf and affixed thereto, for example by screws. 
         [0036]    A rigid tension member  14  has a first end  16  pivotally connected at a first pivot  18  to a plunger head  17  of the plunger  6  and a second end  20  pivotally connected at a second pivot  22  to an anchor element assembly  24 . The first pivot  18  has a knurled outer cylindrical surface  19  securely fitting into a cylindrical hole  21  in the plunger head  17 , the knurling preventing inadvertent removal of the first pivot  18 . The anchor element assembly  24  comprises a mounting member  26 , in the form of a plate, for mounting in a door frame (not shown) and an elongate link member  30  extending from the mounting member  26 . The mounting member  26  is typically rebated into the edge of the door frame and affixed thereto, for example by screws. The second pivot  22  is located at a free end  32  of the link member  30  remote from the plate member  26 . The first and second pivots  18 ,  22  have parallel axes  19 ,  23 . 
         [0037]    Conceivably, the mounting positions of the housing  2  and the anchor element assembly  24  may be reversed, with the housing  2  received in the door frame and the anchor element assembly  24  mounted to the door leaf. 
         [0038]    A hole  34  in the mounting plate  8  permits movement therethrough of the rigid tension member  14  and the link member  30 . 
         [0039]    The rigid tension member  14  comprises a linearly straight body that has a laterally offset reduced thickness central portion  37  between the first and second ends  16 ,  20 . 
         [0040]    The door closer of the invention also incorporates an adjustable damper to provide a decelerated or damped closing action. 
         [0041]    In the illustrated embodiment a hydraulic cylinder/piston damper  50  for damping the movement of the plunger  6  within the housing  2 , having the general structure as disclosed for example in WO-A-2005/124079, is provided. The hydraulic cylinder/piston damper  50  has a threaded adjuster pin  52  for adjusting the operation of the hydraulic damper  50 . The threaded adjuster pin  52  is mounted in the plunger head  17  of the plunger  6  adjacent the first pivot  18  and has an elongate head  54  which extends away from the plunger  6  and lies adjacent to the rigid tension member  14 . At the other end of the threaded adjuster pin  52  a needle valve member  55  of a restrictor valve is provided which is employed to adjust the flow of hydraulic fluid in the damper  50 . The hole  34  permits insertion therethrough of a screwdriver or other tool to adjust the threaded adjuster pin  52 . 
         [0042]    At the other end of the housing  2  a cylindrical end piece  56  is fitted into the housing  2  so as to close off the bore  5  defined by the housing  2 . A piston shaft, hereinafter referred to as a plunger shaft  60 , is fitted to the end piece  56  and extends axially along a portion of the bore  5 , typically about one half of the length of the bore  5 . A reduced diameter portion  62  of the plunger shaft  60  extends through a hole  63  in the end piece  56 , and a lock nut  64  is threaded onto an end of the plunger shaft  60  on the exposed face of the end piece  56 . This arrangement permits the longitudinal position of the plunger shaft  60  in the bore  5  to be adjusted over a small distance after manufacture and assembly of the door closer by turning the lock nut  64 . 
         [0043]    The closed door position is shown in  FIG. 1 . The mounting plate  8  and the plate member  26  abut. The rigid tension member  14  is wholly received in the housing  2 , and the link member  30  is also received in the housing  2 . The helical compression spring  4  has urged the plunger  6  to its most inward position with respect to the housing  2 . 
         [0044]    When the door leaf is opened relative to the door frame about the axis of one or more door hinges (not shown), the plunger  6 , being attached to the door frame, is pulled in a direction outwardly of the housing  2 . Accordingly, the helical compression spring  4  is progressively compressed, as a result of a compression force acting thereon by the plunger  6 , and exerts an inward biasing force acting against the opening pulling force on the door leaf. The open position is shown in  FIG. 2 . The mounting plate  8  is spaced from the plate member  26 . The link member  30  is pulled out of the housing  2  and the rigid tension member  14  is partly received in the housing  2 . The rigid tension member  14  is rotated relative to the plunger  6  about the first pivot  18 . The link member  30  is rotated relative to the rigid tension member  14  about the second pivot  22 . 
         [0045]    In the fully open position, in which the door leaf has been opened by an angle of up to 120°, the rigid tension member  14  is pulled completely out of the housing  2  and the first pivot  18  and the associated end of the plunger  6  are disposed at the hole  34 . The rigid tension member  14  has been rotated relative to the plunger  6  about the first pivot  18  so as to lie, in the fully open position, at an angle of up to about 120° relative to the longitudinal axis of the door closer  2 . The link member  30  has been rotated relative to the rigid tension member  14  about the second pivot  22 . 
         [0046]    After the door leaf is released, the biasing force of the helical compression spring  4  acts to bias the rigid tension member  14  inwardly of the housing  2 , for closing the door. The damper may provide a reduced damping force at the end of the closing operation so as to provide an enhanced closing velocity for overcoming any latch resistance so that the door is securely latched when closed. 
         [0047]    The structure and operation of the hydraulic damping assembly will now be described. 
         [0048]    A hydraulic damper assembly  70  is mounted on the plunger shaft  60  for sliding movement therealong. The hydraulic damper assembly  70  includes an outer tube  72  which extends axially along a portion of the bore  5 , typically about one half of the length of the bore  5 . The outer tube  72  has an integral radially outwardly directed flange  74  at one end  75  thereof that is towards the end piece  56 . The flange  74  and the mounting plate  8  define opposed bearing surfaces against which the opposed ends of a helical compression spring  4  are seated. The helical compression spring  4  surrounds the outer tube  72  and outer tube  72  is free to move along the bore  5  within the internal diameter of the helical compression spring  4  as the spring  4  is progressively compressed or expanded. 
         [0049]    At the other end of the outer tube  72  the end edge  71  is crimped radially inwardly to support the plunger head  17  that is fitted within the outer tube  72 . 
         [0050]    An inner tube  80  is disposed coaxially within the outer tube  32 . One end  82  of the inner tube  80  is fitted, in a fluid-tight manner to the plunger head  17  and another end  84  is fitted to a plunger shaft housing  86  which surrounds the plunger shaft  60 . The adjacent end  75  of the outer tube  32  is also fitted to the plunger shaft housing  86 . 
         [0051]    The inner tube  80 , plunger head  17  and the plunger shaft housing  86  define an inner chamber  90  through which the plunger shaft  60  extends. An outer chamber  92  is defined between the outer tube  72  and the inner tube  80 . At the plunger head  17  the inner chamber  90  and the outer chamber  92  communicate via the restrictor valve comprising the needle valve member  55 . At the plunger shaft housing  86  the inner chamber  90  and the outer chamber  92  communicate via at least one port (not shown) in the plunger shaft housing  86 . This structure forms a hydraulic circuit connecting the inner and outer chambers  90 ,  92 . The inner chamber  90  and the outer chamber  92  are filled with a hydraulic fluid, such as an oil or ethylene glycol. 
         [0052]    The restrictor valve can regulate the flow of hydraulic fluid from the inner chamber  90  to the outer chamber  92 , and thereby control the degree of damping of the hydraulic damping assembly. 
         [0053]    An accumulator  176  comprises an elongate annular foam member which is disposed in the inner chamber  90  adjacent to the plunger shaft housing  86  and surrounds the plunger shaft  60 . The accumulator  176  comprises a body of foamed plastics or rubber material, comprising a closed cell foam structure, such as neoprene. The accumulator  176  is spaced from the plunger boss  104  by at least one rigid spacer  177 , e. g. of nylon, which prevents trapping of the accumulator  176  in any gap between the plunger boss  104  and the inner tube  80 . 
         [0054]    A piston, referred to hereinafter as a plunger valve assembly  100 , is shown in detail in  FIGS. 3 to 5 . 
         [0055]    Referring in particular to  FIG. 3 , the plunger shaft  60  is provided at its end thereof which is remote from the reduced diameter portion  62  fitted into the end piece  56  with a second reduced diameter portion  102  on which a plunger valve assembly  100  is mounted. The plunger valve assembly  100  comprises, in turn, a plunger boss  104  fitted onto the second reduced diameter portion  102 , a plunger washer  105  fitted onto the plunger boss  104 , a plunger seal  106  fitted onto the plunger boss  104 , a plunger fluid flow plate  110  fitted onto the second reduced diameter portion  102 , and a lock nut  112 , threaded onto the end of the second reduced diameter portion  102  so as to secure the plunger valve assembly  100  on the plunger shaft  60 . 
         [0056]    The plunger boss  104  and plunger fluid flow plate  110  are prevented against longitudinal movement along the plunger shaft  60  by the lock nut  112 . However, as described in detail hereinafter, the plunger washer  105  and the plunger seal  106  are mounted on the plunger boss  104  and have a limited range of longitudinal movement. Movement of the plunger seal  106  causes opening or closing of the plunger valve assembly  100 . 
         [0057]    The plunger boss  104  has a central hole  113  through which the second reduced diameter portion  102  of the plunger shaft  60  extends. The plunger boss  104  comprises a large diameter end wall  114  whose external diameter, defined by an outer circumferential surface  115  is slightly less than the internal diameter of the inner tube  80 . Plural through-holes  111  extend through the end wall  114 . A channel body  116  of the plunger boss  104 , integral with the end wall  114 , has a reduced diameter as compared to the end wall  114 . The channel body  116  is substantially cylindrical but includes a plurality, in the embodiment four, longitudinally directed channels  118  formed in its outer circumferential surface  120 . The channels  118  are substantially semi-circular in cross-section and are equidistant around the circumferential surface  120 . The channels  118  each terminate at a closed end  119  located at a position a short distance x (e.g. about 0.5 mm) remote from the end face  124  of the end wall  114 . The closed end  119  is thus near to but spaced from the annular sealing face  124  of the end wall  114 . A junction  121  of the end face  124  and the circumferential surface  120  is spaced from both the closed ends  119  and the through-holes  111 , so that when the plunger washer  105  abuts the end face  124 , a seal is formed therebetween. 
         [0058]    The plunger washer  105  is typically composed of metal and is an annular ring of the same external diameter as the end wall  114  and a thickness greater than the distance x of the closed ends  119  from the end face  124 . The internal circumferential surface  125  of the plunger seal  106  is slidably fitted on the outer circumferential surface  120  of the channel body  118  of the plunger boss  104  and can move longitudinally thereto. Accordingly, when the plunger washer  105  is slid into a position to the left as shown in  FIG. 3  and therefore abuts the end face  124 , the washer  105  covers the closed ends  119  of the channels  118  and there is little or no possibility of hydraulic fluid flow from the channels  118  towards the end face  124  because the washer  105  closes off the ends  119  of the channels  118 . 
         [0059]    The plunger seal  106  comprises an annular body of plastics or rubber material, and has an external diameter which is substantially the same as the internal diameter of the inner tube  80  so that when the plunger seal  106  is received in the inner tube  70 , there is a fluid tight seal between the outer circumferential surface  126  of the plunger seal  106  and the internal surface  128  of the inner tube  80 . The internal circumferential surface  130  of the plunger seal  106  is slidably fitted on the outer circumferential surface  120  of the channel body  118  of the plunger boss  104  and can move longitudinally thereto. The annular end face  132  of the plunger seal  106  facing towards the washer  105  constitutes a sealing face which seals against the washer  105  which is turn is urged against the end wall  114  which acts as a seat for the washer  105  which in turn acts as a seat for the plunger seal  106 . 
         [0060]    The plunger fluid flow plate  110  comprises an annular metal disc  148  having a central opening  150  for receiving the second reduced diameter portion  102  of the plunger shaft  20  and a plurality of, in the embodiment six, conduits  152  extending between the opposed annular faces of the disc  148 . The conduits  152  are circumferentially equidistant and disposed in a satellite fashion around the central opening  150 . The lock nut  112  secures the disc  148  to the plunger shaft  60  but leaves the conduits  152  at least partially exposed. 
         [0061]    The sealed position of the plunger valve assembly  100  is shown in  FIG. 4  and the unsealed position is shown in  FIG. 5 . 
         [0062]    In the sealed position of  FIG. 4 , which is achieved when the hydraulic fluid pressure acts in a direction from right to left in the drawing of  FIG. 4  during closing of the door closer, in which the assembly of the outer and inner tubes  70 ,  80  moves to the right in  FIG. 1  along the plunger shaft  60 , the fluid pressure urges the plunger seal  106  against the washer  105  and the washer  105 , in turn, against the end wall  114  of the plunger boss  104 . Therefore, when the outer circumferential surface  126  of the plunger seal  106  is sealed against the inner circumferential surface  128  of the inner tube  70 , hydraulic fluid within the inner chamber  82  on one side of the plunger seal  106  cannot flow to the other side of the plunger seal  106 . By providing the washer  105  together with the closed ends  119  of the channels  118  being remote from the end face  124  of the end wall, this minimises the possibility of hydraulic fluid being forced between the plunger seal  106  and the plunger boss  104  in the sealed position, which could otherwise cause inadvertent jamming of the plunger valve assembly  100 . A highly efficient seal is provided in this configuration. The closing movement resulting from the spring bias is damped by the restrictor valve. 
         [0063]    In  FIG. 5  however, which shows the unsealed configuration, the plunger washer  105  and the plunger seal  106  has been urged by hydraulic pressure (in a right hand direction in  FIG. 5 ) away from the end face  124  and towards the plunger fluid flow plate  110 . This is achieved during opening of the door closer, in which the assembly of the outer and inner tubes  70 ,  80  moves to the left in  FIG. 1  along the plunger shaft  60 . With the outer circumferential surface  126  of the plunger seal  106  still sealed against the internal circumferential surface  128  of the inner tube  80 , hydraulic fluid within the inner chamber  92  can flow through the plunger valve assembly  100 . Hydraulic fluid can flow through the through-holes  111  and even to some extent over the outer circumferential surface  115  of the end wall  114 , and then radially inwardly through the gap  154  between the end wall  114  and the plunger washer  105 , into the now exposed closed ends  119  of the channels  118 , longitudinally along the channels  118 , radially outwardly under the fluid pressure so as the exit the channels  118  between the seal  106  and the fluid flow plate  110 , and finally longitudinally through the conduits  152  in the plunger washer  110 . There is substantially no seal at the plunger valve assembly  100  in this configuration. The opening movement, against the spring bias, is substantially unrestricted by the plunger valve assembly  100  and is not damped by the restrictor valve. 
         [0064]    This seal accordingly has high efficiency, typically from 80 to 90% according to the test of BS EN 1154 1997, or even as high as 92%. 
         [0065]    In a modification, the washer  105  may be omitted and the annular plunger seal  106  may be made correspondingly wider in a longitudinal direction so that it directly abuts the sealing end face  124  of the boss  104  in the sealed position. 
         [0066]      FIG. 6  shows a top view of the door closer prior to installation between a door leaf and a door frame, the door closer being in combination with a fitting tool for retaining the tension member partly out of the housing, and in particular to permit the mounting plates of the door closer to be oriented at a desired angular relationship in a partly open condition during installation.  FIG. 7  shows a perspective view of the fitting tool shown in  FIG. 6 . 
         [0067]    The fitting tool  150  comprises a U-shaped body  152  with two parallel legs  154 ,  156  extending away from a base  158  and with a central elongate linear slot  160 , open at one end  162 , between the two legs  154 ,  156 . The body  152  comprises a rigid plate member having opposite parallel end faces  158 ,  164  which are orthogonal to the through-direction of the slot  160 . An integral orienting guide part  168  extends orthogonally away from the upper edge  170  of the body  152  remote from the legs  154 ,  156 , so that the fitting tool  150  has an L-shape. 
         [0068]    In use, the tension member  14  is received in the slot  160  to retain the tension member  14  partly out of the housing  2 , and in particular to permit the mounting plate  8  and the mounting member  26  of the door closer to be oriented at a desired angular relationship in a partly open condition during installation. The second end  20  of the tension member  14  includes an enlarged portion  127  that is larger in height (i.e. a direction substantially parallel to the pivot axis of the second pivot  22 ) than the adjacent central portion  37  of the tension member  14 . The enlarged portion  127  thereby provides (see also  FIG. 2 ) a pair of upper and lower abutment surfaces  131 ,  133  of the tension member  14  facing rearwardly, i.e. back into the housing  2  and, when outside the housing  2 , back towards the mounting plate  8 . 
         [0069]    The pair of upper and lower abutment surfaces  131 ,  133  of the tension member  14  is biased by the spring  4  in the housing  2  against the respective legs  154 ,  156  of the fitting tool  150 . The securing of the fitting tool  150  between the mounting plate  8  and the enlarged portion  127  prevents the entire tension member  14  and the elongate link member  30  pivotally attached thereto from being pulled by the spring bias into the housing  2 . The exposed part of the enlarged portion  127  and the elongate link member  30  are of sufficient length to permit sufficient angular separation between the mounting plate  8  and the door frame mounting member  26  to enable them readily to be fitted to the door leaf and the door frame respectively, for example using screws as discussed earlier. 
         [0070]    Accordingly, the door closer is sold to the customer with the fitting tool  150  pre-fitted on the tension member  14 . The installer offers the door closer up to the door leaf  180 , shown in phantom in  FIG. 5 . The L-shape of the fitting tool provides a guide as to how the door closer must be oriented relative to the door leaf. The orienting guide part  169  can only be fitted on the side of the door leaf remote from the hinge axis otherwise it would not be possible readily to remove the fitting tool after fitting of the door closer. 
         [0071]    After fitting the door closer to the door leaf  180  and the door frame  184 , also shown in phantom in  FIG. 5 , the fitting tool  150  is removed by horizontal sliding away (in the direction of arrow A in  FIG. 5 ) from the tension member  14 , permitting the door to be fully closed under the action of the installed door closer. The orienting guide part  168  must be placed against os spaced from the radially outer face  182  of the door leaf with respect to the hinge axis. Otherwise, it would not be possible easily to remove the fitting tool  150  after fitting the door closer to the door leaf and the door frame  184 . Therefore the L-shaped structure of the fitting tool ensures that the door closer is correctly fitted in the correct orientation, and is not inadvertently fitted “inside-out” or “upside down” with respect to the hinge location and angular direction of operation of the door. 
         [0072]    The present invention provides a concealed door closer that can comply with BS EN 1154 1997. The overall dimensions are compact, so that the door closer can be fitted within the door leaf without compromising the structural integrity of the door. However, the compression spring dimensions, and therefore spring force available for closing the door leaf, are sufficient to comply with BS EN 1154 1997. The damping assembly is not only compact, being disposed within the internal diameter of the compression spring, but also it is readily adjustable so that the closure period of the concealed door closer can be reliably controlled to be within the limits required by BS EN 1154 1997. Moreover, the damping characteristics of the concealed door closer can be adjusted after installation, in particular by a person other than a trained installer or engineer, without removal of the unit from the door leaf.