Patent Abstract:
A door closer comprising a housing, a member for driving engagement with a door, the member being rotatable relative to the housing in a door opening direction and in a door closing direction, a spring apparatus within the housing providing a resilient bias, the resilient bias being increased by rotation of the member in the door opening direction and a check device for controlling rotation of the member in the door closing direction and hence closure of the door under the action of the spring apparatus, the door closer having a back check comprising a piston member movable in a cylinder from an initial position against resistance of a fluid medium by rotation of the rotatable member in the opening direction.

Full Description:
FIELD OF THE INVENTION 
   This invention relates to a door closer, herein referred to as being of the kind described, comprising a housing, a member for driving engagement with a door, the member being rotatable relative to the housing in a door opening direction and in a door closing direction, a spring apparatus within the housing providing a resilient bias, the resilient bias being increased by rotation of the member in the door opening direction and a check device for controlling rotation of tie member in the door closing direction and hence closure of the door under the action of the spring apparatus. 
   BACKGROUND OF THE INVENTION 
   It is desirable to provide a back check device to resist opening of a door beyond a certain angle, for example, to prevent damage to a wall which could occur if unrestrained opening of the door were permitted. 
   An object of the present invention is to provide a door closer of the kind described with a new and improved back check. 
   SUMMARY OF THE INVENTION 
   According to the present invention we provide a door closer of the kind described having a back check comprising a piston member movable in a cylinder from an initial position against resistance of a fluid medium by rotation of the rotatable member in the opening direction. 
   Preferably a pair of piston members are movable in opposite directions in a respective chamber against resistance of a fluid medium by rotation of the rotatable member in the opening direction. This provides a compact back check. 
   The or each piston member may be movable in a direction which is tangential to the axis of rotation of the rotatable member. 
   The or each piston member may be movable by a cam follower which is engaged with a cam rotatable by rotation of said rotatable member. 
   Where there are two piston members the cam follower is disposed between the piston members. 
   Spring, biasing means may be provided to return the or each piston to said initial position. 
   The or each piston member may be engaged with a spherical intermediate piston member. 
   Where there are two piston members then, in a first plane, the cam follower is engaged by said intermediate piston members and by said cam to control movement of the cam follower in said plane whilst movement of the cam follower in directions out of the plane is controlled by walls of a passage of the housing from which the cam follower is disposed. 
   The fluid medium may be passed through a metering valve which permits a user defined rate of flow of fluid therethrough. 
   The metering valve may be settable to permit adjustment of the rate of flow of fluid therethrough. 
   The metering valve may be accessible from the exterior of the housing for said adjustment. 
   A door closing cam may be mounted in the housing for turning relative thereto with the rotary member, the door closing cam being acted upon by a spring-loaded door closing cam follower which is reciprocable relative to the housing along a main axis and which urges the door closing cam towards a door closed position. 
   The direction in which the or each back check piston member is movable may be transverse to said main axis. Preferably said transverse direction is at right angles to said main axis. 
   The piston members may be disposed on the opposite side of the axis of said rotatable member to said door closing cam follower. 
   By providing the piston members for the back check on the opposite side of the axis of rotation of the rotatable member to the door closing and check means by virtue of the transversely movable piston members described hereinbefore a relatively strong back check effect can be achieved without any need for increasing the resistance to opening of the door until the door is substantially open, for example, in excess of 90°. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An example of a door closer embodying the present invention will now be described, with reference to the accompanying drawings, wherein:— 
       FIG. 1  is a fragmentary cross-section through a door closer in a vertical plane and with an operating member of the door closer in a rest position; 
       FIG. 2  is a diagrammatic representation of a cross-section through the door closer of  FIG. 1  on the stepped line  2 — 2  of  FIG. 1 ; 
       FIG. 3  is a representation similar to that of  FIG. 2  but of a cross-section on the line  3 — 3  of  FIG. 1 ; 
       FIG. 4  is a fragmentary diagrammatic illustration of parts of the door closer as viewed in cross-section on the line  4 — 4  of  FIG. 1 ; 
       FIG. 5  is a diagrammatic plan view, partly in section, of the door closer of  FIGS. 1  to  4  showing the components when the door has been opened 15°, from an “at rest” position; 
       FIG. 6  is a view similar to that of  FIG. 5  but when the door has been opened  90 ′; 
       FIG. 7  is a view similar to that of  FIG. 5  but when the door has been opened through 180°, and 
       FIG. 8  is a view similar to that of  FIG. 5  but to which certain internal passages have been added. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The device illustrated in the accompanying drawings comprises a hollow housing  10  in which there is mounted, by bearings  59 ,  60  for turning about an axis  11 , a rotary member  12 . An end portion  13  of the member  12  protrudes at the outside of the housing  10  and receives an arm  14 , by means of which the rotary member  12  is connected with a door for turning with the door relative to the housing  10 . Typically, the housing  10  is embedded in a floor and the door is supported for pivoting at the axis  11 . The arm  14  may be attached to the bottom of the door and is typically received in a recess formed in the door. The end portion  13  is non-circular and is received in a complementary opening in the arm at one end thereof. When the door is opened the rotary member is rotated in a door opening direction and in a door closing direction when the door is closed. 
   There is disposed inside the housing  10  a coiled compression spring  15  and a drive mechanism for transmitting motion between the spring and the rotary member  12 . The drive mechanism is arranged to compress the spring  15  when the door and member  12  are turned in a door opening direction from a rest position. The spring then urges the door and member  12  towards the rest position as a result of rotation of the member being caused in the door closing direction. 
   The drive mechanism includes three cam and follower mechanisms. The third cam and follower mechanism is essentially a duplicate of the first cam and follower mechanism. The followers of the first and third cam and follower mechanisms reciprocate relative to the housing  10  with a cylinder  16 . The follower of the second cam and follower mechanisms reciprocates with a piston hereinafter described which slides inside the cylinder  16 . 
   The device illustrated in the drawings is constructed to act as a check on damper and check on damp movement of the door towards the rest position under the action of the spring. It will be appreciated that, without the damping action, the door would be accelerated by the spring throughout movement towards the rest position, which would be unacceptably dangerous. In a case where the door is free to swing in either direction from the rest position, damping also enables the door to be brought to rest, when it reaches the rest position, rather than to pass through the rest position and then to oscillate about the rest position. 
   The cylinder  16  is mounted inside the housing  10  for reciprocation relative thereto along a main axis  17  of the cylinder. The main axis  17  extends centrally along the length of the housing  10  and either intersects the axis  11  or passes near to that axis. The cylinder  16  has at one end an enlarged, hollow head  18 , on which there is formed a seat for one end of the spring  15 . That part of the cylinder  16  other than the head  18  lies inside the spring  15 . The spring extends beyond the cylinder  16  to a further seat  19 , on which an end of the spring remote from the head  18  bears. The cylinder is open at both of its ends. 
   The seat  19  is mounted on a carrier  20  which is supported in one end portion of the housing  10  against movement outwards of the housing. The carrier  20  can turn relative to the housing about the main axis  17  and a non-circular end portion  21  of the carrier protrudes from the end of the housing to facilitate turning of the carrier by means of a suitable tool. The seat  19  is annular and has a female screw thread cooperating with a male screw thread on the carrier  20 . The seat  19  is restrained against turning relative to the housing by the spring  15 . This may be achieved by friction between the spring and the seat. Additionally, there may be formed on the seat  19  an axially projecting lug which cooperates with the spring to prevent turning of the seat relative to the spring. Accordingly, by turning of the carrier  20  relative to the housing  10 , the seat  19  can be screwed along the housing to increase or decrease the stress in the spring  15 . 
   The carrier  20  is integral with a fixed hollow piston  22  which slides inside the cylinder  16 . The piston has an annular seal for bearing on the wall of the cylinder to establish an oil-tight relation between the piston and the cylinder. The piston  22  serves to guide the adjacent end portion of the cylinder  16  for movement relative to the housing along the main axis  17 . 
   Further guide means is provided for guiding the head  18  for movement along the main axis  17  relative to the housing  10 . The further guide means is represented in FIG.  3  and comprises a pair of outer guide elements  23  and  24  incorporated in the housing  10  and a pair of inner guide elements  25  and  26  incorporated in the head  18  of the cylinder. The inner guide elements are formed as rollers and are mounted for free rotation relative to the head  18  about respective axes  27  and  28  which lie on opposite sides of the main axis  17 , are equally spaced from that axis and are perpendicular to that axis. The roller axes  27  and  28  are parallel to the axis  11 . The outer guide elements  23  and  24  have respective flat, mutually parallel faces on which the rollers  25  and  26  run. 
   A first cam  29  lies inside the housing  10 , adjacent to the cylinder head  18 , and is fixed with respect to the rotary operating member  12 . The cylinder  16  is provided with a cam follower for cooperating with the cam  29 . In the example illustrated, the cam follower is a roller  30  which engages the periphery of the cam  29 . For transmitting force between the head  18  of the cylinder and the roller  30 , there is provided a pair of rollers  31  and  32  mounted for free rotation relative to the head  18  about the axes  27  and  28 . Thus, the axes of the rollers  31  and  32  are fixed with respect to the cylinder  16 . The roller  30  is, however, free to undergo limited movement relative to the cylinder, although the roller  30  is trapped in the head  18 . 
   The cylinder  16  is urged towards the axis  11  by the main spring  15 . Accordingly, the rollers  31  and  32  are held in firm engagement with the cam follower roller  30  and the latter roller is held in firm engagement with the first cam  29 . This relationship is achieved, irrespective of manufacturing tolerances and irrespective of normal wear of components which may occur during the service life of the device. 
   A second cam  33 , only shown in  FIG. 1 , which is identical with the cam  29 , is mounted in fixed relation to, but spaced along the axis  11  from, the first cam  29 . The cylinder head  16  is provided with a further pair of rollers corresponding to the rollers  31  and  32  and mounted for rotation relative to the head about the axes  27  and  28  and with a further floating roller  36  corresponding to the floating roller  30 , the roller  36  cooperating with the second cam and with the further pair of rollers in the same manner as that which the floating roller  30  cooperates with the first cam and with the rollers  31  and  32 . 
   A first movable piston  37  is mounted inside the cylinder  16  for reciprocation relative thereto. The piston  37  comprises a head  38  bearing a spherical seat which cooperates with the wall of the cylinder and a piston rod  39  extending from the head  38  in a direction towards the axis  11 . The piston rod  39  passes between the guide rollers  25  and  26  and is thereby guided for movement along the main axis  17 . At its end remote from the head  38 , the piston rod  39  carries a cam follower in the form of a roller  40 . The roller  40  bears on the periphery of a third cam  41  interposed between the cams  29  and  33  and fixed with respect thereto. 
   A second possible piston  43  is also mounted in the cylinder  16  for reciprocator relative thereto. The second piston comprises a head  44  bearing a peripheral seal which cooperates with the wall of the cylinder and a piston rod  45  which extends from the head  44  in a direction towards the piston  37  and the axis  11 . A coiled compression spring  46 , which lies mainly inside the hollow piston  22  and which protrudes therefrom to the head  44  of the piston  43  urges the piston  43  towards the piston  37  and thereby urges the piston  37  towards the axis  11 . This maintains the roller  40  in engagement with the periphery of the cam  41 . 
   The cylinder  16  contains an annular plug  47  which lies between the piston head  38  and the piston head  44 . This plug is fixed with respect to the cylinder and is sealed to the cylinder. For convenience of manufacture and assembly of components of the device, the cylinder may be formed in two parts, which meet at the plug  47 . The plug may be employed to connect these parts of the cylinder together. The piston rod  45  extends through the plug  47  and is sealed with respect thereto by an annular seal mounted in the plug. The plug divides a first chamber  48  in the cylinder  16 , lying between the piston head  38  and the plug, from a second chamber  49  lying between the plug and the piston head  44 . A third chamber  50  inside the cylinder extends from the piston head  44  to the fixed piston  22  and includes the interior of that piston. Passages are provided for the flow of oil between these chambers and the space  51  outside the cylinder  16  which contains the main spring  15 . 
   A passage providing communication between the third chamber  50  and the space  51  contains an adjustable needle valve  52 . The needle valve is screwed into a threaded bore formed in the carrier  20  and a portion of the valve protrudes at the outside of the carrier  20 , so that a tool can be applies to the needle valve to adjust the degree of construction of the flow path past the needle valve. The needle valve extends into an annular restrictor disposed in the central bore of the carrier  20 . Lateral ports extend from this central bore to the space  51  at a position between the restrictor and the adjacent end of the housing  10 . 
   A port  53  is formed in the cylinder  16  at a position between the plug  47  and the piston head  44 . This port provides for relatively free flow of oil between the space  51  and the second chamber  49 . A filter may be provided in the port  53  to prevent solid matter entering the cylinder. Communication between the second chamber  49  and the third chamber  50  is provided by a passage  54  formed in the piston head  44 . This passage contains a non-return valve which permits flow in a direction from the second chamber to the third chamber but prevents flow through the passage  54  from the third chamber to the second chamber. 
   The third chamber  50  is in communication with the first chamber  48  via passages formed in the piston head  44  and the piston rod  45 , which is hollow along its entire length. A recess is formed in that face of the piston head  38  which abuts the piston rod  45 , to ensure free flow between the interior of the piston rod  45  and the first chamber  48 . 
   Referring now particularly to  FIGS. 5  to  7 . On the opposite side of the axis  11  to the cylinder  16  and the head  18  is provided a back check device indicated generally at  110 . The device  110  comprises a pair of spherical intermediate piston members  111  which are received in plastic piston members  112  which, when engaged by the spherical members  111 , are placed in a sealing engagement with the wall of a cylindrical cylinder  113  provided by a cross bore in the housing  10 . The cross bore  113  is closed at opposite ends by threaded plugs  114  and a pair of coiled compression springs  115  are engaged between each plug  114  and the associated piston  112 . 
   A cam follower  116  is received in a slot  117  formed in the housing  10  access being gained for machining purposes by an opening  118  which is closed after assembly of the device by a cylindrical plug  119 . The cam follower  116  is controlled for movement in a plane containing the axis of the spherical members  111  and the cam  41  by engagement therewith whilst movement in a direction at right angles to the plane is effected by engagement of the cam follower  116  with upper and lower surfaces of the slot  117 . 
   The piston members  112  engage in the cylinder  113  to form variable volume chambers  120 ,  121 . Referring now to  FIG. 8 , the chamber  120  is connected by a passage  123  to the chamber  121 . This chamber is connected by a passage  124  to a manually adjustable metering valve  125  which is connected by a passage  126  to the interior  127  of the housing  10 . The valve  125  is accessible via a passage  125   a  in the housing to permit the user adjustment of the rate of flow of fluid therethrough. If desired, alternatively, the valve may have its rate of flow pre-set on assembly. In this case the passage  125   a  is not required. In addition the passage  124  is connected by a passage  128  to a non-return valve  129  which is in communication with the interior  127  of the housing. 
     FIG. 2  illustrates the positions of the first cam  29 , cylinder  16  and the pistons  22 ,  37  and  43 , when the rotary member  12  is in a rest position relative to the housing  10 . This is the position occupied when the main spring  15  is extended. It corresponds to the closed position of a door connected with the rotary member  12 .  FIG. 3  illustrates the position of the cam  41 , guide rollers  25  and  26 , the cylinder and the pistons also when the rotary member  12  is in the rest position. When the operating member is turned from the rest position, the cam  29  drives the floating roller  30  away from the axis  11 , a small, initial, angular movement of the cam causing a relatively large displacement of the roller. Since the rollers  31  and  32  are held in firm engagement with the floating roller  30  and have respective axes which are fixed with respect to the cylinder  16 , the cylinder is caused to move away from the axis  11  with the floating roller  30 . Turning of the cam from the rest position drives the cylinder  16  away from the axis  11  and allows the piston  37  to move towards that axis. Movement of the cylinder away from the axis  11  compresses the main spring  15 . 
   When the associated door is released, the spring  15  drives the cylinder  16  towards the axis  11 . The cam and follower mechanism transmits motion from the cylinder  16  to the operating member  12  so that the door is swung towards the rest position. Turning of the operating member towards the rest position is yieldably opposed by the damping action of the device. 
   As the cam  41  is turned towards the rest position, it drives the roller  40  away from the axis  11 . The piston head  38  is moved towards the plug  47  so that the volume of the first chamber  48  is reduced. Oil is expelled from that chamber along the interior of the hollow piston rod  45  to the third chamber  50 . The piston  43  also is moved away from the axis  11  towards the fixed piston  22  so that the volume of the third chamber  50  also is reduced. Flow of oil from the third chamber to the second chamber  49  is prevented by the non-return valve in the passage  54 . Accordingly, all of the oil expelled from the first chamber  48  and from the third chamber  50  must flow through the orifice restricted by the needle valve  52 . Closing movement of the door is thereby controlled. 
   The shape of the cam  29  is selected to provide that the action of the floating roller  30  on the cam, when the operating member  12  is in the rest position, is a strong centering action, driving the came to and holding the cam in the rest position. The orientation of the cam relative to the housing  10 , when in the rest position, can be adjusted through a small range by adjusting the outer guide elements  23  and  24  in a direction transverse to the axis  11 . Adjustment of these guide elements  24  and  25  may be provided as described in GB-B-2261915. 
   Referring now particularly to  FIGS. 5  to  7 , when the door is first opened through a small angle, for example 15° as illustrated in  FIG. 5 , the cam follower  116  is not engaged by the cam  41  and so no movement of the spherical members  111  occurs and therefore there is no change in volume of the chambers  120 ,  121  and therefore no restriction on opening of the door. When the door is moved through 90° the cam follower  116  comes into engagement with the cam  41  initially; movement of the door beyond 90° causes relatively large movement of the cam follower  116  and hence large movement of the spherical members  111  along the cylinder  113 . However as the door approaches the 180° position then, as best shown in  FIG. 7 , the cam follower  116  is progressively moved to the left in  FIGS. 4  to  6  with consequent movement of the spherical members  111  along the cylinders  113  and consequential restriction in size of the chambers  120 ,  121 . Fluid from these chambers is forced along the passages  123 ,  124  to the metering valve  125  which restricts the rate at which fluid can be discharged from the chambers  120 ,  121 , therefore restricting the rate of movement of the spherical members  111  and so restricting the rate of movement of the cam follower  116  which has the effect of raising the torque required to open the door, thereby providing a back check effect which reduces in value as the door approaches 180° of movement. 
   When it is desired to close the door then normally it is simply released so that the door is returned to its initial position by the spring  15  as hereinbefore described. Such movement is permitted by oil being drawn into the chambers  120 ,  121  through the passage  128  via the valve  129 . 
   Accordingly, the present invention provides a means of controlling the opening movement of a door beyond a predetermined angle, for example 90° to prevent damage to walls and furniture as a result of such opening movement being existent. 
   By providing the two separate piston and cylinder arrangements acting upon the cam following  116  a relatively great back check action can be provided without increasing the size of the housing beyond that necessary to achieve a proper closing action as the back check load required is split between two separate piston and cylinder arrangements. 
   In the present specification “comprises” means “includes or consists of” and “comprising” means “including or consisting of”. 
   The features disclosed refer to a floor spring where space is restricted between the pivot point (axis  11 ) and the door frame. Typically, this distance is of the order of 70 mm. However, the features disclosed could equally apply to a surface mounted overhead closer if a compact back check system is required. 
   The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Technology Classification (CPC): 4