The present invention relates to a door closing device for urging an opened door towards its closed position relative to a door frame. The present invention particularly relates to a door closer of the type which is known in the art as a “free swing” (or “swing-free”) door closer which can be switched to operate in two alternative modes, namely (i) a free swing mode in which the door leaf can swing freely between open and closed positions without any resistance or closing force applied by the door closer and (ii) a door closing mode in which a closing force is applied to the door leaf by the door closer.

Such “free swing” (or “swing-free”) door closers are known in the art of door closer manufacture, and are used in buildings in which free door movement is required but in an emergency, such as after activation of a fire alarm, the door is immediately closed by the application of a closing force by the door closer.

The “free swing” door closer enables a door to be opened without any resistance from a closing force, and closed without any assistance from a closing force, so that the door behaves like a door without any door closer. The absence of any closing force is allows the door to be left in any position, for example ajar, if desired.

However, the door closer can be switched from a “free swing” mode to a door closing mode, so that the door closer applies a closing force, and the door therefore behaves like a door with a conventional door closer. Typically, on activation of a fire alarm, an electromagnetic control switches the door closer to function and close the door securely. The “free swing” function is typically reset by simply opening the door to an opening angle of between 70 - 90 degrees.

Free swing door closers have particular application in buildings in which room access needs to be facilitated, for example in hospitals, nursing homes, residential care homes, etc. to enable wheelchair or reduced mobility access, without compromising fire safety.

Door closers generally fall into two types.

A first type comprises surface-mounted door closers, which comprise a door closer mechanism in a large housing which is fitted to the surface of a door leaf and an articulated arm which connects the door closer mechanism to the door frame. These surface-mounted door closers are large, aesthetically ugly, easily tampered with or damaged and require regular cleaning. A second type comprises concealed door closers, which comprise a door closer mechanism in a small tube which is usually fitted within the body of a door leaf and a tension member, such as a rigid link or flexible chain, connects the door closer mechanism to a plate fitted to the door frame. These concealed door closers are small, aesthetically acceptable and difficult to tamper with than surface-mounted door closers. Concealed door closers do not require cleaning.

A known “free swing” concealed door closer is disclosed in GB2456508B. This known “free swing” door closer requires a highly complicated hydraulic switch system to switch the door closer from a free swing mode to a door closing mode. This device is unreliable since the hydraulic fluid in the hydraulic switch system can leak.

There is a need in the art for a “free swing” concealed door closer which is less complicated and/or more reliable than the “free swing” concealed door closer known from GB2456508B.

There is also a need in the art for a “free swing” concealed door closer which is smaller, more aesthetically acceptable, than known “free swing” surface-mounted door closers.

The present invention at least partially aims to overcome the problems of the known door closers described hereinabove.

Accordingly, the present invention provides a door closer for mounting between a door leaf and a door frame, the door closer comprising: an elongate housing for mounting in one of the door leaf or door frame, the elongate housing having opposite forward and rear end parts, an elongate member disposed in and movable within the housing in a direction extending between the forward and rear end parts, the elongate member having a rear end portion, a spring biasing element disposed in the housing and applying a biasing force to the rear end portion thereby to bias the elongate member towards the rear end part, a tension member having a first end connected to the elongate member and a second end connected to an anchor element assembly, the anchor element assembly comprising a mounting member for mounting in the other of the door leaf or door frame, the tension member and anchor element assembly forming a tension assembly which extends through the forward end part, and a trigger mechanism for latching the rear end portion to hold the elongate member in a forward position against the bias of the spring biasing element and unlatching the rear end portion to cause the spring biasing element to move the elongate member towards the rear end part and to a rearward position, wherein the trigger mechanism comprises a latch member comprising a latch surface and a trigger engaging surface, a trigger member having a trigger surface, and an electric actuator mechanically connected to the trigger member, wherein the latch member is movable between a latched position, at which the latch surface is positioned to engage the rear end portion and thereby hold the elongate member in the forward position, and an unlatched position, at which the latch surface is positioned to disengage the rear end portion to permit the spring biasing element to move the elongate member rearwardly to the rearward position, wherein in the latched position the electric actuator positions the trigger surface of the trigger member to apply a latching force to the trigger engaging surface of the latch member, and the electric actuator is configured to retract the trigger member from the latch member to permit the latch member to move to the unlatched position.

Preferred features are defined in the dependent claims.

An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Figure 1 is a schematic front perspective side view, partly cut-away, of a door closer according to an embodiment of the present invention in a closed configuration, and the door closer being in a door closing mode;

Figure 2 is a schematic front perspective side view, partly cut-away, of the door closer of Figure 1 in an open configuration, and the door closer also being in the door closing mode;

Figure 3 is a schematic front perspective side view, partly cut-away, of the door closer of Figure 1 in a closed configuration, and the door closer being in a free swing mode;

Figure 4 is a schematic front perspective side view, partly cut-away, of the door closer of Figure 1 in an open configuration, and the door closer also being in the free swing mode;

Figure 5 schematically illustrates, partly in cross-section, the door closer of Figure 1, in an open configuration, and the door closer being in the door closing mode, the cross-section showing a hydraulic damper; and

Figure 6 schematically illustrates, in cross-section and in an enlarged and highly simplified form that is not to scale, the hydraulic damper, shown in Figure 5, of the door closer of Figure 1

Figures 1 to 6 show a door closer 2 according to the present invention that can be used for urging an opened door towards its closed position relative to a door frame. The door closer 2 is adapted for mounting between a door leaf and a door frame and is a door closer of the type which is known in the art as a “free swing” (or swing-free”) door closer which can be switched to operate in two alternative modes, namely (i) a free swing mode in which the door leaf can swing freely between open and closed positions without any resistance or closing force applied by the door closer 2 and (ii) a door closing mode in which a closing force is applied to the door leaf by the door closer 2.

As described hereinabove, such a “free swing” (or swing-free”) door closer has particular application in buildings, such as hospitals, nursing homes, etc., in which it is desired for doors to be freely openable in normal use, yet in an emergency situation, for example after a fire alarm has been activated, the door is urged into a closed position by the door closer. In the “free swing” mode the door leaf can be easily held ajar, because no closing force is being applied to the door leaf by the door closer. The “free swing” (or swing-free”) door closer may be configured to be openable in either one opening direction or in two opposite opening directions.

The door closer 2 comprises an elongate housing 4 for mounting in one of the door leaf or door frame. The elongate housing 4 has opposite forward and rear end parts 6, 8. The housing 4 is a planar tube having opposite part-cylindrical sides, typically composed of extruded aluminum. When installed, the planar tube is vertically oriented and the opposite part-cylindrical sides define the upper and lower edges 7, 9 of the housing 4 of the door closer 2.

The housing 4 has a mounting plate 10 affixed thereto, the mounting plate 10 having holes 12 extending therethrough for receiving fixing screws. In use, the housing 4 is typically received in an elongate horizontal cavity in a door leaf (not shown), and the mounting plate 10 is rebated into the edge of the door leaf and affixed thereto, for example by screws.

An anchor element assembly 14 comprises a mounting member 16 for mounting in the other of the door leaf or door frame. The mounting member 16 is a plate and is typically rebated into the edge of the door frame and affixed thereto, for example by screws.

Alternatively, the mounting positions of the housing 4 and the anchor element assembly 14 may be reversed, with the housing 4 received in the door frame and the anchor element assembly 14 mounted to the door leaf.

An elongate member 18 is disposed in the housing 4 is translationally movable, forwardly and rearwardly, within the housing 4 in a direction extending between the forward and rear end parts 6, 8. The elongate member 18 comprises a cylindrical hollow tube 20 and a rear end portion 22. The rear end portion 22 of the elongate member 18 comprises a lateral arm element 24 having a free end 26. In the illustrated embodiment, the rear end portion 22 is fitted to a rear end 28 of the cylindrical hollow tube 20; however, in an alternative embodiment, the cylindrical hollow tube 20 and rear end portion 22 may be integral. Typically, the cylindrical hollow tube 20 is composed of pressed sheet steel. At the rear end 28, an outwardly oriented flange 30 of the cylindrical hollow tube 20 defines a forward-facing end surface 32 against which the rear end portion 22 is fitted so that the position of the rear end portion 22 relative to the cylindrical hollow tube 20 is fixed and preset.

A spring biasing element 36, in the form of a helical compression spring, is disposed in the housing 4. The helical compression spring 36 is fitted, in compression, between the rear end portion 22 of the elongate member 18 and a forward bearing surface 38. The helical compression spring 36 annularly surrounds the elongate member 18 and the helical compression spring 36 and elongate member 18 are aligned along a common longitudinal axis. The helical compression spring 36 applies a biasing force to the rear end portion 22 thereby to bias the elongate member 18 towards the rear end part 6, and away from the forward bearing surface 38.

The forward bearing surface 38 is in the form of a ring which surrounds the common longitudinal axis, and the forward bearing surface 38 is comprised in a mounting member 40. The mounting member 40 comprises an elongate metal body 42 having a longitudinal portion 44 which is spaced from, and extends along, an outer longitudinal edge 47 of the helical compression spring 36 and a lateral portion 46 at a forward end 48 of the mounting member 40 which provides the forward bearing surface 38.

A support structure 50 is slidably mounted along and within the housing 4. The support structure 50 comprises a plate 52 which extends longitudinally along a part of a length of the housing 4 and is slidable between forward and rearward positions. At the forward position the support structure 50 abuts the front end part 6 and at the rearward position the support structure 50 is spaced a small distance, typically less than 20 mm, from the rear end part 8. The mounting member 40 is affixed to the plate 52 by a plurality of threaded bolts 45. This provides that the forward bearing surface 38 is fixed relative to the plate 52 of the support structure 50.

An upper edge 54 of the plate 52 slides within a guide mechanism 55 extending along and within the housing 4. For example, the guide mechanism 55 may comprise a pair of guide rails extending along the inner face of the upper edge 7 of the housing 4. A tension member 56 has a first end 58 connected to the elongate member 18 and a second end 60 connected to the anchor element assembly 14. The tension member 56 and anchor element assembly 14 form a tension assembly 62 which extends through the forward end part 6 of the housing 4. The tension member 56 is a rigid rod which is connected to the elongate member 18 and to the anchor element assembly 14 by respective first and second articulated joints 64, 66. The first end 58 is pivotally connected to the elongate member 18 at a first pivot 68 in the first articulated joint 64 and the second end 60 is pivotally connected to the anchor element assembly 14 at a second pivot 70 in the second articulate joint 66.

The anchor element assembly 14 comprises, in addition to the mounting member 16 in the form of a plate, an elongate link member 72, which extends forwardly from the mounting member 16, to which the tension member 56 is connected by the second pivot 70. The second pivot 70 is located at a free end 74 of the link member 72 remote from the plate member 16. The first and second pivots 68, 70 have parallel axes, which in use are typically vertically oriented.

In the illustrated embodiment the tension member 56 is rigid, but in an alternative embodiment the tension member may comprise a flexible chain.

A hole 76 in the mounting plate 10 permits movement therethrough of the tension member 56 and the link member 72 of the tension assembly 62.

In Figure 2, the door closer 2 is illustrated in an open and unlatched configuration. The door closer 2 is typically sold to the customer in an unlatched but partly-open configuration, in which a separator (not shown) is removably fitted to the tension member 56 in order temporarily to hold the second end 60 of the tension member 56 and the link member 72 out of the forward end part 6, against the bias of the helical compression spring 36, to aid installation of the door closer 2.

In accordance with the present invention, there is provided a trigger mechanism 100 for latching the rear end portion 22, in a latched position, to hold the elongate member 18 in a forward position against the bias of the helical compression spring 36 and unlatching the rear end portion 22, into an unlatched position, to permit the helical compression spring 36 to expand and move the elongate member 18 to a rearward position. The trigger mechanism 100 is mounted on the plate 52 of the support structure 50.

The trigger mechanism 100 comprises a latch member 102, which comprises a rocker element 104 pivotally mounted about a central pivot 106 mounted on the plate 52 of the support structure 50. The latch member 102 comprises a latch surface 108 and a trigger engaging surface 110. The latch surface 108 and the trigger engaging surface 110 are located at respective opposite ends 112, 114 of the rocker element 104. The latch member 102 comprises a protruding lug element 116 having a side surface 118 which forms the latch surface 108, the side surface facing 118 towards the forward end part 6.

The latch member 102 further comprises a protruding reset element 120 which is located forwardly of the lug element 116. The reset element 120 is configured to be engaged by the rear end portion 22 when the elongate member 18 is moved to the forward position thereby to reset the latch member 102 into a latched position from an unlatched position. The protruding reset element 120 has a resetting surface 122 which faces towards the rearward end part 8 and which is engaged by the rear end portion 22 to reset the latch member 102 into the latched position.

The lug element 116 and the reset element 120 form a channel 124 therebetween for receiving a part of the rear end portion 22 of the elongate member 18, and in the illustrated embodiment the free end 26 of the lateral arm element 24 engages the latch member 102.

The trigger mechanism 100 further comprises a trigger member 130 having a trigger surface 132. The trigger member 130 comprises a leg portion 134, which is pivotally mounted about an end pivot 136 to the plate 52 of the support structure 50, and a foot portion 138 connected to the leg portion 134. The trigger surface 132 is provided on the foot portion 138.

The trigger mechanism 100 further comprises an electric actuator 140 mechanically connected to the trigger member 130. The electric actuator 140 is mounted to the plate 52 of the support structure 50. The electric actuator 140 comprises a translationally movable shaft 142 which is in an extended position when the electric actuator 140 is electrically unpowered, as shown in Figures 1 and 2, and in a retracted position when the electric actuator 140 is electrically powered, as shown in Figures 3 and 4. Typically, the electric actuator 140 comprises an electromagnetic solenoid.

A controller 144 for the electric actuator 140 is configured to switch the electric actuator 140 between a powered mode and an unpowered mode in response to an input signal from a fire alarm system (not shown).

In one embodiment of the present invention, the controller 144 is configured to be wired to a source of electrical power and in the absence of the supply of electrical power the controller 144 switches the electric actuator 140 to the unpowered mode, so that the shaft 142 is in the extended position.

In another embodiment of the present invention, the controller 144 comprises a wireless signal receiver 145 and is configured to switch the electric actuator 140 to the unpowered mode upon receipt of a wireless control signal by the wireless signal receiver 145. Typically, the wireless control signal is a sound signal above a minimum decibel threshold, for example a sound signal emoted by a fire alarm.

The electric actuator 140 is mechanically connected to the trigger member 130 by a linkage mechanism 150. The linkage mechanism 150 comprises a first link 152 and a second link 154. The first link 152 has first and second ends 156, 158. The first end 156 is connected to the electric actuator 140, and the second end 158 is rotatably connected to a first end 160 of the second link 154. A second end 162 of the second link 154 is rotatably connected to the trigger member 130. The first link 152 is pivotally mounted about a linkage pivot 164 to the plate 52 of the support structure 50. The first end 156 of the first link 152 is rotatably connected to the electric actuator 140.

Referring in particular to Figures 5 and 6, in which Figure 6 is highly simplified and not to scale, the cylindrical hollow tube 20 comprises a hydraulic damper 34 for damping, or decelerating, the movement of the elongate member 18 within the housing 4 during a door closing operation as described further hereinbelow.

The elongate member 18 comprises an outer tube 166 and an inner tube 168 which is disposed coaxially within the outer tube 166. The outer tube 166 and the inner tube 168 respectively define outer and inner chambers 170, 172 which are in fluid communication and are filled with hydraulic fluid 174 which causes damping of the door closer 2.

A piston damper 176 is provided for sliding movement within the inner tube 168, and thereby in the inner chamber 172. The piston damper 176 is mounted on an elongate shaft 178 which extends, via a slidable fitting, through a hole 180 in a rear end wall 182 of the elongate member 18. The rear end wall 182 is sealingly fitted in a fluid-tight manner to a rear end 208 of the outer tube 166. A rear portion 179 of the elongate shaft 178 is outside the inner chamber 170. A shaft holder 184 is affixed to the plate 52 of the support structure 50. A reduced diameter end 181 of the rear portion 179 of the elongate shaft 178 extends though, and protrudes rearwardly from, the shaft holder 184 and an adjusting lock nut 186 is threadably coupled to the end 181 of the elongate shaft 178. Rotation of the adjusting lock nut 186 can translationally move the elongate shaft 178 forwardly or rearwardly relative to the shaft holder 184 and thereby relative to the elongate member 18 so as to adjust the position of the piston damper 176 in the inner chamber 172. This arrangement permits the longitudinal position of the elongate shaft 178 in the inner chamber 172 to be adjusted over a small distance after manufacture and assembly of the door closer by turning the adjusting lock nut 186.

The elongate member 18 comprises an end member 188 fitted at a front end 190 of the elongate member 18. The first articulated joint 64 and the first pivot 68 are provided on the end member 188.

A threaded adjuster pin 192 for adjusting the operation of the hydraulic damper 34 is mounted in the end member 188 adjacent to the first articulated joint 64 and has an elongate extension 194 which extends away from the elongate member 18 and lies adjacent to the tension member 14. At the other end of the threaded adjuster pin 192, a needle valve member 196 of a restrictor valve 198 is provided which is employed to adjust the flow of hydraulic fluid in the damper 34. The hole 76 in the mounting plate 10 permits insertion therethrough of a screwdriver or other tool to adjust the threaded adjuster pin 192.

A front end 200 of the inner tube 168 is fitted, in a fluid-tight manner, to a front seal member 202 and a rear end 204 of the inner tube 168 is fitted, in a fluid-tight manner, to a rear seal member 206 which surrounds, in a slidable fluid-tight manner, the elongate shaft 178 within the elongate member 18. A front end 207 of the outer tube 166 is fitted, in a fluid-tight manner, to the end member 188 and the rear end 208 of the outer tube 166 is also fitted, in a fluid-tight manner, to the rear end wall 182.

The rear seal member 206, located inwardly of and adjacent to the rear end wall 182 of the elongate member 18, and the rear end wall 182, seal the rear ends of the outer and inner chambers 170, 172.

The inner tube 168, front seal member 202 and rear seal member 206 define the inner chamber 172 through which the elongate shaft 178 extends and in which the piston damper 176 slidingly moves. The outer chamber 170 is defined between the outer tube 166 and the inner tube 168, and sealed by the end member 188, the rear end wall 182 and the rear seal member 206.

At the front seal member 202 the inner chamber 172 and the outer chamber 170 communicate via the restrictor valve 198 comprising the needle valve member 196. At the rear seal member 206 the inner chamber 172 and the outer chamber 170 communicate via at least one port (not shown) in the rear seal member 206.

This structure forms a hydraulic circuit connecting the outer and inner chambers 170, 172, which are filed with the hydraulic fluid 174, such as an oil or ethylene glycol.

The restrictor valve 198 can regulate the flow of hydraulic fluid 174 from the inner chamber 172 to the outer chamber 170, and thereby control the degree of damping of the hydraulic damper 34 during a door closing operation. The piston damper 176 is typically provided with a one-way valve (not shown) therein which permits the degree of damping to be absent or minimal during a door opening operation.

An accumulator 220 comprises an elongate annular foam member which is disposed in the inner chamber 172 at a location between the rear seal member 206 and the piston damper 176, and annularly surrounds the elongate shaft 178. The accumulator 220 comprises a body of foamed plastics or rubber material, comprising a closed cell foam structure, such as neoprene. The accumulator 220 enables flow of hydraulic fluid around the hydraulic circuit connecting the outer and inner chambers 170, 172 without inadvertent jamming of the door closer 2.

The operation of the door closer 2 will now be described.

In summary, when the latch member 102 is in the latched position and the latch surface 108 engages the rear end portion 22 to hold the elongate member 18 in the forward position, the tension member 56 can freely move, absent of any biasing force from the helical compression spring 36, forwardly and rearwardly relative to the forward end part 6 during opening and closing of the door leaf.

In contrast, when the latch member 102 is in the unlatched position and the latch surface 108 is disengaged from the rear end portion 22 to cause the helical compression spring 36 to urge the elongate member 18 rearwardly to the rearward position, during the door opening operation the tension member 56 is moved, against the biasing force from the helical compression spring 36 which is progressively compressed during the opening operation, forwardly relative to the forward end part 6 to open the door leaf. During the door closing operation the tension member 56 is moved, under action of the biasing force from the helical compression spring 36 which is progressively expanded during the closing operation, rearwardly relative to the forward end part 6 to close the door leaf. The closed door position is shown in Figure 1 and Figure 3. The mounting plate 10 and the mounting member 16 abut when the door closer 2 is in the closed door position as shown in Figures 1 and 3. The tension member 56 is wholly received in the housing 4, and the link member 72 is also received in the housing 4 when the door closer 2 is in the closed door position as shown in Figures 1 and 3.

The open door position is shown in Figure 2 and Figure 4.

In Figures 1 and 2, the latch member 102 is in an unlatched position, so that the door closer 2 is in the “door closing” mode.

In Figures 3 and4, the latch member 102 is in a latched position, so that the door closer 2 is in the “free swing” mode.

In the latched position shown in Figures 3 and 4, the latch surface 108 of the latch member 102 is positioned to engage the rear end portion 22 and thereby hold the elongate member 18 in the forward position. The helical compression spring 36 is in a high compression configuration between the rear end portion 22 and the forward bearing surface 38 of the mounting member 40. In the latched position, the electric actuator 140 is in a powered mode and positions the trigger surface 132 of the trigger member 130, in a trigger-engaging position, to apply a trigger force to the trigger engaging surface 110 of the latch member 102.

In the “free swing” mode, the elongate member 18 and the helical compression spring 36 are locked in position relative to the support structure 50.

In the “free swing” mode, the support structure 50 slides within the housing 4 between the forward and rearward positions, respectively shown in Figures 4 and 3. When the latch member 102 is in the latched position, forward and rearward movement of the tension member 56 relative to the forward end part 6 of the housing 4 causes the support structure 50, and the elongate member 18, helical compression spring 36 and trigger mechanism 30 mounted thereto, to be slid respectively forwardly and rearwardly within the housing 4.

In the closed position in the “free swing” mode shown in Figure 3, the support structure 50 has slid to the rearmost position within the housing 4.

When the door leaf is opened in the “free swing” mode as shown in Figure 4, the mounting plate 10 and the mounting member 16 are separated, and the link member 72 and tension member 56 are pulled out of the housing 4. Since the elongate member 18 and the helical compression spring 36 are locked in position relative to the support structure 50, the outward movement of the tension member 56 fitted to the elongate member 18 causes the support structure 50 to slide forwardly within the housing 4 towards the forward position.

When the door leaf is later closed, the support structure 50 slides rearwardly within the housing 4 back towards the rearmost position. Since the helical compression spring 36 is locked in position relative to the support structure 50 and relative to the elongate member 18, the helical compression spring 36 does not function to apply any biasing force to the mounting plate 10 relative to the mounting member 16 during opening and closing of the door leaf.

Such sliding of the support structure 50 within the housing 4 has low friction and so there is low resistance, and no biasing closing force, during opening and closing of the door leaf in the “free swing” mode.

The “free swing” mode is typically the normal operational mode of the door closer 2. The door closer 2 may be switched automatically into a door closing mode in the event of an emergency, for example a fire, requiring the door leaf to be closed.

When the controller 144 for the electric actuator 140 receives an input signal from a fire alarm system, the controller 144 switches the electric actuator 140 from the powered mode to the unpowered mode. Such switching ensures a “fail-safe” operation to trigger the door closing mode in the event of failure of an electrical supply.

As described above, the controller 144 may be wired to a source of electrical power and in the absence of the supply of electrical power the electric actuator 140 is switched to the unpowered mode. Alternatively or additionally, the controller 144 may comprises a wireless signal receiver 145 and the electric actuator 140 is switched to the unpowered mode upon receipt of a wireless control signal by the wireless signal receiver 145.

When the electric actuator 140 is switched into the unpowered mode, the translationally movable shaft 142 moves from the retracted position shown in Figures 3 and 4 to the extended position shown in Figures 1 and 2, and thereby the trigger member 130 is retracted from the latch member 102 to a trigger-release position to permit the latch member 102 to move to the unlatched position. The helical compression spring 36 expands and applies a biasing force to cause the rearward-moving rear end portion 22 to urge the latch member 102 to the unlatched position. In the unlatched position, the latch surface 108 is positioned to disengage the rear end portion 22 to cause the helical compression spring 36 to move the elongate member 18 rearwardly to the rearward position in the housing 4.

As shown in Figure 1, in which the closed door position is shown, and the latch member 102 is in an unlatched position, so that the door closer 2 is in the door closing mode. After disengagement of the rear end portion 22 from the latch member 102, the helical compression spring 36 moves the elongate member 18 and the rear end portion 22 rearwardly to a rearmost position relative to the support structure 50. The rear end portion 22 is translationally spaced from the latch member 102 in a rearwards direction.

The helical compression spring 36 is released from the high compression configuration into a low compression configuration when the door leaf is in the closed position. The bias of the helical compression spring 36 urges the mounting member 40 on the support structure 50 to the forwardmost position within the housing 4, so that the support structure 50 is urged against an inner surface of the mounting plate 10.

As shown in Figure 2, in which the open door position is shown, and the latch member 102 is still in the unlatched position as shown in Figure 1, when the door leaf is opened the mounting plate 10 and the mounting member 16 are separated, and the link member 72 and tension member 56 are pulled out of the housing 4. Since the elongate member 18 and the rear end portion 22 are translationally movable relative to the latch member 102, the outward motion of the tension member 56 pulls the elongate member 18 and the rear end portion 22 towards the forward end part 6 of the housing 4 against the bias of the helical compression spring 36, which is progressively compressed as the door leaf is opened. The support structure 50 remains static, in the forwardmost position against the mounting plate 10.

If the door leaf is opened sufficiently so that the rear end portion 22 moves into contact with the latch member 102, since the latch member 102 is not engaged by the trigger member 30, the latch member 102 is free to rotate and therefore is incapable of latching the rear end portion 22 into a latched position. In the fully open position, the door leaf has been opened by an angle of typically up to 90°.

After the door leaf has been released from the open position, the door closer 2 is returns from the open configuration shown in Figure 2 to the closed configuration shown in Figure 1. During the closing operation, the door closer 2 applies a closing force as a result of the helical compression spring 36 expanding, and thereby the elongate member 18 and the rear end portion 22 are urged rearwardly towards the rear end part 6 of the housing 4. After the door leaf is released, the biasing force of the helical compression spring 36 acts to bias the tension member 56 inwardly of the housing 4, for closing the door.

The helical compression spring 36 provides a high closing moment to enable the door closer to apply to the door leaf a sufficient closing power over the final few degrees of the closing angle, for example up to 4°, to ensure that the door is fully closed, particularly in the event that a door latch mechanism between the door leaf and the door frame provides a resistance to closing over the final few degrees of the closing angle.

During the closing operation using the biasing force of the expanding helical compression spring 36, the damper 34 causes hydraulic fluid to flow around the hydraulic circuit and thereby damp the door closing motion. The damper 34 may provide a reduced damping force at the end of the closing operation so as to provide an enhanced closing velocity for overcoming any door latch resistance, so that the door leaf is securely latched when closed.

The door closer 2 can be returned to the “free-swing” mode from the door closing mode after the electrical actuator 140 has been returned to the powered mode, which cause the trigger member 130 to be returned to the trigger-engaging position.

After the trigger member 130 has been returned to the trigger-engaging position, when the door leaf is opened sufficiently so that the rear end portion 22 moves into contact with the latch member 102, the free end 26 of the lateral arm element 24 of the latch member 102 engages the protruding reset element 120. As the rear end portion 22 of the elongate member moves forwardly, the free end 26 bears against the resetting surface 122 and rotates the latch member 102 thereby to reset the latch member 102 into the latched position from the unlatched position. The free end 26 is received in the channel 124 so that the elongate member 18 is securely held in the latched position.

Therefore the door closer 2 can easily and reliably be reset into the “free-swing” mode from the door closing mode by fully opening the door leaf.

Various modifications to the illustrated embodiment will be apparent to those skilled in the art, without departing from the present invention as defined by the appended claims.