Description of Invention

This invention relates to a door closer for controlling the movement of a door to which it is connected.

Door closers which can hold doors open are well known. They are used for example, in hotel corridors and the like where fire doors may be held open during the day for the convenience of guests, but may be released automatically if smoke is detected or a fire alarm activated. In addition, door closers are used in many other scenarios to ensure that a door automatically closes once a user has passed through the door opening so as to prevent a risk of a fire spreading through the doorway in the event of one existing.

Typically, such door closers can be configured to operate in a way which is desired by the user. For example, in the case of a hotel where the fire doors need to be held open during the day, such door closers may be configured to permit them to hold the door in an open condition until a fire alarm is activated, for example. Alternatively, door closures may be configured to actuate in a ‘swing-free’ way, which is a term well known in the art, which permits the door to be opened and closed with relatively minimal force but which door closers are automatically configured to close the door (if it is in an open or partially open condition) upon detecting a fire alarm or the like. Swing-free door closers are typically utilised where it may be the case that elderly or infirm users might struggle to open the door under the force created by the door closer. Thus the ability to swing the door between open and close conditions and vice versa with minimal force is seen as being particular beneficial. However, such swing-free door closers can give rise to problems. The swing- free functionality is typically activated after the first opening of the door past a certain angular position. Once that door position has been achieved, swing- free is activated and thus the user can then close and thereafter open the door with minimal force. However, because minimal force is required to open and close the door after the swing-free functionality has been activated, it is possible for a user to inadvertently slam the door open or slam the door closed. For example, if the door is in a closed condition, someone walking up to it and pushing it open with a typical hand force may thrust the door open fast which could, for example, collide with a person stood the other side of the door. Alternatively, when the door is in an open condition, but in a swing-free functionality, a user may inadvertently be able to slam the door closed which could trap a user’s hands therein when the door closes within the frame.

The invention has therefore been devised to address this issue.

According to a first aspect of the invention we provide a door closer including: a body defining a chamber therein, said chamber having first and second ends and supporting therein;

a first piston;

a second piston; and

a biasing device,

wherein the first piston, second piston and biasing device are positioned in that order and wherein the first piston is positioned adjacent or near the first end of the chamber and wherein the biasing device is positioned adjacent or near the second end of the chamber,

wherein the biasing device is capable of biasing the second piston towards the first piston, and wherein the second piston prevents the passage of fluid therethrough or therepast.

According to a second aspect of the invention we provide a kit of parts for converting a non-swing-free door to a swing-free door closer, the non-swing- free door closer including a body defining a chamber therein, said chamber having first and second ends and supporting therein a first piston and a biasing device for biasing the first piston towards the first end of the chamber, wherein the kit of parts includes:

a replacement first piston, the replacement first piston having first and second ends and wherein the first end of the first piston includes a one way valve for permitting flow of fluid therethrough and wherein the second end includes a passage for permitting the flow of fluid therethrough;

a second piston, the second piston configured to prevent the passage of fluid within the chamber therethrough or therepast; and

a replacement biasing device which is shorter in length than the original biasing device, wherein the replacement biasing device is capable of biasing the second piston towards the replacement first piston.

According to a third aspect of the invention we provide a method of converting a non-swing-free door to a swing-free door closer, the non-swing-free door closer including a body defining a chamber therein, said chamber having first and second ends and supporting therein a first piston and a biasing device for biasing the first piston towards the first end of the chamber, wherein the method includes:

removing from chamber of the non-swing-free door closer the first piston and the biasing device;

providing a replacement first piston, the replacement first piston having first and second ends and wherein the first end of the first piston includes a one way valve for permitting flow of fluid therethrough and wherein the second end includes a passage for permitting the flow of fluid therethrough;

inserting into the chamber the replacement first piston such that the first end thereof is positioned adjacent the first end of the chamber;

providing a replacement second piston, the second piston configured to prevent the passage of fluid within the chamber therethrough or therepast; inserting into the chamber the second piston such that it is positioned adjacent the replacement first piston;

providing a replacement biasing device which is shorter in length than the original biasing device;

inserting into the chamber the replacement biasing device such that it is positioned adjacent the second piston and such that the replacement biasing device is capable of biasing the second piston towards the replacement first piston.

Further features of the various aspects of the invention are set out in the claims appended hereto.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, of which:

Figure 1 shows a perspective cross-sectional view of a door closer in accordance with the present invention; Figure 2 shows a further cross-sectional perspective view of the door closer of Figure 1 ;

Figures 3 to 6 show perspective views of internal components of the door closer in various stages of operation; Figures 7 to 9 show side cross-sectional views of the door closer in various conditions of operation;

Figure 10 shows a close-up cross-sectional view of a first end of the door closer of figure 1 ;

Figure 11 shows a perspective part-see through view of a second embodiment of a door closer in accordance with the present invention; Figure 12 shows a further perspective view of the second embodiment as shown in Figure 11 with a portion thereof show as being cut through; and

Figures 13 to 15 show further perspective views of component parts of the second embodiment of the door closer in various degrees of operation.

Referring to Figures 1 and 2, these show a door closer in accordance with the present invention, indicated generally at 10. The door closer includes a body 12 which is connectable to a door or frame structure surrounding a door in a manner which is well known to the person skilled in the art. The door closer 10 includes a pinion 11 which is connected by way of linkages or arms to a door. The pinion 11 may be connected by way of a system of levers or even a chain (as seen in use on a concealed door closer). In use, the arm, system of levers, or chain is attached or is held against either a door or its frame so that opening and closing movement of the door is accompanied by axial movement of the pinion 11. The pinion 11 engages with a rack gear provided on a first piston 18 such that rotational movement of the pinion 11 effects axial movement of the first piston 18 within the body 12.

The body 12 defines a chamber having first 14 and second 16 ends. Within the chamber is supported the first piston 18 which is positioned close to the first end 14. Adjacent the first piston 18 is a second, smaller piston, 20 and finally positioned within the chamber is a biasing device 26 in the form of a helical spring, as is well known in typical door closers.

The first end 14 of the chamber is closed by an end cap 12a, with the second end 16 closed off by an end cap 12b. Although not shown much detail in the figures, the end cap 12b provides for the control of fluid therethrough that will be discussed in more detail later.

As can be seen from the figures, the first piston 18, second piston 20 and spring 26 are positioned in that order starting from the left-hand side or first end 14 of the chamber and working towards the second end 16. The first piston 18 is positioned adjacent or near the first end 14 of the chamber and the spring 26 is positioned adjacent or near the second end 16 of the chamber, adjacent the end cap 12b. The spring 26 is configured and is capable of biasing the second piston 20 towards the first piston 18. The second piston 20 includes a peripheral seal 20a to ensure that fluid cannot pass therearound into the chamber in which the spring 26 is supported. As can be seen the second piston 20 includes a formation which is received within the inner cylindrical space defined by the spring 26 so that it is supported therein. This means that movement of the piston 20, for example towards the second end 16 of the body 12, compresses the spring 26. In that condition, the spring 26 would exert a force back onto the second piston 20 to bias it towards the first end 14 of the chamber 12. As will be discussed in greater detail later, however, movement of the piston 20 is controlled by way of restricting the flow of fluid between the various cavities within the door closer 10.

The first piston 18 and the second piston 20 define first 30, second 31 , and third 32 cavities within the chamber of the body 12. In more detail the first cavity 30 is defined between a first end 18a of the piston 18 and the first end 14 of the body 12. The second cavity 31 is defined between the second end is defined between the rear of the second piston 20 and the second end 16 of the body 12. The end 18b of the piston 18 includes a peripheral seal 18c in a similar fashion to the seal 20a. As can be seen, the size of each of the cavities 30, 31 , 32, varies depending on the operational position of the door closer and the axial position of the first 18 and second 20 pistons within the body 12. In more detail looking at the first piston 18 the first end 18a thereof includes a one-way valve 19 in the form of a ball bearing which blocks an axially aligned passage 19a. The one-way valve 19 permits only the flow of fluid therethrough in a direction towards and into the first cavity 30. Thus, fluid is not permitted to flow from the first cavity 30 back through the passage 19a.

The second end 18b of the piston 18 also includes a passage 40 therein for permitting the flow of fluid therethrough from and into the second cavity 31. In this example, the passage 40 is defined by a fluid flow restricting device 42 for controlling the rate of fluid flow through the first passage 40 in both directions. As can be seen later, this restriction is configured so as to prevent forced slamming and/or opening of a door when connected to the door closer 10.

As can be seen in more detail, the first piston 18 is configured such that it defines a fourth cavity 33 positioned between the first 18a and second 18b ends of the piston 18. This fourth cavity 33 communicates with both the passage 19a and the passage 40.

Unlike the piston 18, the second piston 20 does not include any apertures or passages therein, but is configured rather to prevent the passage of fluid therethrough or therepast. Whilst fluid can pass from the fourth cavity 33 through the passage 19a and into the first cavity 30, the passage of fluid from the first cavity 30 back into the fourth cavity 33 is achieved by way of a further passage 44 provided in the body 12. This can be seen in more detail in figure 10 where fluid can pass through the passage 44, in both directions C between the first cavity 30 and the fourth cavity 33. The rate of fluid flow through the passage 44 can be controlled by an adjustment device 46, which in this example is a projection which passes into the passage 44 so as to restrict the cross-sectional area of that passage. Such a feature is well known in the art and provides a degree of control over closing speed of typical door closer.

Advantageously the door closer 10 as shown in the figures is capable of providing swing-free functionality and this will be described in more detail now.

In figures 1 , 3, 4 and 7 the door closer 10 and the various component parts thereof are shown in the configuration which equates to a door closed condition. In this condition if the door is desired to be opened, movement of the door affects rotation of the pinion 11 about its axis, which in turn gives rise to axial movement of the piston 18 towards the second end 16 of the body. As the piston 18 moves from the left to the right it engages the second piston 20 thus also moving that piston 20 towards the second end 16 of the body 12. This in turn compresses the spring 26 and in doing so reduces the size of the third cavity 32. Fluid, typically oil, contained within that third cavity 32 passes through a passage (not shown) in the main body 12 via the end cap 12b (and via a one-way valve 70 therein). Fluid, e.g. oil, within that third cavity 32 is forced through that passage, through the body and enters into the fourth cavity 33 where it then passes through the passage 19a and into the first cavity 30. This movement of fluid is continued until the door reaches a door open condition (that as shown in figures 5 and 8). It can be seen from these figures that the size of the second cavity 31 has remained constant and that is because the part 42 has engaged the second piston 20 so as to move it, with those two parts maintaining contact as the spring 26 is compressed. Because fluid passes out of the third cavity 32, via one way valve 70, it is not possible for fluid to pass back through that passage from the fourth and first cavities 30, 33 and into the third cavity 32. Thus, even if the piston 18 is moved back towards the first end 14 of the body (which would correspond to closing of the door) the second piston 20 maintains its position within the body 12. Thus swing-free functionality has been provided, meaning that the piston 18 can move back towards the first end 14 and also thereafter back towards the second end 16 of the body 12 with relatively little force required to do so. From the position shown in figures 5 and 8, (which correspond to the door open condition) as the piston 18 moves towards the left (i.e. back towards the first end 14) fluid in the first cavity 30 is pressurised but cannot pass through the passage 19a. It instead passes through the passage 44 and into the fourth cavity 33 where it then passes through the fluid flow restricting device 42 and into the second cavity 31. This continues until the door is fully closed, and that configuration can be seen in figures 2, 6, and 9. This operation ensures that the door is prevented from being slammed or forced open or forced or slammed closed. In addition, the first piston 20 can be retrofitted to known door closers so as to provide non-swing-free door closers with the functionality of swing-free door movement. In such a case, all that is required is for the existing spring provided within the door closer to be removed and replaced with the new second piston and shorter spring. In addition, it is necessary to replace the existing first piston within the door closer with the new replacement first piston

18 with the fluid flow restricting device 42 therein. Such a retrofitting or compatibility between an existing door closer and this door closer with swing- free functionality means that efficiencies in manufacture can also be achieved because common housings, end caps and pinions can be used between non- swing-free door closers and the swing-free door closer in accordance with the present invention. Referring to figures 11 and 12, these show an alternative second embodiment of the invention which provides the same swing-free functionality as the first embodiment but instead of fluid passing through the second end 18b of the first piston 18, it instead passes through a passage 50 within the body 12. For ease of reference, features in common with the first embodiment have been given the same reference numeral with the addition of a prime symbol.

As shown in the second embodiment in order to provide swing-free movement of the piston 18' once the second piston 20 has been moved to compress the spring 26', all that is required is to be able to control the flow of fluid between the second cavity 31 ' and the fourth cavity 33'. This is achieved by way of a passage 50 within the body 12' which connects those cavities to each other. Thus the passage 50 includes passage portions 51 and 52 which terminate at respective openings 51 a (communicating with the fourth cavity 33') and 52a (which communicates with the second cavity 3T). In order to control the flow of fluid through the passage 50 and thus be able to control the slamming/opening of the door in swing-free mode, a fluid flow restricting device 54 is provided which can be adjusted so as to reduce the effective cross-sectional area of the passage 50 communicating between the openings 51 a and 52a. Other than that, operation of the door closer 10' is largely similar to the device shown in figures 1 to10. In figure 13 the piston 18' has moved to compress the spring 26 by way of movement of the piston 20'. Thereafter the piston 18' can move (as shown in figure 14) to the left and back towards the first end 14' in swing-free mode and again can move back in the opposite direction to assume the same position as shown in figure 13.

In both embodiments in order to move out of a swing-free operation, it is necessary to permit fluid to enter the third cavity 32' so as to permit the piston 20, 20' to move back towards the first end 14, 14' under the influence of the compressed spring 26, 26'. This is achieved by way of a controlled valve in the end cap 12b. Such a valve may be controlled by way of a permanent magnet or electromagnet which operates under the influence of a sensed fire alarm, for example. In such a configuration, irrespective of where the door is positioned, for example, whether the piston is positioned to the left or right, the piston 20, 20' will start to move towards the first end 14, 14a of the body thus eventually engaging the piston 18, 18' and moving the piston 18, 18' back towards the first end 14, 14' of the body 12, 12'. In doing so movement of the piston 18, 18' rotates the pinion 11 , 1 and thus moves the door to a closed condition. In that condition the door closer is therefore in non-swing-free mode, and is able to resist opening of the door in a typical fashion until swing- free mode is achieved (when the door has been moved open to a certain angular position). When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components. 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.