Patent Description:
Door closers which can hold doors open are well known. They are used for example, in hotel corridors 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. An example of such a door closer can be seen in <CIT>. However, one issue with such prior art door closers is that they require a constant source of power in order to hold a door in its open position. Not only is this costly in terms of the electricity being used, it also means fitting such door closers is more time-consuming and thus expensive as additional wiring is required. In the case of retrofitting such door closers, this can present issues with change to wall coverings and the like, which increases cost.

Other examples of door closers are disclosed in <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

It is an object of the present invention to provide a door closer which addresses this problem.

The present invention provides the advantage that is easy to retrofit and cheaper to run than the door closers in the prior art.

According to a first aspect of the invention, we provide a door closer according to claim <NUM>, including.

Further features of the first aspect of the invention are set out in the dependent claims appended hereto.

Referring to <FIG> a door closer <NUM> is shown including a body <NUM> with a cylindrical chamber <NUM> therein. The chamber <NUM> is closed at one end by a plug <NUM> and at the other end by an end cap <NUM>. The end cap <NUM> is sealed to the body <NUM> by O rings 15a, 15b.

A piston <NUM> is slidably supported within the chamber <NUM> which divides the chamber <NUM> into first and second cavities <NUM>, <NUM>. The piston <NUM> is biased towards the end of the chamber <NUM> closed by the plug <NUM> by a biasing device <NUM>, in this case a spring, positioned within the second cavity <NUM>. The spring could also be placed in the first cavity <NUM>, or indeed in any position that causes the piston <NUM> to be biased towards the end of the chamber <NUM>, without departing from the scope of the present invention.

The piston <NUM> is provided with rack teeth (not shown) along wall <NUM>. Engaged with the teeth are complimentary teeth (not shown) of a pinion <NUM>, which extends out of the body <NUM> in the normal manner for connection to an arm, or 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 piston <NUM> within the cylindrical chamber <NUM>. The movement of the piston <NUM> alters the respective volumes of the first and second cavities <NUM>, <NUM>, although their total volume remains the same. It should be appreciated, however, that the present invention is suited to many other types of door closer, e.g. cam action door closers.

A passageway <NUM> connects the first cavity <NUM> to the second cavity <NUM> to permit the flow of fluid therebetween. In this embodiment it can be seen that the passageway <NUM> is in fluid connection with a piston cavity <NUM> through a bore <NUM>, provided between the main passageway <NUM> and piston cavity <NUM>. Two further bores <NUM>, <NUM> are provided between the main passageway <NUM> and either the piston cavity <NUM> or the second cavity <NUM>, dependant on the position of the piston <NUM>. It should be appreciated though that this is not essential to the working of the invention. The invention only requires that there be a passageway connecting the first cavity <NUM> to the second cavity <NUM>, for permitting the flow of fluid therebetween. In the present example, however, liquid flow passes through the piston cavity <NUM> en route to the first cavity <NUM>.

The cylindrical chamber <NUM> is filled with hydraulic liquid, such as oil, which occupies the first cavity <NUM>, second cavity <NUM>, and piston cavity <NUM>.

A passageway <NUM> is provided between the first cavity <NUM> and the piston cavity <NUM>. The passageway <NUM> contains a check valve (i.e. one way valve) <NUM>.

A connecting passageway <NUM> is provided between the main passageway <NUM> and passageways in the end caps <NUM> within the body, as will now be described.

The connecting passageway <NUM> communicates with a bore <NUM> containing a filter <NUM>, which prevents particles entering the passageways in the end cap <NUM>. The bore <NUM> provides a further passageway which communicates with a valve chamber <NUM>. The chamber <NUM> contains a one-way valve <NUM> including a valve member 33a in the form of a rubber ball, and a biasing device, in this instance a spring 33b. The valve <NUM> permits the flow of liquid from the second cavity <NUM> to the main passageway <NUM>, and therefore from the second cavity <NUM> to the first cavity <NUM> (via the intermediary of the piston cavity <NUM>, although this is not an essential route), but does not permit the reverse flow from the main passageway <NUM> to the second chamber <NUM>. The valve chamber <NUM> communicates with a bore <NUM> leading to a second valve chamber <NUM>.

The second valve chamber <NUM> contains a blocking member <NUM>, for controlling the flow of liquid through the passageway <NUM> between the two cavities, in the form of a ball bearing. The blocking member <NUM> forms part of a magnetic valve <NUM>, which also includes a plunger <NUM>, a permanent magnet <NUM>, a moveable member <NUM>, and a pole switching device <NUM>.

The moveable member <NUM> is moveable, in this example linearly, between first and second positions. In a first position the moveable member <NUM> causes or permits the blocking member <NUM> to assume a blocking position, thus preventing the flow of liquid from the second cavity <NUM> to the first cavity <NUM>. In its second position the moveable member <NUM> causes or permits the blocking member <NUM> to assume a non-blocking position, thus permitting the flow of liquid from the first cavity to the second cavity. In some embodiments, the moveable member <NUM> is a magnetically susceptible moveable member, otherwise known as a magnetically susceptible member.

The term "magnetically susceptible moveable member" is intended to mean any moveable member that is capable of being influenced by a magnetic field. Specifically, it is intended to mean any moveable member that can be moved by a magnetic field, such as, for example, the magnetic field produced by magnet <NUM>. It has been envisaged that the magnetically susceptible moveable member could be provided as a further magnet, though this is not essential to the workings of the invention. All that is required is a moveable member that will move between first and second positions. Examples of materials a magnetically susceptible member could be made from include, but are not limited to, a ferrous material such as iron or steel, cobalt, nickel, boron, or even a rare earth magnet such as neodymium. A magnetically susceptible member could also be made of an alloy of these. Another possibility is that the magnetically susceptible member could be a ceramic magnet.

The pole switching device <NUM> effectively acts to "remove" or "switch" the effect of the magnetic field Mm (not shown) of the magnet <NUM> by producing a magnetic field Mp (not shown) that is in opposition to the magnetic field Mm of the magnet <NUM> so as to effectively cancel out or overcome the magnetic field Mm of the magnet <NUM>. This produces a resultant, or net, magnetic field that is either zero or in the opposite direction to the magnetic field Mm of the magnet <NUM>. In one specific example, the pole switching device <NUM> is an electromagnetic device, e.g. a solenoid. The pole switching device <NUM> is supplied with electricity from power source <NUM>. The power source <NUM> in this embodiment is a <NUM>. 5V battery power source contained in the body of the door closer, but it should be appreciated that alternative sources of power, e.g. a different voltage battery power source or mains electricity, could be used without departing from the scope of the present invention. The pole switching device <NUM> is positioned near to and/or around the magnet <NUM>. It should be appreciated, however, that the pole switching device <NUM> does not need to be positioned around magnet <NUM>. The pole switching device <NUM> only needs to be able to cancel out or overcome the magnetic field of the magnet <NUM>. In one particular embodiment the magnet <NUM> is preferably annular or substantially annular and surrounds the moveable member <NUM>, as shown in <FIG>. In one embodiment the permanent magnet includes an aperture or passage through which the moveable member <NUM> passes. Preferably, the pole switching device <NUM> includes an aperture or passage through which the moveable member <NUM> can pass. Preferably the aperture or passage in the pole switching device <NUM> and the aperture or passage in the permanent magnet <NUM> communicate with each other and are preferably coaxial, thus permitting easily movement of the moveable member <NUM> between its first and second positions.

Where the magnetic field Mp of the pole switching device <NUM> overcomes the magnetic field Mm of the magnet <NUM>, there will be a net magnetic force acting on the moveable member <NUM> which moves it away from the piston and to its second, unblocking, position. In other words, the magnetic field Mp of the pole switching device <NUM> overcomes the magnetic field Mm of the magnet <NUM> that the moveable member <NUM> experiences, i.e. the field local to the moveable member <NUM>. This may provide the advantage of the pole switching device <NUM> requiring less energy as the magnetic field that needs to be overcome will only be a portion of the magnetic field produced by the magnet <NUM>.

In embodiments for which the magnetic field Mp of the pole switching device <NUM> only cancels out the magnetic field Mm of the magnet <NUM>, there will be no force acting on the moveable member <NUM>. Thus, the moveable member <NUM> is permitted to move away from engagement with the blocking member <NUM> due to the pressure exerted on the blocking member <NUM> by the combination of the spring <NUM>, the piston <NUM> and the oil in the first cavity <NUM>.

A sensor (not shown) is provided on the door closer <NUM> which detects if a fire alarm is sounding. If a fire alarm is detected, or if an override switch is activated, and the door needs to be closed, a controller in the door closer receives a signal from the sensor and then operates the power source <NUM> to provide an electrical pulse to the pole switching device <NUM> which causes the opposing magnetic field Mp to the magnet <NUM> to be produced. The magnetic field Mp is produced for a sufficient amount of time to move the moveable member <NUM> towards its second position sufficiently away from the magnet <NUM> (as shown in <FIG>) to its second position so that the magnetic force of the magnet <NUM> no longer acts on the moveable member <NUM>. This permits the blocking member <NUM> to assume a non-blocking position so that oil from the first cavity <NUM> can move along the passageway <NUM> to the second cavity <NUM>, which in turn permits the door to close.

When it is required for the door to be held open again (or indeed after a period of time has passed since the alarm was sensed), a further electrical pulse is provided by the power source <NUM> in the opposite direction through the pole switching device <NUM> to previously. This causes the pole switching device <NUM> to produce a magnetic field -Mp which is synergistic with the magnetic field Mm produced by the magnet <NUM>. The magnetic field -Mp is produced for a sufficient amount of time to move the moveable member <NUM> at least partly towards its first position so that the magnetic force of the magnet <NUM> once again acts on the moveable member and the blocking member is forced to assume a blocking position.

There are a number of envisaged ways that the door closer <NUM> may determine when it is appropriate for the further electrical pulse to be provided. One example way in which the door closer <NUM> may determine when to provide the further electrical pulse is by using a time lag from when the first pulse is produced. For instance, it may be known that it takes roughly three seconds for a door to close ( or partially close to a particular angular position) once the oil, piston <NUM> and spring <NUM> are permitted to move, i.e. once the pulse has been provided. The door closer <NUM> may, therefore, provide the further pulse after three seconds to move the moveable member back to its first position and ensure that the door will be held open when it is opened again. Of course, it should be appreciated that the invention is not limited to a door that takes three seconds to close. The invention can be used on any door that takes any period of time to close.

In one embodiment, a user may be able to set when the further electrical pulse is provided if the door it is being used on closes more quickly or slowly than three seconds. In this embodiment the three second time lag may be provided as a default setting if a user does not choose their own time lag setting.

In another embodiment, the door closer <NUM> may be provided with a door position sensor (not shown). The sensor will let the door closer <NUM> determine whether the door is closed. If the door is closed then the further electrical pulse needs to be provided so the door closer <NUM> is primed and ready to hold the door open when the door is next opened by a user.

In envisaged embodiments not described above a biasing device, such as a spring, may be used to bias the moveable member <NUM> to either its first or second positions. This may be advantageous in either: reducing the energy needed for the pole switching device <NUM> to oppose the magnetic field of the magnet <NUM>; or aiding the magnet <NUM> in returning the moveable member <NUM> back to its first position. Such a biasing device is not essential to the invention, however.

The valve chamber <NUM>, the blocking member <NUM>, the moveable member <NUM>, and the magnet <NUM> can be positioned in either of the first or second cavities <NUM>, <NUM>, or even within the passageway <NUM> connecting the first cavity <NUM> to the second cavity <NUM> without departing from the scope of the present invention. All that is required is that the blocking member <NUM> is moveable between blocking and non-blocking positions.

In the current embodiment the blocking member <NUM>, plunger <NUM> and the moveable member <NUM> are provided as separate components, but it is also envisaged that they could be connected directly or indirectly to each other, or even formed as a single component part) to help ensure they stay in the correct positional relationship.

The valve chamber <NUM> communicates with a further bore <NUM> which in turn communicates with the second cavity <NUM>. In the unlikely event that the door closer <NUM> fails, with the blocking member <NUM> in its first blocking position, and there is a need to close the door, this is still possible to close the door. If a user applies sufficient force to the door, the force of the moveable member <NUM> on the blocking member <NUM> can be overcome by the resulting pressure of the liquid acting on it from the second cavity side. This allows the door to be shut in case of a door closer <NUM> failure.

The door closer <NUM> further includes an adjuster screw <NUM> having a head <NUM> for engagement with a screwdriver or the like, and at the opposite end a plug portion <NUM>. An O ring seal <NUM> is provided around the head <NUM>. With the adjuster screw <NUM> positioned as shown in <FIG>, the plug portion <NUM> is engaged in and hence closes off bore <NUM> from the main passageway <NUM>. When the adjuster screw is screwed outwards the plug portion <NUM> disengages from and hence opens the bore <NUM>. This adjustment allows for the use of the door closer with different arm configurations as will become clear later. As the bore <NUM> is significantly narrower than the main passageway <NUM>, the plug portion <NUM> does not prevent flow of fluid along the main passageway <NUM> when positioned as shown in <FIG>.

Operation of the door closer <NUM> will now be described.

When the door is closed, the door closer <NUM> is positioned as shown in <FIG>. The piston <NUM> is at one end of its travel, towards the plug <NUM>, with the first cavity <NUM> at or near its minimum volume and the second cavity <NUM> at or near its maximum volume.

As the door is opened, with the moveable member in its first position, the pinion <NUM> rotates and drives the piston <NUM> in the direction of arrow A against the bias of the spring <NUM>. The movement of the piston <NUM> reduces the volume of the second cavity <NUM> and forces oil out of the second cavity <NUM>. Initially the flow is via bores <NUM> or <NUM> and <NUM>, the main passage <NUM> and bore <NUM>. But as the piston <NUM> moves axially along the chamber <NUM>, in the direction of arrow A, the end 16a passes the bores <NUM> and subsequently <NUM> such that they are closed off from the second cavity <NUM>. Bore <NUM> remains in communication with the piston cavity <NUM>, however. The fluid then opens one-way valve <NUM>, against the bias of spring 33b, passes through bore <NUM>, and through the filter <NUM>, into connecting passage <NUM>, main passageway <NUM> and bore <NUM>, <NUM> or <NUM> into the piston cavity <NUM>. This flow path is illustrated by arrow <NUM> in <FIG>. As piston cavity <NUM> is of fixed dimensions, oil also flows through the passageway <NUM> into the first cavity <NUM>.

As the blocking member <NUM> is in its blocking position the flow of oil from the first cavity to the second cavity is prevented, and so the door is held in the open position against the bias of spring <NUM>.

If the door closer <NUM> receives a signal that indicates that the door should be in a closed position, for example if a fire alarm is activated or an override switch is activated (e.g. a wifi signal sent to a receiver in or connected to the door closer), an electrical pulse is sent through pole switching device <NUM> sufficient to produce a magnetic field Mp in opposition to the magnetic field Mm of the magnet <NUM> to effectively cancel out or overcome the magnetic field Mm of the magnet <NUM>. This produces a net magnetic force which acts on the moveable member <NUM> and permits the moveable member <NUM>, to move to its second position such that it allows the plunger <NUM> to no longer engage with the blocking member <NUM>, which allows the blocking member <NUM> to move into a non-blocking position as shown in <FIG> and <FIG>. Oil can then flow from the second cavity to the first cavity so that the piston <NUM> can be moved under the bias of the spring <NUM> in the direction of arrow B. The movement decreases the volume of the first cavity <NUM>, forcing oil out of that cavity. As the piston <NUM> moves in the direction of arrow B, oil from the first cavity <NUM> passes through the bore <NUM> into the piston cavity <NUM>, via bores <NUM>, <NUM>, and <NUM> if open, into the main passageway <NUM>, to the connecting passageway <NUM> through the filter <NUM> and bore <NUM>, through valve chamber <NUM>, into bore <NUM>, through valve chamber <NUM> and finally through bore <NUM> to the second cavity <NUM>. This flow path is illustrated by arrow <NUM> in <FIG> and <FIG>. As the piston <NUM> moves in direction B, the bore <NUM> is closed from the piston cavity <NUM>, and subsequently also the bore <NUM> is closed, each of these bores then being opened to the second cavity <NUM> as the piston <NUM> continues to move.

<FIG> and <FIG> show an alternative embodiment. Features in common with the embodiment shown in <FIG> have been given the same reference numeral but with the addition of <NUM>.

The embodiment shown in <FIG> and <FIG> uses the same principle to operate as the first embodiment described, but has a slightly different mode of operation. In this embodiment the moveable member <NUM> is not moved outside of the influence of the magnet <NUM>. Whilst the electrical pulse is supplied to the pole switching device <NUM>, the magnetic field Mp' (not shown) overcomes the magnetic field Mm' (not shown) of the magnet <NUM> and holds the moveable member <NUM> in its second position, thus permitting the blocking member <NUM> to assume a non-blocking position and the door to close. The electrical pulse is supplied for a sufficient period of time to permit the door to close (for instance <NUM> seconds). Once this time has passed, the electrical pulse is no longer supplied and the pole switching device <NUM> no longer produces the magnetic field Mp'. Then, because the moveable member <NUM> is still within the influence of the magnet <NUM>, the magnetic field Mm' causes the moveable member <NUM> to move towards and assume its first position, thus causing the blocking member <NUM> to assume a blocking position. The door is then ready to be held open the next time the door is opened. It should be appreciated that mechanisms for determining how long the pulse needs to be supplied to the pole switching device <NUM> are similar to the mechanisms described in the first embodiment to determine when the second, further, pulse needs to be provided.

A further alternative embodiment is shown in <FIG> and <FIG>. Features in common with the embodiment shown in <FIG> have been given the same reference numeral but with the addition of <NUM>.

In this embodiment the moveable member <NUM> is provided as a further magnet to magnet <NUM>. The moveable member <NUM> is positioned so as to be repelled by the magnet <NUM> so that when no power is supplied to the door closer <NUM> the moveable member <NUM> is forced to be in its first position and the blocking member <NUM>, therefore, assumes a blocking position. In this embodiment the magnet <NUM> and the moveable member <NUM> may be in a substantially side by side configuration. When an electrical pulse is supplied to the pole switching device <NUM> to overcome the magnetic field of the magnet <NUM> the moveable member <NUM> is permitted to move to its second position and the blocking member <NUM> can assume a non-blocking position, thus permitting the door to close. It should be appreciated that mechanisms for determining how long the pulse needs to be supplied to the pole switching device <NUM> are similar to the mechanisms described in the first embodiment to determine when the second, further, pulse needs to be provided.

It should be appreciated that the pole switching device <NUM> need not necessarily produce a magnetic field to overcome the magnetic field of the magnet <NUM> as described previously. The pole switching device <NUM> could be provided as a means of moving the magnet <NUM> such that its magnetic field is moved between a first position to enable blocking of oil flow and a second position which permits oil flow. In the first position the magnet <NUM> is positioned so as to repel the moveable member <NUM>, thus forcing the blocking member <NUM> to assume a blocking position. In the second position the magnet <NUM> is positioned so as to attract the moveable member <NUM>, thus permitting the blocking member <NUM> to assume a non-blocking position.

In a further alternative embodiment the plunger <NUM> and blocking member <NUM> have been replaced by an alternative blocking member <NUM>, shown in <FIG> and <FIG>. Features in common with the embodiment shown in <FIG> have been given the same reference numeral but with the addition of <NUM>. In this embodiment the magnet <NUM> is connected to the blocking member <NUM> such that movement of the magnet <NUM> effects a rotational movement of the blocking member <NUM> about an axis A.

It can be seen that when the magnet <NUM> is in a first position, shown in <FIG>, the blocking member <NUM> is in a blocking position, due to the fluid connection <NUM> in the blocking member <NUM> being misaligned with the bores <NUM>, <NUM>. When the magnet <NUM> is in a second position, shown in <FIG>, the blocking member <NUM> is in a non-blocking position such that the fluid connection <NUM> is in alignment with the bores <NUM>, <NUM>, resulting in fluid being permitted to travel therethrough, as indicated by arrow <NUM>.

Movement of the blocking member <NUM> is effected by movement of the magnet <NUM>. This is effected by providing an electrical pulse to the pole switching device <NUM> to either attract the magnet <NUM> or repel the magnet <NUM>. Attracting the magnet <NUM> causes the blocking member <NUM> to rotate about axis A into a first blocking position. The repulsion of the magnet <NUM> away from the pole switching device <NUM> causes the blocking member <NUM> to rotate about axis A to assume a non-blocking position. It should be appreciated that the magnet <NUM> could be positioned on the opposite side of the blocking member <NUM> without departing from the scope of the present invention. This would mean that when the pole switching device <NUM> attracts the magnet <NUM> it would cause the blocking member <NUM> to rotate into and assume a second non-blocking position, and when the pole switching device <NUM> repels the magnet <NUM> it would cause the blocking member <NUM> to assume a first blocking position. The mechanism by which movement of the door is effected is similar to the first embodiment.

Claim 1:
A door closer (<NUM>) including:
a body (<NUM>) defining a chamber (<NUM>) therein;
a piston (<NUM>) slidably supported within the chamber (<NUM>), and dividing the chamber (<NUM>) into first and second cavities (<NUM>, <NUM>) either side of the piston (<NUM>), which in use receive liquid;
a biasing device (<NUM>) for biasing the piston (<NUM>) towards the first cavity (<NUM>);
a passageway (<NUM>) connecting the first cavity (<NUM>) to the second cavity (<NUM>) for permitting the flow of fluid therebetween;
a blocking member (<NUM>) for controlling the flow of liquid through the passageway between the cavities;
a moveable member (<NUM>) moveable between first and second positions, wherein when the moveable member (<NUM>) is in its first position the moveable member (<NUM>) causes or permits the blocking member (<NUM>) to assume a blocking position, thus preventing or at least inhibiting the flow of liquid from the first (<NUM>) to the second cavity (<NUM>), and wherein when the moveable member (<NUM>) is in its second position the moveable member (<NUM>) causes or permits the blocking member (<NUM>) to assume a non-blocking position, thus permitting the flow of liquid from the first (<NUM>) to the second cavity (<NUM>); and
a permanent magnet (<NUM>) and only one permanent magnet (<NUM>), said permanent magnet (<NUM>) positioned adjacent or close to the moveable member (<NUM>) for holding the moveable member (<NUM>) in its first position;
wherein the door closer includes a pole switching device (<NUM>) and only one pole switching device (<NUM>), that can produce a magnetic field that is in opposition to the magnetic field of the permanent magnet (<NUM>) to effectively cancel out or overcome the magnetic field of the permanent magnet and produce a net magnetic field that is either zero or in the opposite direction to the magnetic field of the permanent magnet (<NUM>) so as to effect movement of the moveable member (<NUM>) between its first and second positions.