AU2007100682A4 - Improved magnetic latch - Google Patents

Description

AUSTRALIA

Patents Act 1990 IMD CONCEPT PTY LTD COMPLETE SPECIFICATION INNOVATION PATENT Invention Title: Improved magnetic latch The following statement is a full description of this invention including the best method of performing it known to us:- Field of the Invention This invention relates to improved magnetic latches. Such latches may be used on gates, windows, doors, particularly with deadlocks, on privacy gates, for fencing, pools, roof racks or the like and in many other applications.

00 Background of the Invention It has been proposed to construct self latching devices which include a magnetic _automatic self-latching action for use on gates and pool gates. Such a device is shown in Australian Patent No AU 76138/91. US 2288688 discloses the use of a magnetic lock for cases, bags and the like.

Existing magnetic latches have problems in terms of their physical size preventing them being used for certain applications. The cost of manufacture is also relatively high and it is not easily possible to adjust their strength to suit different applications.

This application is concerned with improvements to existing magnetic latches particularly in terms of improvement in strength, reduction in the size of the latches to enable use in limited space, and improvements in strength and security of such latches.

The present invention aims to address some or all of those problems and provide an improved magnetic latch.

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.

Summary of the Invention In a first broad aspect, the present invention provides a magnetic latch including a bolt assembly and a retaining member, the bolt assembly including a housing which can be fixed to a first member such as a gate or the like and a bolt in the form of a cylindrical sleeve containing a magnet which is mounted in the housing for movement relative to the housing; and wherein the retaining member may be fixed to a second member movable relative to the first member and defines a recess for receiving a end of the sleeve and either comprises a ferromagnetic material or includes a magnet adjacent the recess.

The use of a hollow sleeve allows for the magnet increases adaptability and Zflexibility in provision of magnets having different sizes and different latching strengths.

The use of magnets in the keeper and bolt, provides increased magnetic strength and means that the latch will operate automatically over longer distances than prior 00 devices. In the embodiment in which the retaining member is formed from a ferromagnetic material, such as stainless steel magnet grade, or zinc plated mild steel, _while this reduces the magnetic attraction, it allows the retaining member to be smaller allowing the latch to be used in applications where there is limited space, such as privacy gates.

The present invention has a number of advantages over existing magnetic latches. In particular, the use of cast aircraft grade aluminium reduces the costs of manufacturing the bolt compared with other latches where the bolt is machined. The aluminium housing is naturally corrosion resistant and does not need to be coated.

The use of magnets in the keeper and bolt, provides increased magnetic strength and means that the latch will operate automatically over longer distances than prior devices.

In a preferred embodiment, the latch incorporates a sound generating device, such as a buzzer, which is activated when the gate is open.

In one embodiment activation is by means of a switch which is sensitive to magnetic force, such as a reed switch, which is ON when the magnet is sufficiently close and the latch is open.

In an alternative embodiment the activation may be mechanical.

The vertical latch including the buzzer unit can help increase the safety of swimming pool specially where small toddlers are around as many studies in Australia and overseas have shown that it takes only a very short time to lose a toddlers in swimming pool areas if not enough security and adult supervision available.

Typically the housing of the latch will incorporate a battery to power the buzzer unit. Alternatively, or in addition, solar cells may be used.

The buzzer unit and battery may be built into the housing of the latch which is made of plastic, resulting in savings in manufacturing cost.

Brief Description of the Drawings Specific embodiments of the drawings of the invention will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 is a side view of a horizontal latch showing the latch open; SFigure 2 is a isometric view of a similar latch to that shown in Figure 1 but one Sin which the retaining member comprises mild steel; Figure 3 shows a latch of similar design to that shown in Figure 1, but using magnets of different sizes, strength in the closed position; Figure 4 shows a latch of Figure 3 in the open position; 00 Figure 5 shows a sectional view through the latch of Figure 2; Figure 6 shows a vertical latch embodying the present invention; Figure 7 shows a vertical section through the latch of Figure 6 with the latch in S the closed position; Figure 8 shows a vertical section through the latch of Figure 6 showing the latch in the open position; Figure 9 shows a vertical latch including a buzzer alarm; and Figure 10 shows a vertical section through the latch of Figure 9.

Detailed Description of Preferred Embodiments.

Referring to the drawings, Figure 1 shows a first embodiment of a magnetic latch 10. The latch 10 comprises two separate parts, a bolt assembly 12, and a retaining member in the form of a socket or keeper 14.

The bolt assembly 12 includes a plastic housing 16 which can be fixed to a gate or the like and which defines a generally tubular through aperture 18 which receives a latch bolt 20. The latch bolt includes a cylindrical sleeve 22 having an annular cross section, having a closed end 24 and an open end 25. The sleeve 22 is preferably made from aircraft grade aluminium. A magnet 26 is located inside the sleeve. The open end of the sleeve is closed with a plastic cap 28 locked in place with a spring pin 30 which passes through the cap into aligned holes in the end of the sleeve 22. A compression spring 32 locates in the housing 16 between the plastic cap end 28 and the housing 16, to bias the latch to open in the direction indicated by the arrow A.

The keeper 14 comprises a plastic housing 38 or structure which can be fixed to a gate post of the like. One face of the keeper defines a recess 40 which in use, receives the closed end 24 of the latch bolt 20. Behind the recess there is a hollow cavity 42 which is closed by a cap 44 and which contains a magnet 46.

In use, the keeper is attached to a gate post and the bolt assembly 12 to a gate aligned so that when the gate is closed, the bolt is aligned with the recess The attraction between the magnets 26 and 46 will typically cause the bolt to automatically move in the direction indicated by the arrow B into the recess 40 when the end of the sleeve 24 is approximately 45mm or less from the magnet 46, although it will be appreciated that the strength of the magnets in the sleeve 22 and housing 38 may be changed in order to increase or decrease the degree of attraction between the magnets. The attraction between the magnets is easily sufficient to overcome the compression spring 32 which is relatively weak.

Figures 2 to 5 show variants of the latch shown in Figure 1 and in those Figures, 00 equivalent components share the same reference numeral as shown in Figure 1.

With reference to Figures 2 and 5, these show a latch/lock 10a in which the keeper 14a is formed from mild steel instead of moulded plastics material and does not contain a magnet but relies on the mild steel to attract the magnet 26a in the sleeve 22.

In this way, the keeper can be much narrower/shorter than the keeper shown in Figure 1 and which makes the latch suitable for use where there is limited space for example, on windows, door jams or narrow posts such as may typically be found in offices. The magnet 26a is somewhat larger than the magnet 26 of the embodiment of Figure 1. The latch lOa may include a key operated lock 60 for locking the latch in the closed, or open position.

Figures 3 and 4 show similar locks shown in Figure 1 having a much larger magnet 26 in the sleeve to increase the strength of the magnet, in closed open and positions respectively.

Although, any suitable magnetic material could be used for the magnets 26, neodymium iron boron magnets are preferred as they combine high saturation magnetisation with good resistance to demagnetisation and are currently the magnets of choice for applications requiring high energy magnets.

Figures 6 to 8 show a vertical embodiment of a magnetic lock. This embodiment also incorporates a socket or retaining member 52 and a latch assembly 54. The retaining member 52 includes a housing 56 which can be fixed to the gate by means of screws or the like, not shown. As is best seen in Figures 7 and 8, a permanent magnet 58 is contained in the housing 56 and in the top part of the housing there is a recess 60, which as will be described below, in use receives one end of a sleeve/latch.

As is best seen in Figures 7 and 8, the latch assembly 54 includes a generally elongate hollow housing 70. At the top of the housing, there is a cap 72 from depends an integral long rigid rod 74. The bottom end of the rod 74 is attached to a hollow aluminium sleeve 76 containing a magnet 78 forming a bolt 79. A spring 80 biases the sleeve gently upwards, although the biasing force of the spring is insufficient to overcome the attraction between the magnets 78 and 58 when the magnets are sufficiently close together. The latch assembly also includes a key operated lock 81 for locking the latch in the closed position.

In use, the keeper 52 is attached to a pool gate or the like and the bolt assembly 54 to the pool gate post aligned so that when the gate is closed, the bolt is aligned with the recess The attraction between the magnets 78 and 58 will typically cause the bolt 79 to automatically move into the recess 60 when the end of the sleeve 76 is approximately 00 35mm or less from the magnet 80, although it will be appreciated that the strength of the magnets in the sleeve 76 and housing 52 may be changed in order to increase or _decrease the degree of attraction between the magnets. The attraction between the magnets is easily sufficient to overcome the compression spring 80 which is relatively 10 weak.

(Ni Figures 9 and 10 show a further version 100 of the vertical latch which includes a buzzer unit to increase the security of the latch specially when the latch is used around swimming pools where toddlers can get access to the pool, by providing an audible sound such as a buzzing noise, when the gate is open.

The buzzer unit is compromised of electronic unit 102 including a speaker that can be activated when the latch in opened position. The housing in perforated at 104 to allow transmission of sound from the speaker. The activation may be achieved in a number of different ways.

In one embodiment the magnet 74 in the sleeve activates a magnetically sensitive sensor in the buzzer unit, such as a reed switch, when the latch is in the open position and close enough to the sensor to activate or switch it on.

Alternatively a mechanical system could be utilised so that when the latch in open position a metal contact between the aluminium housing and the electronic unit activate the unit to start the buzzer. Once the latch in closed position there is will be no further contact and the buzzer unit will switch off.

The buzzer unit is powered by a battery 106 such as a small 12V battery or 9V DSE high voltage Battery, located in the housing In an alternative embodiment the buzzer unit may be powered by a small solar power unit or a combination of a solar power unit and a battery.

In use, when the gate is opened the buzzer system will alert an adult to close the door.

In a variant the main plastic housing 70 may include a LCD small screen (not shown in the drawing) to show the position of the latch on/off or may include an LED or other light which may be arranged to flash when the latch is opened.

The present invention has a number of advantages over existing magnetic latches. In particular, the use of cast aircraft grade aluminium reduces the costs of V manufacturing the bolt compared with other latches where the bolt is machined. The caluminium housing is naturally corrosion resistant and does not need to be coated.

The use of magnets in the keeper and bolt, provides increased magnetic strength N and means that the latch will operate automatically over longer distances than prior devices. Also, the provision of the hollow aluminium sleeve allows adaptability and 00 flexibility in provision of magnets having different sizes and different latching N strengths.

0 The latches described above may be used in many applications including private gates, fencing, particularly pool fencing and child areas and even roof racks.

The vertical latch including the buzzer unit can help increase the safety of swimming pool specially where small toddlers are around as many studies in Australia and overseas have shown that it takes only a very short time to lose a toddlers in swimming pool areas if not enough security and adult supervision available. People who are drowning, particularly toddlers and small children usually do not cry out or make much noise, so if the drowning child is out of sight of a supervising adult, there is little chance that the adult will be alerted to the problem. A buzzer might also be provided for the horizontal latch.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims (3)

1. 2. A magnetic latch as claimed in claim 1 wherein the sleeve comprises aluminium, preferably cast aircraft grade aluminium.
2. 3. A magnetic latch as claimed in claim 1 or claim 2 wherein the retaining member comprises magnet grade stainless steel or zinc plated mild steel and does not include a magnet.
3. 4. A magnetic latch as claimed in any one of claims 1 to 3 wherein the housing of the bolt assembly incorporates a sound generating device, such as a buzzer, which is arranged to be activated when the bolt is distal from the recess and the latch is open. A magnetic latch as claimed in claim 1 wherein the housing of the bolt assembly contains a switch or sensor which is sensitive to magnetic force, such as a reed switch, which is ON when the magnet is sufficiently close to the switch or sensor, and the latch is open. Dated this twenty-fourth day of July 2007 Imd Concept Pty Ltd Patent Attorneys for the Applicant: F B RICE CO