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(11) | EP 2 518 247 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A door catch assembly |
| (57) A door catch assembly 10 for a door comprises a magnetic catch part which comprises
a magnetic part supported by a housing part so that the magnetic part is free to rotate
relative to the housing part about a single pivot point through at least two degrees
of freedom. The housing part comprises a fixed part 110 and a moving part 120, the
moving part 120 having an outer wall 121 that is curved to define a part of a sphere
and being located within a recess in the fixed part which forms a complimentary concave
bearing surface 111, engagement between the moving part 120 and fixed part 110 constraining
the movement of the magnetic part. The underside of the moving part 120 is conical
and the lower end of the recess in the fixed part is closed by a backing surface 300,
such that in use a part of the underside of the moving part 120 may contact a part
of the backing surface 300 to resist axial loads applied to the moving part.
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[0001] This invention relates to improvements in door catches, in particular magnetic door catches for oven doors.
[0002] It is known to provide a door closure mechanism for an oven door which includes one or more magnets fixed to the edge of the door furthest from the hinge. One or more magnetically attractive materials are fixed to the door frame so that when closed the magnet attaches to the material which holding the door shut. In some case, two magnet/materials are provided at spaced locations, typically one at the top and the other at the bottom of the door.
[0003] According to a first aspect the invention provides a door catch assembly for a door, such as the door of an oven, comprising a magnetic catch part fixed to one of the door or the door frame,
characterised in that the magnetic catch part comprises a magnetic part which is supported by a housing part so that the magnetic part is free to rotate relative to the housing part about a single pivot point through at least two degrees of freedom, thereby ensuring a full face contact between the magnetic catch part and a magnetic target part to the other of the door and the door frame so that when the door is closed the magnetic catch part attaches to the magnetic target part through magnetic force.
[0004] By "magnetic" catch part and "magnetic" target part we mean any two parts which will stick together when in contact through magnetic attraction. The attraction should be present at room temperature and also at elevated temperatures common around oven doors, and should be relatively permanent during the life of the door catch assembly.
[0005] The catch part preferably comprises a magnet and the target part a non-magnetised magnetic material, such as a ferromagnetic target, or metal or alloy which is affected by a magnetic field. It may comprise a metal part of a door or door frame or door surround to which the magnet of the catch part can attach itself.
[0006] The invention assures a full face contact between the magnet and target magnetic part even if the door is askew in the frame because the magnet can move to conform to the plate. This gives an more consistent closing force and enables a weaker magnet than otherwise is needed to be used because there is no need to design in a margin to allow for the weakening effect of a non-full face contact.
[0007] The housing portion may comprise a fixed part and a moving part, the moving part having an outer wall that is curved to define a part of a sphere which includes a plane that passes through the diametrical centre of the notional sphere, the moving part being located within a recess in the fixed part which forms a complimentary concave bearing surface that undercuts the moving part to ensure the moving part is free to pivot but is prevented from moving axially. This ball and socket type arrangement constrains the movement to rotation about a single point comprising the centre (virtual) of the spherical surface, and may also substantially prevent any translational movement of the magnet part.
[0008] The wall of the fixed part may fully support all of the outer wall of the moving part that is within the recess, providing a smooth bearing surface and good resistance to axial movement.
[0009] Where an undercut is provided, at least one of the fixed part and the outer wall of the moving part may be resilient to enable the moving part to be inserted into its position of use. Alternatively, the fixed part may be formed as two half parts that are fixed together once the moving part is inserted.
[0010] The two degrees may comprise rotation of the magnet in the horizontal and vertical planes, so called tilt and pan movement, and the support allows both to occur at once. The base portion may also be free to rotate about the pivot point, a so called yaw movement.
[0011] The magnet may comprise a single magnet element which is shaped to define the moving part of the housing portion, or may be a separate magnet that is inserted into a holder that forms the moving portion. It may be secured in place by glue or mechanically.
[0012] The magnet may be supported so that it is slightly proud of the top of the housing part, such that when it is tilted the whole of the magnet remains clear of the top of the housing. It may be arranged so that it is clear when tilted through an angle of up to 2 degrees, or up to 5 degrees or thereabouts in any plane. This ensures the whole of the magnet can engage the target part.
[0013] The fixed part of the housing part may include a fixing by which it can be secured to a door. This may comprise a protruding stud that extends away from the rest of the fixed part to be located in a complimentary recess in the door.
[0014] The metal target part may comprise a flat metal surface which can be secured to the oven door or frame, or may comprise a flat metal surface that is an integral part of the door or frame.
[0015] The underside of the moving part may be cone shaped and the lower end of the recess in the moving part may be closed by a backing surface, which may comprise a part of the surface to which the assembly is secured, such that a part of the underside of the moving part may contact the backing surface to resist axial movement of the moving part, the angle of the generatrix of the conical surface may define the maximum angle of tilt of the moving part. The apex of the moving part may contact the back surface at all times, or at least be located in very close proximity.
[0018] The angle of the cone may define the maximum angle of tilt that can be achieved. Because the moving part and backing surface contact over a relatively long area rather than at a point at the edge which would occur it the moving part was not conical, a better feel and possibly reduced noise on closing occurs. This also ensures that the sides of the fixed part may be arranged so that they do not have to bear a significant load.
[0019] According to a second aspect there is provided a door catch assembly for a door, such as the door of an oven, comprising a magnet fixed to one of the door or the door frame, characterised in that the magnet is supported by a housing part so that the magnet is free to move relative to the base portion about a single pivot point through at least two degrees of freedom.
[0020] According to a third aspect the invention provides an oven which includes a door and a door catch assembly according to the first or second aspect fixed to the door or frame so that when closed the magnet attaches to a metallic target part of the other of the door or frame.
[0021] There will now be described by way of example only one embodiment of the present invention with reference to the accompanying drawings of which:
Figure 1 is a perspective view of a door catch assembly according to a first or second aspect of the invention;
Figure 2 is cross sectional view of the assembly taken along the line A-A' in Figure 1;
Figure 3 is view of the assembly of Figure 1 with the magnet pivoted about its centre;
Figure 4 is a view from above of the assembly of Figure 1; and
Figure 5 is a view of two assemblies of the type shown in Figure 1 as attached to an oven door.
Figure 6 is a view from above of a second embodiment of a magnet catch assembly of the present invention;
Figure 7 is a cross section view from the side along the line B-B of the assembly of Figure 6 showing the magnet tilted by a maximum amount to one side;
Figure 8 is a view from the side of the assembly of Figure 6 when secured to a door which defines a backing surface that the moving part engages; and
Figure 9 is a view from above of the assembly installed as shown in Figure 8.
[0022] Figures 1 to 4 show a door catch assembly 10 comprising a housing part which comprises fixed part 2 comprising a rigid upstanding annular ring 2a of material that extends away from a planar fixing surface 2b. The inner face of the ring is shaped to form a concave bearing surface 4 that has a constant radius of curvature when viewed in cross section. Located within the outer surround part 2 is a moving part of the housing comprising a base portion 1a that comprises a disc of material that has a convex outer face 5 that has the same radius of curvature as the inner face of the ring 2a. The convex outer face 5 forms a part of a sphere. The moving part is free to pivot about its central axis within the fixed part, in the manner of a ball and socket fixing.
[0023] The upper face of the base portion 1a, which is that which faces away from the fixing surface of the outer surround part 2a, is provided with a recess and a magnet 1 is located inside the recess so that it is flush with, or slightly protrudes from the base portion. The face of the magnet is a flat surface 1.
[0024] The fixed portion 2b of the housing is provided with a protruding stud 6 that has a key located on its perimeter. In use, the stud 6 is located within a complimentary cut-out in a door of an oven 30, the key ensuring it can only be located in one orientation. A screw can then be inserted into a bore 7 in the stud 6 to secure it to the door.
[0025] Figure 5 shows a single door catch assembly 10 fitted to a door of an oven near the centre line of the free edge of the door 30. A target area 20 of the oven surround 40 is of metal, or is fitted with a metal plate, so that when the door 30 is closed the magnet attaches to the door or plate holding the door closed to seal the oven. The seal prevents hot air or steam from escaping and the magnets prevent it from being accidentally released.
[0026] In use, the magnet of the assembly 10 is free to pivot about its central point as shown in Figure 3. This ensures that a full face engagement of the magnet surface 1 with the target area 20 is achieved even if the door 30 becomes misaligned. This gives a consistent closing force. Because the base portion is located in the concave groove there is no significant free play in the assembly, and so a solid feel is provided.
[0027] An alternative embodiment of a magnet catch assembly 100 is shown in Figures 6 to 9 of the drawings. Here, the assembly comprises a fixed part 110 and a moving part 120 similar to that described for the first embodiment. The moving part 120 comprises a body 130 which carries a magnet 140 and sits inside a recess defined in the fixed part, a part spherical outer wall of the moving part engaging a part spherical/part cylindrical wall of the fixed part 110.
[0028] The second embodiment differs from that of the first embodiment in that the inward facing wall 111 of the fixed part 110 that engages the outer wall 121 of the moving part is not undercut, i.e. it is not entirely spherical and so does not prevent axial movement of the moving part into the recess. To restrain this movement, a base plate is provided, which could in practice form a part of the surface 300 of the object to which the fixed part is secured as shown in Figure 8.
[0029] The underside of the moving part is conical in shape, being raised at its central apex (in a direction towards the base plate) relative to its edge. When in the neutral position, the apex of the underside contacts the base plate to resist axial movement, yet the cutaway sides still allow it to tilt. The amount of tilt is defined by the angle at which the conical underside falls away. This also provides a good area of contact with the base plate to help resist axial loads when fully tilted.
1. A door catch assembly for a door comprising a magnetic catch part fixed to one of
the door or the door frame, in which:
the magnetic catch part comprises a magnetic part which is supported by a housing part so that the magnetic part is free to rotate relative to the housing part about a single pivot point through at least two degrees of freedom, thereby ensuring a full face contact between the magnetic catch part and a magnetic target part to the other of the door and the door frame so that when the door is closed the magnetic catch part attaches to the magnetic target part through magnetic force,
the housing part comprises a fixed part and a moving part, the moving part having an outer wall that is curved to define a part of a sphere and being located within a recess in the fixed part which forms a complimentary concave bearing surface, engagement between the moving part and fixed part constraining the movement of the magnetic part,
and characterised in that the underside of the moving part is conical and the lower end of the recess in the fixed part is closed by a backing surface, such that in use a part of the underside of the moving part may contact a part of the backing surface to resist axial loads applied to the moving part whilst still permitting tilt of the moving part relative to the fixed part.
2. A door catch assembly according to claim 1 in which the magnetic part of the magnetic
catch part comprises a single magnet element which is shaped to define the moving
part of the housing portion, or a separate magnet that is inserted into a holder that
forms the moving part of the housing part.
3. A door catch assembly according to claim 1 or claim 2 in which the fixed part of the
housing part includes a fixing by which it can be secured to a door.
4. An oven which includes a door and a door catch assembly according to any preceding
claim.