Beverage maker

A coffee maker includes an open topped jug which is a plastics molding. It has a lid which carries a rotary cap from which a leadscrew depends. The leadscrew has a four start thread. A nut member is screw-fitted onto the leadscrew and is part of a one-piece plastics molding which carries and supports an annular separator disc which is heat formed from a thin plastics mesh material. The separator disc comprises a major planar portion and a flared circumferential portion which presents an annular concave surface to the base of the jug. A rod depends from the lid and is a sliding fit in an aperture in the planar portion of the separator disc. The separator disc is driven towards the base by turning the rotary cap and the leadscrew with it. The rod prevents the separator disc from rotating with the leadscrew.

This invention relates to a beverage maker of the kind which comprises a
 cylindrical chamber having a closed end, a pouring spout spaced from the
 closed end and a separator piston disc which is slidable within the
 cylindrical chamber between the pouring spout and the closed end, the
 separator piston disc being permeable to water and the beverage whilst
 being impenetrable to solid raw material from which the beverage is made
 and being adapted to be driven towards the closed end of the cylindrical
 chamber, the arrangement being such that the solid raw material, which is
 usually in a granular form, is placed in the cylindrical chamber between
 the closed end and the separator piston disc and the cylindrical chamber
 is filled with hot water which interacts with raw material to form the
 beverage, the separator piston disc being driven towards the closed end to
 separate the residue of the raw material from the resultant beverage. Such
 a beverage maker is referred to in the rest of this description as "a
 beverage maker of the kind referred to". More particularly, although not
 exclusively, this invention relates to a coffee maker.
 When the cylindrical chamber of a coffee maker is first charged with coffee
 and hot water to make coffee, the coffee maker is left standing with the
 separator piston disc at the end of its travel remote from the closed end
 of the of the cylindrical chamber for a time sufficient to allow the
 coffee to brew. If the cylindrical chamber is the interior of a jug which
 has a lid and if the separator piston disc is the head of a piston which
 has a piston rod which extends through an aperture in the lid so that the
 separator piston disc is caused to slide either way in the cylindrical
 chamber by the application of a thrust applied by hand to the piston rod,
 the piston rod will project upwards from the lid whilst the coffee maker
 is standing to allow the coffee to brew. The upstanding piston rod, which
 is often a small diameter spindle, is liable to be knocked accidentally so
 that the coffee maker may be knocked over. Furthermore, of the lid simply
 sits on the brim of the jug and/or if there is a clearance around the
 piston rod in the aperture in the lid, the disc, the piston rod, and even
 the lid are likely to rock, so that the rod oscillates angularly relative
 to the axis of the jug in a random manner when the thrust is applied by
 hand to the piston rod, unless great care is taken to ensure that the line
 of action of the manually applied thrust is truly vertical and coincident
 with the axis of the jug and of the piston rod. Such rocking can lead to
 splashing of hot water or coffee from within the jug which is undesirable
 and could cause scalding. Also the performance of the necessary piston
 ring seal can be impaired if the separator piston disc is displaced from
 its designed orientation normal to the axis and the side walls of the jug.
 In an extreme situation, the user could lose control of the coffee maker
 so that, in reaction to a misaligned manually applied thrust, it slides in
 an uncontrolled manner on the table. Hence care needs to be taken to hold
 the jug firmly with one hand and to depress the piston so that its rod
 remains as near to coaxial with the jug as possible.
 An object of this invention is to minimise these problems for a user of a
 beverage maker of the kind referred to and more particularly to relieve
 the user of the need to take care to keep the piston rod vertical when
 causing the separator piston to travel downwards within the jug.
 DE-C-74 757 and FR-E-80 894 disclose beverage makers in which a screw is
 provided which is coupled with a separator piston disc and which is
 supported substantially coaxially within a cylindrical chamber for
 rotation about its axis relative to the cylindrical chamber so that the
 separator piston disc moves within the cylindrical chamber with rotation
 of the screw.
 A preferred embodiment of this invention is a coffee maker including an
 open topped vessel having a base and substantially straight sides
 upstanding from the periphery of the base and forming the cylindrical
 chamber and the pouring spout, a lid for fitting to the open top whereby
 to enclose the interior of the vessel, the separator piston disc having a
 planform profile similar to that of the base, means for driving the disc
 downwards within the vessel to separate the residue of the coffee grains
 from the liquid, the disc being provided with a seal around its periphery,
 the seal being operably cooperative with the sides of the vessel so as to
 seal against passage of coffee grains between the disc and the sides of
 the vessel from below the disc to the part of the interior of the vessel
 above the disc, wherein a multistart threaded screw depends from the lid
 by which it is supported for rotation about its axis relative to the lid,
 a component is fixed to the upper end of the screw and is accessible from
 above the lid so that it can by turned whereby to turn the screw about its
 axis, and the disc is formed as a nut which is in screwthreaded engagement
 with the screw so that it rises or descends within the vessel with
 rotation of the screw, there being means operable to hold the disc against
 rotation with rotation of the screw.
 Preferably the screw has a two start or a four start thread.
 The lid, which would be removable, may be releasably fixed to the top of
 the vessel.
 The seal could be a circumferentially-continuous lip seal arranged with its
 annular recess facing the base of the vessel.
 The separator piston disc could be a moulding, one or more portions of
 which comprise a mesh which is incorporated in structure of the remainder
 of the disc during molding. The seal and the disc, including the mesh
 portion or portions incorporated therein, could be formed in a single
 mould, the molding process being a two shot process, one shot moulding the
 disc with the mesh portion or portions therein and the other shot moulding
 the seal.
 Occasionally the piston of a coffee maker which is a beverage maker of the
 kind referred to, locks in mid-stroke whilst it is being driven down
 towards the closed end of the cylindrical chamber. This is due to a
 concentration of coffee grounds building up under the piston ring seal and
 acting as a wedge between the piston ring seal and the cylindrical wall
 along which is slides, to impede further downwards movement of the piston.
 This is acknowledged by purveyors of conventional coffee makers of this
 type who provide instructions for dealing with this problem, those
 instructions being for the user to stop urging the piston down, to lift it
 slightly to enable release of the build up of coffee grounds and then to
 continue pushing the piston down. FR-A-2 300 532 discloses a filter for a
 beverage maker of the kind to which this invention relates which would
 also be vulnerable to this problem.
 The problem of build up of coffee grounds does not arise with a lip seal
 which is a circumferentially continuous lip seal of a soft plastics
 material because it wipes the inner surface of the sides of the vessel as
 the disc is driven downwards. However, if the vessel is formed as a
 plastics moulding so that the sides of its interior taper from top to
 bottom as is customary with plastics mouldings for moulding reasons, it is
 difficult to ensure that the lip seal adequately seals at the top of the
 vessel without the friction between the soft material of the seal and the
 side of the vessel becoming excessive as the piston descends towards the
 base.
 According to another aspect of this invention there is provided a separator
 piston disc and peripheral ring seal for a beverage maker of the kind
 referred to which is a one-piece mesh disc having a major planar portion
 and a flared circumferentially extending peripheral portion which serves
 as the peripheral ring seal portion, the arrangement being such that, when
 the one-piece mesh disc is fitted into a beverage maker of the kind
 referred to, its peripheral edge is in sliding contact with the inner
 surface of the cylindrical wall and is displaced axially with respect to
 the major planar portion, being nearer to the base of the cylindrical
 chamber than is that major planar portion.
 Preferably the major planar portion has a central aperture in which a nut
 member is fitted for engagement with the screw of the aforesaid preferred
 embodiment of coffee maker. The major portion of the one-piece mesh disc
 may be reinforced by radial ribs which project from the nut member over
 the face of the major planar portion which is further from the peripheral
 edge.
 Further, if in order to hold the disc against rotation with rotation of the
 screw, the vessel and the disc have a non-circular cross-section or a
 projection from the inner wall of the vessel is provided which projects
 into the soft material of the lip seal, there is a tendency for the disc
 to rotate relative to the vessel, a leading portion of the soft plastic
 material of the lip seal tending to compress whilst a trailing portion
 tends to be separated from the vessel sufficiently for there to be leakage
 of coffee grains between the seal and the vessel wall which would not be
 satisfactory.

FIG. 1 shows that the coffee maker comprises a hollow vessel 10 in the form
 of an open topped jug having a pouring spout 11 and which is closed at its
 upper end by a lid 12 which is realisably fixed to the brim of the jug.
 The lid 12 is annular and is formed by moulding. The interior of the
 vessel 10 is a substantially cylindrical chamber.
 A rotary cap 13 has an upper portion 13A which has an outside diameter
 greater than the diameter of the central aperture 14 of the lid 12 and a
 depending cylindrical boss 13B which is spigotted into that central
 aperture 14. The cylindrical boss 13B is formed at its lower end with a
 circumferentially continuous rib 13C which is snap fitted through the
 central aperture 14 of the annular lid 12 whereby the rotary cap 13 is
 retained against axial displacement relative to the lid 12 but can be
 rotated relative to the lid 12. A socket 15 is formed substantially
 coaxially in the rotary cap 13, the socket 15 opening downwardly. The
 rotary cap 13 is formed by moulding.
 A two start thread leadscrew 16 is spigotted into the socket 15 of the
 rotary cap 13 and depends therefrom through the centre of the cylindrical
 chamber of the vessel 10 so that its lower end is close to the base 10A of
 the vessel 10. The thread is formed on the exterior surface of the
 leadscrew 16 and the latter is formed by moulding. Indeed the rotary cap
 and the leadscrew could be moulded as a one-piece component. The lower end
 of the leadscrew 16 carries a circlip 17 and may be located relative to
 the base 10A by an upstanding projection (not shown) which is formed
 integrally with the base 10A and which seats in a hole that is formed in
 the bottom of the leadscrew 16.
 A piston disc 18 is screw fitted onto the leadscrew 16 in the manner of a
 nut. The disc 18 is a one piece moulding. FIG. 2 shows that the disc 18
 comprises an annular peripheral portion 19 with four mutually
 perpendicular radial rib portions 20 and a central ring portion 21, there
 being integral mesh portions 22 spanning the apertures bounded by each
 adjacent pair of the rib portions 20 and the arcuate part of the
 peripheral portion 19 that joins the outer ends of the rib portions 20.
 The radial rib portions 20 provide reinforcement. The mesh portions 22 are
 formed of a woven fabric which is incorporated automatically in the
 moulded disc 18 during the moulding step by which the latter is formed.
 The central ring portion 21 has a thread formed in its central aperture,
 that being the thread which engages the thread of the leadscrew 16.
 A moulded lip seal 23, which is formed of a soft sealing material, that is
 to say a plastics material which is softer than the material from which
 the peripheral portion 19, the radial rib portions 20 and the central ring
 portion 21 of the disc 18 are moulded, is fitted around the radially outer
 periphery of the disc 18. The lip seal 23 is formed by the second shot of
 a two shot moulding process which is performed in a single mould, the
 first shot being the formation of the disc 18. The lip seal 23 is a
 circumferentially continuous ring. The annular arcuate recess that is
 formed by the lip seal 23 faces the base 10A of the vessel 10.
 In order to charge the coffee maker for use, the lid 12, the rotary cap 13,
 the leadscrew 16 and the piston disc 18 are removed from the vessel 10.
 Coffee grains are introduced into the vessel 10 through the open top. The
 vessel 10 is filled with water to just below the spout. The lid 12, rotary
 cap 13, leadscrew 16 and piston disc 18 are refitted with the piston disc
 18 adjacent the lid 12. When the coffee is brewed and ready to drink, the
 user rotates the upper portion 13A of the rotary cap 13 manually thereby
 rotating the leadscrew 16 and driving the piston disc 18 down towards the
 base 10A of the vessel 10 whereby to separate the residue of the coffee
 grains from the liquid, liquid coffee being allowed to pass through the
 interstices of the mesh portions 22 of the piston disc 18 during travel of
 the piston disc 18. The circlip 17 limits downwards travel of the piston
 disc 18 and ensures that the latter is removed from the vessel 10 with the
 leadscrew 16 for charging and cleaning.
 Use of a multi-start thread, especially a two start thread gives a larger
 displacement of the piston disc 18 for rotation of the cap 13 than would
 be achieved by a single start thread. It also helps to overcome resistance
 to movement of the piston disc 18 due to friction of the lip seal 23 on
 the sides of the vessel 10 and gives a more even distribution of load
 around the leadscrew so that the action of the mechanism is smooth. The
 circumferentially continuous lip seal 23 is intended to provide a
 circumferentially continuous barrier to the passage of coffee grains
 between the periphery of the piston disc 18 and the inner wall of the
 vessel 10. The piston disc 18 contributes to the location of the leadscrew
 16 within the vessel 10.
 FIG. 3 shows that the rotary cap could be replaced by an arm 24 which is
 fixed to the top of the leadscrew 16A that projects up through the central
 aperture 14 of the lid 12. The arm 24 may have a rotary knob 25 at its
 outer end. Alternatively the rotary cap 13 may be provided with such an
 arm which may be hinged to the cap so that it can be folded and stowed
 within the planform area of the upper portion 13A of the cap 13 and folded
 out only when it is needed to turn the leadscrew 16.
 Rotation of the leadscrew 16 could be powered either mechanically or
 electrically as an alternative to the manual operation described above.
 The annular lid could be simply seated on the brim of the vessel 10 rather
 than being realisably fixed thereto as described above. The vessel 10
 could be circular in cross-section in which case provision should be made
 to constrain the piston disc 18 from rotating with the leadscrew 16. The
 vessel 10 could be made of glass. The leadscrew could be machined from
 stainless steel. The mesh portions of the piston disc could comprise a
 series of circular holes for strength reasons.
 FIG. 4 shows another form of coffee maker in which this invention is
 embodied. Parts of the coffee maker shown in FIG. 4 which are similar to
 corresponding parts of the coffee maker shown in FIGS. 1 and 2 are
 identified by the same reference numeral.
 The vessel 10 is formed by moulding. As is usual with such moulded
 products, the side walls of the vessel 10 taper slightly towards the base
 of the vessel 10. It may be circular or non-circular in cross-section.
 The leadscrew 16B has a four-start thread. As an alternative to being
 formed by moulding. The leadscrew 16B could be produced by selecting a
 length of bar having a cross-section which is substantially square with
 shallow concave faces and by twisting that length of bar to form it into
 the leadscrew 16B.
 A nut member 26 is screw-fitted onto the lead screw 16B. The nut member 26
 is formed as part of a one-piece plastics moulding which also includes a
 number of radially extending ribs 27 of which two are shown in FIG. 4. The
 lower portion of the nut member 26 extends through the central aperture of
 an annular separator piston disc 18A so that the ribs 27 extend over the
 upper surface of a central planar portion 28 of the piston disc 18A. The
 planar portion 28 is a major portion of the piston disc 18A. The remainder
 of the piston disc 18A comprises a flared circumferentially extending
 peripheral portion 29. The flared peripheral portion 29 presents an
 annular concave surface to the base 16A and has a peripheral edge 31 which
 is nearer to the base 10A than is the major planar portion 18. The radial
 ribs 27 provide reinforcement for the major planar portion 28.
 The annular separator disc 18A is heat formed from a thin plastics mesh
 material. The mesh material of the separator disc 18A is cut from a sheet
 of such thin mesh material before it is heat formed into the disc 18A. The
 cut edges would have been frayed edges, comprising circumferentially
 spaced strands of the plastics material of the mesh. Those frayed edges
 are tidied up during the heat forming process, individual strands of the
 plastic material being fused together one to another but the resultant
 edges will still be frayed rather than being formed into a
 circumferentially continuous hoop. The mesh is joined to the nut member 26
 at the edge of the central aperture as well as to the undersides of the
 ribs 27. It may be so joined as part of the moulding process by which the
 nut member 26 with its ribs 27 was formed. Alternatively it may be so
 joined by bonding. In another embodiment the mesh may be clamped to the
 undersides of the ribs 27 by similar ribs below the mesh.
 A rod 32 depends from the lid 12 substantially parallel to the leadscrew
 16B and to one side of the leadscrew 16B partway between the leadscrew 16B
 and the side of the vessel 10. The rod 32 is a sliding fit in an aperture
 33 which extends through one of the ribs 27 and the planar portion 28 of
 the mesh material separator disc 18A. A link 34 is joined at one end to
 the bottom of the rod 32. The lower end of the leadscrew 16B is journalled
 in the link 34. If the cross-section of the vessel 10 is not circular, the
 rod 32 ensures that the lid 12 and the annular separator piston 18A are
 aligned one with another for insertion into the vessel.
 The link 34 limits downwards travel of the piston disc 18A and ensures that
 the latter is removed from the vessel 10 with the lead screw 16B for
 charging and cleaning.
 The rod 32 constrains the piston 18A from turning with the leadscrew 16B.
 Use of a multi-start thread, especially a four-start thread, in addition
 to giving a larger displacement of the piston disc 18A for rotation of the
 cap 13 than would be achieved by a single start thread, gives a more even
 distribution of load around the leadscrew 16B so that the action of the
 mechanism is smooth. The fabric nature of the mesh material of the
 peripheral portion 29 of the annular separator piston 18A and its frayed
 edge 31 cater for the taper of the interior of the vessel 10. Because of
 the fabric nature of the mesh material and the frayed edge 31, the
 peripheral portion 29 readily conforms to the inner surface of the sides
 of the vessel 10 against which it is held by the pressure of the mixture
 of undissolved coffee grains and liquid as it is slid along the inner
 surface of the vessel 10 towards the base 10A with movement of the piston
 disc 18A towards the base 10A. The fact that the peripheral portion 29 is
 circumferentially continuous ensures that it provides a circumferentially
 continuous barrier to the passage of coffee grains between it and the
 inner wall of the vessel 10. The diameter of the frayed edge 31 is
 sufficient to ensure contact between the peripheral portion 29 and the
 inner surface of the sides of the vessel 10 at the top of the travel of
 the piston disc 18A. Hence that contact will increase with movement of the
 piston disc 18A towards the base 10A.
 The annular separator piston disc 18A could be formed from an appropriate
 thin woven metal mesh rather than from the thin plastics mesh material
 described above.