KITCHEN MACHINE

This invention relates to multi-purpose kitchen machines, such as stand mixers, and it relates more particularly to an arrangement by means of which an attachment, such as a mincer attachment intended for use therewith can be securely latched to a kitchen machine when in use.

Multi-purpose kitchen machines, such as stand mixers, are typically provided with a number of drive outlets, all driven directly or indirectly (e.g. by way of gearing) from a powerful electric motor. The various outlets present drive connections configured to accommodate attachments designed to perform various tasks; the drives provided at the various outlets operating at driving speeds and torques appropriate to the attachments they are intended to accommodate, thereby to enable the machine and its attachments to be used for a variety of purposes in the kitchen.

One such attachment comprises a mincing attachment which can be removably latched to the kitchen machine so as to pick up the drive from a drive outlet with a horizontal axis; the drive outlet usually being presented at the front of the machine. The mincing attachment typically includes a housing containing a hopper into which meat, or other material to be minced, can be inserted to contact a suitable macerating device of any convenient kind, such as a spirally bladed scroll cutter, driven in rotation from the appropriate drive outlet of the kitchen machine, and an apertured extruder plate through which the minced meat can emerge for collection. The drive outlet is driven at a relatively low

speed by way of a speed-reducing gearbox coupled to the electrical driving motor of the kitchen machine. ^~

Since the meat introduced into the hopper may contain bone and/or gristle which can trap the macerating device and cause the drive to stall, it is necessary to provide a facility for the rotational drive to be reversed, either automatically (in response to detection of a stall) or manually under the direct control of a user. Difficulties arise, however, in this respect, since powerful driving forces are generated under such circumstances, and the reversal of the rotational drive can generate sufficient torque to delatch the attachment from the kitchen machine.

The invention aims to reduce the aforementioned difficulty and according to the invention from one aspect there is provided a kitchen machine comprising an electric drive motor, drive means linking the motor to at least one rotary drive outlet of the machine, and elements of a bayonet or screw fixing whereby an attachment having co-operative elements of the fixing can be temporarily secured to the kitchen machine by relative manual rotation between the attachment and the machine, to pick up rotary drive from the said outlet for a rotary food processing implement of the attachment; characterised in that the machine further comprises locking means for automatically locking said attachment against accidental removal from said fixing by counter-rotary forces, and manually operable releasing means for disabling said locking means to allow deliberate removal of said attachment from the machine.

Preferably, the attachment and the machine respectively carry arcuate flanges and arcuate slots forming co-operative elements of a bayonet fixing, and the automatic locking means comprises at least one pin member mounted to said machine adjacent a bayonet-receiving slot and resiliency urged outwardly therefrom, whereby the pin member is depressed against resilient force when the arcuate flange of the attachment is introduced to the receiving slot of the fixing, and whilst the attachment is rotated into its secured position, whereupon said pin member springs out behind said flange to block removal of said flange from said slot.

In a particularly preferred embodiment, the bayonet fixing comprises a pair of diametrically opposed flange and slot fixtures, and each of said fixtures has a said pin member associated therewith.

In further preferred embodiments, the said at least one pin member can be retracted against said resilient force by manually operable means to permit removal of the attachment from the machine once the processing has been completed.

The manually operable means conveniently comprises a lever movable between first and second positions, and cam members associated with said lever and said at least one pin member such that, with said lever in said first position, the said at least one pin member is free to move with and against said resilient force whereas with the lever in said second position, said at least one pin member is retracted against said resilient force to permit removal of the attachment from the machine.

Preferably, the lever is spring loaded towards said first position, such that said automatic locking is provided as a default condition.

Preferably, in any event, the rotary food processing implement of said attachment comprises a spirally bladed scroll member, and foodstuffs processed thereby are urged towards an end plate of the attachment; said end plate being formed with a plurality of apertures through which foodstuffs processed by means of the rotation of said scroll member within the attachment can extrude.

It is typically preferred that the attachment carries a hopper through which foodstuffs to be processed can be introduced into the interior of the attachment.

Typically, the attachment is a mincing attachment for mincing meat introduced in roughly cut chunks into said hopper.

In order that the invention may be clearly understood and readily carried into effect, one embodiment thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

Figure Ia through If show a kitchen machine combination in accordance with one embodiment of the invention, and they illustrate in sequence how an attachment can be attached to, latched to, delatched from and detached from the machine; and

Figure 2 shows in greater detail than Figure 1, and in exploded perspective view, certain elements of the latching mechanism described with reference to Figure 1.

Common reference numbers are used for similar elements throughout the figures and in the following description.

Referring now to Figure Ia, a mincing attachment 10 intended for temporary attachment to a kitchen machine in accordance with one embodiment of the invention, to pick up rotary drive therefrom, comprises a housing 12 which contains a macerating device (not shown) which can take any convenient form but in this case comprises a spirally bladed scroll member of known kind. The internal configuration of the housing 12 is designed, in known manner, to co-operate with the macerating device to finely chop, or mince, meat inserted into the housing by way of a hopper tube 14. The duly processed meat is extruded out of the housing 12 through an array of apertures such as 16 in an end plate 16a secured by a screw-threaded bezel 18 to the housing 12.

Thus it will be appreciated that the minced meat is extruded to emerge forwardly, through the apertures such as 16, in a generally horizontal direction from the attachment 10. Accordingly, the rotational axis of the scroll member is disposed horizontally and typically passes through the centre of the end plate 16a.

At its opposite end to the plate 16a, the housing 12 is apertured to permit the macerating device to pick up rotary drive from a kitchen machine in accordance with one example of the invention, part of which is shown at 22, by way of a horizontally disposed drive outlet 24. As previously mentioned, the drive outlet 24 is driven at a relatively low speed by way of a speed-reducing gearbox coupled to the electrical driving motor of the kitchen machine. In the views shown in the drawings, certain elements of the gearbox assembly are visible, though they would normally be encased within a housing which has been removed to enable the significant features of the invention to be shown.

The rotary drive outlet 24 has associated therewith one element, in this example a pair of arcuate slots 26 and 28, of a bayonet fixture allowing the attachment 10 to be removably secured to the machine for use. The co-operative element of the bayonet fixture, in this case a pair of arcuate flanges such as 30, is carried by the attachment 10.

Thus, as so far described, the attachment 10 can be mounted to the machine 22 by means of the co-operative elements 26, 28 and 30 of the bayonet fixing. The macerator device housed in the attachment 10 can be driven in rotation from the drive outlet 24 and meat introduced into the housing 12 of the attachment 10 by way of the tube 14 is minced and extruded out through the apertures such as 16.

In the event, however, that the meat being minced should contain bone, gristle or other non-compressive substance, the rotation of the macerator device may stop and the rotary drive may stall. In such circumstances, it

is necessary to reverse the rotary drive, to free the blockage. This reversal may be done automatically, in response to the sensing of a stall, or incipient stall, condition (e.g. detection of an increase in the supply current drawn by the electrical drive motor of the kitchen machine) or manually by a user, but in any event the forces associated with a sudden reversal of the drive from a stall, or near-stall condition tend to rotate the attachment 10 relative to the kitchen machine 22 and thus loosen, or even completely detach from one another, the elements of the bayonet fixing.

In such circumstances, the attachment 10, which is a heavy component, can fall from its fixing and may cause injury and/or damage.

The invention prevents such an occurrence by positively and automatically latching the attachment in place to the kitchen machine in a manner which also permits the ready removal of the attachment from the machine when desired by the user.

In this embodiment, the positive and automatic latching is achieved by the provision of a pair of locking pins, such as 20, which are situated near the entry ends of the arcuate bayonet slots 26 and 28, carried on the forward face of the kitchen machine 22 adjacent the drive outlet 24. The locking pins such as 20 are resiliently urged outwardly from the machine 22 towards the attachment 10 and are thus compressed into the machine as the attachment 10 is placed in position for use and pushed against the machine for temporary attachment thereto, as shown in Figure Ib. When the attachment 10 is rotated counter-clockwise, as shown in Figure Ic, to inter-engage the co-operative elements of the bayonet fixing, the arcuate

flanges such as 30 carried by the attachment 10 slide into the arcuate slots 26 and 28 carried by the kitchen machine 22. Once the flanges have fully entered the slots, they clear the locking pins such as 20. These pins thus spring out, under the resilient force, to assume their original positions, and block the arcuate slots, preventing clockwise rotation of the attachment, as would be required for removal, and thus securely latching the attachment 10 to the kitchen machine 22.

Under these circumstances, reversal of the drive direction will not release the attachment 10 from the machine 22.

When it is desired to remove the attachment 10 from the machine 22, the user rotates a lever 32 in a clockwise direction from a first position, as shown in Figures Ia through Ic, to a second position as shown in Figure Id. In the first position, which is a stable or default position, the lever has no effect upon the locking pins such as 20, which thus operate exactly as described above. In its second position, however, the lever 32 acts indirectly upon cam members such as 34, in a manner which will be described in more detail hereinafter, to withdraw the pin members such as 20 into the kitchen machine; thus freeing the elements of the bayonet fixture for relative rotation as shown in Figure Ie, and thereby permitting removal of the attachment 10 from the machine 22 as shown in Figure Ie.

It will be appreciated that the arrangement can be configured so that the lever 32 is moved anti-clockwise from its first to its second position if preferred, with the cam members 34 being reconfigured accordingly.

Referring now to Figure 2, the elements of the latching arrangement associated with the kitchen machine 22 are shown in greater detail.

An outlet collar 36 which carries the grooves 26 and 28 of the bayonet latching mechanism is fixed to the kitchen machine 22 so as to surround the drive outlet 24 thereof. The collar 36 is securely fixed to the kitchen machine 22, for example by means of screws or other fastenings, such that it does not move relative to the machine 22.

The outlet collar 36 also provides a housing for a locking ring 38, which caries the locking pins 20 and the cam members 34; the locking ring 38 being mounted so that it cannot rotate relative to the drive outlet 24. The axial length of the housing provided by the collar 36, however, is sufficient to permit the locking ring 38 to move to and fro relative to the kitchen machine 22, along the drive axis of the outlet 24, sufficiently that the pins 20 can move between the positions described earlier, in which they alternately block or are clear of the entrances to the bayonet grooves 26 and 28. The ring 38 is resiliently urged outwardly from the kitchen machine 22 by means of a pair of compression springs 40 which bear against the outwardly facing surface of the kitchen machine 22 and engage over small location protrusions (not shown) in the facing surface of the locking ring 38. By this means, the ring 38 is urged away from the kitchen machine 22, tending to place the pins 20 into their blocking position with reference to the bayonet grooves 26 and 28.

A rotary ring 42, which can rotate relative to the collar 36, carries the lever 32 and a pair of actuators, such as that shown at 44, which engage the cam members 34 carried by the locking ring 38. The cam actuators such as 44 pass through apertures such as that shown at 46 in the outlet collar 36.

In operation, rotation of the rotary ring 42 by means of the lever 32 causes, by the combined effects of engagement of the cam actuators such as 44 with the cams 34 and the resilient force provided by the springs 40, the locking ring 38 to be moved axially to and fro relative to the kitchen machine 22. Thus, the locking pins 20 can be resiliently urged to their outermost positions, in which they prevent removal from the bayonet grooves 26, 28 carried by the machine 22 of the bayonet flanges such as 30 (see Figure Ia) carried by the attachment 10, or withdrawn towards the surface of the kitchen machine 22 so as to permit such removal, depending upon the position of the lever 32. It will be appreciated that, when the pins 20 are in their outermost position, corresponding to a first extreme position of the lever 32, they do not prevent the attachment 10 being latched to the machine 22 because the bayonet flanges such as 30 carried by the attachment 10 can be used manually to push the pins 20 inwardly against the resilient pressure exerted by the springs 40. Once the flanges such as 30 have been rotated fully into the grooves 26, 28 however, the springs 40 are able to urge the locking ring 38 and thus the pins 20 carried thereby, back to their outermost position which prevents the reverse rotation required to remove the flanges such as 30 from the grooves 26, 28.

In order to permit such removal, the lever 32 needs to be rotated, relative to the outlet collar 36, from its first extreme position towards a second extreme position, in which the cam actuators such as 44 move relative to the cam members 34 to force the ring 38 back towards the kitchen machine 22, against the force of the springs 40, sufficiently far that the pins 20, carried by the ring 38, are withdrawn from their blocking positions relative to the grooves 26 and 28.

The lever 32 is urged towards its first extreme position by means of an extension spring 48 which is connected at one end to the rotary ring 42 and is anchored at its other end to a convenient fixed point on the collar

36 or elsewhere on the machine 22. By this means, the first extreme position of the lever becomes a stable or default position; thereby preventing the lever 32 being inadvertently left in the second extreme position which, of course, does not provide the security of latching together the two elements of the bayonet fixture.

In the first position of lever 32, it will be appreciated that the lever has no substantial influence on the locking ring or the pins carried thereby, and that secure latching of the attachment 10 to the machine 22 therefore occurs automatically. The lever is moved temporarily to its second position merely to permit deliberate unlatching of the attachment 10 from the machine 22, and then, once released, returns automatically to its first position under the influence of the extension spring 48.