GB2414381A

GB2414381A - Safe kitchen appliance which only works when its container is correctly positioned

Info

Publication number: GB2414381A
Application number: GB0412087A
Authority: GB
Inventors: Roland Eden
Original assignee: Kenwood Marks Ltd
Current assignee: Kenwood Marks Ltd
Priority date: 2004-05-29
Filing date: 2004-05-29
Publication date: 2005-11-30
Also published as: GB0412087D0

Abstract

The kitchen appliance contains a clutch that selectively engages and disengages the drive between a motor and an implement within the container 23. The clutch only engages the drive when the container 23 is in the correct position. Preferably the container 23 is a bottomless goblet. Preferably drive shafts 10 associated with the motor and implement are connected to each other via saw-toothed plates 4, 13. Preferably the plates 4, 13 are urged apart by a resilient spring (15, figure 1). The goblet 23 can be kept in position by a screw thread or bayonet fixing. The disclosed appliance is a liquidiser.

Description

1 241 4381

SAFETY SYSTEM

This invention relates to safety systems and it relates especially, though not exclusively, to such systems for electrically operated kitchen appliances such as blenders, food processors and the like.

Many appliances used in the kitchen contain cutting or macerating knives or blades which are rotatable at reasonably high speeds by means of powerful electric motors and thus can present significant risk to users, as well as to children and others who may interfere with unattended appliances, unless appropriate safety measures are incorporated.

Most kitchen appl lances manufactured by reputable companies have safety systems intended to protect users, and others, from accidental contact with rotating knives or blades, and most existing systems work reasonably well under most circumstances. However, there is a continual quest for safety systems exhibiting improved security and robustness, and the present invention aims to provide such a system. The invention also aims to provide an electrically powered kitchen appliance incorporating such a safety system.

According to the invention there is provided a safety system for selectively engaging and disengaging drive between a motor and an implement intended to be driven by said motor so as to rotate within a container; the system comprising a clutch device acting upon a shaft driven by said motor and means associated with said container for actuating the clutch device to engage said drive only when said container is correctly placed to contain said implement.

Preferably, the container comprises a bottomless goblet having a base side-wall adapted to be located in place around said implement by a readily releasable and securable means such as screw threads or a bayonet fixing. By this means, the implement can be utilised with different goblets.

lo It is further preferred that the means associated with said container for actuating the clutch device comprises the lower rim of the side-wall of said bottomless goblet which, when the goblet is screwed or otherwise located into place, engages a movable member that actuates said clutch device. is

The clutch device preferably comprises first and second plate members associated respectively with aligned portions of said shaft, the said members being urged apart by resilient means towards their disengaged condition. The motion of said movable member is intended to overcome the force exerted by said resilient means and to effect driving engagement between said first and second plate members.

Preferably, the facing surfaces of the first and second plate members are formed or otherwise provided with driving means intended to ensure their co-rotation when engaged. in a preferred embodiment, said driving means comprises complementary undulations of a saw-tooth or similar form.

The invention also encompasses a kitchen appliance incorporating a safety system in accordance with any of the foregoing.

In order that the invention may be clearly understood and readily carried into effect, one embodiment thereof will now be described with reference to the accompanying drawings, of which: Figure l shows, in crosssectional view, part of a system in accordance 0 with one example of the invention, with the clutch disengaging the drive, and Figure 2 shows, also in cross-sectional view, the same part of the system with the drive engaged.

Referring now to the drawings, the components of the system to be described are housed within a base I of a domestic electrical appliance, in this case a liquidiser. A drive coupling 2 is mounted for rotation in a bearing 3 located in a lower part of the base l, and is configured to be driven by the vertically disposed output shaft of an electric motor (not shown) mounted in any convenient manner beneath the base 1. The electric motor may be of any type convenient and suitable for use in the context of the appliance in question.

The drive coupling 2 is fixed to a drive plate 4 which is provided on its upper surface with driving means 5 (visible only in Figure l), comprising in this example undulations of a saw-tooth or similar form, for a purpose which will become clear later.

Located in an upper part of the base 1 are the remaining components of the system, including an upwardly-extending drive spindle 10, which is supported for rotation in two bearings, I l and 12; the latter bearing also being slidable on the spindle lO, and is adapted to drive a rotatable implement (not shown) such as a cutting or grinding instrument comprising two or more blades. The spindle 10 is connected at its lower lO end to a clutch plate 13, the lower surface of which is formed with driving means 14 (visible only in Figure 1) which is complementary to the drive means 5 on drive plate 4 and intended to ensure the co-rotation of the plates 4 and 13 when engaged. It will be understood in this respect that any known arrangement or configuration of opposing clutch plate surfaces designed to promote positive drive between the two when engaged can be used as desired.

As shown in Figure 1, the clutch plate 13 is normally urged upwardly, and thus away from the drive plate 4, by means of a centrally mounted spring 15 bearing against a washer 16 fixed to the lower end of the spindle 10. The bearing 12 is also urged upwardly by the spring 15, and is disposed as shown in Figure 1 when the drive is disengaged, with its upper surface close beneath the bearing l 1. A pressure plate 17 associated with the bearing 12 provides support for a plurality (in this example four) of springs such as l 8 arranged symmetrically around the spindle 10 and resiliently supporting an actuator member 19 that is formed with a radially extending flange 20.

The flange 20 extends sufficiently far radially to enter a region 21 into which a lower rim 22 of the side-wall of a bottomless container or goblet 23 can extend when the container 23 is operationally disposed, as shown in Figure 2, on the base 1, with a seal 24 provided to ensure that fluid materials processed in the container 23 do not leak into the base 1.

In Figure 2, the container 23 is shown as being screwed into position on the base 1, but it will be appreciated that any convenient arrangement for lo operationally attaching the container to the base can be used. For example, in some embodiments, a bayonet connection may be preferred.

As shown in Figure 2, when the container 23 is screwed fully home into its operational location on the base 1, its lower rim progresses sufficiently far into the region 21 as to contact the upper surface of the flange 20 of actuator member 19 and urges it downwards, against the force ofthe springs such as 18, forcing the pressure plate 17, bearing 12 and the clutch plate 13 downwards also, against the force of spring 15, so that the driving surfaces of clutch plate 13 and drive plate 4 are brought together.

In this condition, when the electric motor is actuated, the rotational drive which it imparts to drive coupling 2 is transmitted via the clutch device to the spindle 10, and thence to the rotational implement, which at such time is safely disposed within and surrounded by the container 23.

If the container 23 is absent, the clutch plate 13 remains in its disengaged (uppermost) condition and in such circumstances, even if power is inadvertently supplied to the electric motor and a cutting implement has been left in place on the spindle 10, a safe situation obtains because the clutch device does not transmit the motor drive to the spindle 10. In effect, the drive plate 4 would merely spin freely, and since that component is totally enclosed and, in any case, is not configured as a cutting instrument, the system provides total safety.

l o It will be appreciated that the system as described herein provides protection not only in circumstances where the electric motor might be actuated by mischievous, malicious or inadvertent operation of a power switch, but also in circumstances where a short circuit or other electrical mischance or breakdown actuates the motor independently of the power ] 5 switch.

Claims

CLAIMS: 1. A safety system for selectively engaging and disengaging drive

between a motor and an implement intended to be driven by said motor so as to rotate within a container; the system comprising a clutch device acting upon a shaft driven by said motor and means associated with said container for actuating the clutch device to engage said drive only when said container is correctly placed to contain said implement.

lo
2. A system according to any preceding claim, wherein the clutch device comprises first and second plate members associated respectively with aligned portions of said shaft, the said members being urged apart by resilient means towards their disengaged condition.
3. A system according to claim 2, wherein facing surfaces of the first and second plate members are formed or otherwise provided with driving means intended to ensure their co-rotation when engaged.
4. A system according to claim 3, wherein said driving means comprises complementary undulations of a saw-tooth or similar form.
5. A system according to any preceding claim, wherein the container comprises a bottomless goblet having a side-wall adapted to be located in place around said implement by a readily releasable and securable means.
6. A system according to claim 5 wherein said readily releasable and securable means comprises screw threads.
7. A system according to claim 5 wherein said readily releasable and securable means comprises a bayonet fixing.
8. A system according to any of claims 5 to 7, wherein the means associated with said container for actuating the clutch device comprises the lower rim of the side-wall of said bottomless goblet which, when the goblet is correctly placed to contain said implement, engages a movable actuator member that actuates said clutch device.
9. A system according to claim 8, wherein the motion of said movable actuator member is sufficient to overcome the force exerted by said resilient means and to effect driving engagement between said first and second plate members.
10. A safety system substantially as herein described with reference to and/or as shown in the accompanying drawings.
11. A kitchen appliance incorporating a safety system in accordance with any preceding claim. 2s