AU770438B2 - Food mixer - Google Patents

Description

AUSTRALIA

Patents Act 1990 STANDARD PATENT COMPLETE SPECIFICATION FOOD MIXER FIELD OF THE INVENTION The following invention relates to food mixers. More particularly, though not exclusively, the invention relates to mixers typically used for mixing cake ingredients.

Such mixers conventionally have a pair of counter-rotating beaters which extend downwardly from a mixing head into a mixing bowl. The beaters are offset from the vertical centre axis of the bowl such that upon rotation of the bokwl, all of the cake ingredients are blended by the beaters.

Such food mixers include a base having a turntable or carousel upon which the mixing bowl sits. From the base there extends a post upon which there is pivotally mounted a mixing head from which the beaters depend. A powerful electric motor situated within the head is connected by transmission means to the beaters. In some machines, torque output from this motor is also transferred via a mechanical transmission to the base so as to effect rotation of the turntable or carousel. In less expensive machines, the turntable rotates as a result of the interaction of the beaters with the ingredients in the bowl. There is a significant loss of the motor's torque in the mechanical transmission from the motor to the base and turntable. For this reason, it is necessary to use an expensive motor having a torque output not only sufficient to drive the beaters through the cake ingredients but also to overcome mechanical losses in transmission to the turntable.

Also known are hand-held mixers having a pair of counter-rotating beaters depending therefrom. Such devices can be used conveniently by holding the device over a mixing bowl, saucepan or other vessel and manoeuvring the device such that the motor-driven beaters are moved manually about the vessel for thorough mixing. Some such handheld devices can also be used in conjunction with a base having a rotating turntable upon which a bowl sits. Such devices have an auxiliary output shaft from the motor for coupling to a transmission mechanism in the base to effect rotation of the turntable. These mixers suffer from the same problems as those fixed-head mixers discussed above.

OBJECT OF THE INVENTION It is an object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages and/or more generally to provide an improved food mixer.

DISCLOSURE OF THE INVENTION According to the invention there is provided a food mixer having: a base configured to support a bowl, a rotatable member mounted to the base for rotating the bowl when the bowl is supported by the base, a first motor for driving the rotatable member and located within the base, a head supported by the base and detachable therefrom to enable hand-held operation of the head, a beater connecting member supported by the head and configured to receive a beater such that the beater extends into the bowl when the bowl is supported by the base, and a second motor for driving the beater connecting member and located within the head.

"In one preferred embodiment of the invention the mixer includes a base-head connector configured for providing both mechanical and electrical interconnection of the base and head. Preferably, the mixer includes a shroud surrounding the base-head connector for serving as guard against inadvertent contact between an operator of the food mixer and the base-head connector.

In another embodiment, the head and the base each include a respective power connector for connection to a power source.

In a preferred embodiment, in addition to the beater connecting member, the mixer includes another beater connecting member supported by the head and configured to receive a further beater for counter-rotating the further beater.

In a preferred embodiment the food mixer includes a first speed control for adjusting an operational speed of the first motor and a second speed control for independently controlling an operational speed of the second motor.

In a preferred embodiment the first motor drives at least one of a shaft and a belt for transmitting power to the rotatable member.

BRIEF DESCRIPTION OF THE DRAWING A preferred form of the present invention will now be described by way of example with reference to Figure 1 which is a schematic cross-sectional elevational view of a food mixer.

DESCRIPTION OF THE PREFERRED EMBODIMENT In Figure 1 there is schematically depicted a food mixer employing a pair of electric motors. The head 12 is detachable from the base 11 for use separately in mixing the ingredients of a bowl, saucepan or other vessel. The head 12 incorporates a beater motor 13 receiving power via an electrical cord 34. Transmission of torque from motor 13 is via a transmission 15 to beaters 14 connected at beater connectors 35. A fan 31 cools the transmission 15 and motor 13.

The head 12 includes a pair of contacts 33 within a safety recess 39. These contacts 33 receive power from cord 34. This is the same source of power that powers motor 13.

A speed control switch, dial or series of buttons (not shown) is provided on head 12 for controlling the speed of motor 13.

Within the base 11 there is situated a turntable motor 25 having an independent speed control 18. Speed control 18 and motor 25 receive their power from wires 29 attached to a pair of electrically conductive hooks 32 situated above pivot 24. These hooks 32 serve not only to physically secure the head 12 in position, but also to conduct electric current from recessed contacts 33 with which they individually connect. The hooks 32 can be provided with engagement surfaces 40 that bear against correspondingly shaped surfaces 41 in the safety recess 39. The tip portion 42 of each hook 32 can form the necessary electrical contact with the respective recess contact 33 in the head 12. In addition to forming the electrical contacts 33 in a safety recess 39, further safety is provided by means of a protective shroud 43 that surrounds the hooks 32 in base 11.

The shroud is hollow so as to receive protruding parts 44 of the head 12, but more importantly provides an obstacle to inadvertent user contact with the hooks 32 which would be live by virtue of their contact with electrical contacts 33 during the act of attaching or detaching the head 12 to and from the base 11, respectively. That is, the protective shroud 43 assists in preventing a person from touching the hooks 32 when they are electrically live. The shroud 43 includes a recess 45 through which cord 34 can pass when the head 12 is attached to base 11.

The motor 25 has a worm gear 36 on its output shaft cooperating with another worm gear upon shaft 37. This shaft has another worm gear 38 situated beneath the bowl 23 for engaging with an annular rack or like formation (not shown) formed on the underside of turntable 22.

In use, the head 12 can be lifted from the base 11 whereupon there is no electrical contact between the two components. The head 12 can be used manually to mix the ingredients of a remote bowl, saucepan or other vessel. When it is desired to use the head 12 with a rotating bowl 23, it can be attached to the hooks 32 for both mechanical support and for conveying electric power to motor 25. The speed of beaters 14 can be adjusted by manipulation of the speed control feature (not shown) described above whereas the rotational. speed of bowl 23 can be adjusted independently by manipulation of speed control 18. When mixing is finished, the head 12 can be pivoted upwardly whilst maintaining contact with hooks 32 by operation of pivot 24. This will enable the beaters 14 to be removed. Alternatively, the head 12 can be removed from the base 11 for subsequent removal of the beaters 14.

In another embodiment of the invention, instead of the speed control 18 and the motor being connected by the wires 29 to the hooks 32, they are connected, rather, to a further electrical cord 46 (indicated by broken-chain lines). Accordingly, the speed control 18 and motor 25 are supplied with power via the cord 46 rather than via the head 12 and the contacts 33. This allows the motor 25 to be powered even when the head 12 is detached from the base 11.

It will be appreciated by those skilled in the art that the invention is not limited to the specific embodiments described, and may be embodied in many other forms. For example, a drive belt can be used instead of a worm gear arrangement to rotate the turntable.

Claims (8)

1. A food mixer having: a base configured to support a bowl, a rotatable member mounted to the base for rotating the bowl when the bowl is supported by the base, a first motor for driving said rotatable member and located within the base, a head supported by the base and detachable therefrom to enable hand-held operation of the head, a beater connecting member supported by said head and configured to receive a beater such that the beater extends into said bowl when the bowl is supported by the base, and a second motor for driving said beater connecting member and located within said head.

2. A food mixer according to claim 1 including a base-head connector configured for providing both mechanical and electrical interconnection of the base and head.

3. A food mixer according to claim 2 including a shroud surrounding said base- head connector for serving as guard against inadvertent contact between an operator of food mixer and the base-head connector.

4. A food mixer according to claim 1 wherein the head and the base each include a respective power connector for respective connection to a power source.

A food mixer according to any one of claims 1 to 4 wherein in addition to said beater connecting member, said mixer includes another beater connecting member supported by said head and configured to receive a further beater for counter-rotating the further beater. o.oo

6. A food mixer according to any one of claims 1 to 5 including a first speed control for adjusting an operational speed of said first motor and a second speed control for independently controlling an operational speed of said second motor.

7. A food mixer according to any one of claims 1 to 6 wherein said first motor drives at least one of a shaft and a belt for transmitting power to said rotatable member.

8. A food mixer substantially as herein described with reference to Figure 1. DATED this 15 th day of October 2003 Ian Geoffrey Wilson Patents Attorneys for the Applicant: HALFORD CO o a a a a