Agitating – Operator supported
Reexamination Certificate
2001-11-23
2002-06-04
Cooley, Charles E. (Department: 1723)
Agitating
Operator supported
Reexamination Certificate
active
06398403
ABSTRACT:
BACKGROUND
This invention relates to a bell-shaped shield for use on a household appliance, particularly a hand blender or a hand mixer, having a space formed by the inner wall of the shield and accessible from the bottom via an opening through which food is supplied and discharged, a blade-like processing tool inside the space being adapted to be set in rotation by a drive shaft so that the food is caught, comminuted and/or mixed by said tool.
A shield of this type is known from U.S. Pat. No. 3,299,924, for example. The shield continues in upward direction in a sleeve provided with a bore in which a drive shaft is rotatably mounted and carried in bearings so as to be supported axially. The drive shaft extends through the wall of the shield via a bore, projecting with its free end a small amount into the space of the essentially bell-shaped shield. On this free end is a blade-like processing tool for comminuting and mixing or puréeing food materials, said processing tool being constructed to extend in a direction transverse to the longitudinal direction of the drive shaft. The other end of the drive shaft is connected by way of a coupling device to an electric motor of a hand mixer. The drive shaft extends concentrically with the sleeve and the shield.
With the hand mixer in operation, food is drawn by the rotary movement of the processing tool through the opening at the free end of the shield, comminuted and, on account of the centrifugal forces generated by the blade, expelled through the slits provided in the wall of the shield. Hence with the appliance activated for a time of some length, the food is returned repeatedly to the processing tool where it is reduced and expelled again out of the shield. As this occurs, it is possible, of course, not only for the food materials to escape to the outside through the slits but also for parts of it to escape over the brim of the opening from where they are then drawn in again centrally by the processing tool. When using the hand blender attachment the food is therefore comminuted, mixed and aerated. The latter occurs when the processing tool rotates at sufficiently high velocity and the suction forces are of a magnitude causing air to be drawn in from the surface. This can also happen, however, when the shield plus drive mechanism is frequently lifted, meaning that it is moved close to the surface of the food and not only held at the bottom of the vessel filled with largely liquid. food. With this mixing device it is difficult to achieve thorough reduction and mixing of the food in a minimum of time because the inside space of the shield is of a more or less rotationally symmetrical configuration.
It is an object of the present invention to provide a shield for a rotary processing tool of a household appliance, particularly an electric hand mixer or a hand blender, with which it is possible to mix, comminute and aerate the food far more intensively in a minimum of time. Furthermore, it is desirable that the shield afford ease of manufacture and cleaning.
SUMMARY OF THE INVENTION
This object is accomplished in accordance with the present invention by equipping a shield with bulges on its inner surface the food materials drawn in by the processing tool as the result of the suction forces arising during its rotation are caught and expelled radially outwardly and simultaneously in peripheral direction. According to the invention the food is fed into the bulges, which lie further out radially, as well as against the wall sections. That part of the food which impacts against the wall sections is decelerated there and diverted so that a major part of it is returned to the processing tool where it is reduced and mixed again. A further part of the food gets into the bulges and is moved downward and out through the opening. The result therefore is a continuous mixing, comminuting and aerating cycle.
The bulges have the effect of producing a particularly turbulent flow in the space of the shield, causing the food materials to be intensively mixed and reduced. Large pieces of food are also better caught by the processing tool when they enter the bulges, are trapped there and directed back to the processing tool. Owing to the fact that the food moves in the bulges at a lower speed and may even come to a stand-still there occasionally, also such food materials as project into the bulges in the space between the radial outer edge of the blade and the inner wall of the shield, such as large pieces, can be decelerated to such an extent that, when caught by the processing tool, they are still so sluggish as to be easily cut by the fast running blade. As a result of the bulges the kinetic energy transmitted to the food in the form of radially and peripherally directed movement in addition to the cutting energy from the processing tool also causes pieces of food lying against the inner wall of the shield to be abruptly diverted in their movement. Part of the food materials are even returned to the processing tool and immediately cut again, mixed and conveyed outwards.
As mentioned in the foregoing, the processing tool is preferably a blade having crescent-shaped elements extending radially away from both sides of the drive shaft and equipped with cutting edges on their leading sides as seen in the direction of rotation, said crescent elements—like a propeller —being twisted and set in such a way as to produce a type of pumping effect causing the food to be drawn in by the processing tool and then expelled radially outwards. The shield forms a certain mixed circuit by which already reduced food as well as food that is still unreduced is fed towards and away from the blade, comminuted and mixed. A large portion of the food is also expelled from the shield radially outwardly allowing new food to enter the space of the shield through the opening when passages are constructed in addition laterally in the wall of the shield.
With the bulges extending in the longitudinal direction of the shield they are readily accessible for cleaning from the opening. The bulges may have a cross section of any desired shape such as angular, tapered, semicircular, oval, etc. It is to be noted, however, that the elevations adjoining each bulge laterally must not extend radially inwards into the blade's radius of action. According to the invention it could even suffice for just a single clearance space to be constructed on the inner wall of the shield. It is particularly advantageous, however, for several clearance spaces to be spread around the circumference of the inner wall as this generates a particularly turbulent flow in the space of the shield.
In order to be able to hold the shield particularly steady and free from vibrations during the mixing or comminuting operation it is an advantage for the clearance spaces to be spaced evenly apart on the inside of the circumference and to be constructed if possible with the same dimensions. The opening of the shield is preferably always bigger than the biggest diameter of the blade. It will be appreciated that smaller diameters could be selected for the opening but this might have an adverse effect on cleaning and installing the blade in the space of the shield.
Providing bulges that extend in the direction of the drive axis of the shield, taking the shortest route results in a particularly vertical impact of the food against the inner wall of the shield, producing optimal puréeing, comminuting and mixing results. A shield of this type is also easy to move back and forth and up and down in a vessel.
In one embodiment, the bulges emerge as elevations on the contour of the envelope surface. In this arrangement the wall of the shield is selected just thick enough for the clearance spaces constructed on the inner side to form elevations on the outer envelope surface. It would also be conceivable, however, for the outer envelope surface to have no elevations, meaning for it to have a smooth surface. In this case the wall of the, shield would have to be selected thick enough for the bulges to be able to penetrate far enough in to
Butinyà Anna
Carreras Frances
Hernandez Alejandro
Peñaranda Mariano
Rebordosa Antonio
Braun GmbH
Cooley Charles E.
LandOfFree
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