Agitating – Operator supported
Reexamination Certificate
1999-04-28
2001-02-27
Soohoo, Tony G. (Department: 1723)
Agitating
Operator supported
C366S331000
Reexamination Certificate
active
06193404
ABSTRACT:
The present invention relates to a portable electric appliance or hand-held blender particularly, but not exclusively, for preparing food.
BACKGROUND OF THE INVENTION
Such appliances are well known and are in widespread use. They comprise a case having a handle and containing an electric motor which rotates a first end of a shaft included in a fixed tube or sleeve, with the tool being mounted at the other end of the shaft. The tool is driven at high speed and is plunged into food that is to be prepared, where the tool chops, blends, emulsifies, etc. the food.
The problem which arises with that type of appliance is essentially a problem of hygiene. Given the presence of an electric motor, it is not possible to clean the appliance properly, particularly in a dishwasher, and in particular it is not possible to sterilize the leading end carrying the tool that is to come into contact with successive preparations that are generally different. Unfortunately, the tool rotating at high speed acts as a pump providing upward suction. This means that in spite of the precautions taken concerning sealing, a small portion of the blended and chopped liquids rises inside the tube where it can often putrefy under the action of bacteria.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the present invention is to mitigate that drawback and to enable a hand-held blender to be provided that is capable of being used on a catering scale, together with the necessary hygiene qualities.
According to the invention, in the hand-held blender comprising a case having a handle, said case including an electric motor for rotating a first end of a shaft included in a tube secured to the case, with a tool being mounted at the second end of said shaft, a removable endpiece secured to the tool is mounted on the free end of the tube, the tool is mounted so as to be removable inside the endpiece.
It is thus possible to remove the endpiece for thorough cleaning or sterilization. It is thus possible not only to remove the endpiece, but also to dismantle the tool for more thorough cleaning or maintenance, in particular of the bearing that lies behind the tool.
According to yet another characteristic of the invention, the base of the motor unit is sealed, with the necessary air inlet and outlet being situated in the top portion thereof to establish an appropriate flow of cooling air. The sealing of the bottom portion prevents food penetrating into the motor unit during normal use and thus prevents bacteria forming inside it, it also reduces the risk of an electrical accident in the event of the appliance being dropped since the ventilation orifices are high, and it prevents carbon dust from the brushes penetrating into the food that is being prepared.
The electrical power supply circuit preferably includes a “loss-of-voltage” card. In the event of the thermal protection contacts opening (e.g. because the motor is overheating), then the loss-of-voltage card is no longer powered and prevents the motor being restarted until the user has acted deliberately on the on/off switch of the appliance. User safety is thus improved.
In certain particular applications where heat is applied continuously to the receptacle, in which the food is raised to a temperature that may be as high as 100° C., a large increase in temperature has been observed at the bearing of the bell, the heat being transmitted to the bearing by the metal shaft of the tool. Since the bearing is embedded in plastics material, which is a thermal insulator, it is difficult to evacuate the heat transmitted by the tool. This phenomenon is accentuated by the heating specific to the bearing due to the shaft of the tool rotating at a speed that may be as great as several thousand revolutions per second. This gives rise to a serious risk of overheating.
In a preferred embodiment, a heat bridge is established by means of a heat-conducting ring mounted between the bell and the bearing. In this way, heat can be evacuated under good conditions. The bearing is thus in thermal contact with the bell whose large surface area makes it possible to evacuate heat from the bearing.
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Duane Morris & Heckscher LLP
Robot-Coupe (S.N.C.)
Soohoo Tony G.
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