Drive for a coffee-making device

DETAILED DESCRIPTION It is the object of the present invention to simplify a coffee-making device of the type described above considerably by substantially reducing the number of components used for it.
This object is achieved in a coffee-making device of the type described above in that said drive mechanism for said piston is provided with means for converting a uniform rotating motion into a non-uniform reciprocating motion.
The closing and opening characteristic of the piston in the cylinder unit can be influenced, in other words optimized, by converting the uniform rotating motion of the drive motor into a non-uniform motion.
Such a non-linear motion characteristic of the piston can be obtained in any way known in the prior art.
An example that can be mentioned is a curved disc which is driven by the rotary motor and in turn drives the piston.
A certain opening and closing characteristic of the piston can be obtained through the special shape of the curve.
Another possibility is to use a crankshaft structure.
In this way a particularly compact structure can be obtained with a single drive motor.
More particularly, the actual coffee-making process can be carried out irrespective of the coffee material, or the quantity of coffee material can be varied, without special measures as regards structure being necessary.
A particularly simple structure can be obtained by using a swivelling arm structure for moving the cover on the cylinder.
Owing to the fact that the swiveling arm rotates substantially about the axis of the crankshaft, a particularly compact device is obtained.
Such a swivelling arm structure can be driven in any way known in the prior art.
However, it is preferably driven by the crankshaft.
If the structure is designed in a suitable manner, it is possible for it to be driven directly by the crankshaft, in other words without interposing gearwheels and other transmission mechanisms.
The reciprocating motion of the rocker arm in order to place the cover on the free end of the cylinder in a sealing manner can also be carried out in any way known in the prior art