Variable speed food mixer incorporating a variable transmission ratio belt drive

A food mixer comprising:

• a frame,
• a mixing tool,
• means supporting said mixing tool for rotation relative to said frame, a first pulley and a second pulley mounted for rotation relative to said frame,
• a driving belt extending around the first and second pulleys and forming a driving connection between said pulleys, driving means for driving said first pulley and
• a drive train providing a driving connection between said driving means, said first pulley, said second pulley and said mixing tool, at least one of said first and second pulleys being a pulley of which the effective diameter is variable, and
• control means for varying said effective diameter to vary the transmission ratio between said first and second pulleys and thus between said driving means and said mixing tool,
• wherein said control means includes a sensor for sensing the effective diameter of said variable pulley;
• means to compare said effective diameter to a desired transmission ratio;
• and means to adjust said effective diameter to provide said desired transmission ratio.

A food mixer comprising a frame, a mixing tool, means supporting said mixing tool for rotation relative to said frame, a first pulley and a second pulley mounted for rotation relative to said frame, a driving belt extending around the first and second pulleys and forming a driving connection between said pulleys, driving means for driving said first pulley and a drive train providing a driving connection between said driving means, said first pulley, said second pulley, and said mixing tool, at least one of said first and second pulleys being a pulley of which the effective diameter is variable, and control means for varying said effective diameter to vary the transmission ratio between said first and second pulleys and thus between said driving means and said mixing tool,

• wherein said pulley of variable diameter comprises two co-axial, axially spaced discs having opposing frusto-conical surfaces, means mounting at least one of said discs for axial movement towards and away from the other, and wherein said belt s a V-belt cooperating with said frusto-conical surfaces,
• wherein said control means includes
• a lever,
• actuating means for pivoting said lever,
• thrust bearing means operable between said movable disc of said variable diameter pulley, whereby pivotal movement of said lever will cause axial displacement of said movable disc via said thrust bearing means, and
• position sensing means for sensing the position of said lever and for providing a corresponding signal representative of the transmission ratio between said pulleys.