Vacuum blender

A blender comprising:

• a blender body including a container support case, an outer container seated on the container support case, a grinding blade, and a blade driving unit rotating the grinding blade;
• and
• an inner container unit including an inner container which is disposed in the outer container and in which the grinding blade is positioned, and an inner container driving unit rotating the inner container;
• wherein the outer container is opened and closed by an outer container cover, the inner container is opened and closed by an inner container cover, and the inner container cover is rotatably assembled to the outer container cover,
• a blade rotation shaft of the blade driving unit is installed to be axially rotated in a hollow formed in an inner container rotation shaft of the inner container driving unit, such that the blade rotation shaft and the inner container rotation shaft are axially rotated independently of each other, and an intermediate rotation shaft unit connecting the blade driving unit and the grinding blade to each other and connecting the inner container driving unit and the inner container to each other is installed in the outer container,
• wherein the blade driving unit and the inner container driving unit are mounted in the container support case, and the outer container is detachably connected to the container support case,
• the intermediate rotation shaft unit includes:
• a first intermediate rotation shaft connecting the blade rotation shaft of the blade driving unit and the grinding blade to engage with each other;
• and
• a second intermediate rotation shaft connecting the inner container rotation shaft of the inner container driving unit and the inner container to engage with each other, and
• the second intermediate rotation shaft and the first intermediate rotation shaft axially rotate independently of each other while the second intermediate rotation shaft surrounds the first intermediate rotation shaft,
• wherein the first intermediate rotation shaft has an upper portion key-fastened to the grinding blade and a lower portion key-fastened to the blade rotation shaft, and
• the second intermediate rotation shaft has an upper portion key-fastened to the inner container and a lower portion key-fastened to the inner container rotation shaft.