Hinge assembly for vacuum packaging machine

A vacuum packaging machine including a vacuum tub having a vertical fron wall and a vetical rear wall into which tub food packages to be sealed are placed and a lid pivotally attached to said machine to selectively cover and seal said vacuum tub such that a vacuum can be drawn therein, and comprising:

• a. a perimeter lip at least partially surrounding said tub, said lip including a horizontally level rear portion extending along and directly to the rear wall of said tub;
• b. a hinge assembly pivotally connecting said lid to said machine, said hinge assembly including:
• i. a stationary hinge plate connected to said machine with a pair of pins spaced apart and protruding outward therefrom;
• ii. a movable hinge block connected to said lid, said hinge block including a curved slot, said slot being sized to accommodate and to slide along said protruding pins as said hinge block and said lid is moved between open and closed positions, said pins and said curved slot creating a virtual pivot point behind said machine about which said lid pivots relative to said machine whereby said lid pivots upward and backward about said virtual pivot point, thus avoiding contact with said horizontally level rear lip portion of said tub;
• and
• iii. a gas spring mechanism attached between a rear side of said machine and said hinge block, said spring mechanism biasing said hinge block, and thus said lid, toward said open position, said hinge block including a plurality of attachment points to which said spring mechanism can be selectively attached to vary the moment arm of said spring mechanism.