Concentric spiral spring counterbalance mechanism

A counterbalance mechanism for biasing a panel relative to a structure, the counterbalance mechanism comprising:

• a first attachment strap configured for attachment to a panel;
• an arbor attached to the first attachment strap, wherein the arbor is centered about and defines a winding axis;
• a second attachment strap rotatably supported by the arbor and rotatable relative to the arbor and the first attachment strap about the winding axis, wherein the second attachment strap is configured for attachment to a vehicle structure;
• a spiral spring having a plurality of coils wound about the winding axis, and operable to bias the first attachment strap and the second attachment strap angularly relative to each other about the winding axis;
• and
• a spring support fixedly attached to the second attachment strap and including an annular wall disposed circumferentially about and concentric with the winding axis;
• wherein the annular wall is radially positioned relative to the winding axis to contact an outermost coil of the spiral spring to position the spiral spring in a substantially concentric orientation about the winding axis;
• wherein the spiral spring includes an inner spring end attached to the arbor, and an outer spring end attached to the annular wall of the spring support, such that the arbor winds the spiral spring as the second attachment strap and the arbor rotate about the winding axis relative to the first attachment strap;
• wherein the second attachment strap includes a positioning mechanism operable to position the annular wall of the spring support relative to the second attachment strap such that a central axis of the annular wall is co-axial with the winding axis;
• and
• wherein the positioning mechanism includes at least two tabs formed by the second attachment strap and positioned to contact the annular wall of the spring support when the spring support is positioned with the central axis of the annular wall co-axial with the winding axis.

A counterbalance mechanism for biasing a panel relative to a structure, the counterbalance mechanism comprising:

• a first attachment strap;
• an arbor attached to the first attachment strap;
• a second attachment strap rotatably supported by the arbor and rotatable relative to the arbor and the first attachment strap about a winding axis;
• a spiral spring having a plurality of coils wound about the winding axis, and including an inner spring end attached to the arbor and an outer spring end coupled to the second attachment strap;
• and
• a spring support attached to the second attachment strap and including a wall radially spaced from the winding axis;
• and
• an adjustment screw in threaded engagement with the wall and presenting a screw end in contact with an outermost coil of the spiral spring;
• wherein the adjustment screw is adjustable toward and away from the winding axis to adjust a radial distance between the screw end of the adjustment screw and the winding axis to position the spiral spring in a substantially spiral orientation about the winding axis.