Closure unit for a container, combination of such a closure unit and a container and method for closing a container

A closure unit for a container which closure unit is suitable to be re-used repeatedly for the container, and which closure unit comprises a substantially flat cover element for closing off the aperture in the container,

• which cover element is provided with a tension element, for creating a pressure force that presses the cover element to a rim that surrounds the aperture of the container in the situation wherein the closure unit is applied onto the container for closing off the aperture;
• which tension element is provided with couplings for cooperation with the container in order to create the pressure force, wherein the tension element in a closed position is enclosing at least the perimeter of the substantially flat cover element and is pressing the substantially flat cover element at least at one contact surface while the couplings of the tension element are in cooperating contact with the container;
• wherein the tension element is composed of at least two mutually displaceable parts, the mutually displaceable parts being moveable from an open position to the closed position, as well as being conversely movable from the closed position to the open position which allows a user to alternate between the closed position and the open position repeatedly, which open position and closed position achieve respectively an open configuration and a closed configuration of the tension element which allows for a respective opening and closing of the aperture of the container onto which the closure unit is applied and thus allows for the consequent repeated re-use of the closure unit for the container, wherein the closed position of the mutually displaceable parts, in the situation wherein the couplings of the tension element are in cooperating contact with the container, results in at least one contact surface of the tension element being pressed in a direction having at least a pressure force component perpendicular to the flat cover element,
• wherein the at least two mutually displaceable parts of the tension element are rotatably connected by a hinging connection, which hinging connection abuts an abutment structure provided on the upper side of the cover plate in order for the hinging connection to function as a lever.