Closure panel extension mechanism with multiple springs

Abstract

An extension mechanism for coupling with a closure panel to assist in opening and closing of the closure panel of a vehicle between a fully closed position and a fully open position of the closure panel, the extension mechanism including: an inner tube having an outer surface; an outer tube having an inner surface and overlapping the inner tube for at least a portion of the outer surface along anextension axis, such that the inner surface and the outer surface are adjacent to one another when overlapped; a first spring positioned along the extension axis in an interior of the outer tube; a second spring positioned along the extension axis in an interior of the inner tube; a seal positioned between the inner surface and the outer surface; and a stopper to engage the first spring at one endand engage the second spring at an opposite end such that the first spring and the second spring are in series with one another along the extension axis; wherein the one end and the opposite end arespaced apart from one another such that the seal is positioned between the one and opposite end.

Description

technical field [0001] The present disclosure relates to balancing mechanisms for closing panels. Background technique [0002] Some vehicles are equipped with closure panels, such as lift doors, that are driven between an open position (position 2) and a closed position (position 1) using an electric drive system. Retention systems have been proposed to provide such vehicles with the ability to assist the operator of the closure panel to maintain a third position retention point (or position 2) during the opening and closing operations, thereby helping to resist the weight of the closure panel itself . Since the closing torque provided by the weight of the closure panel is greater than the opening torque provided by the electric drive system, without these retention systems, the closure panel may drop back at the top end of the operative opening range. Such proposed holding systems are complex and expensive in some cases and may not provide an adequate failsafe mode (in t...

AI Technical Summary

Problems solved by technology

However, one disadvantage is that the parallel configuration does not make the spring constant K more flat in the stop-hold region of the lift gate load curve

[0004] However, even with a parallel spring arrangement, the problem remains that the kinematics (mass, center of gravity, and angle of travel) of a typical vehicle liftgate produce a non-linear liftgate load curve

Thus, a less optimal balance load curve may result in poorer performance of the lift gate's balance system (ie, smaller stop-and-hold, greater manual effort, larger and more expensive drive train, etc.)

[0005] Another disadvantage of some telescoping tube lift gate actuators and balancing mechanisms is that a seal is required in the middle of the length of the telescoping tube as a seal between the concentric tubes

The resulting shorter springs can result in higher spring rates that are limited to lower loads (for the same stress level) and generally have larger differences relative to the liftgate load curve

[0006] Another disadvantage of the presence of seals for balancing devices with telescoping tube configurations is that since two concentric tubes must be sealed together (for example, in an overlapping arrangement) around the middle portion of the balancing device, The seal must be accommodated by a ridge (or protrusion) extending outward from the outer surface of the outer tube of the telescoping tube arrangement

However, if the seal is placed inside the bellows, the travel of the spring as well as the diameter of the spring (i.e. the smaller diameter) will have to be changed, which will affect the load curve matching ability of the balancing device

[0007] Thus, other disadvantages of current retention systems include the bulky form factor that takes up valuable vehicle cargo space, the need to have additional lift support systems in series such as gas struts and other counterbalance mechanisms, the need for large maneuvers at the panel handle unacceptable effects of manual opening and closing operations with applied manual force, undesired force peaks that do not provide a smoother manual force / torque curve, the need to use vehicle battery power to maintain a third position holding point, and / or or temperature effects caused by variable manual work required by the operator due to fluctuations in ambient temperature

Images