FIELD OF THE INVENTION

The present invention relates to linear actuators and, more particularly, to a ball screw actuator for accommodating assembly misalignment.

BACKGROUND

This section provides background information related to the present disclosure which is not necessarily prior art.

Components of linear actuators, such as ball screw actuators, may be misaligned relative to each other or to the structural components that they are provided to impart motion to. In a ball screw actuator, a nut is rotationally fixed and in threaded engagement with a lead screw and/or ball screw. As the lead screw is rotated by a motor, the rotational motion of the lead screw is converted to translational motion of the nut, which may be fixed to an additional component to effect translation of the associated component. However, as shown inFIG. 2, if the component(s) that the nut is fixed to is misaligned, relative to the lead screw, the lead screw must flex to some extent to maintain alignment of the nut and ball screw. As the nut is moved closer to the electric motor (i.e., away from the distal end of the lead screw), the flexing capability of the lead screw is more restricted, friction and binding between the nut and screw increased, and operational efficiency is reduced. Additionally, the ball screw actuator may be damaged and the lifespan is reduced.

As can easily be understood, the number of applications in which a ball screw actuator is employed is large. An example of an application that benefits from a ball screw actuator is a passenger boarding bridge of the type used in airport facilities to provide passengers access to parked aircraft without exposing the passengers to the weather and ambient conditions between the parked aircraft and the terminal, as shown inFIG. 1. These bridges are freestanding passenger boarding bridges that are attached or adjacent to the airline terminal at a fixed, but horizontally rotatable, end and will be driven into position at the outboard end of the passenger boarding bridge to interface with a parked aircraft. The aircraft usually accommodated with these bridges are jet aircraft ranging in size from small aircraft to large intercontinental passenger aircraft. The bridges must be vertically adjusted to match the height of the respective doorways of the passenger bridge and the aircraft. An electrically driven ball screw actuator is useful in facilitating the height adjustment of the passenger bridge. However, the same misalignment issues may be present in such applications. Accordingly, addressing this issue would be well received by ball screw actuator manufacturers and manufacturers of systems that employ such actuators, e.g., aircraft passenger bridge manufacturers.

SUMMARY OF THE DISCLOSURE

This section provides a general summary of the disclosure and is not to be interpreted as a complete and comprehensive listing of all of the objects, aspects, features and advantages associated with the present disclosure.

According to one aspect of the disclosure, a linear actuator assembly includes a motor. The linear actuator assembly also includes a ball screw rotatably driven by the motor. The linear actuator assembly further includes a nut coupled to the ball screw and rotationally fixed, the nut translatable along the ball screw upon rotation of the ball screw. The linear actuator assembly yet further includes a flange having a first surface and a second surface, the nut mounted to the first surface and the second surface having a non-planar geometry, the non-planar geometry defined by curvature about an axis from a first side of the flange to a second side of the flange, the first side and the second side of the flange being on opposite sides of the flange from each other.

According to another aspect of the disclosure, a linear actuator assembly includes a motor. The linear actuator assembly also includes a ball screw rotatably driven by the motor. The linear actuator assembly further includes a nut coupled to the ball screw and rotationally fixed, the nut translatable along the ball screw upon rotation of the ball screw. The linear actuator assembly yet further includes a first flange having a first surface and a second surface, the nut mounted to the first surface and the second surface having a radius of curvature about an first axis, the curvature of the second surface curving outwardly from a first side of the first flange to a second side of the first flange, the first side and the second side of the first flange being on opposite sides of the first flange from each other. The linear actuator assembly also includes a spacer having a third surface and a fourth surface, the third surface having an inwardly curved surface corresponding to the second surface of the first flange, the fourth surface having an outwardly curved surface extending from a third side of the spacer to a fourth side of the spacer, the third side and the fourth side being on opposite sides of the spacer from each other.

Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

