US-12618429-B2 - Eccentric bolt for attaching mission pod to aircraft

US12618429B2US 12618429 B2US12618429 B2US 12618429B2US-12618429-B2

Abstract

Systems and methods are provided for eccentric bolt. One embodiment is an eccentric bolt to secure a clevis and lug fitting. The eccentric bolt includes a head and a shank. The shank includes multiple shank sections that successively decrease in diameter in an axial direction from the head toward a tail end of the shank. One of the shank sections is an eccentric shank section that is off-center with respect to a center axis of the shank. The eccentric shank section is configured to engage the lug prior to engagement of concentric shank sections with the clevis. While the eccentric shank section is engaged with the lug, the shank is configured to rotate to align the concentric shank sections with the clevis, and to insert through the clevis and lug fitting to compensate for misalignment of the clevis and lug fitting.

Inventors

Thomas J. Harleman

Assignees

THE BOEING COMPANY

Dates

Publication Date: 20260505
Application Date: 20211215

Claims (20)

1 . An assembly, comprising: an aircraft having an externally projecting lug containing a bearing having a passage; a mission pod having a clevis comprising a pair of forks respectively having a first hole and a second hole concentrically aligned with each other, and the first hole is larger in diameter than the second hole; an eccentric bolt for securing the clevis to the lug to thereby form a clevis and lug fitting detachably coupling the mission pod to the aircraft, the eccentric bolt comprising: a head; and a shank comprising: multiple shank sections that successively decrease in diameter in an axial direction from the head toward a tail end of the shank, wherein one of the shank sections is an eccentric shank section that is off-center with respect to a center axis of the shank, and multiple ramps tapering the diameter between adjacent ones of the shank sections, and each ramp extends continuously around a circumference of the shank; and wherein the eccentric shank section is configured to engage the passage of the bearing of the lug prior to engagement of concentric shank sections with the forks of the clevis, and the ramps are configured to allow the shank to be partially inserted into the lug and rotated to aid further insertion of the shank as increased alignment is achieved between the concentric shank sections and the first and second holes in the clevis.
2 . The assembly of claim 1 wherein in the axial direction from the head toward the tail end of the shank, the shank sections include: an upper shank section that is concentric and sized to correspond with the first hole of the clevis, the eccentric shank section that is eccentric and sized to correspond with the passage of the bearing of the lug; and a lower shank section that is concentric and sized to correspond with the second hole of the clevis.
3 . The assembly of claim 2 wherein: with the shank sections securely fit within the first and second holes and the passage of the clevis and lug fitting, the eccentric bolt is configured to react loads in a vertical direction perpendicular to the axial direction of the eccentric bolt and to react loads in a horizontal direction perpendicular to the axial direction of the eccentric bolt.
4 . The assembly of claim 2 wherein: one of the ramps is an eccentric ramp that tapers a diameter of the eccentric shank section to the lower shank section.
5 . The assembly of claim 4 wherein: the multiple ramps are configured to facilitate alignment of the eccentric bolt with respect to the clevis and lug fitting.
6 . The assembly of claim 2 wherein the shank further includes: a bottom shank section that is concentric and threaded for securing a nut.
7 . The assembly of claim 2 wherein: the shank is sized such that the eccentric shank section is configured to engage the bearing of the lug before the upper shank section engages the first hole of the clevis and before the lower shank section engages the second hole of the clevis.
8 . The assembly of claim 7 wherein: with the eccentric shank section engaged before the upper shank section and the lower shank section: the eccentric shank section is configured to secure a centerline of the lug to enable vertical adjustment of the clevis with respect to the lug, and to enable rotation of the eccentric bolt until the eccentric bolt fits through the clevis and lug fitting to compensate for the misalignment.
9 . The assembly of claim 1 , wherein the lug projects from a fuselage of the aircraft.
10 . The assembly of claim 1 , wherein the bearing is a spherical ball bearing.
11 . A method of attaching a mission pod having a clevis, to an aircraft having a lug, the clevis comprising a pair of forks respectively having a first hole and a second hole concentrically aligned with each other, and the first hole is larger in diameter than the second hole, and the lug is an externally projecting lug containing a bearing having a passage, the method comprising: positioning the lug between the forks of the clevis to approximately axially align the passage in the bearing with the first and second holes in the clevis to form a clevis and lug fitting; inserting an eccentric bolt partially through the clevis and lug fitting until an eccentric shank section of a shank of the eccentric bolt engages the lug, and the eccentric bolt has multiple shank sections that successively decrease in diameter in an axial direction from a head toward a tail end of the shank, and the shank sections include concentric shank sections and the eccentric shank section, which is off-center with respect to a center axis of the shank, and the shank includes multiple ramps tapering the diameter between adjacent ones of the shank sections, and each ramp extends continuously around a circumference of the shank; engaging the eccentric shank section with the passage of the bearing of the lug prior to engaging the concentric shank sections with the forks of the clevis; rotating the shank of the eccentric bolt to align the concentric shank sections with the first and second holes in the clevis; bearing the ramps against edges of the first and second holes while rotating the shank as increased alignment is achieved between the concentric shank sections and the first and second holes in the clevis; and inserting the eccentric bolt further through the clevis and lug fitting in a manner compensating for misalignment between the passage and the first and second holes, to engage the clevis with the eccentric bolt and thereby attach the mission pod to the aircraft.
12 . The method of claim 11 further comprising: installing a keeper on the eccentric bolt to prevent the eccentric bolt from rotating; reacting loads with the eccentric bolt in a vertical direction perpendicular to the axial direction of the eccentric bolt; and reacting loads with the eccentric bolt in a horizontal direction perpendicular to the axial direction of the eccentric bolt.
13 . The method of claim 11 wherein the eccentric shank section includes an eccentric ramp that tapers a diameter of the eccentric shank section, the method further comprising: inserting the eccentric bolt partially through the clevis and the lug until the eccentric ramp engages the lug and resists sliding through the lug due to misalignment between the first and second holes and the passage respectively of the clevis and the lug.
14 . The method of claim 11 , further comprising: attaching a first end of the mission pod to the aircraft by installing a first straight bolt through a first joint; attaching a second end of the mission pod to the aircraft by installing a second straight bolt through a second joint; and attaching the first end of the mission pod to the aircraft by installing the eccentric bolt through the clevis and lug fitting, which is a third joint for attaching the mission pod to the aircraft, and the installation of the eccentric bolt compensates for misalignment between the first joint and the third joint.
15 . The method of claim 14 further comprising: rotating the eccentric bolt to compensate for horizontal misalignment between the first joint and the third joint; and adjusting the clevis vertically to compensate for vertical misalignment between the first joint and the third joint.
16 . The method of claim 11 , wherein in the axial direction from the head toward the tail end of the shank, the shank sections include: an upper shank section that is concentric and sized to correspond with the first hole of the clevis, the eccentric shank section that is eccentric and sized to correspond with the passage of the bearing of the lug; and a lower shank section that is concentric and sized to correspond with the second hole of the clevis.
17 . The method of claim 16 , wherein the multiple ramps include an eccentric ramp that tapers a diameter of the upper shank section to the eccentric shank section.
18 . The method of claim 17 , wherein: the multiple ramps are configured to facilitate alignment of the eccentric bolt with respect to the clevis and lug fitting.
19 . The method of claim 11 , wherein the shank further includes: a bottom shank section that is concentric and threaded for securing a nut.
20 . The method of claim 11 , wherein the step of inserting the eccentric bolt through the clevis and lug fitting in a manner compensating for misalignment between the passage and the first and second holes comprises: vertically adjusting the clevis with respect to the lug, and rotating the eccentric bolt until the eccentric bolt fits through the passage and the first and second holes of the clevis and lug fitting.

Description

RELATED APPLICATIONS This non-provisional patent application claims priority to U.S. Provisional Patent Application No. 63/141,437 filed on Jan. 25, 2021, which is incorporated by reference as if fully provided herein. FIELD The disclosure relates to the field of fasteners, and in particular, to an eccentric bolt. BACKGROUND Some aircraft, such as military aircraft, may be equipped with so-called mission pods that detachably secure to an external surface of the aircraft. The pods may house various components or payload that facilitate execution of various operations. For example, a pod may carry electronics for mission-specific communications or surveillance. It is generally beneficial for the pods to be easily swapped on the aircraft for mission adaptability. Additionally, it is beneficial for the pods to attach with different aircraft in a manner that is secure and aligned despite manufacturing tolerance differences among aircraft. SUMMARY Embodiments described herein use an eccentric bolt for attaching a mission pod to an aircraft. The eccentric bolt is inserted through a joint, such as a clevis and lug fitting, that attaches a mission pod with the external surface of the aircraft. Due to manufacturing tolerances of the aircraft, two joints of the aircraft for attaching a pod may be slightly misaligned. The eccentric bolt advantageously enables fine adjustment in one of the joints to correct or compensate for the misalignment between the aircraft and the pod mounting fittings. Moreover, the eccentric bolt facilitates quick, secure attachment of the mission pod to the aircraft in a compact size without drilling. One embodiment is an eccentric bolt to secure a clevis and lug fitting. The eccentric bolt includes a head and a shank. The shank includes multiple shank sections that successively decrease in diameter in an axial direction from the head toward a tail end of the shank. One of the shank sections is an eccentric shank section that is off-center with respect to a center axis of the shank. The eccentric shank section is configured to engage the lug prior to engagement of concentric shank sections with the clevis. While the eccentric shank section is engaged with the lug, the shank is configured to rotate to align the concentric shank sections with the clevis, and to insert through the clevis and lug fitting to compensate for misalignment of the clevis and lug fitting. A further embodiment is a method of attaching a first structure having a clevis to a second structure having a lug. The method includes positioning the lug between forks of the clevis to approximately align respective holes in an axial direction to form a clevis and lug fitting, and inserting an eccentric bolt partially through the clevis and lug fitting until an eccentric shank section of the eccentric bolt engages the lug. The method also includes rotating the eccentric bolt to compensate for horizontal misalignment of the clevis and lug fitting, and adjusting the clevis vertically to compensate for vertical misalignment of the clevis and lug fitting. The method further includes inserting the eccentric bolt further through the clevis and lug fitting to engage the clevis with the eccentric bolt and attach the first structure with the second structure. A further embodiment is a method of attaching a mission pod with an aircraft. The method includes attaching a first end of the mission pod to the aircraft by installing a first straight bolt through a first joint, and attaching a second end of the mission pod to the aircraft by installing a second straight bolt through a second joint. The method also includes attaching the first end of the mission pod to the aircraft by installing an eccentric bolt through a third joint to compensate for misalignment between the first joint and the third joint. Other example embodiments may be described below. The features, functions, and advantages that have been discussed can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be seen with reference to the following description and drawings. DESCRIPTION OF THE DRAWINGS Some embodiments of the present disclosure are now described, by way of example only, and with reference to the accompanying drawings. The same reference number represents the same element or the same type of element on all drawings. FIG. 1A is a front view of an aircraft. FIG. 1B is a front perspective view of the mission pod attached to an external body of the aircraft via one or more joints. FIG. 2 is a perspective view of an eccentric bolt in an illustrative embodiment. FIG. 3 is a side cross-sectional view of the eccentric bolt partially inserted through a clevis and lug fitting in an illustrative embodiment. FIG. 4 is a flow chart illustrating a method of attaching a first structure having a clevis to a second structure having a lug in an illustrative embodiment. FIG. 5 is a bottom view of a mission pod attached wi