Pitch link with track adjustment indicators

Patent metadata

Field	Value
Publication number	US-10239609-B2
Application number	US-201715656929-A
Country	US
Kind code	B2
Filing date	Jul 21, 2017
Priority date	Jul 21, 2017
Publication date	Mar 26, 2019
Grant date	Mar 26, 2019

Abstract

A system and method for measuring, or otherwise determining pitch length adjustments to a pitch link coupled to a rotor blade in a rotorcraft includes vertical track adjustment indicators machined onto an exterior of the tube of the pitch link and a vertical reference indicator machined onto an exterior of the upper or the lower rod of the pitch link. A metric of a pitch length adjustment can be determined by tracking or counting how many track adjustment indicators pass the reference indicator while the tube of the pitch link is being turned in either direction for increasing or decreasing the pitch length. The track adjustment indicators can be relied upon to track one or a series of adjustments for tracking a rotor blade installed in a rotor assembly.

First claim

What is claimed is:

1. A system comprising:
a rotor assembly comprising:
a pitch link configured to be coupled with a rotor blade and with a swash plate, the pitch link having an first end and a second end opposite the first end and a vertical axis extending from the first end to the second end;

wherein the pitch link comprises:
a tube having a first portion extending towards the first end of the pitch link, and a second portion opposite the first portion, the second portion extending towards the second end of the pitch link;
a first rod comprising a first rod head and a first rod body extending therefrom along the vertical axis, the first rod head being disposed at the first end of the pitch link, the first rod head configured to couple the pitch link to the rotor blade, and the first rod body threaded into the tube at the first portion of the tube; and
a second rod comprising a second rod head and a second rod body extending therefrom along the vertical axis, the second rod head being disposed at the second end of the pitch link, the second rod head configured to couple the pitch link to the swash plate, and the second rod body threaded into the tube at the second portion of the tube;

wherein:
the first rod head has an outer vertically planar surface marked with a reference indicator, and the tube has an outer surface marked with a plurality of track adjustment indicators at the first portion of the tube along a circumference of the tube, the track adjustment indicators being vertical and substantially perpendicular to the circumference;
the pitch link has a pitch length from the first end to the second end that is adjustable while the pitch link is coupled to the rotor blade and the swash plate, in accordance with a vertical displacement of the tube relative to the first rod and the second rod effected by a turning the tube in a first direction and a second direction around the vertical axis, the first direction configured to increase the pitch length, and the second direction opposite the first direction configured to decrease the pitch length;
a number of track adjustment indicators entirely or partly passing the reference indicator while the tube is being turned in one of the first direction and the second direction is configured to indicate of an amount of adjustment to the pitch length; and
the first rod is an upper rod or a lower rod of the pitch link, wherein:
when the first rod is the upper rod, the second rod is a lower rod, the first end of the pitch link is an upper end of the pitch link, the second end of the pitch link is a lower end of the pitch link, the first rod head is an upper rod head, the second rod head is a lower rod head, the first rod body is an upper rod body, the second rod body is a lower rod body, the first portion of the tube is an upper portion of the tube, and the second portion of the tube is a lower portion of the tube; and
when the first rod is the lower rod, the second rod is the upper rod, the first end of the pitch link is the lower end of the pitch link, the second end of the pitch link is the upper end of the pitch link, the first rod head is the lower rod head, the second rod head is the upper rod head, the first rod body is the lower rod body, the second rod body is the upper rod body, the first portion of the tube is the lower portion of the tube, and the second portion of the tube is the upper portion of the tube.

2. The system of claim 1 , wherein the track adjustment indicators are shallow grooves on the outer surface of the tube.

3. The system of claim 2 , wherein the shallow grooves have a same vertical length as one another.

4. The system of claim 2 , wherein the shallow grooves comprise twelve vertical grooves evenly spaced around an entirety of the circumference of the outer surface of the tube.

5. The system of claim 4 , wherein:
the shallow grooves include a plurality of short shallow grooves and a plurality of long shallow grooves;
each short shallow groove is positioned between two adjacent long shallow grooves; and
the shallow grooves begin at a top edge of the upper portion of the tube, the plurality of short shallow grooves extending vertically downwards towards the lower portion of the tube for a first length, and the plurality of the long shallow grooves extend downwards towards the lower portion of the tube for a second length longer than the first length.

6. The system of claim 1 , wherein the reference indicator is a shallow vertical groove machined into the outer vertically planar surface of the upper rod head.

7. The system of claim 1 , wherein a marking is configured to be applied to a first track adjustment indicator that is vertically aligned with the reference indicator prior to adjusting the pitch length, wherein the marking identifies the first track adjustment indicator as a starting point providing an initial pitch length for the pitch link.

8. The system of claim 7 , wherein pitch length adjustment indications on the pitch link consist of the marking on the first track adjustment indicator, the track adjustment indicators on the upper portion of the tube, and the reference indicator on the upper rod head.

9. The system of claim 1 , wherein the track adjustment indicators are vertical hash marks engraved in the outer surface of the tube, and the reference indicator is a vertical hash mark engraved in the outer vertically planar surface of the upper rod head.

10. The system of claim 1 , wherein the first direction is a counter-clockwise direction, the second direction is a clockwise direction, and the tube further comprises:
a labeling on a middle of the tube between the upper portion and the lower portion, the labeling indicating the counter-clockwise direction for the turning of the tube that increases the pitch length, and indicating the clockwise direction for the turning of the tube that decreases the pitch length.

11. The system of claim 1 , wherein the pitch link further comprises:
an upper jam nut around a neck of the upper rod body beneath the upper rod head; and
a lower jam nut around a neck of the lower rod body above the lower rod head, wherein the upper jam nut and the lower jam nut are configured to be tightened relative to the tube to restrict the turning of the tube while being engaged in an operation of a rotorcraft, and are configured to be loosened relative to the tube to allow the turning of the tube for adjusting the pitch length.

12. The system of claim 1 , wherein the tube comprises:
a tube body;
an upper insert mounted inside the tube body in the upper portion of the tube; and
a lower insert mounted inside the tube body in the lower portion of the tube;
wherein the upper rod body is threaded into the upper insert and the lower rod body is threaded into the lower insert;
wherein the lower rod body has lower exterior threading of a first density;
wherein the upper rod body has upper exterior threading of a second density different than the first density; and
wherein the upper exterior threading and the lower exterior threading are both right-handed.

13. A rotorcraft comprising:
a mast configured to rotate around a principal axis, wherein the principal axis extends along a length of the mast;
a yoke coupled to the mast, wherein a rotation of the mast rotates the yoke around the principal axis;
a plurality of rotor blades coupled to the yoke around a circumference of the yoke, wherein a rotation of the yoke rotates the plurality of rotor blades around the principal axis, and wherein a tip of each of the plurality of rotor blades traces a tip path while the rotor blade is rotating around the principal axis;
a rotating ring couple

Assignees

• Bell Helicopter Textron Inc

Inventors

• Davis Hunter Jay
• Wiinikka Mark Adam

Classifications

• F16C7/06

  Adjustable connecting-rods · CPC title

• B64C27/54

  Mechanisms for controlling blade adjustment or movement relative to rotor head, e.g. lag-lead movement · CPC title

• B64C27/605 Primary

  including swash plate, spider or cam mechanisms · CPC title

• B64C11/06

  for variable-pitch blades · CPC title

• B64C11/301

  characterised by blade position indicating means · CPC title