1. Field of the Invention
This invention relates to the mechanical arts. In particular, this invention relates to a keeper mechanism providing a visual signal indicating whether or not a latch is loaded.
2. Discussion of the Related Art
Various types of latches join and lock aircraft panels, such as aircraft cowlings, to one another. A typical latch includes a hook mounted to one aircraft panel that engages a keeper mounted to another aircraft panel. Furthermore, the latch generally includes a handle that actuates the hook through a linkage. When the handle is in the closed position and the hook is engaged with the keeper, the latch is closed securing the aircraft panels to one another. When the latch is closed, the hook imparts a certain amount of force, or load, upon the keeper. If necessary, the operator can release the aircraft panels from one another by rotating the handle to the open position such that the hook disengages from the keeper.
A problem with these latches is a ground crew inspector cannot visually verify whether or not the hook has properly engaged the keeper. Therefore, the inspector cannot be sure that the latch is properly closed. A further problem associated with these latches is that if the hook or the keeper are not in the proper position, or are broken, it is possible to close the latch without the hook properly engaging the keeper. This results in an unsafe condition in which the aircraft panels could open during flight.
Various types of indicators have been utilized with latches that join and lock aircraft panels to one another to provide a visual signal to ground crew inspectors indicating whether or not the hook and the keeper are properly engaged. For example, one type of indicator includes a feeler mechanism that fits over and slides relative to the hook. When the hook properly engages the keeper, the feeler mechanism engages the keeper and is positioned to allow the handle to close. On the other hand, when the hook does not properly engage the keeper, the feeler mechanism also does not engage the keeper, and the feeler mechanism prevents the handle from closing. Also, the handle remains pivoted upwards toward its open position, and does not match the contour of the aircraft panel. Thus, the handle""s position is a signal to the ground crew inspector that the hook did not engage the keeper and the latch is not properly closed.
A disadvantage of such prior indicators is that they are mounted on the latching device and are readily accessible by the operator. Unfortunately, this means that the indicators are sometimes subject to extreme operator abuse and are often damaged, broken, or intentionally overridden by the operator. For example, the previously described feeler mechanism can be manually overridden by simply pulling the feeler mechanism into place such that the handle closes, even though, the hook is not engaged with the keeper. In extreme cases, an operator may simply break the feeler mechanism. Thus, there is a potential that the aircraft could fly in an unsafe condition. A further disadvantage of the prior indicators is that they only sense whether or not the hook has engaged the keeper and do not indicate if the hook has engaged the keeper with force such that the latch is in a loaded position.
A prior keeper mechanism, without an indicator, allows for the engagement of a hook with a keeper and the adjusting of the latch load. The keeper mechanism includes a housing, a clevis, having a clevis opening and a clevis shaft, an adjusting nut, and a detent spring. The clevis opening is located outside of the housing and the clevis shaft extends inside the housing. The adjusting nut is located inside the housing and is threadably mounted around the clevis shaft. A detent spring interfaces with the adjusting nut and prevents the adjusting nut from rotating. After the hook engages the clevis and the latch is closed, an operator can control the load imparted by the hook upon the keeper by adjusting the position of the adjusting nut relative to the clevis opening.
A disadvantage of this type of keeper mechanism is that it is possible for the distance between the adjusting nut and the clevis opening to be great enough that when the latch is closed there is no load between the hook and keeper, and thus, the keeper cannot provide a minimum load for the latch. Without a minimum load, the keeper cannot be secured. A further disadvantage of the keeper mechanism is that it does not provide a visual indication of whether or not the hook is properly engaged with the keeper such that the latch is closed and the hook imparts at least the requisite minimum load upon the keeper.
In view of the above, it should be appreciated that there is a need for a keeper mechanism that indicates whether or not the hook is engaged with the keeper such that the latch is closed and loaded, includes an indicator that is safe from operator abuse and cannot be manually overridden, and provides a minimum load for the latch. The present invention satisfies these and other needs and provides further related advantages.
The invention resides in a keeper mechanism. Various embodiments of the inventive he keeper mechanism provide advantages over known keeper mechanisms in that they indicate whether or not the hook is engaged with the keeper such that the latch is closed and loaded, includes an indicator that is safe from operator abuse and cannot be manually overridden, and/or provide a minimum load for the latch.
The keeper mechanism is utilized with a latch having a hook. The latch is moveable between an unloaded position and a loaded position. In one embodiment, the keeper mechanism include a housing, a housing extension, a clevis, an adjusting nut, a detent spring, and an indicator. The housing has an exterior surface and an interior surface. The housing also has opposing ends and a mounting wall connected to one end of the housing. The mounting wall includes an opening. The housing extension has opposing ends, with one of the opposing ends connected to the housing, such that the housing extension protrudes from the exterior surface of the housing. The other end of the housing extension includes an indicator opening. The clevis includes a clevis opening positioned outside of the housing, at one end of a clevis shaft. The clevis shaft passes through the opening in the mounting wall and extends into the housing. The adjusting nut is threadably mounted to the clevis shaft and is positioned within the housing. The detent spring mounts to the interior surface of the housing and is in sliding contact with the adjusting nut.
The indicator is housed within the housing extension and includes a bulb-shaped sensing end, which engages the adjusting nut, and a flag end, positioned adjacent the indicator opening. The indicator is moveable between a flagged position and an unflagged position. In the flagged position, the flag end extends outside of the housing extension and indicates when the latch is in an unloaded position. In the unflagged position, the flag end does not extend outside of the housing extension and indicates when the latch is in a loaded position. Thus, the flag end of the indicator provides a visual indication of whether or not the hook is properly engaged with the keeper and the latch is closed and in a loaded position. This is advantageous in that the indicator allows ground crew inspectors to visually verify the status of the latch. A further advantage of the invention is that the indicator is housed within the housing extension so the indicator is less susceptible to operator abuse.
In an alternative embodiment of the invention, the housing does not include a housing extension or an indicator. However, this embodiment does include a biasing spring which has opposing ends. One end of the biasing spring is positioned adjacent the mounting wall. The other end of the biasing spring interfaces with the adjusting nut. The biasing spring advantageously provides a minimum load for the latch. It is advantageous for the latch to have a minimum load, since with a minimum load, it is known that when the latch is closed the hook and the keeper mechanism are linked together by at least a minimum amount of
Another embodiment of the invention includes the housing extension, indicator, and biasing spring of the previous embodiments. This embodiment also includes an adjustment slot adjacent the mounting wall. The adjusting nut has a front section adjacent the end of the adjusting nut nearest the mounting wall. Additionally, the adjusting nut has an end section located at the end of the adjusting nut furthest from the mounting wall. The end section includes a plurality of grooves. A sloped surface is located between the front section and the end section. The detent spring has at least one knee which is in sliding contact with one of the plurality of grooves in the end section of the adjusting nut.
This embodiment also includes a retaining ring connected to the interior surface of the housing between the adjustment slot and the housing extension. In addition, the indicator includes a lip adjacent the bulb-shaped sensing end and a cylindrical indicator shaft extending from the bulb-shaped end to the flag end. An indicator spring is mounted inside of the housing extension and surrounds the cylindrical indicator shaft between the lip and the indicator opening. Thus, this embodiment includes the features and advantages of both prior embodiments of the invention since this embodiment includes the housing extension, the indicator, and the biasing spring.
Some embodiments of the present invention include a remote cabling system. One end of the remote cabling system connects to the flag end of the indicator. The other end of the remote cabling system connects to a remote flag, such that the remote flag is visible when the flag end extends outside of the housing extension.
Other embodiments of the present invention include an electronic monitoring device contacts the flag end of the indicator. The electronic monitoring device generates an electrical signal when the flag end extends outside of the housing extension.
The remote cabling system and electronic monitoring device are advantageous since they allow for remote monitoring of the latch. In particular, the remote cabling system and electronic monitoring device notify an observer at a location remote from the latch whether or not the latch is closed and in a loaded position.
Other features and advantages of the present invention will be set forth in part in the description which follows and the accompanying drawings, wherein the preferred embodiments of the present invention are described and shown, and in part will become apparent to those skilled in the art upon examination of the following detailed description taken in conjunction with the accompanying drawings, or may be learned by practice of the present invention. The advantages of the present invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.