Claims:1. An engagement and disengagement mechanism for Air Transport Rack (ATR) chassis, the mechanism comprising:
a tray member comprising a bottom plate having at least two guiding means at the junction across the horizontal axis, a vertical back plate having two side flanks joining the bottom plate, the vertical back plate is provided with a plurality of plug connectors;
a chassis member having a front end and a rear end, the chassis member disposed to slide on the tray member with the help of the guiding means of the tray member, the rear end of the chassis member provided with receptacle connectors corresponding to the plug connectors; and
a locking assembly means positioned at the front of the tray member which facilitates the chassis member to reach to a pre-set position in order to allow the user to provide a rotary motion using a tool of the locking assembly for the transverse movement of the chassis member for engagement and disengagement with the tray member.

2. The locking assembly means of claim 1, comprising:
a movable block, a fixed block, a ball screw assembly, a stopper, a washer and a cotter pin, wherein the ball-screw assembly including a screw with groove to accommodate steel ball in it and a mating nut, wherein the nut portion of the ball-screw assembly is attached to the fixed block, the screw portion passes through moving block and the stopper such that the screw is arrested to the stopper using the retaining washer and the cotter pin, and wherein the stopper in turn is fixed to the moving block making the ball screw, the stopper and the moving block a single entity.

3. The mechanism of claim 1, wherein the engagement and disengagement mechanism is designed for a precise movement of 21 mm of the chassis member disposed to the tray member, wherein the mechanism converts the rotary motion of the screw to the transverse movement of the chassis member.

4. The mechanism of claim 1, wherein the screw of mechanism is rotated anticlockwise to retract the moving block outward by 21mm for allowing smooth and controlled disengagement.

5. The mechanism of claim 1, wherein the screw is operated by a torque controlled tool to facilitate proper engagement and disengagement of the connectors.

6. The mechanism of claim 1, wherein the chassis member is placed on the top of the tray member and the guided means to allow smooth sliding over tray member, wherein the projection at the front bottom of the chassis member rests on the groove of the moving block, and wherein the clockwise rotation of the screw allow the precise movement of the chassis member along with the moving block of the locking assembly means.

7. The mechanism of claim 1, wherein the chassis member includes 4 numbers of ARINC 600 receptacle connectors on the rear panel and tray member includes 4 numbers of ARINC 600 plug connectors at back plate.

8. The mechanism of claim 1, wherein the guiding means made of stainless steel strip.
, Description:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10, rule 13)

“An engagement and disengagement mechanism for an Airborne Equipment”
By

Bharat Electronics Limited,
Corporate Office,
Outer Ring Road, Nagavara,
Bangalore - 560045

The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the invention
This invention relates to avionics equipment, and more specifically to assembly for securing chassis member to avionics tray member.

Background of the invention
As is well known to those skilled in the avionics packaging and installation art, the electronics chassis or electronics units must be capable of being routinely installed and removed for maintenance and/or replacement purposes. Usually, each chassis is mounted on, and secured to, a tray which in turn is permanently secured to a shelf in the electronics bay or bays of the aircraft. While some electronic units are permanently mounted within the avionics bay, other electronic units may be portable such that the units can be removed from the bay and transported to and from the aircraft, such as the well-known aircraft “black box.” Such electronic unit housings are placed on fixed trays which are permanently mounted in an equipment bay of aircraft, for example in the cockpit of an aircraft. Consequently, a plurality of avionics equipment mounting trays is provided in the avionics bay of an aircraft. The avionics equipment mounting trays include a support structure for holding the portable electronic unit or a mating wire harness or plug for plugging a portable electronic unit into a system and enabling communication between the portable electronic unit and the central control system.
Installing a chassis unit on board aircraft, helicopters or other vehicles presents more or less difficult problems of bulk, manipulation, positioning and then fastening or locking. The total estimated force required for disengaging four ARINC 600 connectors is 1500N, and is difficult to apply the required force manually. Usually, each chassis is mounted on and secured to a tray which in turn is permanently secured to a shelf in the electronics bay or bays of the aircraft. At the rear of chassis, they include the portion of a connector comprising a multiplicity of pins of small diameter which are therefore relatively fragile and which engage with portion of the connector which is permanently fixed to the rear of the tray. The chassis must have a proper engagement with the plug portion of the connector to ensure proper operation of the avionics equipment in the chassis, thereby affecting the proper operation of the avionics equipment. The proper alignment of receptacle connectors of electronic unit & plug type connectors of tray member is essential for electrical connectivity during engagement. The manually establishing engagement and disengagement by push and pull methods at rear end and non-accessible region of electronic unit direct to misalignment and resulting in damaging of the connectors. Because of the location of the connectors, it is impractical to visually align chassis member with tray member while inserting the chassis member. Also manually pushing the chassis for engagement may results in damaging of tray side connectors.
There are several systems for reducing the necessary forces, a handle with extracting cams, an articulated lever with a knurled nut, a system comprising an endless screw and a rack, and a removable electric or electronic equipment assembly comprising a box and a housing uses worm gear based mechanism and gang channels. A mechanism of this type has some disadvantages, like they are suitable only for less than three connectors, because of the limitation of using worm gear based mechanism, which cannot withstand the required force for the engagement of multiple connectors. Other problems encountered, during aligning the chassis on gang channel it will be tedious work and possibility of damaging the channel is more during installation of chassis on tray and requires special/custom made torque limited tool is required for operation.
Thus, it would be desirable to provide a locking assembly means that result in proper engagement and disengagement between receptacle connectors with the corresponding plug connectors while applying an appropriate torque on it to hold chassis member in position on the avionics equipment tray member.

Summary of the Invention
An aspect of the present invention is to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below.
Accordingly, in one aspect of the present invention provides an engagement and disengagement mechanism for Air Transport Rack (ATR) chassis, the mechanism comprising: a tray member, a chassis member, and a locking assembly means. The tray member comprising a bottom plate having at least two guiding means at the junction across the horizontal axis, a vertical back plate having two side flanks joining the bottom plate, the vertical back plate is provided with a plurality of plug connectors. The chassis member having a front end and a rear end, the chassis member disposed to slide on the tray member with the help of the guiding means of the tray member, the rear end of the chassis member provided with receptacle connectors corresponding to the plug connectors. The locking assembly means positioned at the front of the tray member which facilitates the chassis member to reach to a pre-set position in order to allow the user to provide a rotary motion using a tool of the locking assembly for the transverse movement of the chassis member for engagement and disengagement of connectors with the tray member.
Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

Brief description of the drawings
These and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:
Figure 1 shows a perspective view of a chassis member, a tray member and a locking assembly for engagement and disengagement of the chassis member on the tray member in aircraft, according to an exemplary embodiment of the present invention.
Figure 2 is an assembled perspective view of a locking assembly in engagement of a chassis member with a tray member, according to an exemplary embodiment of the present invention.
Figure 3 is an exploded perspective view of a locking assembly for engagement and disengagement of a chassis member with a tray member of FIG. 2, according to an exemplary embodiment of the present invention.
Figure 4 is a cross-section view of a locking assembly across A-A of Figure 2 in engagement of a chassis member with a tray member, according to an exemplary embodiment of the present invention.
Persons skilled in the art will appreciate that members in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

Detailed description of the invention
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.
It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a component surface” includes reference to one or more of such surfaces.
By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.
Figs. 1 through 4, discussed below and the various embodiments used to describe the principles of the present disclosure in this document are by way of illustration only and should not be construed in any way that would limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged system. The terms used to describe various embodiments are exemplary. It should be understood that these are provided to merely aid the understanding of the description, and that their use and definitions in no way limit the scope of the invention. Terms first, second, and the like are used to differentiate between objects having the same terminology and are in no way intended to represent a chronological order, unless where explicitly stated otherwise. A set is defined as a non-empty set including at least one element.

The avionics chassis member in the aircraft is as per ATR (Aircraft Transport Rack) standard. The chassis member with form factor of one long ATR contains four numbers receptacle ARINC 600 shell 2 connectors on the rear panel. The avionics chassis member is mounted on the aircraft with tray member to hold 4 numbers of ARINC 600 plug connectors. The locking assembly means is mounted below the tray member to control engagement and disengagement of the chassis member from the tray member. The locking assembly means bring to an end after proper engagement of the connectors and their disengagement to ensure proper installation, safety and maintainability of avionics equipment on aircraft. The engagement/disengagement mechanism converts rotary motion (estimated torque is 1.91 N-m) by torque clutch means of hexagonal socket to the precise transverse movement.
Figure 1 shows a perspective view of a chassis member, a tray member and a locking assembly for engagement and disengagement of chassis member on tray member in aircraft, according to an exemplary embodiment of the present invention. A tray member 3 comprising of a bottom plate provided with a guiding means 11 of stainless steel strip through length for sliding of a chassis member 1 over it and a cooling duct 7 is provided at the bottom for supplying the cooling air from aircraft ECS (Environmental Control System) to the chassis member 1. The tray member further includes a vertical back plate provided with plug connectors 4 of four numbers ARINC 600 plug connectors. The vertical plate having two side flanks which are in the form of open triangles joining the bottom plate. The vertical back plate is provided with pin 5 at side ends for positioning of chassis member 1 and to mate with its counterpart the locating cup mounted on the chassis member 1. The hold down clamp 6 is provided at ends of bottom plate to completely arrest the mate chassis member 1 on tray member. A chassis member 1 having a front end and a rear end, and the said chassis member 1 comprising a bottom plate provided with guide portion 10 made of stainless steel strip and are disposed to slide on the tray member 3 with the help of the guiding means 11 of the tray member 3. The stainless strip protects chassis member 1 from scratches during engagement & disengagement from tray member 3. The rear end of the chassis member 1 provided with receptacle connectors 2 of four numbers ARINC 600 receptacle connectors corresponding to the plug connectors 4 of tray member 3.
Figure 2 is an assembled perspective view of a locking assembly in engagement of a chassis member with a tray member, according to an exemplary embodiment of the present invention. A locking assembly 8 means positioned at the front of the tray member 3 to facilitate the chassis member 1 to reach to a pre-set position. The chassis member 1 is placed on the top of the tray member 3 and the guided means to allow smooth sliding over tray member 3. The projection at the front bottom of the chassis member 1 is placed on the groove of the locking assembly (moving block member 14). After that user provide a clockwise rotary motion using a hexagonal socket torque controlled tool 9 to the locking assembly 8 allowing the precise movement of the chassis member 1 along with the moving block member 14 of the locking assembly means 8 for engagement of connectors of chassis member 1 with connectors of tray member 3. The engagement and disengagement mechanism is designed for a precise movement of 21 mm of the chassis member 1 disposed to the tray member 3 to convert the rotary motion of the locking assembly means 8 to the transverse movement of the chassis member 1. The locking assembly 8 is drive by a torque controlled tool to facilitate proper engagement and disengagement of the connectors.

Figure 3 is an exploded perspective view of a locking assembly for engagement and disengagement of a chassis member with a tray member of FIG. 2, according to an exemplary embodiment of the present invention. The locking assembly comprising a movable block 14, a fixed block 16, and a ball screw assembly 13, a stopper 16, a washer 18 and a cotter pin 17. The ball-screw assembly 13 includes a screw with groove to accommodate steel balls in it and a mating nut. The nut portion of the ball-screw assembly 13 is attached to the fixed block 16 and the screw portion passes through moving block 14 and the stopper 16 such that the screw is arrested to the stopper 16 using the retaining washer 18 and the cotter pin 17 as shown in FIGURE 2. Further, the stopper 16 in turn is fixed to the moving block 14 making the ball screw 13, the stopper 16 and the moving block 14 a single entity as shown in Figure 4. The screw is rotated anticlockwise using a torque controlled tool 9 of the locking assembly 8 to retract the moving block 14 outward by 21mm for allowing smooth and controlled disengagement of the connectors.

We Claim:

1. An engagement and disengagement mechanism for Air Transport Rack (ATR) chassis, the mechanism comprising:
a tray member comprising a bottom plate having at least two guiding means at the junction across the horizontal axis, a vertical back plate having two side flanks joining the bottom plate, the vertical back plate is provided with a plurality of plug connectors;
a chassis member having a front end and a rear end, the chassis member disposed to slide on the tray member with the help of the guiding means of the tray member, the rear end of the chassis member provided with receptacle connectors corresponding to the plug connectors; and
a locking assembly means positioned at the front of the tray member which facilitates the chassis member to reach to a pre-set position in order to allow the user to provide a rotary motion using a tool of the locking assembly for the transverse movement of the chassis member for engagement and disengagement with the tray member.

2. The locking assembly means of claim 1, comprising:
a movable block, a fixed block, a ball screw assembly, a stopper, a washer and a cotter pin, wherein the ball-screw assembly including a screw with groove to accommodate steel ball in it and a mating nut, wherein the nut portion of the ball-screw assembly is attached to the fixed block, the screw portion passes through moving block and the stopper such that the screw is arrested to the stopper using the retaining washer and the cotter pin, and wherein the stopper in turn is fixed to the moving block making the ball screw, the stopper and the moving block a single entity.

3. The mechanism of claim 1, wherein the engagement and disengagement mechanism is designed for a precise movement of 21 mm of the chassis member disposed to the tray member, wherein the mechanism converts the rotary motion of the screw to the transverse movement of the chassis member.

4. The mechanism of claim 1, wherein the screw of mechanism is rotated anticlockwise to retract the moving block outward by 21mm for allowing smooth and controlled disengagement.

5. The mechanism of claim 1, wherein the screw is operated by a torque controlled tool to facilitate proper engagement and disengagement of the connectors.

6. The mechanism of claim 1, wherein the chassis member is placed on the top of the tray member and the guided means to allow smooth sliding over tray member, wherein the projection at the front bottom of the chassis member rests on the groove of the moving block, and wherein the clockwise rotation of the screw allow the precise movement of the chassis member along with the moving block of the locking assembly means.

7. The mechanism of claim 1, wherein the chassis member includes 4 numbers of ARINC 600 receptacle connectors on the rear panel and tray member includes 4 numbers of ARINC 600 plug connectors at back plate.

8. The mechanism of claim 1, wherein the guiding means made of stainless steel strip.

Abstract

An engagement and disengagement mechanism for an Airborne Equipment

The present invention relates to an engagement and disengagement mechanism for an Air Transport Rack (ATR) chassis. In one embodiment, the mechanism including a tray member, a chassis member and a locking assembly means which is positioned at the front of the tray member. The locking assembly facilitates the chassis member to reach to a pre-set position in order to allow the user to provide a rotary motion using a tool of the locking assembly for the transverse movement of the chassis member for engagement and disengagement with the tray member.

FIGURE-2