|Title of Invention||
A LOW SHOCK BALL-LOCK SEPARATION MECHANISM FOR SEPARATING UPPER STAGE AND SATELLITES FROM A SPACE LAUNCH VEHICLE
|Abstract||A low shock ball-lock separation mechanism for separating upper stage and satellite of a space launch vehicle is provided in this invention. The said mechanism comprises locking the interface rings by means of balls and keeping them in a locked condition by a rotatable retainer ring provided with radial holes for the release of balls during separation. The retainer ring is actuated by a pair of thrusters preferably pyrotechnic thrusters. The entire separation technique is dependent only on the actuation of anyone of the thrusters thus improving reliability. This separation mechanism will facilitate an extremely low shock while separation.|
The invention relates to a low shock ball-lock separation mechanism for separating upper stage and satellites from a space launch vehicle.
Considerable difficulty has been experienced in designing launch vehicle separation mechanism, which will result in the immediate separation of its payload from the launch vehicle. A clean and immediate break between the space vehicle and payload resulting in low shock, free from contamination and flying debris is particularly important to avoid any possible damage to sensitive components.
In the prior art > a series of explosive bolts provided at equally spaced intervals about the periphery of the connecting interface have been, used as a separation device for satellite separation. This arrangement provided a sure method of separating the satellite. However, the problem of detonating each bolt simultaneously to obtain an immediate break and to control the shock induced has never been satisfactorily solved.
Another mechanism utilized for separating satellite from a launch vehicle is that of the expanding tube assembly (XTA), This arrangement also provided a sure way of separating the satellite by the severance of tiie connecting structure. However it has been found practically impossible to control the shock induced,
A- series of V shaped blocks mounted over the interface flanges and preloaded by thin bands which are connected by sever able tension bolts have been used as a separation device for satellite separation, This arrangement though provided a sure method of separating the satellite, the problem of applying uniform tension along the circumference for small diameter interfaces and associated shock has never been satisfactorily solved.
The invention provides a mechanism which overcomes the problems discussed above. This is accomplished by locking interface rings by means of balls and keeping them in locked condition by a relatable retainer ring provided with radial holes for the release of balls during separation. The retainer ring is actuated by a pair of thrusters preferably pyrotechnic thrusters. The entire separation technique is dependent only on the actuation of any one of the thrusters thus improving reliability-
Thus the invention provides a low shook ball-look separation mechanism for separating upper stage and satellites of a space launch vehicle, comprising an upper adaptor forming part of the upper stage of the space launch vehicle, the said upper adaptor being provided with an annular groove on its hub to receive a Dortion of a set of steel balls, a flange having a set of holes
t or attacking the upper stage and plurality of compression fjprings bearing on the surface of the flange to act on the upper adapter, a lower adaptor attached to lower stage and having one portion mated with the said upper adaptor, a set of steel balls positioned in the holes provided on the hub of the said lower adaptor. a relatable retainer ring having a lock position and release position to keep the balls in the holes provided on the of the lower adapter in lock position, radial holes being provided in the said retainer ring for the escape of balls in the release position, at least a pair of thrusters being provided for rotating the retainer ring with respect to the lower adaptor to a predetermined position and a mechanical stopper being mounted on the lower adapter for stoping the rotation of the retainer ring and move the locking balls radically outwards due to the action of the compression springs positioned between the flanges of the upper adapter and lower adapter for forcing them apart and separating the upper stages from the launch vehicle upon in 11 of the Fade thrusters .
It is an objective of this invention to provide a .separation mechanism which will facilitate an immediate and even separation of the satellite from a launch vehicle.
Vet of this invention is to prov3de a separation mechanism for satellites, which will induce extremely low shock while separation.
still another objective of this invention is to provide a mechanism which will induce no contamination or flying debris during separation.
Another objective of the invention is to provide a separation mechanism with releasing means for releasing all the locking points simultaneously to avoid a condition termed "tip off" daring separation.
Another objective of this invention is to provide a separation mechanism for spacecraft separation which is extremely simple in design yet highly reliable.
These and other objectives and advantages of this invention will become more apparent upon reading the specification in conjunction with the accompanying drawings.
Fig. 1 is a side lavational view of the last two stages of a multistage launch vehicle partially cut away showing satellite separation mechanism integrated with vehicle payload deck and satellite.
Fig. 2 is a segmental view showing an enlarged cross section of the low shock ball-lock separation mechanism according to the i Invention .
Fig, 3 IS a cribs sectional view taken along the sectional Iines AA in fig. 1.
Fig 4 is a sectional elevation of the ball lock separation mechanism according to the invention along YY in fig. 3.
Fig. 5 air’s a Judgmental view showing a cross section of a prior art separation mechanism,
The seperation mechanism according to the invention is a separable ,joint similar in concept to a bal 1 bearing. 11
essentially consists of an upper adapter for satellite and
lower adapter for vehicle mated in a tongue and groove configuration . Tile are yield together by means of balls fjecured in position by a rotatable retainer ring. The balls are radially preloaded between the inner and outer rings which are provided witti annular groove to accommodate tlte balls, The middle ring is provided with number of holes to tiold the balls in position and is axially pre-loaded. The retainer ring has two posit ions, namely a look position and a release position. It is provided with radial holes and when aligned with the balls in the middle r ing ,
transfered from the inner ring to the middle ring which are
attached to the separating masses. The separation of the satellite is achieved by displacement of the outer ring from the lock position to the release position by means of the pyrothrusters. The rotary motion of the retainer ring is restricted by a stopper. Precompressed helical springs positioned in between the flanges of the adapter rings provide the relative velocity during separation. A telescopic spring guide may be used as a strut for preloading the joint.
Referring to fig. 1, only a portion of the upper stage and satellite are illustrated to show the environment in which the separation mechanism is operational. Obviously, the principles could be applied to the separation of any of the various upper stages in a multistage vehicle.
The upper stage (12) of a space vehicle (10) is provided with a pay load deck (14) for mounting auxiliary payloads. The satellite (15) is mounted over the separation mechanism (18) according to the invention in a conventional manner such as bolting.* The integrated assembly is mounted over the payload deck (14) by bolting. The details of the separation mechanism according to the invention are illustrated in figs. 2 to 4.
initiated rotate the retainer ring (20) to its release position.
Helical compression springs thrusters (26) mounted between the
upper adapter and lower adapter, provide the relative velocity to the separated stages. The spring thruster (26) which is telescopic is mounted to lower adapter (18) is held captive to the lower stage on separation.
Fig. 5 illustrates a prior art arrangement. The upper adaptor (27) mated to the lower adaptor (28) in a tongue and groove configuration are attached by bolting. Both the legs of the upper adaptor are pre-notched to define the severance plane. Mild delouating cord (MDC) contained within an extruded elastomer matrix introduced into an elliptically deformed stainless tube (29) is embeded in the groove of the upper adaptor (27). Both ends of the cords are connected to electrical detonators (30) through detonator transfer joints. Disconnection of the stages is achieved by the severance of the structure at the notched location due to the expansion of the elleptically deformed tube (29) into a circular section by the detonation of the MDC resultir^g in a shock pulse.
The operation of the seperation mechanism according to the invention is as follows,
Brior to separation of the satellite, the mechanism is checked to satisfy that it withstands all flight loads and environmental conditions. The satellite is free to separate from the launch vehicle when the retainer ring is rotated. Once the final stage is in orbit, and at the desired orientation, the satellite is ready to be separated from the launch vehicle. This is accomplished by igniting the pressure cartridges of the pyrothruster (24) thrusting against the lug of the rotatable retainer ring (20) will rotate the retainer ring (20) after shearing the screws (21) and all the balls (19) are released. Due to the spring force available at the interface, the separation is immediate and simultaneous along the entire circumference.
With the locking balls (19) removed, there is nothing to hold together the lower and upper adapters and the satellite is jettisoned. The entire operation takes place in a short Interval of time and with the necssary symmetry, the problem of tip-off is minimised. The rotation of the retainer ring (20) has to overcome only the frictional forces at the ball contact points, and the force required for the failure of shear screws
The Rftparati on mechanism (16 > consists of an upper adapter (17> provided with a flange for attachment with the satellite and a hul» liaving an annular groove to receive a portion of a set of balls interfacing with a lower adaper (18) The Jower adapter tiaving a i*ub mating with the upper adapter (17> in a tongue and groove arrangement and a f lange for bolting witti t Ite payload iler.di is provided with a number of holes to locate a set of balls (19). The balls (19) interposed between the upper adapter and lower adapter is held in position by a rotatable retainer ring (20 ) , The reta ii^er ring (20) has two positions namely a lock position and a release position. The retainer ring (20) is provided with radial holes (20A) for the escape of balls during release. The retainer ring The retairjer ring v 20 > is rotated through a specified angular displacement and is limited by a stopper (22). The stripper ( 22 > is mounted over the lower adapter ( 18) by bolts (23) and locating pin. A pyrothruster (24) for driving the retainer ring ( 20 > is mounted r»n a l^racket ( 2b > throvjgh threads provided on ttiem . Th*-; bn^ctiet, 1;^ mourt teri over t tie lower adopter ( IB ) by bo ( Is ( I 3 > ruirl 1 ».»*;at i?»g p in . 'I'tic pyro thruster (24) when
The operation of the prior art evtbodinent shown in fig. 5 is similar to the embodiment of the separation mechanism shown in figs. 1 to 4. However* it differs in the manner the separation is achieved. The disconnection of the stages is achieved by the severance of the connecting structure by the expansion of the elleptically deformed tube into a circular one by the explosive action associated with high shock level. From the above description, it can be seen that this invention has a particular advantage over prior art devices since it provides an arrangement which will allow separation of the stages with little or no "tip off" and shock level. It is further evident that the structure is extremely simple in design, with a minimum number of moving parts all of which enhance its reliability. The components of the separation mechanism are designed for ease of assembly. The separation structure is of minimum weight, the weight of the upper stage being further reduced by the method of attachment of all components to the lower adaptor. The operation of the separation mechanism according to the invention is achieved by the initiation of any one of the pyrothrusters, providing a foolproof arrangement and high reliability.
The bpper adapter and lower adaptor are mated in a tongue and groove ^cint configuration and is axially preloaded to improve the .ioxnt characteristics. Spring thrusters combined with
preloading struts maintained between the flanges enhance its load carrying capability. The retainer ring is radially preloaded and secured in position by a pair of brass shear screws and is made to rotate by the action of pyro thruster only. After the shearing of the said shear screws the separation of the stages occur. The rotation of the retainer ring by the action of a pair of pyro thrusters is achieved by initiation of any one of them. All components mounted on the lower adaptor ring automatically falls upon separation of the upper and lower stages, thus reducing the mass carried on the upper stage. The rotation of the retainer ring is capable of effecting simultaneous relase of all balls thus effecting a clean separation of the satellite. The separation is achieved with all the balls and sheared portion of the shear screw fully contained thus making the system free from flying debris and contamination. The rotation of the retainer ring has to overcome only the frictional forces and the force required to shear the shear screws. Therefore the energy released by the system on separation is considerably less resulting in a low shock.
The low shock ball-look separation mechanism according to the invention provides excellent results when used in launch vehicles.
1 . A low shock ball-lock separation mechanistic for separating upper stage from a space launch vehicle, comprising an upper adaptor (17) forming part of the upper stage (12) of the space launch vehicle, the said upper adaptor (17) being provided with an annular groove on its hub to receive a portion of a set of steel balls positioned in the holes provided on the hub of the said lower adaptor (18), a relatable retainer ring (20) having a lock position and release position to keep the balls in the holes provided on the hub of the lower adapter (18) in lock position, radial holes being provided in the said retainer ring (20) for the escape of balls in the release position, at least a pair of thrusters (24) being provided for rotating the retainer ring (20) with respect to the lower adaptor (18) to a predetermined position and a mechanical stopper (22) being mounted on the lower adapter (18) for stopping the rotation of the retainer ring (20) and move the locking balls (19) radically outwards due to the action of the compression springs (28) positioned between the flanges of the upper adapter (17) and lower adapter (18) for forcing them apart and separating the upper stage from the launch vehicle upon initiation of the said thrusters (24).
2- A separation mechanism as loaned in claim 1, wherein the
said thrusters (24^ are pyrotechnic thrusters.
3. A separation mechanism as claimed in claims 1 or wherein
the retainer ring (20) is preloaded radically and secured In
position by a pair of brass shear screws (21).
4. A separation mechanism» as claimed in any one of the
previous claims» wherein the retainer ring (20) is provided with
a pair of lugs enabling the retainer ring to rotate with respect
to the lower adapter (18),
5. A separation mechanism, as claimed in any one of the
previous claims, wherein the upper adapter (17) and the lower
adapter (18) are mated to form a tongue and groove joint
6. A low shock ball-lock separation mechanism for separating
upper stage and satellites of a space launch vehicle,
substantially as hereinabove described and illustrated with
reference to the accompanying drawings,
|Indian Patent Application Number||36/MAS/2000|
|PG Journal Number||13/2008|
|Date of Filing||13-Jan-2000|
|Name of Patentee||INDIAN SPACE RESEARCH ORGANISATION|
|Applicant Address||ANTHARIKSH BHAVAN, NEW BEL ROAD, BANGALORE 560 094,|
|PCT International Classification Number||B 64 G 1/00|
|PCT International Application Number||N/A|
|PCT International Filing date|