Chemistry: electrical current producing apparatus – product – and – Cell support for removable cell – For plural cells
Reexamination Certificate
1998-06-15
2001-03-27
Maples, John S. (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Cell support for removable cell
For plural cells
C429S120000, C429S158000, C429S186000, C244S158700
Reexamination Certificate
active
06207315
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to spacecraft battery systems and, more particularly, to a technique resulting in a more compact arrangement of battery cells in a spacecraft.
2. Description of the Prior Art
Conventional two dimensional battery packaging methods need more spacecraft resources (mounting space, mass and heat pipes) to handle the increased number of battery cells required for higher power. Double stacking cells (arranging them three dimensionally as recommended in this disclosure) greatly reduces these resource demands. Present spacecraft place all battery cells in one plane (a two dimensional arrangement) on a panel which is directly mounted to a thermal radiator with embedded heat-pipes. Demands for greater eclipse power increase the number of cells so the two dimensional area devoted to batteries must also increase. Arranging battery cells in two planes with a common mounting plate between them allows for a more compact arrangement so the battery assembly can be removed from the spacecraft faces (a limited mounting area resource) and placed remotely.
Present spacecraft already use up all the north/south panel mounting area reserved for payload but conventional two dimensional batteries will require some of this area as payload power increases. The mounting area saved by three dimensionally arranged battery cells can now be devoted to adding payload Modern satellite geosynchronous satellite batteries comprise a series connection of cells (most commonly nickel hydrogen cells at the present time) and include a suitable construction for distributing heat within the battery and removing excess heat. The series connections and thermal subsystems are typically carried out by distributing the individual cells across a two dimensional planar surface.
It was with knowledge of the foregoing state of the technology that the present invention has been conceived and is now reduced to practice.
SUMMARY OF THE INVENTION
The present invention relates to a spacecraft battery system according to which battery cells are arranged in two planes with a common mounting plate between them allowing for a more compact arrangement. By so doing, the battery assembly can be removed from a limited mounting area resource of the spacecraft such as the north/south faces and placed remotely. To this end, a first cellular network comprised of a plurality of battery cells in electrical continuity are mounted on and spread in a single plane over a first mounting surface of a planar mounting panel and a similarly constructed second cellular network is mounted on and spread in a single plane over a second, opposed, mounting surface of that same planar mounting panel, the plane of the second cellular network being spaced from the plane of the first cellular network. The system includes a plurality of heat pipes embedded in the planar mounting panel and thermally connected with each of the battery cells for distributing heat uniformly across the planar mounting panel. The system also desirably includes a thermal radiator for radiating heat to deep space and heat conducting means thermally connecting the planar mounting panel to the thermal radiator means for drawing heat away from the planar mounting panel and to the thermal radiator means.
FIG. 1
illustrates a typical location of a battery assembly
20
adjoining a bus equipment assembly
22
for a spacecraft
24
(such as a geosynchronous spacecraft) where a pair of opposed faces are generally kept away from direct solar energy impingement. In a geosynchronous communications satellite, these faces are called the north and south faces
26
,
28
, respectively, and are the prime panel mounting areas and thermal radiators for the bus equipment, batteries and communications payload equipment. There is limited area for mounting all equipment directly onto these thermal radiator panels so if the batteries require more mounting area, then the communications payload equipment mounting area and or bus equipment mounting area must be reduced to compensate.
FIG. 2
illustrates a conventional battery technique, a two dimensional arrangement in which a plurality of battery cells
34
for a battery
36
mounted on a panel
38
are spread in a single plane over the prime battery panel mounting area. There may be embedded heat pipes (not shown) in this battery radiator panel which are used to isothermalize all the battery cells to produce a more efficient battery. In this instance, the battery assembly shares real estate with the bus equipment panel. However, higher power spacecraft of the future will require larger batteries which will result in more prime panel mounting area devoted to batteries and less to the equipment the customer really desires, such as the bus equipment.
FIG. 3
illustrates a representative application of the single plane (two dimensional) technology to an advanced spacecraft with higher power requirements for eclipse, depicting a modified enlarged battery assembly
20
A and a smaller bus equipment assembly
22
A, for example.
FIG. 4
illustrates a perspective view of a conventional battery mounting arrangement.
FIGS. 3 and 4
illustrate that as the number of battery cells
34
increases, the prime panel mounting area devoted to batteries increases proportionately so that the battery assembly
20
impinges into areas previously reserved for the bus equipment assembly
22
which then must be transferred to the communications payload equipment panel mounting area
40
as seen in FIG.
5
. The problem is that higher power is being sought so as to increase the payload capability of the spacecraft
41
but the negative result is a decrease in the prime area available for payload mounting below what is provided today.
One way to mitigate the loss of panel mounting area for higher power spacecraft is to develop battery cells with higher capacity but the same mounting footprint per cell. These larger cells can then yield the required higher total watt-hour capability while maintaining the same battery panel mounting area as a lower power spacecraft. However larger battery cell developments are costly and time consuming and entail program schedule risks. The simplest implementation of higher power is to increase the number of battery cells.
Another way to maintain payload equipment mounting area is to move the single plane (two dimensional) of battery cells
34
internal to the spacecraft
42
as illustrated in FIG.
6
. The problem with this implementation is that it occupies a substantial volume. It is very difficult to isothermalize (i.e., maintain isothermal conditions within) a battery spread over this large area and there are many possible leakage paths for heat to degrade the low temperature environment favored by the batteries. Also, since the batteries must have their own separate and unique temperature environment they must be heavily blanketed and blocked from viewing the very hot communications payload equipment. But effectively accomplishing this thermal isolation also blocks crossbody thermal radiation paths that are needed for cooling the propulsion fuel as well as all of the electronics for the spacecraft.
A three dimensional battery packaged in two or more planes of cells provides an effective means for decreasing the prime panel mounting area devoted to batteries and is the essence of this invention.
A primary feature, then, of the present invention is the provision of a technique resulting in a more compact arrangement of battery cells in a spacecraft.
Another feature of the present invention is the provision of a spacecraft battery in which the individual series connected cells are distributed in three as opposed to two dimensions resulting in a more compact battery design that consumes less mounting area on the spacecraft and thereby allows the spacecraft to carry additional equipment.
Still another feature of the present invention is the provision of such a spacecraft battery equipped with internal mounting planes which in turn contain heat pipes to distribute heat
Gelon Walter S.
Hall John C.
Maples John S.
Perman & Green LLP
Space Systems Loral, Inc.
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