Batteries: thermoelectric and photoelectric – Photoelectric – Panel or array
Reexamination Certificate
1999-12-03
2001-09-04
Chapman, Mark (Department: 1753)
Batteries: thermoelectric and photoelectric
Photoelectric
Panel or array
C136S292000
Reexamination Certificate
active
06284967
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a solar generator, particularly for spacecraft. The solar generator or collector comprises panels that are stowed as a packet for transport and unfolded for deployment.
BACKGROUND INFORMATION
Solar generators or collectors are commonly used as power supplies for spacecraft such as telecommunication satellites. The terms “generator” and “collector” are used interchangeably herein. Solar collectors have panels that are initially folded for stowing the collector while transporting the satellite into an earth orbit. The panels are unfolded into an open state for deployment when the orbit has been reached. During the transport phase the collector shall need as little space as possible. On the other hand, the deployed surface area shall be as large as possible for transforming solar energy into electrical energy. Moreover, the deployment of the collector must be possibly free of trouble in order not to imperil the satellite's mission. Thus, a high degree of reliability particularly in the unfolding of the solar collector is necessary. Moreover, in order to test the kinematic and dynamic characteristics of the collector panels during an unfolding operation it must be possible to simulate such unfolding under gravity conditions on earth. Such testing must be possible with a minimum effort and expense.
Conventional solar generators of this type have a number of panels articulated to one another and foldable as well as unfoldable in a particular direction similar to the movement of the pleats of a bellows. The total deployed surface area of such solar collectors is limited by the acceptable maximal longitudinal extension of the panels away from the body of the satellite.
U.S. Pat. No. 4,988,060 (Janson et al.) discloses a solar collector with a plurality of panels interconnected to form panel wings which are symmetrically secured to a spacecraft. Hinges are arranged in alternate fashion along ridges of the individual panels sections so that the sections can be pulled out in the manner of pleats and folded back together into a package.
U.S. Pat. No. 4,293,731 (Schweig et al.) discloses a solar collector of lightweight construction including foldable panels. Journal pins passing through a journal loop and through a forked coupling provide hinges for the folding and unfolding.
European Patent Publication EP 0,754,625 A1 discloses a solar generator in which a first group of panels is foldable and unfoldable in one direction while further panels are foldable and unfoldable in a second direction. Such a structure increases the deployed surface area of the collector. The individual panels of the first group are connected by hinges and the panels of the second group are hinged to the first panel so that they can be flapped open. However, flapping open the panels of the second group causes relatively large disturbing moments that adversely affect the flight of the spacecraft. Another drawback is the fact that testing such generators with flap open motions under earth gravity conditions require a substantial effort and expense.
German Patent Publication DE 197 13 363 A1 discloses a method for increasing a surface area by first stacking surface elements that are partly interconnected by flap hinges and then unfolding the elements in the manner of a paper folding operation.
Aviation Week+Space Technology; Aug. 14, 1967, pages 72 to 88, describes in an article “Requirements for Solar Arrays Spurring New Techniques” various roll-up solar cell arrays.
Roll-up techniques can provide relatively large surface area panels when deployed. However, deployment can be problematic.
“Raumfahrtforschung” (Space Travel Research), Vol. 5, 1969, pages 205 to 212, describes in an article “New Technologic Methods for Solar Cell Devices” various requirements that must be met by solar collectors suitable for space travel. Advanced panel fabrication methods are disclosed that permit welding panel components and avoid using adhesives. Roll-out and fold-out collectors are described.
OBJECTS OF THE INVENTION
In view of the foregoing it is the aim of the invention to achieve the following objects singly or in combination:
to avoid drawbacks of conventional solar collectors, more specifically to provide folding and unfolding features that will avoid or at least substantially reduce imposing of disturbing moments onto the spacecraft to which the collector is mounted;
to combine rotational folding movements of individual first panels relative to each other with compound movements including lateral, linear motion components of second panels to avoid generating undesirable torque moments;
to optimize the available collector surface area in its deployed state relative to the collector's weight;
to assure a reliable deployment of the collector panels and their retraction into an inactive state under all operating conditions; and
to facilitate the testing of folding solar collectors under earth gravity conditions.
SUMMARY OF THE INVENTION
A solar generator according to the invention comprises the following features in combination. A plurality of first solar collector panels are articulated to one another for folding and unfolding said first collector panels in a rotating motion in a first direction (D
1
). At least one second collector panel is journaled by couplers to one first collector panel, whereby the couplers enable said at least one second collector panel to follow a compound motion including a lateral linear motion component extending in a second direction (D
2
) for laterally shifting said at least one second collector panel when said at least one second panel is unfolded or folded.
Preferably, the first and second motion directions extend perpendicularly to one another so that the at least one second panel, due to its coupling to one first panel, can follow a lateral linear motion component perpendicularly to said first direction when said at least one second panel is folded or unfolded in said second direction. Preferably, the unfolding of the second panels can take place only after the first panels or panel packets have been unfolded in the first direction.
An important advantage of the solar generator according to the invention is its ability to have a substantially larger collector surface area without increasing the collector length away from the spacecraft compared to conventional collectors. Further, the folding and unfolding of the present solar collector panels does not exert on the spacecraft torque moments that could have an adverse influence on the spacecraft or space flight body. Still another advantage is seen in that the foldability of the present collector panels is highly reliable because simple articulation hinges and coupling journal elements are employed. It is unexpected that the combination of two motion directions for the folding and unfolding of the panels is as reliable as the folding and unfolding of a conventional panel combination that permits folding and unfolding in only one direction. Moreover, the present folding operations can be tested on the ground under gravity conditions with little effort and expense.
According to the invention the first panels or packets of first and second panels are articulated to one another by hinges permitting the deployment out of a folded, stacked condition into an open operative position by first pulling the first panels or packets apart in the manner of bellows pleats and then shifting the second panels laterally out of the packets.
According to one embodiment of the invention (
FIGS. 1 and 2
) first panels are sandwiched between second panels in the stacked condition to form packets (
FIG. 2A
) each including at least one first panel and at least two second panels. In a second embodiment (
FIGS. 3 and 4
) the packets contain two panels with a first panel positioned on top of a second panel, whereby a stack formed of such packets comprises a second panel at the bottom and a first panel at the top of the stack with first and second panels stacked therebetween (FIG.
3
A). In a third embodiment (F
Hakan Alo
Seifert Frank
Chapman Mark
Daimler-Chrysler AG
Fasse W. F.
Fasse W. G.
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