FR2787867A1 - Solar oven has supple mirror with umbrella-type frame mounted on cradle support so it can be aligned with sun - Google Patents

Abstract

The solar oven consists of a supple mirror made especially from a plastic with a reflective or metallised surface in the form of an umbrella with ribs that allow it to be deployed for use or folded for transport. The mirror is suspended from a tubular structure (4) mounted on an astronomical cradle support by means of a shaft in North and South bearings (7, 8) and a wheel (12) for aligning it with the sun. The mirror reflects the suns rays onto a cooking pot suspended at its focal point.

Description

SOLAR OVEN

  It is known that in many developing countries the only energy used by people who generally have very little resources comes from wood. Its exploitation by levies on large areas, and on sites increasingly distant from places of life, is the cause of deforestation, and moreover this activity induces great fatigue for the populations - in majority

  women - researching and transporting wood.

  The oven object of the present invention is

  intended more particularly for countries with strong sun-

  In addition, o in general the population has only scarce resources. It makes it possible, from solar energy exclusively, to produce for example cooking by heating pots, or of elements with a view to grilling food, the latter after heating being usable outside the instrument; for by

  for example, heating water, or performing sterilization

  tions; or to heat ceramic cartridges

  that, intended for the energy supply of refrigerated-

absorption rators.

  The solar oven according to the invention, described below, and not limitation is constituted - Fig.1 and 2, Pl.1, and Fig. 3, P1.2 of the following organs: - a telescope, whose mirror reflecting sunlight is made of flexible material (1), preferably plastic, having a high reflecting power, or even by a metallized fabric

surface.

  The plastic material - such as mylar or other - is stretched over a structure comprising whales (3), articulated and flexible, secured to one end of a

  tubing (2), foldable like an umbrella.

  This structure, once unfolded, gives the "mirror"

  the concave shape close to a spherical cap (1).

  This cap is suspended from a structure in tubes (4), plugged in and blocked in connecting elements (5), constituting the body of the telescope, and being presented as a triangulated assembly of high rigidity,

for low weight.

  L The fireplace (F) - Fig. 3 coincides with the container or the object collecting the energy, such as the pot

figured in (13).

  An orifice (6), in the center of the cap, makes it possible to evacuate the rain water, or the liquid which may fall from the pot during handling, and also to carry out

  cleaning the "mirror" of the instrument.

  - a mount, of the cradle type, comprising only one axis of movement, north / south axis, called polar, and supported by 2 bearings: one (7), north bearing (for the northern hemisphere) , and the other, south landing (8), each

  these bearings preferably being provided with a roller

ball bearing.

  The bearing soles are supported at (9), on the top of 2 masonry pillars supporting the instrument, by the axis of the cradle (10) of the mount; this axis is provided with a counterweight (11), in the form of a

can filled with sand for example.

  At the level of the bottom bearing (8), the axle carries a wheel

  (12) - for example a bicycle - allowing handling

  lation, timing and manual -or automatic-

  of the frame in relation to the sun.

  The frame according to the invention has the originality of not having a setting axis in declination

  (axis D); the instrument being exclusively for solar use

  re, and the sun moving during the year relative

  in the ecliptic plane from + to - 15, depending on the

  sounds, axis D is deleted; but to capture during

  all year long solar energy corresponding to the ob-

  jective of desired power, the plastic cap is brought to a diameter such that the practical opening of the instrument (1.3m in the project drawn in Fig. 1 and 2) is housed in a clearance of + and - 15,

  or a total diameter of the cap of 1.8 m.

  An indirect advantage of the device is that if

  limits of -15 or + 15, the opening of 1.3m, corres-

  lays at the nominal power of the instrument, as

  and as the sun approaches the plane of the eclip-

  tick, we have an overpower, which reaches in the ecliptic, a value in the ratio of surfaces

(about 1.9) ..

  - Guidance (for morning aiming and centering

  throughout the day) can be done manually-

  is lying. A screen (23), Fig. 4, P1.3, perforated with 2 perpendicular slots (25), is integral with one of the tubes of the structure. With the instrument pointed at the sun, the image of the cutout (25) is silhouetted on the screen (24), in the form of a bright cross (26). The screen (24) carries in its center an engraved circle (27) in which the image (26) is inscribed exactly, when the optical axis of the instrument points the sun (Z, Z), align with the same figure, between the center of the cross (25) and the center of the circle (27) is parallel to this optical axis. Centered on the circle (27), a rectangle

  also engraved on the screen, taking into account the displacement

  ment of the declining sun, determines the zone of the limiting displacement of the image of the cross on the screen, such as in (29), corresponding to the limiting displacement

  of the solar image on the pot to heat.

  - Movements of the frame along the axis

  polar, are carried out by means of the maneuvering wheel

  vre (12), to maintain the image of the cross in the rectangle engraved on the screen, and therefore maintain

that of the sun on the pot.

  This wheel (12) is provided with 180 (passage of the horizontal

  area on the west horizon) at the rim,

  notches (20), 60 in number for example. Space-

  ment of these notches corresponds to the fact that the image of the sun, while the frame remains fixed, blocked

  on a notch, always forms on the pot.

  The immobilization of the wheel is obtained by a pin which comes to be embedded and blocked by simple wedging in a support (22) integral with the pillar (9). When the sun's illumination of the cross

  on the screen reaches the engraved outer frame, the opera-

  tor removes the ankle, shifts the wheel a notch,

and fixes the ankle again.

  A notch disposed in position such as (23), immobilizes the frame in the rest position, such

that it appears in FIG. 1.

  An improvement of the instrument, starting from

  the bicycle wheel used without tire, makes it possible to

  read an automatic frame drive; the wheel constitutes a winch, provided with a flexible link passing through the hollow part of the rim. This winch is integral with the drum of a weight unwinder; equipped with a speed stabilizer (fin regulator)

  - or by an engine of suitable power - for

  rer by means of such simple mechanics, a drive-

  only requiring image monitoring

forming on the screen.

  - The container constituting the target is essential -

  built to optimize the capture of solar energy: it is advantageously black in color,

(for example in cast iron).

  The pot to be placed in the hearth of the instrument is suspended, according to the invention, to a bracket (14) in a fixed position at the hearth, during heating; to remove it from the instrument, rotate the bracket (14) by a quarter of a circle, the vertical pole of the bracket pivoting in a crapaudine, secured

of the pillar.

  The suspension is carried out by a cable sliding in the tube of the stem, cable provided at one of its ends with the hook for suspending the pot, at the other with a handle provided with a fixing ring; two pitons arranged on the pillar allow the immobilization in 2 positions: Pot located at the focus of the instrument, in position (13), heating position; the cable which supports it is hooked to the locking pin, in the "HT" position. The heating finished, we rotate the stem; the pot moves from position (13) to position (16). To remove the pot, we go up the cable by means of the handle, to the locking pin, in position

  "BS", to allow the dropout.

  The rotation of the stem to obtain its correct position

  tion - pot at hearth level - is stopped by means of cleats secured to the vertical post of the stem; these cleats (17) come to rest on

positioning plates (18).

  The operation of the furnace according to the invention has been simplified by the fact that in the design of this instrument, the following objectives have been privileged:

  - easy integration in developing countries

  pement, for users who do not usually have access to complex tools; everything that could

  appearing too sophisticated has been eliminated.

  -the oven does not require any particular precision in

  the initial assembly, nor for its daily use.

  - great ease of transport: all the components are removable or foldable; all the elements of an oven

  complete can be transported without problem.

  -the local workforce, given the extreme simplicity of the device, can realize the necessary infrastructure (low walls), and the assembly: tubes of the structure encased in end caps; axis (polar) mounted on 2 ball bearings, accepting faults

  alignment, and simply pegged on the walls.

  -the whole is thus achievable locally under the guidance of a guide who will provide initial training, allowing subsequent assemblies without assistance,

  from the supply of organs such as: col-

  energy reader (flexible cap), pole axis and bearings, structure tubes, manipulation wheel, bracket and suspension cable, setting stop, screens

pointing and guiding.

  -the use of a pot, of a type similar to that used on traditional stoves, by the populations concerned, should not cause any destabilization of these populations. Its handling is simple and without

  danger: the pot is always fixed during heating

  ge; it is the instrument that turns around.

  -the reliability of the oven, which does not include any automation, but only stalls against stops, and

  blocking by dowels and notches, allows exploitation

  long-term operation without mechanical maintenance, and operation without any other source of energy than

solar energy.

  -the oven presents little danger. Apart from the risk of burns, identical to that which is encountered in the case of traditional homes (boiling water), the risk due to the direct action of the sun is very reduced20 by the fact that access to the home of the instrument East

  almost impossible accidentally.

  The power obtained is particularly suitable

  for the treatment of heating problems envisaged

  managed by means of a solar oven according to the invention.

  For example, with a cap as mentioned on pages 2 and 3, opening diameter of the telescope of 1.3m, and taking into account the efficiency due to the optics chosen, it is possible to obtain approximately 2 5 to 3 kW of power, and reach more than 5 kW of power

  in times when the sun is in the plane of the ecliptic

  than. With a useful opening mirror of 1 m, i.e. a shell diameter of 1.4 m, while having an oven of around 1.5 to 3 kW, it is possible to reduce

  total footprint within 2 m.

  By way of example, and without limitation, the most interesting applications which can be treated with a solar oven, as described according to the invention, must be cited: - obtaining hot water in order to produce in particular cooking in a pot.

  - heating of plates or bricks (lo-

  wedge), placed in place of the pot, at the hearth, maintained in a metal net, to obtain cooking grids, used outside the instrument, or even allowing water heating, by immersion

  hot bricks in containers full of water.

  - obtaining a baking oven, by hanging the hearth of the instrument, a terracotta enclosure (of local manufacture); indirect cooking, with the body

  hollow used after heating, outside the instrument.

  - heating of irons, arranged in the metallic net

  at the focus of the instrument, to treat tissue.

  - pasteurization or sterilization of milk.

  - distillation of water, by installation in the hearth of the

boiler of a still.

  - sterilization of surgical instruments, sterilization

sator being placed in the hearth.

  - refrigeration: heating of ceramic cartridges, in the metal net, to constitute the heating element

  fant of an absorption refrigerator.

  Still as an example of ration use-

  nel of solar ovens according to the invention, the installation

  tion of several large, high-power solar ovens, allowing the treatment of products for collective use, each of them being more particularly permanently fitted with an adapted accessory such as, among those mentioned above: distilled water production, sterilized milk production

  or sterilization of surgical instruments.

Claims (10)

  1 / The solar oven according to the invention is characterized in that it is constituted by a telescope whose organs to be heated are arranged at the level of the hearth   of the device, constituting a simple, useful instrument   exclusively using solar energy to meet cooking and heating requirements in developing countries, and replacing the use of traditional fireplaces using wood as fuel. 2 / The solar oven according to claim 1, is characterized in that the instrument, constituted by a telescope, whose mirror collecting the energy (l) is produced by means of a flexible, reflecting wall, by the nature of its constituent material, or by metallization of its surface.   3 / The solar oven according to claims 1 and   2, is characterized in that the structure of the mirror with flexible wall, is integral with a frame such as that of an umbrella, formed of articulated ribs, (3) and a tube, the whole being able to be deployed and folded , like a parasol, allowing easy transport.   4 / The solar oven according to claims 1, 2   and 3 is characterized in that the telescope collecting   solar energy, is attached to an astronomical mount /_(.10).   cradle mique, the polar axis being supported by 2   bearings, preferably with ball bearings.   / The solar oven according to any one of the claims   dentes prce / is characterized in that the cradle mount does not have a declination axis, supported by the polar axis, allowing the pointing of the instrument on the sun, moving from - 15 to + 15 relative to the plan of the ecliptic; and that this deletion is   compensated in the instrument by an opening of the cap   constituting the concave mirror, such as this   nière covers the theoretical opening of an instrument moving from -15 to + 15 relative to the plane of 1 ' ecliptic during the year.   6 / The solar oven according to any one of claims   Précé / dIeSaractérisé in that having a mirror covering the declination offset of +/- 15 from the plane of the ecliptic, allows to have an increasing power as and   as the sun gets closer to this plane.   7 / The solar oven according to any one of claims   previous / dentggt characterized in that the guide and the   dragging of the instrument pointed at the sun, are performed manually, by leaps and bounds, by means of a wheel (12), integral with the polar axis (10), allowing the maneuver, and provided with notches (20) in which passes a pin (21), blocked in the orifice of a support (22) fixed in the frame, and ensuring the immobility of the telescope after the pohntage. The spacing of the notches between them is such that the image of the sun on the container (13) passes completely through the latter, before it   it is necessary to shift the instrument a notch.   to have the image presence again solar on the container.   8 / The solar oven according to any one of the claims   your previous / is characterized in that the drive wheel (12), of the polar axis (10), for the automation of the frame is driven by a flexible link, wound on a drum secured to a motor,   9 / The solar oven according to any of the references. /previous.-   ons is characterized in that the aiming and guiding device on the sun is produced by means of a diaphragm (23) on the one hand, and a screen (24) on the other hand   on the center of which is drawn the drawing of the perfora-   tion (26) of the diaphragm, the center of the perforation (25) of the latter, and the center of the design (27) on the screen being on an alignment parallel to the axis of the telescope. The screen comprises a second trace (28) corresponding to the limits of displacement of the image of the perforation of the diaphragm, during the displacement of the sun, the frame being locked on a notch of the drive wheel, and therefore, of the displacement of the image   sun on the container, receptacle of energy.   / The solar oven according to any one of the res-   dications preceding, is characterized in that the mount allows the complete reversal of the telescope, the flexible cap constituting the mirror can be oriented convex faxe towards the zenith, to constitute a position of rest and protection in bad weather and rain; the instrument is locked in this position by the stop pin (21) passed through a notch (23) of the drive wheel provided for this purpose. The different operations of the frame are facilitated by the fact that the instrument is in indifferent equilibrium around the polar axis (10), thanks to the adjustment achievable by the counterweight. (11) hollow, filled with sand.   11 / The solar oven according to any one of the claims   tio / ngst characterized in that the energy receptacle (13) preferably consisting of a container, is fixed relative to the ground, the instrument rotating around it. This member, preferably black and metallic, is suspended by a cable from a pivoting bracket (14), around its mast forming the axis of the bracket (15); the container can thus take two positions, defined by means of 2 retainers, (BS) and (HT) on which the cable operating handle hangs: one, high position (HT), the container is held at focus of the telescope, the other, after   pivoting of the stem - to position (16) -   low position (BS), allows to bring the container to the ground level.   12 / The solar oven according to any one of the res-   dications previous is characterized in that the ins-   trument is made with folding and dismountable members, such as the mirror made of flexible material (1), stretched on a structure with whales (3) articulated like an umbrella, or even that the single axis (10) of   the mount is mounted on 2 bearings (7) and (8).   13 / The solar oven according to any one of the res-   dications previous is characterized in that the ins-   trument allows to heat a liquid housed in a container - placed at the center of the instrument - forming   pot (13), as well as full or hollow bodies -   placed in a net at the focus of the instrument- forming grill or oven.