DE29700839U1 - Solar cooker - Google Patents

Description

Andreas Wem .I.*..* *..* ·&idigr;· ··' *

Hauptstr. 43 g

79689 Maulburg Maulburg, 16.1.97

Solar cooker

Description:

The invention relates to an alternative type of solar cooker. Solar cookers are devices for using solar thermal energy that convert sunlight into 'concentrated heat'. There are box cookers in which the sun's radiation falls through a glass or foil cover into the light-absorbing cooking chamber, reflection cookers that concentrate the radiation under a pot using a parabolic or concave mirror made of glass or reflector foil, and collector cookers in which a heat carrier is heated up in radiation-absorbing channels and gives off the heat to the food being cooked. Box and collector cookers are suitable for cooking or baking, reflector cookers for cooking, baking and frying. The net efficiency of reflector cookers is the highest at over 50% [Staatsinstitut für Schulpädagogik und Bildungsforschung München 12/92, pilot project on environmental education "We cook with the sun"]. Other applications of solar cookers are drinking water treatment, distillation of water, drying and commercial use in dyeing works, but also power or electricity generation by means of parabolic Stirling engines or cooling via zeolite dehydration [Stefan Zech: Refrigerator with solar drive, FH Munich 1995].

Disadvantages of many cookers (especially the concave mirror cooker) are the complex design and manufacture, high weight, susceptibility to damage, instability and sensitivity, risk of glare, high adjustment and cleaning effort, large space requirements and the difficulty in dismantling.

The cooker shown in Fig. 1 is modular and essentially consists of a magnifying glass/mirror system and a support frame. It uses a Fresnel lens that creates a focal spot, the beam cone of which is deflected by a flat mirror. Collecting Fresnel lenses are used in lighthouses, overhead projectors and spectacle optics, as condensers, burning glasses, reading magnifiers, etc. A V-shaped, variable-aperture bracket 1 holds a Fresnel magnifying glass 3 with its extendable leg ends 2 and with the other end brings a flat mirror 4 into the beam path at an oblique angle. The distance of the mirror from the magnifying glass can be adjusted using the leg ends. The beam deflection can also be varied using the tiltable mirror holder 5 and the adjusting screw 6. This magnifying glass/mirror system is rotatably mounted in the slots of the support frame 7, 8. The axis of rotation between the legs 8 of the support frame is also designed as an absorber holder 9 and is located in the focal point of the deflected beam cone. The legs 10 hold the V-bracket 1 from the pivot point at a distance that can be changed in stages. A cable winch consisting of a crank axle 11, rotary knob 12, cable 13, deflection pulley 14 and a friction device 15 adjusts the magnifying glass/mirror system to the vertical position of the sun. The azimuth is adjusted by moving the support frame on the ground. An additional mirror 16, which is connected to the

Andreas Wem .&iacgr;. *..* *..* ·&idigr;· ··* '

Main Street 43g

79689 Maulburg Maulburg, 16.1.97

(Continued description of solar cooker)

connected to the support frame 8, illuminates the food being cooked or the consumer !8 and at the same time provides glare protection.

The advantages of the magnifying glass cooker are the light, inexpensive and robust Fresnel lens made of plastic film and its availability in various sizes and focal lengths. The cooker frame and the lens have good focal spot stability. The magnifying glass cooker can be refilled continuously vertically and horizontally according to the position of the sun. Furthermore, a continuous change in the focal spot diameter is possible and by using different magnifying glass sizes, different cooking performances are also possible. Further advantages are the adjustable beam cone deflection, simple and quick dismantling, low maintenance, high stability and good glare protection and lighting options for the heating point. Various consumers, e.g. a cooking pot, zeolite cartridges, a Stirling engine, fuel and melting material, etc. can be placed in the absorber holder 9. The device is therefore very suitable for exhibition or training purposes in the field of technology, optics, solar technology and, depending on the dimensions, both as a toy and for real practical applications.

Claims (3)

Andreas Wem .&idigr;. *..* '.·* ·»· ··* * Hauptstr. 43g 79689 Maulburg Maulburg, 16.1.97 Solar cooker Protection claims: 1. Solar cooker according to Fig. 1 for focusing light under a consumer 18, characterized in that - a Fresnel magnifier 3 is used for focusing or - different sized magnifying glasses or powers can be installed using the V-shaped or variable opening bracket 1 (top view not shown) or - the beam cone of the magnifying glass 3 is deflected by a flat mirror 4 or - the new focus location 9 is outside the light cone close to the magnifying glass or - the lens/mirror system is rotatably mounted in each focus location 9 or - a fixed consumer mount 9 is installed in the new focus location or - the focus location and focal spot diameter can be variably adjusted within certain limits. 2. Device according to claim I, characterized in that - the new focus location can be changed or fixed using a tiltable mirror holder 5 and the adjustment screw or - the focal spot diameter can be continuously adjusted by changing the magnifying glass/mirror distance using the leg ends 2 or - the focal spot diameter can be increased by gradually lowering the axis of rotation or absorber holder 9 on the legs 10. 3. Device according to claim 1 and 2, characterized in that - the magnifying glass/mirror system is hung from above in slots (not shown) of the support legs 8 and can be removed without additional disassembly or - the cooking area or the consumer 18 can be illuminated by an additional and movable mirror 16 or this can serve as a glare protection.