AU422248B2 - Cooking gas heater - Google Patents

Description

S20,392/70 The present invention relates to a cooking gas heater ani more particularly to a cooking gas heater having a heating plate providing a uniform heat distribution thereon. Heretofore, a so-called Schwank burner in which a heat resistive plate provided with a number of holes to spout flames therefrom has been generally used. The Schwank burner has a disadvantage that it is in danger of backfiring in the event the supply of the gas and air mixture is reduced and the nozzle is overheated. Accordingly, the Schwank burner has been required to be equipped with a fire controller to safely control the heating temperature of the burner. The construct- ion of the gas heater of this type is therefore complicated. There is known another type of a cooking gas heater. which employs a ring burner. This type of a gas heater has a defect that the central and marginal portion thereof provides high temperature and the annular intermediate portion has extremely low temperature. It has been, therefore, very difficult to obtain a uniform temperature distribution in the cooking gas heater devices. Under the above state of the art, it has been long desired that a novel and improved cooking gas heater should be developed. It is, therefore, the primary object of- the present invention to provide an improved cooking gas heater which provides a uniform temperature distribution and has no danger of backfire. Another object of the present invention is to provide a cooking gas heater having means for uniformly heating the food thereon. A further object of the present invention is to -2 22

20,392p70 provide a cooking gas heater having means for preventing backfire. A still further object of the present invention is to provide a cooking gas heater in which the heating plate is provided with a heat insulating p11te6fixed thereto on the backlsurface thereof to effect a uniform temperature distribution thereon. Other objects and features of the present invention together with the advantages thereof will be made more apparent from the following description taken in conjunction with the accompanying drawings in which the single figure shows a cross sectional view of the gas heater for cooking in accordance with the present invention. Now referring to the drawings, the reference numeral 1 denotes a mixing tube of L-shape having at the top end thereof- a nozzle 4 and at the lower end portion thereof an air intake hole-3. The lower end of the mixing tube 1 is connected with a gas pipe 2 to supply gas fuel. The mixing tube 1 is enclosed in a casting consisting of a side wall 10 and a bottom 12 respectively having at least one air exhaust port 9 and a secondary air intake hole 11. The side wall 10 is provided with a heat resistive heating plate 5 fixed or fitted thereon. The nozzle 4 of the mixing tube 1 is located at the central portion of the casing, and around the nozzle 4 there is a heat resistive heat insulating plate 7 having a hole 8 to let the top portion of the mixing tube extending therethrough. The heat-resistive heat insulating plate 7 is made of prous heat resistive material whichwill-insu-ate-the heat andLradiates/ Sthee-heafc-as-a 3-cndary heat source. The -baceksurface of the

heating plate 5 is provided with a layer of fire-proof heat

20,392. 17 insulating material 6 coated thereon. The fireproof heat insulatinq material may be ceramic or mixture of ceramic heat resistive cement and perlite. The layer of the heat insulat- ing material is provided on the back surface of the heating plate 5 over a _range smaller than the whole size of the plate with a proper thickness to soften the direct heat against the plate when the gas fuel is supplied into the mixing tube through the gas pipe 2, the gas is mixed with air taken in through the air intake 3 of the tube 1 and the mixed fuel is spouted out of the nozzle 4. if the gas-spouted out of the nozzle 4 is set off the gas is burned with the aid of sufficient supply of air introduced through -the secondary air intake hole 11 at the bottom 12 of the casing. The flame spouted out of the nozzle 4 located at the center of the casing under the heating plate is made to extend horizontally between the heating plate with the heat insulating layer, 6 and the heat insulating plate 7. Thus, the heating plate 5 is indirectly heated and the heat insuiated.'plate 7 is directly heated by the flame. in accordance with the cooking gas heater of the present invention, the heating plate 5 to heat or cook the food placed thereon-is indirectly heated by the combustion gas. Since the surface combustion is performed on the surface of the heat insulating material layer 6, the incomplete combustion at the initial stage of combustion can be prevented1 and the temperature efficiency is improved. And since the flame is extended horiz~ontally over the heat insulating plate 7, the uniform beating can be effected all over the beating plate up to the marginal portion th ereof. 424

20,3927 Furthermore, since the burner body is covered by the beating plate 5. the burner will not be affected by the tpilt soup or the like cooked thereon and the food can be directly cooked thereon. The backfire occurring due to the overheat and reduction of the supplied fuel is prevented by the provision of a space around the nozzle 4 to let the secondary air pass therethrough. Prior Art A heating plate of 240 mm x 240 mm size without any heat insulating layer in accordance with the present invention was heated by the gas combustion burner of the same type as shown in the drawing together with the heat insulating plate of 180 mm diameter. The result was as follows: the temperature at the portion 30 mm from the center of the heating plate was 6700C and that at the portion 80 mm from the center thereof was 400 0 C. The temperature difference through the heating plate was such a large one. which would be improper for cooking. Example This Invention A fire-proof beat insulating layer.of 5 mm thick was coated on the above prior art heating plate. The heat insulating material used was a mixture of perlite of 3-5 mm granularity and heat resistive-cement. The size of the coating of the heat insulating layer was 110 mm in diameter. The heating plateM thus made was heated under the same condition as that of the above prior art example. The result was as follos: the temperature at the portion 30 mm from the centerlof the heating plate was 590 C and the-temperature at the portion 80 re from the center theeo was 600OC. The '22248k

20,392170 temperature difference through the heating plate was small and higher temperature was obtained over the heating plate.

422248

20, 392asgo The claim defining the invention is follows: 1. A cookinga gas heater comprising an open topped heater casing having at least one air exhaust port at the side wall and a se6ondary air intake at the lower portion thereof, a heat resistive heating plate horizontally mounted on the upper portion of said casing, a heat insulating plate positioned beneath and spaced from said heating plate, a fire- proof heat insulating layer coated on the lower surface of said heating plate, said heat insulating layer being coated on the heating plate over an- area smaller than the whole area thereof so that the marginal portion thereof may not be coated thereby, a mixing tube having a nozzle at the top end thereof which is located under the central portion of said heating plate and projecting into or through a central aperture In the insulating plate such that an annular space exist~s between the nozzle and surrounding insulating plate.

DATED this THIRD day of MTAROR, 1972 FUJI PHOTO 0 P1ZA1 CO., -ITD.

Patent Attorneys for the Applicant SPRIJSON FERGUSON

422248

2013 927O

422248 8 r

20j392170

20v39270

20,392/70

201392 7a

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