Title of Invention

"AN IMPROVED DEVICE USEFUL FOR MAKING DOSAS AND OTHER SIMILAR PRODUCTS."

Abstract

The present invention relates to an improved device useful for making dosas and other similar products. An improved device of the present invention is particularly useful for spreading and cooking / baking of dosa batter into any shape, in particularly circular and elliptical shapes. Geometrical shapes so obtained by using the improved device of the present invention are of uniform dimension and are obtained in a continuous / intermittent manner. The batter employed may be such as rice, urd dhal, soji, or a combination thereof. The improved device of the present invention is therefore useful as an improved machine for spreading, cooking / baking and discharging of dosas and other similar products. Based on floating spreader, floating scraper and revolving hot plate concept, an improved device to produce dosas is proposed for the first time according to this invention.

Full Text

The present invention relates to an improved device useful for making dosas and other similar products. An improved device of the present invention is particularly useful for spreading and cooking / baking of dosa batter into any shape, in particularly circular and elliptical shapes. Geometrical shapes so obtained by using the improved device of the present invention are of uniform dimension and are obtained in a continuous / intermittent manner. The batter employed may be such as rice, urd dhal, soji, or a combination thereof. The improved device of the present invention is therefore useful as an improved machine for spreading, cooking / baking and discharging of dosas and other similar products. Based on floating spreader, floating scraper and revolving hot plate concept, an improved device to produce dosas is proposed for the first time according to this invention. As an important traditional food in South India, different varieties of dosas stand next to only cooked rice. Though they are more popular in South India, dosas are considered as a delicacy and gaining popularity even in other parts of the country and abroad. There is a gradual increase in liking for dosas and idlies along with Chapathis. One of the main problems in these not ^occupying the prime place is the tedious operation involved in preparation of the same. In large hotels, industrial canteens and hostels, hundreds of dosas are prepared and consumed everyday. All the preparatory operations are carried out manually. Attempts to produce and market machines for preparation of dosas are being made by some industries without success. The users are deprived of a suitable machine for large-scale preparation of dosas. In case a commercially viable improved device is made available for various operations involved in dosa preparations such as batter spreading, cooking / baking, oiling, curry dispensing , would result in reduction in labour and drudgery on the part of chefs, help in hygienic operations, and enhance uniformity in quality and quantities. It would pave the way for large-scale production of dosas as convenient food in hotels, industrial canteens, hostels and other mass feeding centers. Hitherto the process of spreading cooking / baking and scraping of food materials such as dosas and the like, is based on manual spreading and cooking / baking on hot plates. For this purpose, a device as shown in figure 1 of the drawings accompanying this specification is being currently used. In manual spreading and cooking / baking, the device consists of a hot plate (a) for cooking / baking and a large spoon / cup (b) to spread batter in to a sheet. The spiral hand movement would produce circular / elliptical sheet of batter on the hot plate. Oil is used to avoid sticking of the batter to the hot plate. The formed batter is baked / cooked in to dosas on the hot plate, which is heated by LPG burner (c) or electricity or by any other commonly available fuels such as firewood, kerosene, and coal. The cooked dosa is removed from the hot plate with the help of a spatula. All these steps are done manually. The manual spreading and cooking / baking process of making dosas using this known device has the following drawbacks. 1) The variation in the feed rate of batter sheet is not possible as the spreading rates are fixed and determined by the operator. 2) In the process of manual spreading and cooking, sheet produced would stick either to the hot plate or to the spoon / cup predominantly due to lack of skill. Separation of the sheet from the hot plate is difficult thereby making the process not viable for making certain kinds of products on large scale. 3) By this process, it is very difficult to achieve a uniform thickness and colour of the product. Thickness and colour varies from spread to spread. Even in single sheet there is variation in thickness and colour from point to point. 4) The process is labour intensive and manual drudgery is very high which would reduce the efficiency of the operator. A mechanical device for preparation of dosas was brought out by an Indian company in south India. The machine is a tabletop model with a production capacity of 15 - 20 dosas per hour. The dosas were in elliptical shape with an approximate dimension of 125 x 75 mm and a thickness of less than 1.5 mm. The batter is spread automatically using a floating die on a cylindrical drum. The drum is rotated at a constant speed using an electric drive and the heat is supplied through an infrared source. The cooked / baked dosas are scraped out after a travel of approximately 340° of angular rotation. The major drawbacks of the above noted machine are: 1. Very low production rate. 2. Strict raw material specification and its monopolistic source of supply. 3. Small size of dosas. 4. High initial investment. In the copending patent application no. 1252/Del/97, we have described and claimed a device useful for making dosas and other similar products. In the drawings accompanying this specification, Figure 2 represents an embodiment of the device of our copending patent application no. 1252/Del/97, which comprises of: a geared motor (1), spreader assembly (2), revolving hot plate assembly (3), circular burner with accessories (4), scraper (5), oiler (6), curry dispenser (7), main frame with necessary insulation (8), batter pump attached to a vessel (9), a solenoid valve (10), sprocket assembly (11), an electronic timer (12), an electrical panel board (13), a temperature indicator (14), a hood with sight glass (15), antifriction bearings (16), a base support (17), a pivot bearing (18), and a rotatable vertical shaft (19). The hot plate is driven by a set of sprockets and chain (or a set of worm and worm wheel), which are mounted on a shaft housed in anti-friction bearings. The sprocket assembly is driven by the geared motor through a roller chain. The dispenser assembly consists of a pump / solenoid valve attached to a receiver with a bypass line. The device also carries a curry / chutney dispenser for discharging the same on to the cooked Dosa. The oiling assembly consists of drip nozzle and hopper. Oiling unit is located after the spreader assembly. Oiling is done in two stages during the process of Dosa making (i) for initial greasing / for uniform heat transfer and (ii) for roasting the batter spread in the form of a spray. The Cooked Dosas are scraped, rolled and discharged by a straight edged curved blade and collected in a tray. All the above-mentioned assemblies are mounted on a channel frame, which is insulated around the burner and covered on all the sides. The whole assembly is mounted on swivel castors for easy movement of the device to the required place. Materials like Steel / Stainless Steel / Steel coated with PTFE / Brass are used in the-fabrication of the device. All the necessary electrical parts of the device are housed inside the panel board attached to the main frame. The batter is prepared by grinding rice and urd dhal with sufficient quantity of water in known proportion to a predetermined time to get the required fineness. The batter is allowed to ferment for 8 - 10 hours in a closed stainless steel vessel. The prepared batter is charged into a vessel connected to the feed side of the screw pump. The pump / solenoid valve is fitted in the discharge pipeline and the electronic timer controls the intermittent batter deposition on the hot plate in predetermined quantities and appropriate time interval. Each batter deposit is spread into an elliptical disk of uniform thickness by the spreading device as the hot plate rotates. Automatic oiling device sprays a very thin coat of edible oil on the spreadsheet of batter. This will not only improve the organoleptic properties of the dosa but also helps in rapid and uniform heat transfer and cooking of the dosa as it travels on the hot plate. Depending on the moisture content of the batter, the cooking time is adjusted either by the sprocket train / worm and worm wheel or by an electronic inverter. In case the dosas are need to be filled with curry, the material from the curry dispenser can be filled on the dosas before they are rolled and discharged. The cooked dosas are scraped, rolled and discharged by a scraper and collected in a tray. The device of our copending patent application no. 1252/Del/97 has the following drawbacks: 1. The hot plate has the tendency to distort during the process of heating and operation. 2. The distortion of the hot plate produces non-uniform thickness of the product. 3. Due to distortion of the hot plate the scraper needed flexibility to move vertically and rotate as well. 4. The screw pump fitted on the machine is very costly and needs regular attention. 5. There is no water cleaning arrangement during the process of operation. The main object of the present invention is to provide an improved device useful for preparation of dosas and other similar products which obviates the above noted drawbacks. Another object of the present invention is to provide an improved device for spreading, cooking / baking and scraping of dosas continuously / intermittently and capable of varying the time of dispensatioi^atter spreading rates. A further object of the present invention is to provide an improved device wherein even with the distortion of the hot plate , scraping and discharge of baked dosa is made possible by providing a floating scraper. Yet another object of the present invention is to provide an improved device for uniform spreading, cooking / baking and scraping of dosas and other similar products by varying the gap between the floating spreader assembly and hot plate assembly. Still another object of the present invention is to reduce manual drudgery. Another object is to provide hygienic conditions through mechanized operation. Yet another object is to increase productivity with a cost-effective dosa making device. Still another object is to provide a device capable of working with ready mix batter as well as a wide range of conventionally prepared batters. The improved device of the present invention overcomes the drawbacks of the traditional methods of preparation of dosas and hitherto known dosa-making machine/device. The device of the present invention is an improvement and overcomes the drawbacks of our copending patent application no. 1252/Del/97 such as rate of production, uniformity in thickness and colour, and hygienic method of preparation and ease of operations. Production of dosas using an improved automatic floating spreader, floating scraper, batter cum oil dispenser and revolving hot plate is hitherto not known. The automatic floating spreader has a compression spring to accommodate a non-uniform distortion developed on the hot plate during the process of heating. The distortion of the hot plate moves the Teflon edge of the spreader up and down to maintain uniform thickness of the batter spread. The floating spreader is bolted to the main frame with suitable fasteners. The floating spreader has the provision to vary the thickness of the dosa by rotating the thumb wheel against the compression spring, in operation. The floating scraper is provided with a compression spring arrangement to accommodate the non-uniform distortion developed on the hot plate during the process of heating. The floating scraper along with the water dam is made to move up and down by the hot plate, accommodating the non-uniform distortion. The batter cum oil dispenser, is used for the dispensation of the batter and the oil simultaneously. The opening of the batter and oil ports of the valve is controlled by a timer. The quantity of batter, oil and the dwell period of dispensation can be regulated through the valve. The complete assembly of batter cum oil dispenser is mounted on the main frame. Based on this concept an improved device to produce dosas into uniform sheet of rice and urd dhal and any other batter of various desired thickness is proposed by us for the first time according to this invention. The invention is based on the finding that continuous / intermittent dosa sheet of uniform geometry and thickness can be achieved. The improved device using this principle can be used for the preparation of dosas and other similar products. In the drawings accompanying this specification, figure 3 represents an embodiment of the improved device of the present invention for spreading, cooking / baking and scraping of dosas and other similar products. Figure 4 of the drawings shows details of the floating spreader assembly (22) consisting of a set of horizontal square bars (42,45), vertical rods (43) with thumb wheel (46), compression springs (44). Figure 5 of the drawings shows details of the floating scraper assembly (25) consisting of a horizontal straight edged scraper (47), a vertical rod (49) with a compression spring (48), fixed on main frame (28). Figure 6 of the drawings shows details of the batter cum oil cum water dispenser (26) consisting of a batter container (37), oil container (38), water container (39), a solenoid (53) actuated valve (54). In an embodiment of the present invention the device useful for making dosa and other similar products consists of a geared motor (20), a gear box (21), floating spreader assembly (22), revolving hot plate assembly (23), circular burner with accessories (24), floating scraper assembly (25), batter cum oil cum water dispenser (26), curry dispenser (27), main frame with cover and necessary insulation (28), LPG solenoid valve (29), an electronic timer (30), an electrical panel board (31), a temperature controller with sensor (32), a hood with sight glass (33), a set of castors (34), a set of bearing supports for hot plate (35), a mechanical / digital electronic counter (36), a batter container (37), an oil container (38), water tank (39), an AC drive (40), and rotatable vertical shaft (41). The present invention provides an improved device useful for making dosas and other similar products \vhich comprises, a main frame (28) having a set of castors (34) for easy movement of the improved device. A rotating horizontal hot plate assembly (23) is driven by a geared motor (20) and a gear box (21) and an AC drive (40), supported by a set of bearings supports (35). The hot plate is heated by a circular LPG burner with its accessories (24) and the temperature of the hot plate is regulated by a temperature controller with sensor (32) through a LPG solenoid valve (21). The batter cum oil dispenser (26) is timed by an electronic timer (30) and the thickness of the dosa in controlled by a floating spreader assembly (22). The water tank (39) and the batter cum oil dispenser (26) is mounted on the floating spreader assembly (22). The floating spreader assembly (22) and floating scraper assembly (25) are mounted on the main frame (28). A panel board (31) is mounted on the main frame (28) for easy operation of the machine and the panel board houses the AC drive (40) for controlling the speed of the hot plate (23) and a mechanical digital electronic counter (36) and an electronic timer (30). The batter and the oil are contained in the batter container (37) and an oil container (38), which is mounted on the batter cum oil dispenser (26). A curry dispenser is mounted on the hood with sight glass (33) for dispensing the curry on to the baked dosas. The floating scraper assembly (25) is fastened to the main frame (28) through a vertical round bar (49) having a compression spring (48) assembled on to the round bar (49) and the horizontal straight edged scraper (47) rests on the hot plate (23). The floating spreader assembly (22), comprises of a set of horizontal square bars (42,45) fastened to the main frame (28) . Two thumb wheels (46) and vertical rods (43) connects the square bars (42,45) through a set of compression springs (44) placed between the square bars (42, 45). Pressure is exerted by the thumb wheel (46) to lower bar (42) on to the hot plate (23). The batter cum oil dispenser (26), is used for the dispensation of the batter and oil simultaneously. The batter cum oil dispenser consists of a solenoid (53), to actuate the valve (54) for dispensing the batter(37) and oil (38). A water tank (39) is mounted below the solenoid (53) and the valve(54). The opening and closing of the batter cum oil dispenser (26) is by an electronic timer (30). Accordingly the present invention provides an improved device useful for making dosas and other similar products, which comprises a main frame (28) mounted prime mover (20,21,40) connected by means, such as worm gear, belt and pulley, to the bottom of a rotatable vertical shaft (41), the rotatable vertical shaft being supported at the upper portion by one or more bearing support (35) fixed on the top part of the said main frame (28), the said rotatable vertical shaft (41) being fixed at the top end to a horizontal concentrically placed rotatable hot plate (23), the rotatable hot plate (23) being provided at its bottom with means for heating (24), the said rotatable hot plate (23) being provided at the top with separate main frame mounted means such as a batter cum oil cum water dispenser (26), a floating spreader assembly (22), curry dispenser (27) and a floating scraper assembly (25), the said batter, oil, water dispenser (26), the floating spreader (22), curry dispenser (27) and the floating scraper (25) being provided with a removably fixed covering hood (33). In an embodiment of the present invention the prime mover used may be a geared motor (1) and a gear box (21) having means for speed control such as an AC drive (40) connected by means of a set of sprockets and chain. In another embodiment the hot plate assembly (23) used may be provided with a food grade nonstick coating. In yet another embodiment of the present invention, the means for heating used may be such as liquid petroleum gas (LPG) burner, in built /external electrical heating elements. In still another embodiment of the present invention , these is provided a means for regulating the temperature of the hot plate assembly (23) consisting of LPG solenoid valve (29) connected to a temperature controller.(32). In another embodiment of the present invention, the means for batter , oil and water dispensing is by a batter cum oil cum water dispenser (26) consisting of a batter container (37), an oil container (38) and a water tank (39). In another embodiment of the present invention, the means for dispensing of batter and oil is by means of a batter cum oil dispenser (26) controlled by an electronic timer (30). In another embodiment of the present invention , the means for scraping, used may be a floating scraper assembly (25) consisting of a horizontal straight edged scraper (47) movably mounted on to the main frame (28) by means of a vertical bar(49) having a compression spring (48). In still another embodiment of the present invention, the means for spreading used may be a floating spreader assembly (25) consisting of two vertically movable horizontal square bars (42,45) connected through two compression springs(44) mounted on two vertical rods (43) having top thumb wheels (46). In yet another embodiment of the present invention , the means for controlling the operation of the improved device is provided in a panel board (31) consisting of an electronic timer (30), a temperature controller with sensor (32), a digital mechanical/electronic counter (36) and an AC drive (40). In another embodiment of the present invention, the means provided for cleaning the hot plate assembly (23) may be water contained in a water tank (39). In a further embodiment of the present invention, the means is provided for moving the improved device from place to place is such as a set of castor (34) wheels. In yet another embodiment of the present invention, the means for holding the batter oil and water may be such as a batter container (37), an oil container (38) and water tank (39). The following example is given by way of illustration and should not be construed to limit the scope of the present invention. Example - 1 Working of the device is explained in the following example with particular reference to making rice-dhal dosas. Batter is prepared by grinding rice and urd dhal with sufficient quantity of water in known proportion to a predetermined time to get the required fineness. The batter is allowed to ferment for 8 - 10 hours in a closed stainless steel vessel. The prepared batter is charged into the batter vessel and the solenoid allows the batter to be discharged on to the hot plate assembly through the electronic tinier in predetermined quantities and appropriate time interval. Each batter deposit is spread into an elliptical disk of uniform thickness by the spreading device as the hot plate rotates. Automatic oiling device sprays a very thin coat of edible oil on the spreadsheet of batter. This will not only improve the organoleptic properties of the dosas but also helps in rapid and uniform heat transfer and cooking of the dosa as it travels on the hot plate. Depending on the moisture content of the batter, the cooking / baking time is adjusted by an electronic AC drive. In case the dosas are to be filled with curry, then the material from the curry dispenser can be filled on the dosas before they are rolled and discharged. The cooked dosas are scraped, rolled and discharged by a scraper assembly and collected in a tray. The main advantages of the present invention are: 1) Predetermined spreading rates of batter can be obtained by varying the time of dispensation. 2) Varying the gap between the floating spreader assembly and the hot plate assembly can produce sheet having uniform thickness. 3) Even with the distortion of the hot plate the floating scraper can scrape and discharge the baked from the hot plate assembly. 4) Dosas with uniform colour and texture can be produced by controlling the residence time and hot plate temperature of cooking / baking. 5) The device is useful for spreading, cooking / baking and discharging different varieties of dosas, with different percentage of moisture, and other ingredients like salt, oil etc. 6) The improved device would produce dosas hygienically with minimum manual drudgery. 7) Easy to synchronize the rate of sheet output and rotational speed of the hot plate by varying the speed of the prime mover. 8) Operation and maintenance is easy and cost effective too. 9) The cost of the machine is comparatively very less. We claim 1. An improved device useful for making dosa and other similar products, which comprises a main frame (28) mounted prime mover (20,21,40) connected by means, such as worm gear, belt and pulley, to the bottom of a rotatable vertical shaft (41), the rotatable vertical shaft being supported at the upper portion by one or more bearing support (35) fixed on the top part of the said main frame (28), the said rotatable vertical shaft (41) being fixed at the top end to a horizontal concentrically placed rotatable hot plate (23), the rotatable hot plate (23) being provided at the bottom with means for heating (24), the said rotatable hot plate (23) being provided at the top with separate main frame mounted means such as a batter cum -oil- cum water dispenser (26), a floating spreader assembly (22), curry dispenser (27) and a floating scraper assembly (25), the said batter, oil, water dispenser (26), the floating spreader (22), curry dispenser (27) and the floating scraper (25) being provided with a removably fixed covering hood(33). 2. An improved dosa-making machine as claimed in claim 1 wherein the prime mover used is a geared motor (20) and a gear box (21) having means for speed control such as an AC drive (40) connected by means of a set of sprockets and chain. 3. An improved dosa-making machine as claimed in claim 1-2, wherein the hot plate assembly (23) used is provided with food grade non-stick coating. 4. An improved dosa-making machine as claimed in claim 1-3, wherein the means for heating used is such as a liquid petroleum gas (LPG) burner, in-built / external electrical heating elements. 5. An improved dosa-making machine as claimed in claim 1-4, wherein is provided a means for regulating the temperature of the hot plate assembly (23) consisting of a LPG solenoid valve (29) connected to a temperature controller with sensor (32). 6. An improved dosa-making machine as claimed in claim 1-5 wherein the means for batter, oil and water dispensing is by a batter cum oil cum water dispenser (26) consisting of a batter container (37), an oil container (38) and water tank (39). 7. An improved dosa-making machine as claimed in claim 1-6, wherein the means for dispensing of batter and oil is by a batter cum oil dispenser (26) controlled by an electronic timer (30). 8. An improved dosa-making machine as claimed in claim 1-7, wherein the means for scraping, used is a floating scraper assembly (25) consisting of a horizontal straight edged scraper (47) movably mounted on to the main frame (28) by means of a vertical bar (49) having a compression spring (48). 9. An improved dosa-making machine as claimed in claim 1-8 wherein the means for spreading used is a floating spreader assembly (22) consisting of two vertically movable horizontal square bars (42,45) connected through two compression springs (44), mounted on two vertical rods (43) having top thumb wheels (46). 10. An improved dosa-making machine as claimed in claim 1-9, wherein the means for controlling the operations of the improved device is provided in a panel board (31) consisting of an electronic timer (30), a temperature controller with sensor (32), a mechanical / electronic counter (36) and an AC drive (40). 11. An improved dosa-making machine as claimed in claim 1-10 wherein means provided for cleaning the hot plate assembly (23) is water contained in the water tank (39). 12. An improved dosa-making machine as claimed in claim 1-11, wherein means provided for moving the improved device from place to place is such as a set of castor (34) wheels. 13. An improved dosa-making machine as claimed in claim 1-12, wherein means for holding the batter oil and water is such as a batter container (37), an oil container (38) and water tank (39). 14. An improved device useful for making dosas and other similar products substantially as herein described with reference to the example and Figures 3 to 6 of the drawings accompanying this specification.

Documents:

286-del-2002-abstract.pdf

286-del-2002-claims.pdf

286-del-2002-correspondence-others.pdf

286-del-2002-description (complete).pdf

286-del-2002-drawings.pdf

286-del-2002-form-1.pdf

286-del-2002-form-18.pdf

286-del-2002-form-2.pdf

286-del-2002-form-3.pdf