Title of Invention


Abstract A WET GRINDER This invention relates to a wet grinder which Performa’s more efficiently and consunses less power. To overcome intermittent stoppage of the roller stones and to provide uniform speed of rotation the roller rod assessable is provided with dancing rollers. Dancing rollers are compression spring provided in the forked pivot connecting the holder and the swing arm. Toothed gears are provided on the base stone and on either side of the roller stone, and on either side of the roller stone. This teeth of these gears mesh with each other. The vertical force exerted by the compression spring and the drive through gear system ensures smooth functioning and effective grinding.
Full Text

This invention relates to a wet grinder particularly a table top wet grinder.
Everyday Indian cooking includes wet grinding of cereals raasalas, coconut and pulses, Manual grinding is now replaced by modern techniques and devices developed to meet consumer demands, Mixie and liquidisers were found inadequate and unsatisfactory for Indian cooking as the high speed of rotating blades results in heating the dough or batter. Food articles prepared from such batter or dough are found to be substantially inferior in taste and texture. Electrically operated stone wet grinders developed subsequently avoided a few draw backs of mixie grinding. Low speed of rotation and stone grinding surfaces reduce excessive heating of the ground batter. But grinders of this type occupy large floor space and do not have stream lined appearance preferred by modern city dwellers. Furthermore, cleaning and other operations are also difficult and cumbersome. Tilting wet grinders solved this problem to a certain extend.
Table top wet grinders were developed to meet the demands of modern homes, style and door. As most of the components are made of moulded plastics and are easily detachable, cleaning and other operations are easy and not cumbersome. In table top wet grinders, the containers in which batter is ground are detachable and the ground batter may be stored therein till desired. This avoids wastage and reduces labour,

Problems faced with or the drawbacks in using wet grinders hitherto known in the art will be described in detail hereinafter.
In mortar and pestle type wet grinders, a pestle fastened to a post by flexible link means is movably housed in the stone pit of the base stone member. When the base stone is driven, the pestle picks up speed due to friction created in between them by surface contact and lateral force. Substances to be ground, pass through the space in between the pestle and base stone cavity and are crushed in between due to the lateral load of the pestle, This load is transmitted to the pestle through the link means attached to the post and repeated rotation result in the formation of batter. Surface contact between the base stone cavity and the pestle is reduced considerably due to the presence of rice and other grains filling the gap between the two during grinding operation. As the grinding proceeds, lack of surface contact reduces the friction created between the two, resulting in reduced speed of rotation. The sticky nature of the batter formed also adds to the reduction of speed of the pestle. These factors result in increasing the time for grinding and consequential power consumption.
Tilting and table top type of grinders also exhibit these drawbacks. It is observed that the speed of rotation of the cylindrical rollers in both the above types is reduced considerably during the course of grinding and that the starting

speed is not maintained throughout the grinding operation.
Intermittant stopping is also frequently observed. Another drawback is that the existing types of wet grinders are not fully effective in grinding oily substances like fried onions, masaias and vada compositions, mainly due to the slippery consistency of such compositions. Dhal and coconut bits caught in between the two stone surfaces temporarily lift the roller stones upwards resulting in loss of surface contact between the two surfaces.-These factors contribute to stoppage of the device, enhanced power consumption and increase in grinding time. Manufacturing variations during machining of the stone surfaces enhance these problems.
This invention has been developed with a view to overcome the aforementioned problems in the conventional, tilting and table top models of wet grinders.
The invention will be described herein after with reference to the table top type of wet grinder having a rotatable drum provided with a flat stone base, driven by a prime mover. A rotatably mounted rod has two roller stones horizontally disposed with respect to the flat base stone. A holder means pivoted to a swing arm through a forked joint holds the roller rod and the roller stones. The fork is hingedly connected to the holder means through a female cavity which aligns with the male end of the holder. The swing arm suspending the holder therefrom exerts

vertical pressure and prevents the roller rod assembly from rotating alone with the dmm. A compression spring is provided in the swing arm in contact with the fork to exert vertical load or pressure through the fork to the holder. The fork pivoting and the compression siting in the holder enable the holder to swing in berth the directioiK. This also enables the rollers in the assembly to dance according to the up and down movements of the rollo- stones and flat stone thus prowding better surface craitact between the two and avoiding uneven surface teiKion.
The flat stone and the roller stones of tlK grinder acctxding to this invention are
provided with means for positive drive to avoid any speed reduction during operation.
Oa& embodiment of the positive tfrive means has a tootled gear wheel fixed to the flat
stone. Each of the two rolla' stones disposed diametrically oj^site each other at a
distance away from the centre axis of the roller holder also has two toothed gear
wheels. These gear wheels axe located at 180° and they engage with the gear wlieel
provided on the flat stone. When the dmm rotate, the toothed gear wheel fixed to the
flat stone meshes with the gear wheels of the roller sttmes to drive them. Any known
type of gear v^eels may be used in the drive. The flat stone and the roller stooss
r between the mealing gears thus ensuring positive drive without ray ^>eed redaction.
Substances to be groimd are {a-essed in between at — —-

uniform speed resulting in batter production. Slippage, intermittent stopping and reduction of speed of rotation are avoided increasing grinding efficiency and decreasing power consumption. Grooves provided on the roller stones also facilitate grinding. Any other positive drive means may also be used to achieve uniform speed of rotation,
The wet grinder according to this invention comprises a rotatably drivable drum provided with flat stone base and a roller rod assembly consisting of a roller rod having atleast two rotatable roller stones horisontally disposed to the said flat stone and a holder for the said roller rod, connected to a swing arm, characterised in that the said roller rod assembly is pivoted to the swing arm through dancing rollers, and the said flat stone and the roller stones are provided with positive drive means to drive the same at uniform speed.
This invention will now be described with reference to the figures in the accompanying drawings wherein like numerals indicate the same parts throughout.
Fig. 1 shows a sectional view of the dancing roller system and the positive drive system of the roller assembly.
Fig. 2 shows the top view of the positive drive system to the roller assembly.
Fig. 3 shows the top view of the roller stone with the toothed gear wheel.

Fig. 4 shows the main toothed gear wheel fixed to the flat base stone and
Fig. 5 shows the schematic assembly of the grinder according to this invention.
Rotatably drivabie drum of the wet grinder is represented by reference numeral 14 and the flat stone base of the drum is indicated by numeral IS. The drum is detachably mounted on a drive shaft 31 by means of a toothed gear wheel 20 fixed to the flat stone 18 with the help of nut 19. The roller stones of the roller assembly are indicated by reference numeral 15 and the roller rod holding the roller stones is shown by numeral 22. Projection 16 on the roller rod prevent the roller stones from slipping out of the rod. Nut assembly 17 fixes the roller stones to the roller rod 22. The holder,of the roller rod is shown by numeral 1 and the swing arm which holds the roller assembly by numeral 7. The forked pivot is shown by 11. Reference numerals 2, 4, 5 and 9 are fixing means of the dancing roll assembly and 6, 10, 12 and 23 are gasket like protective coverings known in the art.
The compression spring 8 connects the forked joint to the swing arm 7. The hinged Joint is covered by a rubber diaphragm shown by numeral 3 to protect the pivot joint and prevent the batter from entering into the cavity. Motor driving the wet grinder is shown by nuraerai 29 and belt connecting the motor to the shaft is represented by numeral 26. Gear wheels in the

roller stones are indicated by numeral 13. The pins of these wheels mesh with the gear wheels of the flat stone.
Though the invention has been described herein above with a particular embodiment, it is to be understood that obvious equivalents known to persons skilled in the art are within the scope of this invention and the appended claims.

1. A wet grinder comprising a rotatabiy drivable drum provided with a fiat stone base and a roller rod assembly consisting of roller rod having atleast two rotatable roller stones horizontally disposed to the said flat stone and a holder for the said roller rod connected td a swing arm characterised in that the said roller rod assembly is pivoted to the swing arm through dancing rollers and the said flat stone and roller stones are provided with positive drive means to drive the same at uniform speed.
2. The wet grinder as claimed in claim 1 wherein the dancing roller consists of a housing connecting the swing arm and the holder pivotally through a forked joint, the said housings, having a compression spring for exerting vertical load to the

roller assembly.
3. The wet grinder as claimed in claims 1 and 2 wherein the
positive drive means is a set of gears meshing with each other,
4. The wet grinder as claimed in claims 1 to 3 wherein a toothed
gear wheel is located on the flat base stand and two toothed gear
wheels are provided on the inner periphery of each of the roller
stones, the teeth of the base gear wheel meshing with that of the
roller stones.
5. The wet grinder as claimed is- any of the preceding—claims

wherein the roller stones are provided with grooves,
8. The wet grinder as claimed in any of the preceding cairns
wherein protective means such as rubber gasket is provided around
the joints.
?. The wet grinder as claimed in any of the preceding claims
wherein the rotatable drum is detachable and the grinder is a
table-top model.
8. A wet grinder substantially as herein described with
particular reference to the figures in the accompanying drawings.


505-mas-1997 abstract duplicate.pdf

505-mas-1997 abstract.pdf

505-mas-1997 claims duplicate.pdf

505-mas-1997 claims.pdf

505-mas-1997 correspondence others.pdf

505-mas-1997 correspondence po.pdf

505-mas-1997 description (complete) duplicate.pdf

505-mas-1997 description (complete).pdf

505-mas-1997 drawing duplicate.pdf

505-mas-1997 drawing.pdf

505-mas-1997 form-1.pdf

505-mas-1997 form-26.pdf

Patent Number 196388
Indian Patent Application Number 505/MAS/1997
PG Journal Number 30/2009
Publication Date 24-Jul-2009
Grant Date
Date of Filing 12-Mar-1997
# Inventor's Name Inventor's Address
PCT International Classification Number B02C2/04
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA