FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
AND
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
“LOW NOISE JAR FOR MIXER GRINDER”
We, Bajaj Electricals Limited, an Indian National, of 45/47, Veer Nariman Road, Fort Mumbai- 400001, India.
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION
The present invention relates to the field of consumer electrical goods, particularly home appliances, and more particularly kitchen appliances. Specifically, the present invention provides a low noise jar for mixer grinder.
5
BACKGROUND OF THE INVENTION
Mixer grinders are a staple item in Indian kitchens, which are used for mixing grinding a
variety of ingredients. Typically, such mixer grinders work at high RPM, and therefore,
the mixer grinder jars generate a lot of noise. Such conventional mixer grinders jars are
10 also vibration prone. Thus, there is a continuing need to improve upon the noise and
vibration generation in such mixer grinder jars without reducing operating efficiency.
SUMMARY OF THE PRESENT INVENTION
This section is intended to introduce certain objects of the disclosed method and system
15 in a simplified form, and is not intended to identify the key advantages or features of the
present disclosure.
In an aspect of the present invention, there is provided a jar for a mixer grinder for noise
reduction, comprising: an inner layer forming a hollow portion of the jar for receiving
therein a material for grinding such that the inner layer defines an inner surface and an
20 outer surface; an outer layer extending from a base of the jar towards a rim of the jar,
defining an outer cover of the jar; a middle layer disposed between the inner layer and the outer layer and covering at least a part of the outer surface of the inner layer and inner surface of the outer layer; and at least a dampener located between the inner layer and a locking nut of the jar.
25 In an aspect of the present invention, the middle layer covers at least 25% to 50% of the
outer surface of the inner layer.

In an aspect of the present invention, the middle layer comprises a plurality of patches of at least a vibration dampening material disposed between the inner layer and the outer layer.
In another aspect of the present invention, the jar comprises a sealing ring to seal the gap
5 between the outer surface of the inner layer and the rim of the inner surface of the outer
layer.
In yet another aspect of the present invention, the jar comprises a washer located between the dampener and the locking nut.
In yet another aspect of the present invention, the outer layer is made of a polymeric
10 material selected from the group comprising acrylonitrile butadiene styrene (ABS), nylon,
Glass filled Nylon, polypropylene, Glass filled Polypropylene, polycarbonate; a metallic material selected from the group comprising aluminium, aluminium alloy, stainless steel, sheet metal, and combinations thereof.
In still another aspect of the present invention, the inner layer is made of material selected
15 from the group comprising stainless steel, glass, polycarbonate, ABS, aluminium, and
ceramic.
In still another aspect of the present invention, the washer is made of wear resistant polymer material selected from the group comprising nylon, Polytetrafluoroethylene, Polyoxymethylene, and Hylam.
20 In another aspect of the present invention, the middle layer is a material selected from the
group comprising vulcanised butyl rubber, unvulcanised butyl rubber, natural rubber, nitrile butadiene rubber, silicone, polyurethane, and ethylene propylene diene monomer.
In an aspect of the present invention, the dampener is a rubber-based material selected
from the group comprising nitrile butadiene rubber, butyl rubber, silicone, and
25 polyurethane.
In another aspect of the present invention, the outer layer extends from the base of the jar and covers the middle layer.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

In order to explain the technical solution in the embodiments of the present application
more clearly, the drawings used in the description of the embodiments will be briefly
introduced below. It is obvious that the drawings in the following description are only
some embodiments of the application. For those skilled in the art, without any creative
5 work, other drawings can be obtained based on these drawings.
Figure 1 depicts a cross-section of a jar for mixer grinder for noise reduction, in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
10 In the following description, for the purposes of explanation, various specific details are
set forth in order to provide a thorough understanding of embodiments of the present invention. It will be apparent, however, that embodiments of the present invention may be practiced without these specific details. Several features described hereafter can each be used independently of one another or with any combination of other features. An
15 individual feature may not address any of the problems discussed above or might address
only one of the problems discussed above.
Some of the problems discussed above might not be fully addressed by any of the features
described herein. Exemplified embodiments of the present invention are described below,
as illustrated in various drawings in which like reference numerals refer to the same parts
20 throughout the different drawings.
The present invention provides a jar for a mixer grinder for noise reduction, comprising:
an inner layer forming a hollow portion of the jar for receiving therein a material for
grinding such that the inner layer defines an inner surface and an outer surface; an outer
layer extending from a base of the jar towards a rim of the jar, defining an outer cover of
25 the jar; a middle layer disposed between the inner layer and the outer layer and covering
at least a part of the outer surface of the inner layer and inner surface of the outer layer; and at least a dampener located between the inner layer and a locking nut of the jar.
The inner layer of the jar of the present invention is made of a material selected from the
group comprising stainless steel, glass, polycarbonate, ABS, aluminium, and ceramic. In
30 a preferred embodiment, the inner layer is made of food grade stainless steel. In an
4

embodiment, the thickness of the inner layer is uniform. In another embodiment, the thickness of the inner layer is non-uniform, for instance, the thickness of the inner layer is more near the base and less near the rim relative to the base. In an embodiment, the thickness of the inner layer is in the range of 0.4 to 1.2 mm.
5 The outer layer of the jar of the present invention is made of a material selected from the
group comprising acrylonitrile butadiene styrene (ABS), nylon, Glass filled Nylon,
polypropylene, Glass filled Polypropylene, polycarbonate; a metallic material selected
from the group comprising aluminium, aluminium alloy, stainless steel, sheet metal, and
combinations thereof. In a preferred embodiment, the outer layer is made of ABS
10 material. In an embodiment, the thickness of the outer layer is uniform. In another
embodiment, the thickness of the outer layer is non-uniform, for instance, the thickness of the outer layer is more near the base and less near the rim relative to the base. In an embodiment, the thickness of the outer layer is in the range of 1.5 to 4 mm. In an embodiment, the outer layer is an extension of the jar base.
15 The middle layer occupies the gap between the inner layer and the outer layer. In an
embodiment, the gap between the inner layer and the outer layer is uniform. In an embodiment, the gap between the inner layer and the outer layer is non-uniform.
In an embodiment, the middle layer covers about 25% of the outer surface of the inner
layer. In another embodiment, the middle layer covers about 50% of the outer surface of
20 the inner layer. In yet another embodiment, the middle layer covers about 25-50% of the
outer surface of the inner layer.
In an embodiment, the middle layer comprises a plurality of patches of at least a vibration dampening material disposed between the inner layer and the outer layer. The vibration dampening material is selected from the group comprising vulcanised butyl rubber,
25 unvulcanised butyl rubber, natural rubber, nitrile butadiene rubber, silicone,
polyurethane, and ethylene propylene diene monomer. In a preferred embodiment, the material is unvulcanised butyl rubber. In an embodiment, the thickness of the vibration dampening material is uniform. In another embodiment, the thickness of the vibration dampening material is non-uniform, for instance, the thickness of the vibration
30 dampening material is more near the base and less near the rim relative to the base. In an

embodiment, the thickness of the vibration dampening material is in the range of 2.5 to 5 mm.
In an embodiment, the middle layer comprises a plurality of patches of at least a vibration
dampening material wherein the lateral gap between edges of any adjacent patches is
5 uniform. In an embodiment, the lateral gap between edges of any adjacent patches is non
uniform. In another embodiment, the lateral gap between at least two edges of any adjacent patches is uniform. In an embodiment, the lateral gap between edges of any adjacent patches is substantially minimal. In an embodiment, the gap is in the range of 1 to 5 mm. In an embodiment, the plurality of patches is positioned in an intermittent
10 manner within the gap to form the middle layer. In another embodiment, the plurality of
patches is positioned in a patterned manner within the gap to form the middle layer. It is understood by a person skilled in the art that the shape, and number of the patches of the vibration dampening material is not a limiting feature of the invention. It is also understood by a person skilled in the art that the plurality of the patches comprised in the
15 middle layer may be of a single shape or at least two shapes, and is not a limiting feature
of the invention. The shape, and number of patches can be readily adapted as per requirement of the user. The middle layer of the jar is covered in its entirety by the outer layer which extends from the base of the jar.
The jar of the present invention further comprises a sealing ring to seal the gap between
20 the outer surface of the inner layer and the rim of the inner surface of the outer layer. The
sealing ring forms a protective seal to protect the middle layer and to prevent food
particles, dust, etc. from entering and accumulating within the middle layer or the gap
between the outer layer and the inner layer. The sealing ring may also function to maintain
the integrity and vibration dampening characteristics of the middle layer. In an
25 embodiment, the sealing ring is made of silicone or similar pliable material. In another
embodiment, the sealing rings is made of a rubber-based material. In yet another embodiment, the sealing ring is made of a polymeric material. In yet another embodiment, the sealing ring is an adhesive.
In a conventional jar, the jar attaches with the motor base of a mixer grinder appliance by
30 a locking nut. However, such an arrangement is also a significant source of vibrations and
noise generation during operation of the mixer grinder. To further reduce noise and
6

vibration generation in the jar during operation, at least a dampener is provided between
the inner layer of the jar and the locking nut. The dampener is made of a material selected
from the group comprising nitrile butadiene rubber, butyl rubber, silicone, and
polyurethane. In a preferred embodiment, the dampener material is Nitrile butadiene
5 rubber. The jar of the present invention is also provided with a washer located between
the dampener and the locking nut. The washer can be made of wear resistant polymer material selected from the group comprising nylon, Polytetrafluoroethylene, Polyoxymethylene, and Hylam. In a preferred embodiment, the washer is made of Nylon. The washer allows for wear resistance while tightening the locking nut on top.
10 In an exemplary exemplification of the present invention, as seen in Figure 1, a cross-
section view of a jar (100) for a mixer grinder for noise reduction is provided. The jar (100) inner layer (102) is made of Stainless Steel, and has an inner surface and outer surface. The inner layer (102) forms the hollow portion for material to be grinder. Blades for grinding are located at the bottom of the jar within the inner layer (not shown). Outer
15 layer (104) extends from the base of the jar and extends up to a predetermined height of
the jar (100), preferably not more than 50% of the height of the jar (100). A gap is formed between the outer surface of the inner layer (102) and the inner surface of the outer layer (104). This gap is occupied by a plurality of patches of a vibration dampening material to form the middle layer (106). An exemplary example of the vibration dampening material
20 is Unvulcanised butyl rubber. The vibration dampening material substantially occupies
the gap between the inner layer (102) and the outer layer (104). The jar (100) also comprises a sealing ring (110) located between the rim of the outer layer (104) and the outer surface of the inner layer (102) so as to seal the gap/ middle layer (106). The sealing ring (110) prevents ingress of dust, moisture, food particles, etc. into the gap/middle layer
25 (106). It is to be understood that though the middle layer (106) in Figure 1 appears
continuous, there are plurality (at least 2) of patches of vibration dampening material positioned adjacent to each other with minimal gap between adjacent patches (not shown). Figure 1 also shows the position of the dampener (108), which is located between the locking nut of the jar (100) and the inner layer (102). The dampener (108) as the
30 nomenclature suggests, dampens the transfer of vibrations from the operation of the motor
to the jar (100), thus further reducing the noise generation and vibrations in the jar (100) itself. The dampener (108) is preferably made of a rubber-based material. There is further

provide a washer (112) (not shown), which is a nylon washer so as to provide a secure fit for the dampener (108).
The particular configuration of the jar (100) of Figure 1 provides for sufficient isolation
of the jar (100) from the motor unit (not shown) and other components, resulting in
5 significant reduction of vibration and noise generation during operation of the mixer
grinder jar (100).
In order to evaluate the noise reduction, an experiment was conducted to compare the
noise reduction of a conventional jar and the jar (100) of the present invention. To perform
the experiment, dry grinding of 200g Chana Dal was performed for 10 seconds.
10 Moreover, Industrial Data Acquisition (DAQ) system was used for noise and vibration
capture and time-averaged sound pressure level (LAeq) was recorded. The value of LAeq recorded for the conventional jar was 94dBA, whereas the value of LAeq recorded for the jar (100) of the present invention was 88dBA, thereby resulting in a reduction of about 6 dBA.
15 Compared to conventional mixer grinder jars, the jar (100) of the present invention is able
to achieve a reduction of about 6 dBA in noise. The reduction in noise is within acceptable levels, which is achieved with the particular configuration of the jar (100) of the present invention, particularly without having to cover the entire outer surface of the inner layer with any dampening material, which provides cost saving, manufacturing efficiency, and
20 reduced usage of materials.
LIST OF REFERENCE NUMERALS
(100) jar for a mixer grinder for noise reduction;
(102) inner layer of jar (100);
25 (104) outer layer of jar (100);
(106) middle layer of jar (100); (108) dampener; (110) sealing ring; and

(112) washer.

I/We claim:
1. A jar (100) for a mixer grinder for noise reduction, comprising:
an inner layer (102) forming a hollow portion of the jar (100) for receiving
therein a material for grinding such that the inner layer (102) defines an
5 inner surface and an outer surface;
an outer layer (104) extending from a base of the jar (100) towards a rim of the jar (100), defining an outer cover of the jar (100);
a middle layer (106) disposed between the inner layer and the outer layer
and covering at least a part of the outer surface of the inner layer (102) and
10 inner surface of the outer layer (106); and
and at least a dampener (108) located between the inner layer and a locking nut of the jar (100).
2. The jar (100) as claimed in claim 1, wherein the middle layer (106) covers at least
15 25% to 50% of the outer surface of the inner layer (102).
3. The jar (100) as claimed in claim 1, wherein the middle layer (106) comprises a
plurality of patches of at least a vibration dampening material disposed between
the inner layer (102) and the outer layer (104).
20
4. The jar (100) as claimed in claim 1, comprising a sealing ring (110) to seal the
gap between the outer surface of the inner layer (102) and the rim of the inner
surface of the outer layer (104).
25 5. The jar (100) as claimed in claim 1, comprising a washer (112) located between
the dampener (108) and the locking nut.
6. The jar (100) as claimed in claim 1, wherein the outer layer (104) is made of a
polymeric material selected from the group comprising acrylonitrile butadiene
30 styrene (ABS), nylon, Glass filled Nylon, polypropylene, Glass filled
10

Polypropylene, polycarbonate; a metallic material selected from the group comprising aluminium, aluminium alloy, stainless steel, sheet metal, and combinations thereof.
5 7. The jar (100) as claimed in claim 1, wherein the inner layer (102) is made of
material selected from the group comprising stainless steel, glass, polycarbonate, ABS, aluminium, and ceramic.
8. The jar (100) as claimed in claim 5, wherein the washer (112) is made of wear
10 resistant polymer material selected from the group comprising nylon,
Polytetrafluoroethylene, Polyoxymethylene, and Hylam.
9. The jar (100) as claimed in claim 1, wherein the middle layer (104) is a material
selected from the group comprising vulcanised butyl rubber, unvulcanised butyl
15 rubber, natural rubber, nitrile butadiene rubber, silicone, polyurethane, and
ethylene propylene diene monomer.
10. The jar (100) as claimed in claim 1, wherein the dampener (108) is a rubber-based
material selected from the group comprising nitrile butadiene rubber, butyl rubber,
20 silicone, and polyurethane.
11. The jar (100) as claimed in claim 1, wherein the outer layer (104) extends from
the base of the jar (100) and covers the middle layer (106).