Indian Patents. 234012:SAFETY DEVICE FOR DOOR LOCK OPERATION IN APPLIANCES .

Title of Invention	SAFETY DEVICE FOR DOOR LOCK OPERATION IN APPLIANCES .
Abstract	The present invention relates to a safety device for door lock operation in appliances, which comprises: a spring loaded plunger (7) for locking upward movement of spring loaded slider (8); a rubber diaphragm (6) for sensing air pressure; a spring loaded slider (8) for locking plunger (5) of the door lock; a pressostat for controlling the level of water in the water chamber

Full Text	FIELD OF THE INVENTION The present invention relates a safety device for door lock operation in appliances. BACKGROUND OF THE INVENTION Appliances such as Washing Machine and Dishwasher use water as prime media for carrying out the desired operation of washing or cleaning. Depending on the design feature, the temperature of water during part of the operation can vary upto 95° C. All such appliances carry a loading port or hole for loading articles to be cleaned or washed into appliances. After loading the articles the port or hole is closed by the door which gets locked to the main body or cabinet by the device "Door Lock'\ After closing the door, the appliances are switched on for electric power supply. The door lock is functional from the start operation or program or cycle till the end of operation or program or cycle. At the end of cycle the door lock unlocks the door for subsequent opening to take out the articles from the appliances. The door lock used in the appliances now days are basically operating on the thermistor and bimetal principle and they are called thermal door locks. This concept is used in practically all the machines. In some machines the door locks used are of magnetic type also. Door Lock operation in general is illustrated in relation to Fig 1, wherein door lock has three contact terminals 'L' for input live power supply. 'N' for input neutral power supply and 'C for output live power supply. The slider 3 for locking plunger 5, bi-metallic strip 2 for deflecting spring contact plate 4, thermister 1 for heating bi-metallic strip 2, plunger 5 for locking the door of the appliance, spring contact plate 4 for making contact of terminal 'L' and 'C and upward and downward movement of slider 3, spring 6 for return movement of plunger 5. All prime components are covered in housing 7. With the closure of door of appliance, the plunger 5 slides against the pressure of spring 6 to the position where the "locking" function takes place. At this position the portion P of the plunger 5 comes below the hole at the portion H on the housing 7. When appliance is switched "ON" the power supply through electric circuit of the appliance is available between L & N where as L & C are open for the current path. Due to supply between L & N the thermister I gets heated and the heat is transmitted to bimetallic strip 2. Bimetallic strip at a particular temperature which is defined by the constituting metals of the bimetallic strip, buckles. This in turn deflects the contact plate 4 to establish current, path between L & C as well as to lock the sliding movement of plunger 5 through slider 3. The door lock is in locked condition throughout the working cycle of appliance or till such time power supply is available to the door lock. At the end of working cycle, the power supply to the door lock gets cut off. As a result the thermister (I) cools down, bimetallic strip 2 restores the original position. This deflects the contact plate 4 which in turn deflects slider 3 to unlock the sliding movement of plunger 5. Unless taken care of by some other design, such door lock, in case of non-availability of power supply or supply failure, restore to the unlock condition thereby unlocking the door. Under "no power" situation where in appliance is also under incomplete operation cycle with water inside (in between start and end position) if user intentionally or unintentionally opens the door, the water splashes out of the appliance. Depending on selection of operating parameters and stage of operation, water can be of any temperature upto 95° centigrade. Under all such and similar situations, it is unsafe to have a stage of "unlocked door" in between the operating cycle of the appliance. SUMMARY OF THE INVENTION The object of the present invention is to provide a safety device for door lock ensuring the locked condition of the door under the situation when water chamber of the appliances carries water inside. The another object of the present invention is to provide a safety device for door lock for preventing the door from opening when water chamber of the appliance carries water inside and prevents hot or cold water spilling out of the appliance resulting in the safety of the user as well as reduces inconvenience due to spillage. According to the present invention there is provided a safety device for door lock operation in appliances, which comprises: a spring loaded plunger (7) for locking upward movement of spring loaded slider (8); a rubber diaphragm (6) for sensing air pressure; a spring loaded slider (8) for locking plunger (5) of the door lock; a pressostat for controlling the level of water in the water chamber. The safety device of the present invention, in the absence of water, in the water chamber, the air column pressure on rubber diaphragm (6) is released, thus making the spring loaded plunger (7) slide in the direction of the rubber diaphragm, which results in the movement of the spring loaded slider (8) from its position; thus releasing the plunger of the door lock for its sliding movement to unlock the door of the appliance; The safety device of the present invention, in the presence of water in the water chamber, the air pressure in the elastic tube (9) presses the said rubber diaphragm (6) which slides the spring loaded plunger (7) which in turn pushes the spring loaded slider (8), which in turn locks the position of the door lock plunger (5) which results in the locking of the door of an appliance in presence of water irrespective of availability of power supply and the said plunger (5) of the door lock is unable to slide back under the effect of the spring. The safety device establishes a link between the water content in the appliance chamber where articles are physically cleaned or washed and the door lock. It enables door lock to retain locked condition of door irrespective of availability of power supply when the water is present in the water chamber. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS: We shall now describe the main invention with reference to accompanying drawings which are given by way of illustration but does not restrict the scope of invention Figure 1 illustrates the operation of the door lock in prior art Figure 2 illustrates the various components of the safety device for door lock of the present invention. Brief description of safety device for door lock operation in appliance is described in relation to Fig. 2. Safety device consists of spring loaded plunger 7 for locking upward movement of slider 8, rubber diaphragm 6 for sensing air pressure and sliding spring loaded plunger 7, spring loaded slider 8 for locking plunger 5 of door lock (Fig. 2). These prime components are encased in housing and assembled in door lock 1 as shown in Fig.2. The sliding path of plunger 7 and sliding path of slider 8 are intersecting each oilier as shown in Fig. 2. Rubber diaphragm is linked to pressostat through air passage in additional elastic lube 9 with the help of'T joint 4. Rectangular hole 'FT is provided in the housing for movement of slider 8 (Fig. 2) of safety device. Slot 'P' provided on plunger 5 to be used for locking movement of plunger 5 by safety device slider (Fig. 2). Pressostat or pressure switch is the component used in appliance which determines and controls the level of water in the water chamber. Level of water detected through the pressure of air column in the elastic tube 3 which is connected to the water chamber through rubber hose. Spring loaded slider 8 is linked to the plunger 5 of the door lock as shown in figure 2. Operation of the safety device (Fig. 2) of the present invention - On availability of water in the water chamber, the air pressure in the elastic tube 9 presses the rubber diaphragm 6 which slides the spring loaded plunger 7. This movement of plunger 7 pushes the spring loaded slider 8, which in turn locks the position of door lock plunger as shown in figure 2. Under this condition even if the power supply to the door lock fails or terminated, the plunger 5 of the door lock as shown in figure 1 will not be able to slide back under the effect of the spring. As a result the door of the appliance will remain in locked condition when the water is available in the water chamber. The situation where in water chamber does not contain water will effectively release the air column pressure on rubber diaphragm 6. This in turn will make spring loaded plunger 7 slide in the direction of rubber diaphragm. As a result spring loaded slider 8 will move from its position there by releasing plunger of the door lock for its sliding movemert to unlock the door of the appliance. WE CLAIM : 1. A safety device for door lock operation in appliances, which comprises: a spring loaded plunger (7) for locking upward movement of spring loaded slider (8); a rubber diaphragm (6) for sensing air pressure; a spring loaded slider (8) for locking plunger (5) of the door lock; a pressostat for controlling the level of water in the water chamber wherein in the absence of water, in the water chamber, the air column pressure on rubber diaphragm (6) is released, thus making the said spring loaded plunger (7) slide in the direction of the rubber said diaphragm (6), which results in the movement of the said spring loaded slider (8) from its position; thus releasing the said plunger (5) of the door lock for its sliding movement to unlock the door of the appliance; characterized in that, in the presence of water in the water chamber, the air pressure in the elastic tube (9) presses the said rubber diaphragm (6) which slides the said spring loaded plunger (7) which in turn pushes the said spring loaded slider (8), which in turn locks the position of the said door lock plunger (5) which results in the locking of the door of an appliance in presence of water irrespective of availability of power supply and the said plunger (5) of the door lock is unable to slide back under the effect of the spring. 2. The safety device for door lock operation in appliances as claimed in claim 1, wherein the said spring loaded plunger (7), rubber diaphragm (6), a spring loaded slider (8) and locking plunger (5) are encased in bousing and assembled in door lock (1). 3. The safety device for door lock operation in appliances as claimed in claims 1 & 2, wherein the sliding path of plunger (7) and sliding path of spring loaded slider (8) are intersecting each other. 4. The safety device for door lock operation in appliances as claimed in claims 1 to 3, wherein the said rubber diaphragm (6) is linked to said pressostat through air passage in additional elastic tube (9) with the help of a ' T joint (4). 9 The present invention relates to a safety device for door lock operation in appliances, which comprises: a spring loaded plunger (7) for locking upward movement of spring loaded slider (8); a rubber diaphragm (6) for sensing air pressure; a spring loaded slider (8) for locking plunger (5) of the door lock; a pressostat for controlling the level of water in the water chamber

Full Text

FIELD OF THE INVENTION
The present invention relates a safety device for door lock
operation in appliances.
BACKGROUND OF THE INVENTION
Appliances such as Washing Machine and Dishwasher use water as
prime media for carrying out the desired operation of washing or
cleaning. Depending on the design feature, the temperature of water
during part of the operation can vary upto 95° C. All such appliances
carry a loading port or hole for loading articles to be cleaned or washed
into appliances.
After loading the articles the port or hole is closed by the door
which gets locked to the main body or cabinet by the device "Door
Lock'\ After closing the door, the appliances are switched on for electric
power supply.
The door lock is functional from the start operation or program or
cycle till the end of operation or program or cycle. At the end of cycle the
door lock unlocks the door for subsequent opening to take out the articles
from the appliances.
The door lock used in the appliances now days are basically
operating on the thermistor and bimetal principle and they are called
thermal door locks. This concept is used in practically all the machines.
In some machines the door locks used are of magnetic type also.
Door Lock operation in general is illustrated in relation to Fig 1,
wherein door lock has three contact terminals 'L' for input live power
supply. 'N' for input neutral power supply and 'C for output live power
supply. The slider 3 for locking plunger 5, bi-metallic strip 2 for
deflecting spring contact plate 4, thermister 1 for heating bi-metallic strip
2, plunger 5 for locking the door of the appliance, spring contact plate 4
for making contact of terminal 'L' and 'C and upward and downward
movement of slider 3, spring 6 for return movement of plunger 5. All
prime components are covered in housing 7.
With the closure of door of appliance, the plunger 5 slides against
the pressure of spring 6 to the position where the "locking" function takes
place. At this position the portion P of the plunger 5 comes below the
hole at the portion H on the housing 7. When appliance is switched "ON"
the power supply through electric circuit of the appliance is available
between L & N where as L & C are open for the current path. Due to
supply between L & N the thermister I gets heated and the heat is
transmitted to bimetallic strip 2. Bimetallic strip at a particular
temperature which is defined by the constituting metals of the bimetallic
strip, buckles. This in turn deflects the contact plate 4 to establish current,
path between L & C as well as to lock the sliding movement of plunger 5
through slider 3. The door lock is in locked condition throughout the
working cycle of appliance or till such time power supply is available to
the door lock.
At the end of working cycle, the power supply to the door lock gets
cut off. As a result the thermister (I) cools down, bimetallic strip 2
restores the original position. This deflects the contact plate 4 which in
turn deflects slider 3 to unlock the sliding movement of plunger 5.
Unless taken care of by some other design, such door lock, in case
of non-availability of power supply or supply failure, restore to the
unlock condition thereby unlocking the door.
Under "no power" situation where in appliance is also under
incomplete operation cycle with water inside (in between start and end
position) if user intentionally or unintentionally opens the door, the water
splashes out of the appliance. Depending on selection of operating
parameters and stage of operation, water can be of any temperature upto
95° centigrade. Under all such and similar situations, it is unsafe to have a
stage of "unlocked door" in between the operating cycle of the appliance.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a safety device for
door lock ensuring the locked condition of the door under the situation
when water chamber of the appliances carries water inside.
The another object of the present invention is to provide a safety
device for door lock for preventing the door from opening when water
chamber of the appliance carries water inside and prevents hot or cold
water spilling out of the appliance resulting in the safety of the user as
well as reduces inconvenience due to spillage.
According to the present invention there is provided a safety device
for door lock operation in appliances, which comprises:
a spring loaded plunger (7) for locking upward movement of spring
loaded slider (8);
a rubber diaphragm (6) for sensing air pressure;
a spring loaded slider (8) for locking plunger (5) of the door lock;
a pressostat for controlling the level of water in the water chamber.
The safety device of the present invention, in the absence of water,
in the water chamber, the air column pressure on rubber diaphragm (6) is
released, thus making the spring loaded plunger (7) slide in the direction
of the rubber diaphragm, which results in the movement of the spring
loaded slider (8) from its position; thus releasing the plunger of the door
lock for its sliding movement to unlock the door of the appliance;
The safety device of the present invention, in the presence of water
in the water chamber, the air pressure in the elastic tube (9) presses the
said rubber diaphragm (6) which slides the spring loaded plunger (7)
which in turn pushes the spring loaded slider (8), which in turn locks the
position of the door lock plunger (5) which results in the locking of the
door of an appliance in presence of water irrespective of availability of
power supply and the said plunger (5) of the door lock is unable to slide
back under the effect of the spring.
The safety device establishes a link between the water content in
the appliance chamber where articles are physically cleaned or washed
and the door lock. It enables door lock to retain locked condition of door
irrespective of availability of power supply when the water is present in
the water chamber.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
We shall now describe the main invention with reference to
accompanying drawings which are given by way of illustration but does
not restrict the scope of invention
Figure 1 illustrates the operation of the door lock in prior art
Figure 2 illustrates the various components of the safety device for
door lock of the present invention.
Brief description of safety device for door lock operation in
appliance is described in relation to Fig. 2. Safety device consists of
spring loaded plunger 7 for locking upward movement of slider 8, rubber
diaphragm 6 for sensing air pressure and sliding spring loaded plunger 7,
spring loaded slider 8 for locking plunger 5 of door lock (Fig. 2). These
prime components are encased in housing and assembled in door lock 1
as shown in Fig.2. The sliding path of plunger 7 and sliding path of slider
8 are intersecting each oilier as shown in Fig. 2. Rubber diaphragm is
linked to pressostat through air passage in additional elastic lube 9 with
the help of'T joint 4. Rectangular hole 'FT is provided in the housing for
movement of slider 8 (Fig. 2) of safety device. Slot 'P' provided on
plunger 5 to be used for locking movement of plunger 5 by safety device
slider (Fig. 2).
Pressostat or pressure switch is the component used in appliance
which determines and controls the level of water in the water chamber.
Level of water detected through the pressure of air column in the elastic
tube 3 which is connected to the water chamber through rubber hose.
Spring loaded slider 8 is linked to the plunger 5 of the door lock as shown
in figure 2.
Operation of the safety device (Fig. 2) of the present invention -
On availability of water in the water chamber, the air pressure in the
elastic tube 9 presses the rubber diaphragm 6 which slides the spring
loaded plunger 7.
This movement of plunger 7 pushes the spring loaded slider 8,
which in turn locks the position of door lock plunger as shown in figure
2. Under this condition even if the power supply to the door lock fails or
terminated, the plunger 5 of the door lock as shown in figure 1 will not be
able to slide back under the effect of the spring. As a result the door of
the appliance will remain in locked condition when the water is available
in the water chamber.
The situation where in water chamber does not contain water will
effectively release the air column pressure on rubber diaphragm 6. This in
turn will make spring loaded plunger 7 slide in the direction of rubber
diaphragm.
As a result spring loaded slider 8 will move from its position there
by releasing plunger of the door lock for its sliding movemert to unlock
the door of the appliance.
WE CLAIM :
1. A safety device for door lock operation in appliances, which
comprises:
a spring loaded plunger (7) for locking upward movement of spring
loaded slider (8);
a rubber diaphragm (6) for sensing air pressure;
a spring loaded slider (8) for locking plunger (5) of the door lock;
a pressostat for controlling the level of water in the water chamber
wherein in the absence of water, in the water chamber, the air
column pressure on rubber diaphragm (6) is released, thus making the
said spring loaded plunger (7) slide in the direction of the rubber said
diaphragm (6), which results in the movement of the said spring loaded
slider (8) from its position; thus releasing the said plunger (5) of the door
lock for its sliding movement to unlock the door of the appliance;
characterized in that, in the presence of water in the water chamber,
the air pressure in the elastic tube (9) presses the said rubber diaphragm
(6) which slides the said spring loaded plunger (7) which in turn pushes
the said spring loaded slider (8), which in turn locks the position of the
said door lock plunger (5) which results in the locking of the door of an
appliance in presence of water irrespective of availability of power supply
and the said plunger (5) of the door lock is unable to slide back under the
effect of the spring.
2. The safety device for door lock operation in appliances as claimed
in claim 1, wherein the said spring loaded plunger (7), rubber diaphragm
(6), a spring loaded slider (8) and locking plunger (5) are encased in
bousing and assembled in door lock (1).
3. The safety device for door lock operation in appliances as
claimed in claims 1 & 2, wherein the sliding path of plunger (7) and
sliding path of spring loaded slider (8) are intersecting each other.
4. The safety device for door lock operation in appliances as
claimed in claims 1 to 3, wherein the said rubber diaphragm (6) is linked
to said pressostat through air passage in additional elastic tube (9) with
the help of a ' T joint (4).
9

The present invention relates to a safety device for door lock operation in
appliances, which comprises: a spring loaded plunger (7) for locking
upward movement of spring loaded slider (8); a rubber diaphragm (6) for
sensing air pressure; a spring loaded slider (8) for locking plunger (5) of
the door lock; a pressostat for controlling the level of water in the water
chamber

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Patent Number

234012

Indian Patent Application Number

717/CAL/2001

PG Journal Number

18/2009

Publication Date

01-May-2009

Grant Date

29-Apr-2009

Date of Filing

26-Dec-2001

Name of Patentee

IFB INDUSTRIES LIMITED

Applicant Address

14 TARATOLLA ROAD, KOLKATA

Inventors:

#	Inventor's Name	Inventor's Address
1	BIJON NAG	39 HUMAYUN KABIR SARANI, KOLKATA 700053

PCT International Classification Number

D06F 37/06

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA