FORM 2
THE PATENT ACT 1
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION FILTER-CLOG MONITORING DEVICE
2. APPLICANT
MAHINDRA & MAHINDRA LIMITED
1, GATEWAY BUILDING, APOLLO BUNDER, MUMBAI - 400001.
AN INDIAN COMPANY.
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION:
The present invention generally relates to indication of filter clogging, by measuring differential pressure across filter. Filter clog indicating helps the equipment operator to monitor condition of the filter and provides useful early signals for deciding on changing of the filter before it chokes completely. More particularly, it relates to a low cost filter-clog indicating device using a diaphragm and having simple construction.
BACKGROUND OF THE INVENTION:
In automotive applications, especially in tractors, hydraulic systems like transmission lubrication cum hydraulic system, engine lubrication system, even engine fuel system, etc. use filters to remove contaminants from the fluids. Contaminants get into the circulating fluid from internal and external sources, and adversely affect performance/working of the circulating fluid. Fluid with excessive contaminants increases wear of the system components and also develops higher viscosity. More power gets used up to make such high-viscosity fluid circulate in the system. The filter-system(s) used to remove particulate contaminants present in the circulating fluid need to be replaced promptly before they get choked up/ dysfunctional, in order to maintain functional reliability of the equipment or machinery and protect it from getting damaged.
It is a regular practice to change filters at predetermined intervals based on certain standardized calculations and considerations deciding its life. This practice, however, could result in either early disposal of the yet properly functioning or usable filter, or overuse of an already

dead (fully clogged) filter which will deteriorate the system performance or life.
The life of a filter is monitored by a device commonly referred to as a 'filter indicator'. Normally these indicators are calibrated for a predetermined threshold value. When the filter pressure exceeds this preset value, warning indication/ alarm through electrical signal or visual means is provided to the user prompting to change the filter. This is generally an "Ok-or-not-OK" type of signal. Hence it is appropriate to monitor the pressure differential across the filter in continuous manner to understand useful life remaining at any point of time.
Pressure gauges such as the one disclosed in the US Patents 6981421, 4347744 & 2722837 uses diaphragm coupled with magnet to sense the differential pressure across the filter, and the hall-effect sensor positioned near the magnet generates signal corresponding to the pressure differential sensed. These gauges use a dial pointer coupled with helix arrangement, to indicate the sensed pressure. Disadvantage of these gauges is need of calibration through complex adjustment system to set the initial zero value. Fluids which are paramagnetic in nature will become extremely polarized due to the magnet present in these indicating systems.
Filter monitoring devices as described in US patents 5702592 and 7552626 also make use of magnetic means to sense and indicate the pressure, and may not be suitable for use with paramagnetic fluids or fluids that contain paramagnetic or permanent magnetic additives. Also, these devices are of filter-mounted type which necessarily

requires separate means to communicate to the indicator means in remote location, adding complexity.
The devices shown in US patents 6089098 and 4084072, and GB Patent 1057855 use some means of magnet connected with diaphragm to open or close an electrical circuit and thus act as a switch which will give indication to the user when a predetermined value is reached. Thus they do not provide simple indication of pressure differential in a continuous manner such that usefulness of the filter or its condition with respect to the need to replace could be accessed by the user.
A floating piston is used to indicate the filter condition as described in the US patent 3411477 which may allow the unfiltered fluid to get communicated with filtered oil. Thus it adversely affects the primary function of the filter. The filter housing has to be made transparent to check the float piston position to monitor the filter condition. This type of device becomes specific-purpose or application-specific, as it has to be designed for each particular application and could not be used universally for any pressure vaiues as the spring tension has to be changed for any given application.
OBJECTIVE OF THE INVENTION;
The present invention overcomes the shortcomings associated with the background art and achieves other advantages not realized by the background art.
The main objective of the present invention is to provide a simple, cost effective, filter-replacement cost optimizing and efficient filter-clog

monitoring device and indicating mechanism suitable for any type of fluid.
Another objective of the present invention is to monitor pressure differential of a filter used with any given fluid including paramagnetic type or having paramagnetic additives and provide a visual indication of the measured pressure differential to facilitate the user to assess the condition of the filter at any point of time.
Yet another objective of the present invention is that the device could be used for any type of fluid filters and of any make without need of any significant modification to the filter.
Yet another objective of the present invention is to provide means for continuous monitoring of the filter condition and provide indication of remaining useful life of the filter.
Yet another objective of the present invention is that the indicating device could be mounted at any convenient place in the equipment or machinery and connected with the filter to be monitored.
Yet another objective of the present invention is to avoid mix-up of the filtered and unfiltered fluid at the pressure sensing or indicating device.
Yet another objective of the present invention is to provide simple means to set a band of zero to maximum level.

Yet another objective of the present invention is to provide means for connecting electrical signal generating devices to indicate the filter condition (at a remote / farther away place like dash-board/ instrument panel).
In accordance with present invention, one aspect of the filter-clog monitoring device comprising an enclosure that is made in two pieces and pressed/joined together forms the fluid cavity and a flexible diaphragm of corrugated type having planar center portion is mounted in the fluid cavity. The diaphragm forms two chambers in the enclosure. One chamber is connected to inlet side of the filter and the other side is connected to the outlet side of filter. The central portion of the diaphragm is moveable with response to the pressure difference between the inlet and outlet sides of the filter. Also comprising a float connected to the diaphragm by a pin which is coupled with the central portion of the diaphragm. The float moves inside a transparent chamber in relation to the diaphragm deflection. A spring is placed above the float inside the transparent chamber to provide the float with return motion. A maximum level indication is placed over the transparent chamber. The maximum level indication shall be tailor-positioned for any particular filter model.
BRIEF DESCRIPTION OF THE DRAWINGS:
FIG. 1 is a front elevation view of the filter-clog monitoring device
according to the present invention. FIG. 2 is a top plan view of the filter clog indicator. FIG. 3 is a cut-sectional view taken along line 3 - 3 of FIG. 2. FIG. 4 is a cut-sectional view of another embodiment of the present
invention.

FIG. 5 is a cut-sectional view of yet another embodiment of the
present invention with diaphragm connected to a float lever. FIG. 6 is a top view with reference to FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT:
With reference to above mentioned FIG. 1 to 3, filter clog monitoring device 19 contains an enclosure having combined with a first shell 1 and a second shell 2 which are of circular shape in cross section. The first shell 1 and the second shell 2 are sealed together at their open end along with diaphragm 3 of corrugated type. The diaphragm splits the enclosure into two chambers; form a first chamber 22 with the first shell 1 and form a second chamber 21 with the second shell 2. The second chamber 21 is provided with a second opening and connected to the filter's outlet port by a second conduit means 11. The first chamber 22 is provided with a first opening and connected to the filter's inlet port by a first conuit means 12. The diaphragm 3 has a coupling means 4 at the center thereof for attaching a connecting rod 5.
The second shell 2 necessarily contains provision to adopt a visual indication device 23 with the help of neck 20 provided on top end surface 24 of the second shell 2. The visual indication device 23 necessarily contains an indication chamber 6 which is made of transparent material and preferably circular shape in cross section. The indication chamber 6 is placed and secured with help of neck 20. The top of the indication chamber 6 is threadingly closed with a cover 7.

The indication chamber 6 houses a float 9 which is slidably disposed in the chamber 6 and connected to a connecting rod 5. An elastic member 10 is placed above the float 9 inside the indicating chamber 6 to maintain original position of the diaphragm 3. The elastic member shall be a compression spring. In one of the embodiments of the present invention, the top cover 7 is a threaded type used to adjust the pre-tension of the compression spring 10. A marking band 8 is placed over the indicating chamber 6 at particular distance from the float that is predetermined for any given filter.
In another embodiment of the present invention as described in the FIG. 4, the float 9 can directly be mounted over the coupling means 5 of the corrugated diaphragm 3 inside the second shell 2. The compression spring 10 is placed inside the second sheff 2 between the float 9 and the top end surface 24 thereof. The second shell 2 is made up of transparent material. The marking band 8 is placed over the second shell 2 at predetermined position to indicate the 'maximum' condition for any given filter, that is, in connection with the filter clog monitoring device 19.
In an another embodiment of the present invention as described in FIG. 5, a float lever 14 is connected to the coupling means 4 on the diaphragm 3 with the help of a pivot means 13. The other end of the float lever 14 is connected to the rheostat assembly 15. The rheostat assembly 15 necessarily contains electrical resistor and contact points that varies electrical resistance and provides a means for pressure signal. The electrical unit 16 is mounted on the top end surface 24 of the second shell 2 to enclose the internal wiring to the rheostat

assembly 15 and provides external connecting means via a first terminal 17 and a second terminal 18.
Referring to FIG. 3, the diaphragm 3 separates the second chamber 21 and the first chamber 22 and provides tight sealing between said chambers for avoiding leakage from one chamber to another chamber. Corrugated shape of the diaphragm 3 accommodates any excessive deflection caused due to higher fluid pressure in the chambers. The diaphragm 3 deflects towards the second chamber 21 as the pressure in the second chamber 21 becomes lower than that in the first chamber 22. The deflection of the diaphragm has direct relationship with the clog condition of the filter that is being monitored with the present invention.
The deflection of the diaphragm 3 causes the connecting rod 5 to lift the float 9 inside the indication chamber 6. The equipment user can visually observe the movement of the float 9 inside the transparent indication chamber 6. The float 9 raises from the initial position as the diaphragm 3 starts responding to the pressure difference between the two chambers 21 & 22 due to the filter clogging during the operation over time. At a particular condition when the filter clogs to the maximum allowable limit beyond which usage of the filter system could cause potential damage to the equipment, the float 9 inside the transparent indicating chamber 6 will reach the level of the marking band 8 that is provided over the indicating device 23, indicating 'maximum' level reached. The float 9 in the level of marking band 8 gives visual indication to the user that the filter being monitored has reached its specified life limit and needs to be changed. The compression spring 10 keeps the float 9 in original position thus keeps

the diaphragm in original position when the pressure differential is negligible (near zero). The float 9 at any level below the marking band 8 position provides the information of the remaining life of the filter being monitored with the present invention.
In one of the preferred embodiments, the second chamber 21 and the first chamber 22 shall be connected to inlet and outlet ports of the filter, respectively. In this particular arrangement, the deflection of the diaphragm 3 will be in the side of first chamber 22 and the float 9 connected to the coupling means 4 by the connecting rod 5 moves in downward direction towards the chamber 22. During such downward motion generally vacuum forms in the space above the float 9 which may hold the float in the withdrawn position itself even after removal of the pressure differential that causes the diaphragm deflection thus provides a permanent indication of the filter condition. A vacuum release means provided in the cover 7 can release the vacuum to reset the position of float 9 to initial condition. In this arrangement it is necessary that the marking band 8 is normally positioned below the float's initial position and the compression spring 10 may be placed below the float 9 and seated against the top face of chamber 21.
In another embodiment of the present invention as described in the FIG. 4, the float 9 moves in response to the deflection of the diaphragm 3 by the movement of coupling means 4. The compression spring 10 placed above the float 9 provides sufficient force to keep the float 9 and diaphragm 3 in original position. The level of the float 9 indicated visually by the transparent second shell 2. As the float 9 reaches the marking band 8 provided on the second shell 2, it thus

provides the user the necessary information about the condition of the filter being monitored.
In a further additional embodiment of the present invention as described in the FIG. 5, the coupling means 4 moves in response to the deflection of the diaphragm 3 due to the pressure differential across the diaphragm in the chambers 21 & 22. The movement of the coupling means 4 gets transferred to the rheostat assembly 15 by the float lever 14. The float lever 14 placed above the coupling means 4 and secured by the pivot means 13 allows the motion transfer from the coupling means 4 to the float lever 14. Construction of the pivot means 13 allows the float lever 14 to be in working condition with the coupling means 4 during angular movement of the float lever 14. The rheostat assembly 15 varies the electrical resistance as per the movement of float lever 14 in relation to the pressure differential sensed by the diaphragm 3. This variation in resistance is communicated to the electrical indication device provided in the equipment as the condition of the filter, by converting the electrical signal according to the filter being monitored. The resistance level normally calibrated between minimum to maximum pressure differential across the filter thus provides indication of initial and maximum useful life of the filter, the terminals 17 & 18 are provided at the electrical unit to use in connection with the indicating device.
It will be readily appreciated by those skilled in the art that modifications may be made to the invention without departing from the concepts disclosed in the foregoing description. Accordingly, the particular embodiments described in detail herein are illustrative only and are not limiting to the scope of the invention, which is to be given

the full breadth of the appended claims and any all equivalents thereof.

We claim:
1. A filter-clog monitoring device for operatively incorporating with a fluid-filtering device to give indication on performance thereof to operator comprising:
a first shell provided with a first opening on lateral surface thereof;
a second shell provided with a second opening on lateral surface thereof; wherein said first shell and said second shell are joined together along with a diaphragm;
wherein said first shell along with said diaphragm form a first chamber;
wherein said second shell along with said diaphragm form a second chamber;
a coupling means provided at center of said diaphragm for operably connecting a connecting rod therewith;
wherein top surface of said second shell is formed with a neck adapted to receive a visual indication device;
wherein said visual indication device comprising:
an indication chamber made of transparent material and closed
with a cover on top end thereof;

a float adapted to sfidably move from first position to second
position;
at least a marking band positioned around said indication
chamber at a predetermined location spaced from first position;
an elastic member disposed between the float and the cover for
maintaining the first position of the float.
2. The filter-clog monitoring device as claimed in claim 1, wherein planar surface of said diaphragm is formed with corrugated surface for effective and precise deflection thereof with pressure difference.
3. The filter-clog monitoring device as claimed in claim 1, wherein said first opening is connected with a first conduit for fluidly coupling with inlet of filter and said second opening is connected with a second conduit for fluidly coupling with outlet of filter.
4. The filter-clog monitoring device as claimed in claim 1, wherein said elastic member is a compression spring.
5. The filter-clog monitoring device as claimed in claim 1 and 4, wherein said cover is threadingly closed with said indication chamber for adjusting strain energy of said compression spring.

6. The filter-clog monitoring device as claimed in claim 1, wherein said second shell shall be made of transparent material and said float and said elastic member arrangement shall be disposed in said second chamber by directly positioning said float on said diaphragm via said coupling means instead of providing said visual indication device.
7. The filter-clog monitoring device as claimed in claim 6, wherein said marking band shall be positioned around said second shell at a predetermined location spaced from first position.
8. The filter-clog monitoring device as claimed in claim 6, wherein said elastic member and said float shall be replaced by a float lever and a rheostat assembly for indication of performance of the filter clog monitoring device through electrical signal.
9. The filter-clog monitoring device as claimed in claim 8, wherein
one end of said float lever is operably pivoted with said coupling
means via a pivot means, and another end is disposed on said
rheostat assembly so as to vary resistance of current flow as the
diaphragm deflects and subsequently the float lever moves along
the resistance path of current flow.

10. The filter-clog monitoring device as claimed in claim 9
wherein said rheostat assembly is incorporated with an electrical unit for sending electrical signal to indication devices.