FIELD OF INVENTION
This invention relates to signal cut off device for filter clogging indicator of
tractor. This results in life enhancement of hydraulic system of tractor.
BACKGROUND OF THE INVENTION
A current application of agricultural tractors is the field operations as well as
road applications with focus on Construction & Industrial application, tipping
trolley application and many more.
Hydraulic pump continuously creates the suction to take hydraulic oil through
filter mounted in line on suction line. Hydraulic oil gets contaminated by
different sources like wear and tear of center housing component, gear box
component, hydraulic linkages and hydraulic body etc. So the contamination
generated through all these components may choke the hydraulic filter and
choking of hydraulic filter can result in bypass valve open and then
contaminated oil goes to hydraulic pump which results in pump to seize or
damage of hydraulic system and lifting time for three point linkage system will
also increase. To avoid all these problems generated by filter choking, the filter
clogging indicator along with a temperature sensor is one feature which
indicates the differential pressure, in suction line of hydraulic system of tractor
on cluster panel to operator (if the temperature and pressure values are within
prescribed limits).
Hydraulic gear pump is the main source of power (prime mover) for tractor
hydraulic system. Its main function is to take oil from the sump through filter
and to pass pressurized oil to distributor to distribute it in hydraulic system of
tractor. This hydraulic pump can be malfunctioned or seized due to various
reasons given hereinbelow:
2 3 JUN 2014
1) Aeration in suction line.
2) Contact with contaminations.
3) Insufficient supply of hydraulic oil.
Aeration problem arises due to leakage in suction line of system while the
contamination and insufficient oil supply is caused due to improper
functioning of hydraulic oil filter. Now reduction of the contamination level in
oil is possible but contamination level can't be negligible. As the oil sump for
transmission system and hydraulic system is same. The contamination by
transmission and hydraulic components cause chocking of hydraulic filter if oil
/
is not changed periodically. In case of chocking of hydraulic filter, the bypass
valve inside the hydraulic filter gets open and allows the oil to flow through it.
However, contaminated oil flowing through the bypass valve can seize the
hydraulic pump and damage hydraulic system of tractor. Noise is created in
system due to contaminated oil which is not recommended. Also the seizing of
hydraulic pump results in non-functionality of hydraulic system of tractor.
Hence, to avoid the pump to seize, there is requirement of a pressure indicator
which can show the filter chocking problem.
The hydraulic pump takes the oil from sump through filter and delivers it to
the distributor of hydraulic system. The filter clogging indicator is unit consists
of pressure sensor and one dial gauge. Filter clogging indicator works on
pressure difference between inlet oil pressure to filter and outlet oil pressure
after filtering. The filter clogging sensor is mounted on suction line between the
hydraulic filter and the pump while the dial gauge is mounted on cluster panel
which is in front of operator.
The connection is provided between filter clogging indicator and the dial gauge.
Whenever the filter gets chocked, the change in pressure sensed by the sensor
and it sends the signal to dial gauge. So operator come to know about the
2 3 JUN 2011
chocking of hydraulic filter and can take care of that accordingly, in such a
way, the hydraulic pump failure can be avoided or life of hydraulic pump
increases.
The filter clogging indicator is having advantages as follows:-
1) Prevents hydraulic pump to seize.
2) Indicates hydraulic filter chocking.
3) Avoids hydraulic system damage by contaminated hydraulic oil flowing
through bypass valve of filter.
However, it is also associated with the following drawbacks:-
1) After starting of tractor, initially viscosity of oil is high, as initially the
temperature of hydraulic oil is less , it gives large pressure difference of oil
between inlet and outlet of filter then filter clogging indicator gives signal to
dial gauge i. e. filter is choked but the real condition is that filter is not
chocked. Pressure difference is created due to high viscosity.
2) The same problem occurs in winter season because in winter season oil
temperature is low and its viscosity is high. This causes aggravation to the
operator and he/she may change the filter when not needed or not change
the filter when it is actually clogged, feels irritating and sometime he/she
neglects signal given by filter clogging indicator and it adds operating cost.
Hence, the present invention is introduced to address the aforesaid drawbacks.
OBJECTS OF THE INVENTION
The primary object of the present invention is to provide an improved hydraulic
system of tractor for efficient functioning of filter clogging indicator which
overcomes disadvantages associated with the prior art.
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2 3 JUN 2011
Another object of the present invention is to provide an improved hydraulic
system of tractor for efficient functioning of filter clogging indicator which is
reliable and efficient.
Still another object of the present invention is to provide an improved hydraulic
system of tractor for efficient functioning of filter clogging indicator wherein
filter clogging indicator gives accurate result.
Yet another object of the present invention is to provide an improved hydraulic
system of tractor for efficient functioning of filter clogging indicator which is
simple in construction.
SUMMERY OF THE INVENTION
According to this invention, there is provided an improved hydraulic system of
tractor for efficient functioning of filter clogging indicator comprising of a
temperature sensor connected to filter clogging indicator, wherein said filter
clogging indicator signals the dial gauge when the pressure drop caused due to
clogging of filter & not due to increase of viscosity of oil due to low temperature.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from
the ensuing description when read in conjunction with the accompanying
drawings and wherein:
Fig. 1 shows: An improved hydraulic system of tractor according to present
invention.
Fig. 2 shows: Operation of the filter clogging indicator in the hydraulic
system of tractor.
Fig.3 shows: Operation of the filter clogging indicator in the hydraulic
system of tractor when pressure drop does not increase than
the specified value.
DETAIL DESCFUPTION OF THE PRESENT INVENTION WITH REFERENCE
TO THE ACCOMPANYING DRAWINGS
This invention is directed to an improved hydraulic system of tractor for
efficient functioning of filter clogging indicator.
Now, reference may be made to fig. 1 indicating the following:-
- Cutoff device (Temperature sensor)- l
- Filter clogging indicator-2
- Dial gauge-3
- Hydraulic filter-4
- Oil sump-5
- Hydraulic system-7
The hydraulic system comprising of a temperature sensor (cut off device) (I)
connected to filter clogging indicator (2), wherein said filter clogging indicator
signals (S) the dial gauge (3) when the pressure drop caused due to clogging of
filter & not due to increase of viscosity of oil due to low temperature. The cut off
device i.e. temperature sensor cut offs signal from filter clogging sensor when
temperature of oil drops below specified limit. The temperature sensor (TS) is
provided with a pressure sensor (PS). The system is as shown in fig. 1.
Thus, the filter Clogging Indicator forwards signal to dial gauge when pressure
drop increases beyond specified limit & temperature of oil goes above a
specified value. Secondly, a temperature sensor along with pressure sensor is
provided, which gives signal to pressure sensor at specified temperature only.
The temperature sensor is provided in the form of bimetallic strip. A bimetallic
strip is used to convert a temperature change into mechanical displacement.
The strip comprises of two strips of different metals which expand at different
2 3 JUN 20\l
rates as they are heated. The strips are joined together throughout their length
by riveting, brazing or welding. The different expansions force the flat strip to
bend one way if heated, and in the opposite direction if cooled below its initial
temperature.
Operation
In normal condition, Temperature sensor senses temperature of oil, Filter
Clogging Indicator senses pressure difference between inlet and outlet of filter
oil. If temperature of oil goes above specified value, bimetallic strips move in
upward direction. If the pressure difference exceeds specified value, pressure
sensor moves in downward direction and the circuit gets closed when both the
conditions are satisfied as shown in fig. 2.
In case, pressure drop exceeds above specified value but temperature of oil is
not above specified value, cut off device cuts signal going to dial gauge. This
occurs in winter season and also at the starting of tractor. In this condition,
the temperature of oil is less and viscosity is high. It gives large pressure
difference due to which Filter Clogging Indicator starts to give signal to dial
gauge. This drawback is removed by means of temperature sensor.
If pressure drop does not increase than the specified value, Filter Clogging
Indicator does not move downwards. In this case no circuit is closed and hence
no signal is given to dial gauge as shown in fig. 3.
Hence, when actual filter is clogged, only then Filter Clogging Indicator gives
signal to dial gauge.
Advantageous Features
1) Filter clogging indicator gives accurate result regardless of starting of
tractor and winter season.
2) Filter is changed when it is really clogged. Therefore, whole life of filter is
utilized.
3) Operator's aggravation minimized.
It is to be noted that the present invention is susceptible to modifications,
adaptations and changes by those skilled in the art. Such variant embodiments
employing the concepts and features of this invention are intended to be within
the scope of the present invention, which is further set forth under the
following claims: -
P ease reply to
* (C) Indian and Foreign Patents & Trade Marks Telegram : "DAVARCO
ESTABLISHED 1932 Telephone : 26418980 (0)
L. S. DAVAR & CO. 264381 62
26232328
PATENTS AND TRADE MARKS ATTORNEY'S Fax : (91) (11)29234443
511 (IST FLOOR) KALKAJI EXTENSION 26464498
41431140
NEW DELHl - 110019 E-mail : Isdavar@ndf.vsnl.netin
CASH SECTION LAST DATE: 24.06.2014
Dated 18th June, 2014 No. of Pages: 12
No. of Claims: 08
The Controller of Patents,
The Patent Office Branch,
NEW DELHI
Re: Filing complete of the provisional to patent application no. 1859 /DELI20 13 dt.
24.06.2013 for "Signal cut off device for filter clogging indicator of tractor" in the
name of ESCORTS LIMITED.
************
Dear Sir,
In connection with the above patent application we enclose herewith the following:
1. Complete specification (in duplicate);
2. Abstract (in duplicate);
3. Informal drawing (in duplicate) ;
4. Form-5.
Kindly take the enclosed documents on record.
Yours faithfully, 1 ,
(SOMA RANI MIS p OF L.S.DAVAR & CO.,
Encl: as stated above
Srm/s.
H.O.: 32, RADHA MADHAB DUTTA GARDEN LANE, KOLKATA-700 010 INDIA
PH.: 2363-3251,2363-3252,2363-3253,2287-3996,2287-5918,2280-5536
FAX : 033 2287-5886,22876292,2281-7165,23633248,2363-3249

WE CLAIM:
1. An improved hydraulic system of tractor for efficient functioning of
filter clogging indicator comprising of a temperature sensor connected
to filter clogging indicator, wherein said filter clogging indicator
signals the dial gauge when the pressure drop caused due to clogging
of filter & not due to increase of viscosity of oil due to low
temperature.
2. An improved hydraulic system of tractor for efficient functioning of
filter clogging indicator as claimed in claim 1, wherein the cut off
device i.e. temperature sensor cut offs signal from filter clogging
sensor when temperature of oil drops below specified limit.
3. An improved hydraulic system of tractor for efficient functioning of
filter clogging indicator as claimed in claim 1 or 2, wherein the
temperature sensor is provided with a pressure sensor.
4. An improved hydraulic system of tractor for efficient functioning of
filter clogging indicator as claimed in any of the preceding claims,
wherein the filter clogging indicator forwards signal to dial gauge
when pressure drop increases beyond specified limit & temperature of
oil goes above a specified value.
5. An improved hydraulic system of tractor for efficient functioning of
filter clogging indicator as claimed in any of the preceding claims,
wherein a temperature sensor along with pressure sensor is provided,
which gives signal to pressure sensor at specified temperature only.
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6. An improved hydraulic system of tractor for efficient functioning of
filter clogging indicator as claimed in any of the preceding claims,
wherein the temperature sensor is provided in the form of bimetallic
strip comprising of two strips of different metals which expand at
different rates as they are heated.
7. An improved hydraulic system of tractor for efficient functioning of
filter clogging indicator as claimed in any of the preceding claims is
associated with the advantageous features such as herein described.
8. An improved hydraulic system of tractor for efficient functioning of
filter clogging indicator substantially as herein described with
reference to the accompanying drawings.