FIELD OF THE INVENTION
The invention generally relates to safety feature for detection of gas filling
condition and automatic engine off to ensure safety without user intervention.
More particularly, the invention relates to a self-diagnostic system to prOVide
indication and protection for refuelling of alternative fuels driven vehicle. The
invention further relates to a method of self-diagnosis and communication in
alternative fuels system of a vehicle.
BACKGROUND OF THE INVENTION
Automobiles are driven by internal combustion engines (ICE). For driving the
ICE, commonly used fuels are Gasoline, Diesel & now days CNG/LPG(or its
variants) are used.
These fuels are filled in a specific fuel tank. This tank can be refilled through
various Petrol/Diesel pump stations in case of normal Petrol/Diesel vehicles.
In addition, for CNGvehicles, there is a separate kind of tank used and these
special tanks can be refilled only at CNG stations. However, no specific safety
measuresare available in prior art in respect of refuelling the automobiles in the
fuel-filling stations. Thus different safety measures are self-devised by the
fuelling stations.
The CNGfilling is usually done at a very high pressure of around 200bar. The
storing of CNG at this high pressure including storage in fuel tank demands
maintenance of high-standard of safety.
If the automobiles engine is in running state, and the vehicle operator
accidentally or deliberately tries to drive-out the vehicle from the refuelling point,
during or after CNGfilling while CNGfilling hose is still connected, the same may
lead to a serious accident. The reason being that the high pressure CNGshall still
be particularly available in the hose, which may spread out in the adjacent
environment very quickly leading to possible fire hazards.
Hence as a practice, it is essential to turn off the engine before CNGfilling and
restarting the vehicle only after the hose is detached. This is manually ensured
by the vehicle operator or the pump. However, an inadvertence to follow the
practice, might lead to a major accident at these refuelling stations.
Nevertheless, prior-stopping of the engine during CNGfilling can be checked and
ensured easily for types of vehicle having refuelling nozzle located at the front
hood of the car. But, the process of checking becomes more difficult for vehicles
having the nozzle in the side of the vehicle body (as today's engines are much
more silent), leading to visibility offset.
The fault detection process of prior art is therefore completely manual without
having any mechanised or automated control feature. Hence there is a need to
introduce a robust system which is not depending on the user, but to the system
itself (and can shut down the engine automatically during CNGfilling).
As a safety against fire hazard, at the time of CNGfilling, follOWing regulatory
reqUirement is defined in Automotive Indian Standards (AIS 028, clause-2.2.5):
"Filling connections in motor vehicles shall be fitted with a system that prevents
the engine starting when the dust plug or dust protection cap is·removed. This
system shall isolate the starting device of the vehicle." This will ensure that
vehicle can not be driven while CNGpipe is still attached to the vehicle. However, the standard does not cater for the potential safety hazard for vehicles
when brought for refilling, with the engine in running mode. In case of CNG
filling process, if sWitching off the vehicle as per gUidelines is not followed by the
user at CNGstation, this may lead to inadvertent safety hazard.
The vehicles for alternative fuels applications specifically warrant:
1. a superior technical detection system, enabled to provide accuracy to the
safety needs for fuel system in particular at the time of fuel filling.
2. proposing a fault-detection system such that safety needs is implemented in
particularly for the alternative fuels power train of the alternative fuels
systems.
Although the fault-detection system for alternative fuels vehicles can be
automated to prevent engine from running during CNGfilling as conceptualized
hereinabove, there still remains a further possible hazard for example, a
alternative fuels based vehicle gets stranded at traffic signal or due some other
circumstances, with the fuel-lid accidentally remaining opened say for reasons
not attributable to refuelling, the vehicle operator while restarting the engine
shall be disabled to start the engine, without detecting the cause of restartfailure.
The operator will be subsequently enabled to detect that the open-status
of the fuel lid is disallowing restarting of the engine which however, is
undesirable for the vehicle-manufacturer including the users.
OBJECTS OF INVENTION
It is therefore an object of the invention to propose a system for fault detection
in a alternative fuels system of a vehicle in a running-mode and transmission of
fault data to a user. SUMMARY OF THE INVENTION
The invention is about the fuel lid open/ close status display in these systems.
This a feature aimed at assisting the user by alerting him about the above
possible scenarios in the system. Additionally, the communication of such
detected faults is communicated to the user by glowing a lamp is to be used on
pre-defined pattern (for e.g. blinking, continuous ON, off depending on the fuel
lid open/ close status).
The systems referred in this disclosure cover all kind of vehicles running in CNG,
for example:
1. Vehicles that can be driven by both conventional fuels and alternative fuels
(like CNG).
2. Vehicle that can be driven by alternate fuels (CNG)only (Also, covers vehicles
with small fuel tank (Gasoline/Diesel) for limp-home purpose).
Accordingly, there is provided a safety system for detection of fuel-lid status
during refuelling of a vehicle and real-time communication of the detected status
of prevent accident, the vehicle comprising an engine activated by operating an
ignition SWitch,a storing motor providing initial rotation to the engine, a plurality
of engine sensors to acquire vehicle operation data, at least one fuel tank with a
fuel lid, a fuel level/pressure sensor, a fuel-lid switch an electronic control unit
(ECU), and a signal transmission line connecting a display means and the ECU,
the system is configured to receive signal from the fuel lid in respect of open or
close status of the fuel lid; upon SWitchingon the ignition switch monitor status
of all the devices including peripheral devices of the engine/fuel system; check
the fuel-filling status if the engin~ speed is above a threshold value; communicate to the display device the open status of the fuel lid including
refuelling condition of the vehicle; and disable the ignition switch to be on
corresponding to the open status of the fuel lid.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - shows a schematic diagram of the detection system in an engine
system of the vehicle according to the invention.
Figure 2 - shows a flow-chart for implementing the detection steps in the
fault detection system.
DETAIL DESCRIPTION OF THE INVENTION
As shown in figure-1, during a normal start-up, the engine [9], is turned ON by
activating the Ignition switch [3] (hereafter referred to as IGSW), and engage
the starter motor [10] through the IGSW (3) or through a controller [1]
(hereafter referred to as ECU). The starter motor [10] then rotates the engine
(9) and generates an initial engine speed (hereafter referred to as RPM)which is
required by the engine (9) to start automatically for firing. During this time, the
fuel is delivered to the engine (9) through the dedicated fuel lines [12]. The ECU
(1), based on a plurality of sensors [5] and logics incorporated inside the ECU,
determines the spark timing, fuel quantity, and fuel injection timing. This allows
the engine to gain the required RPMand thereafter it rotates without Starter
motor's assistance.
As shown in figure-2, the invented system comprises: - an ECU (1) (Electronic control unit) and/a CNG ECU for driving CNG
system (Optional);
- a Speedometer or similar display device (2);
- an Ignition switch (3);
- a Fuel lid switch (4);
- a plurality of Sensors (5);
- a CNG tank (6);
- a CNG receptacle (7);
- a CNG fuel level/pressure sensor (8);
- an Engine (9);
- a Starter motor (10);
- a Fuel Lid (11);
- a Fuel line (12); and
- a Communication line (13) (CAN/Serial line)
During implementation of this invention, a sensing mechanism is provided in the
fuel lid [12] which sends signal to the designated ECU. Based on the sensing
results, the fuel lid is detected as either open or close. This explains the user
intent of getting the fuel filled through receptacle [7].
Similarly, the Ignition switch status is also sensed constantly and the data is
made available to the ECU. The ECU constantly monitors these signals and stores
the parameters in software flag FLSW and IGSW respectively.
The ECU constantly monitors these signals and stores the parameters in software
flag FLSW and IGSW respectively.
The invention is based on extensive study done to study the user drive pattern pattern at filling stations and FMEA of system to identify the condition in which
wrong judgment can occur.
In an implementation of this invention, the sensor values and internal ECU
circuits are constantly monitored by ECU. Based on these inputs and internal
processing of same, ECU will judge whether fuel filling is being done or not, and
takes appropriate action for inhibiting the engine from continuing running during
CNG fi iiing.
Figure-2 shows the process flow-chart in the form of a logic.
The sequence is as follows:
Let VSPD: Vehicle Speed
RPM: Engine RPM
VEHRUN: Status of Vehicle running (Indirect measure)
FLSW: Fuel lid status
CNGFIL: CNG filling detected
IGSW: Ignition switch status
ENGOFFREQ: Engine OFF request. In case it is TRUE, the engine running will be
inhibited by fuel cut etc. In case it is FALSE, no action will be taken by the ECU
for this logic.
Filling can be detected by reading the FLSW values.
In yet another possible implementation, the CNG filling can be monitored by
continuously checking the CNG pressure coming through CNG pressure sensor
[8]. In case, the previous value is less than the current value, it can be said that
the filling is going on. For e.g.:
d(CNG Filling volume)/dT > K,
K is any variable that can be calibrated depending on the logic.
It can be assumed that whenever CNG is filling (based on above formula), the
IGSW is ON state and is a safety hazard.
The implementation is explained as follows:
When filling is detected, fuel lid is Open. ECU will continue to monitor these
values.
If FLSW=OPEN
Or CNG filling is detected through some other measure.
CNGFIL=DETECTED
When filling is not detected, fuel lid is Closed. ECU will continue to monitor these
values.
If FLSW=CLOSE
Or CNG filling is not detected through some other measure.
CNGFIL=NOTDETECTED
hence
If
IGSW=ON
& RPM >= 0 & VSPD <= 10kmph
& VEHRUN= NO
&FLSW=OPEN
& CNGFIL=DETECTED
Then,
ENGOFFREQ=TRUE
Otherwise,
ENGOFFREQ=FALSE.
In addition, the system is capable of detecting certain malfunction in the system,
and the ENGOFFREQwill be set as FALSE,to avoid user being stranded on road.
salient Points of Invention
1. System is able to detect the engine running during CNG filling and is able
to take appropriate countermeasures, thus ensuring additional safety.
2. The system cannot be overridden by user.
3. Consideration of user not being stranded somewhere due to a fault in the
system.
WE CLAIM
1. A self-diagnostic system to provide indication and protection for refuelling
of alternative fuels driven vehicle, the system comprising an electronic
control unit incorporated with a logic rule; a fuel lid having a fuel-lid
switch; a plurality of engine operation sensor; a CNG fuel level/pressure
sensor, an ignition sWitch; and at least a communication line connected
between the ECUand a display device, the system is operable to:
- receive from the fuel-lid switch signals representing close or open status
of the fuel lid by the ECU;
- collect data relating to ignition switch status from the engine sensors by
the ECU;
disable the ignition switch to re-start the engine if fuel-lid signals
displays an open status; and
- enable the ignition switch to restart the engine when the display status
exhibits a close status.
2. A self-diagnostic system to provide indication and protection for refuelling
of alternative fuels driven vehicle as substantially described and illustrated
herein with reference to the accompanying drawings.