Claims:WE CLAIM:

1. A fuel pumping system for delivering injection fuel to engine combustion chamber comprising:-
- a fuel input port means connected to feed line,
- a barrel (6) with an interior connected to the input means for receiving fuel from the input port means,
- a plunger (5) operably reciprocating within the barrel(6)
- an inlet check valve (7) operably associated with the input port means, barrel (6) and plunger (5), to suck in fuel from the feed line into the barrel corresponding to the reciprocal motion of the plunger within the barrel (6)
- a solenoid (8) operably associated with an engine control unit,
- a poppet valve (9) operable by the solenoid (8) for its energisation, and
- a Snubber valve connector (1) operably associated with poppet valve (9), and barrel (6) to allow flow of fuel from the barrel (6) into the engine combustion chamber when the poppet valve (9) is in energized state and allow flow of fuel from the barrel (6) into return-line when the poppet valve (9) is in de-energised state.
2. The fuel pumping system as claimed in claim 1, wherein the inlet check valve (7) is an unidirectional valve allowing flow of fuel only from the feed line to the barrel.
3. The fuel pumping system as claimed in claim 1, wherein the snubber valve (1) includes an outlet connector (3) which is a floating orifice plate with a spring arrangement, for reducing secondary injection of fuel into the engine combustion chamber.
4. The fuel pumping system as claimed in claim 1, wherein the solenoid valve is operable on constant voltage.
5. The fuel pumping system as claimed in claim 1, wherein the poppet valve is operable by solenoid valve which operation includes detection of closure of poppet valve by detecting the current profile with the engine control unit.
6. The fuel pumping system as claimed in claim 5, wherein the engine control unit operating the solenoid valve is adapted to record the closure pulse width for required delivery thereby during low delivery and non-closure events the engine control unit determines the required closure pulse width including negative pulse width and controls the fuel delivery.
7. The fuel pumping system as claimed in claim 5 & 6, wherein the engine control unit operating the solenoid is adapted such as to vary the current pulse to control the fuel delivery, whereby the mass delivery is determined by duration of pulse width.
8. The fuel pumping system as claimed in claims 5-7, wherein the engine control unit operating the solenoid is adapted to calculate the closure pulse width which is the time duration from the start of solenoid to the start of pumping.
9. The fuel pumping system as claimed in claims 5-8, wherein the engine control unit operating the solenoid is adapted to calculate the positive seated pulse width which is time duration between the start of closure event to end of pumping, and (adjust the instantaneously changing) closure event for every instant to achieve an adjusted same value of seated pulse width at each instant and thereby a consistent delivery of fuel into the engine combustion chamber.
10. The fuel pumping system as claimed in claim 5-9, wherein the engine control unit operating the solenoid is adapted to provide a negative seated pulse width that is the current to the solenoid is shut off prior to the closure event, when engine is at high speed and light load, thereby ensuring the end of pumping event prior to the closure event.
11. The fuel pumping system as claimed in claim 10, wherein the engine control unit operating the solenoid for adapted such that engine control unit also records the average historical closure event to calculate and determine the estimated closure time.
12. The fuel pumping system as claimed in claim 11, wherein the engine control unit operating the solenoid for detecting the current profile is adapted such that engine control unit detects accurately the armature closure event by monitoring the frequency of peak current period and ensuring that the pump is having full and consistent fuel delivery capability with the fully seated armature.
13. The fuel pumping system as claimed in claim 12, wherein the engine control unit operating the solenoid is adapted to capture the changes in closure time due to variable factors such as engine RPM, battery voltage, temperature, wire resistance and pump aging and conduct calibration from referral closure point to determine the quantity of fuel to be delivered to the engine for a given seated pulse width at a given speed and which calibration.
14. The fuel pumping system as claimed in claim 12, wherein the engine control unit operating the solenoid is adapted to capture the impedance change during the motion of the armature, correspondingly change the current within the solenoid, and further capture the rapidly changing impedance when the armature reaches its seat and generate a rapid corresponding change of current rises and delays through the solenoid.
, Description:FIELD OF INVENTION:

The field of invention is relates to a low cost fuel injection system for a single cylinder diesel engine. To meet tighter emissions

OBJECT OF INVENTION:

To design a low cost fuel injection system for single cylinder engine application to meet the stringent emissions in place of a more sophisticated common rail system.

BACKGROUND OF INVENTION:

To meet BSVI 3 wheeler emissions SCUP is designed in place of high cost DCR

DESCRIPTION OF INVENTION:

The invention is having a plunger-barrel arrangement along with spill control solenoid operable with engine control unit and an inlet check valve which aids the filling of the pump from the top to improve the volumetric efficiency, and it is unidirectional which allows fuel only to enter the pump.
The principle of operation is that a plunger “5” reciprocates within barrel “6” by which the diesel is sucked in through check valve “7” (Figure 1)
A Solenoid “8” actuates a poppet valve “9” by energizing. During energizing the fuel is directed through Snubber connector “1” to engine combustion chamber. During de-energised state the fuel will be directed to return line.
The solenoid “8” is controlled by ECU (Engine control unit), the timing of actuation can be synchronized with engine TDC.
The out let connector assembly –snubber – has a floating Orifice plate on a spring, which aids in reducing secondary injection. (Figure 3)
The main function of solenoid is to close the poppet valve “9” which defines the start of injection.

It works on “bip” technology which detects the closure of the poppet valve by sensing the current profile wherein method is unknown is prior art.

Bip advantage defines the start of injection, to provide consistent delivery over the life of solenoid.

DETAILS OF BIP TECHNOLOGY

The Basic concept of Closure detection (BIP) Technology is explained as below, I.e. How the ECU detects the Poppet valve closure during pumping event with solenoid current.
Acronyms
Acronym Description
SPW Seated Pulse Width
BIP Another term for armature closure
CPW Closure Pulse Width
SOP Start of Pumping
EOP End of Pumping
SOS Start of Solenoid current pulse
PWM Pulse Width Modulation

Fuel delivery is controlled by varying the current pulse within the solenoid. The mass of delivery is determined by duration of pulse width. The Start of pumping (SOP) is when the armature closes and fully seated,
Closure Pulse width (CPW) is the time duration from Start of Solenoid (SOS) to the start of pumping (Figure 7). SPW is auto adjusted in accordance to CPW to define the duel delivery.

Solenoid Drive requirements (Figure 9)
Current Rise:- Zero Current to peak current
Peak Current :- End of current rise to the closure event
Peak after closure :- This peak current from closure even to the hold event , This even prevents the bouncing of armature and aids in identifying the closure detection.
Hold Current :- Typically held at 8Amperes at lower duty cycle to reduce current consumption

Closure Over view as per the invention:-

In order to control the SCUP pump in a consistent and reliable manner, the ECU must be able to detect the armature closure (BIP) event. The pump will have full and consistent fuel delivery capability once the armature has fully seated. Understanding when the pump starts delivering full fuel is critical to the overall performance of the system and the same has been achieved advantageously in the invention.

The time it takes for the armature to fully seat so the pump can deliver full fuel is constantly changing. There are many factors that will affect the closure time of the armature such as engine RPM, battery voltage, temperature, wire resistance, and pump aging. The ECU will need to capture the changes in closure time due to these variables.

Calibration is referenced from the closure point. The calibration for the pump details how much fuel is delivered to the engine for a given SPW at a given speed. It is critical that the ECU have active closure detection and compensation on the active cylinder injection event as this is how the pumps are calibrated. This will ensure the most stable and best performing system.

Closure Detection Strategy (Figure 10)

Accurate closure detection can be achieved through high speed monitoring of the solenoid drive current. More specifically, by monitoring the frequency of peak current period, the ECU can accurately determine the closure event.

Theory behind current profile:-

As the armature begins to move, the impedance of the overall system begins to change. This change in impedance affects the rate at which the current is able to change within the solenoid. This impedance changes rapidly once the armature reaches its seat, thus creating a rapid change in the way the current rises and decays through the solenoid. By monitoring the current for this change, closure can be detected.

The invention uses a combination of circuitry and software to control the solenoid current to properly detect closure. This combination is used to reduce software intensive tasks while maintaining the capability to detect closure and SOI

Outcome

With this design it is demonstrated to meet BSVI emission limits for three wheeler CI application
The examples and embodiments are provided only for the purpose of understanding and none of them shall limit the scope of the invention. All variants and modifications as will be envisaged by skilled person are within the spirit and scope of the invention.