VARIABLE PRESSURE FUEL INJECTION SYSTEM

TECHNICAL FIELD:

The present subject matter, in general, relates to a fuel injection system of a vehicle and in particular, relates to a variable pressure fuel injection system with an electronically controlled fuel pressure regulator.

BACKGROUND:

Fuel pressure regulators are provided in a fuel injection system of a vehicle to maintain a desired fuel pressure across a fuel injector. A fuel pressure regulator eliminates sudden and undesirable fluctuations occurring in the fuel pressure in order to ascertain atomization of fuel injected by the fuel injector. Appropriate atomization of fuel is essential in order to maintain fuel economy and substantial reduction in the emission rate.

Typically, a mechanical fuel pressure regulator is located in a fuel inlet line between a fuel pump and the fuel injector for maintaining a constant pressure across the fuel injector at a predetermined pressure. The mechanical fuel pressure regulator has an air reference chamber and a fuel reference chamber .separated by a diaphragm. Generally, a spring with a known spring rate is provided in the air reference chamber of the mechanical fuel pressure regulator. The rating of the spring determines the magnitude of fuel pressure to be maintained in the fuel reference chamber and consequently in the fuel inlet line.

The desired pressure of fuel across the fuel injector is preset by the manufacturer of the pressure regulator. However, . setting the fuel pressure at a preset value does not ensure optimum atomization of fuel at all operating conditions of the vehicle. This may affect fuel efficiency and fuel economy, thereby leading to reduced power output developed by the engine. Further, inappropriate air-fuel mixture may hamper the efficiency and reliability of the engine, in addition to increased amount of emissions.

SUMMARY:

The subject matter described herein is directed to a variable pressure fuel injection system with an electronically controlled fuel pressure regulator. The present subject matter proposes a solution to maximize the fuel efficiency of the vehicle. In addition to a higher fuel economy, low emission rates are also achieved by the present subject matter. This is achieved by effective atomization of the fuel injected into an internal combustion engine. In accordance with at least one embodiment of the present subject matter, a variable pressure fuel injection system comprising a fuel inlet line, a fuel outlet line and a fuel injector is provided. The fuel injector is hydraulically connected to the fuel inlet line and injects the pressurized fuel into the engine. The variable pressure fuel injection system further comprises a control system having an electronically controlled fuel pressure regulator hydraulically connecting the fuel inlet line and the fuel outlet line. The fuel pressure regulator includes a housing having an inlet chamber, an outlet chamber and a passage connecting the inlet chamber and the outlet chamber. The inlet chamber is connected to the fuel inlet line whereas the outlet chamber is connected to the fuel outlet line. The fuel pressure regulator also includes an actuator assembly having a movable armature and a coil that encloses the movable armature. The movable armature controls

the flow of fuel from the inlet chamber to the outlet chamber. The variable pressure fuel injection system further comprises an electronic control unit that energizes the coil based on different operating conditions, thereby reciprocating the movable armature to regulate fuel pressure entering into the fuel injector at different operating conditions. A pressure sensor is also disposed in the fuel inlet line. The pressure sensor measures the pressure in the fuel inlet line and communicates with the electronic control unit for control of the fuel pressure regulator.

In another embodiment of the present subject matter, the variable pressure fuel injection system comprises the fuel inlet line, the fuel outlet line and the fuel injector. The fuel injector is hydraulically connected to the fuel inlet line. The fuel injector injects pressurized fuel to the engine. The variable pressure fuel injection system includes a control system having a fuel pressure regulator hydraulically connecting the fuel inlet line and the fuel outlet line. The fuel pressure regulator includes a housing having an actuator chamber and a fuel chamber. The actuator chamber and the fuel chamber are separated by a diaphragm. An actuator assembly is disposed in the actuator chamber. The actuator assembly includes a movable armature and a coil enclosing the movable armature. A pressure plate assembly is disposed in the fuel chamber. The pressure plate assembly is attached to the movable armature for regulating flow of fuel from the fuel inlet line to the fuel outlet line. An electronic control unit is provided in the variable pressure fuel injection system that energizes the coil based on different operating conditions, thereby reciprocating the movable armature to regulate the fuel pressure entering into the fuel injector. A pressure sensor is disposed in the fuel inlet line for measuring the pressure in

the fuel inlet line. The pressure sensor communicates with the electronic control unit for precise control of the fuel pressure regulator.

These and other features, aspects, and advantages of the present subject matter will become better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS:

The above and other features, aspects and advantages of the subject matter will be better understood with regard to the following description, appended claims, and accompanying drawings where:

FIG 1 shows a block diagram of a variable pressure fuel injection system of a vehicle.

FIG 2 shows a sectional view of a fuel pressure regulator of a variable pressure fuel injection system of a vehicle according to a first embodiment of the present subject matter.

FIG 3 shows a perspective view of the fuel pressure regulator of a variable pressure fuel injection system of a vehicle shown in Fig. 2.

FIG 4 shows a sectional view of the fuel pressure regulator of a variable pressure fuel injection system of a vehicle according to a second embodiment of the present subject matter.

FIG.5 shows a sectional view of the fuel pressure regulator of a variable pressure fuel injection system of a vehicle according to a third embodiment of the present subject matter.

DETAILED DESCRIPTION:

The subject matter described herein is directed to a variable pressure fuel injection system of a vehicle and in particular relates to a variable pressure fuel injection system with an electronically controlled fuel pressure regulator. The present subject matter proposes a solution to maximize the fuel efficiency of the vehicle by electronically varying the pressure of the fuel injected inside an engine cylinder at different operating conditions of the vehicle. In addition to higher fuel economy, lower emission rates are also achieved by the present subject matter as proper atomization of the injected fuel is ensured.

FIG.l shows a block diagram of a variable pressure fuel injection system of a vehicle. In the variable pressure fuel injection system, pressure of fuel from a fuel tank 100 is varied depending upon different operating conditions of the vehicle. The variable pressure fuel injection system utilizes a control system for regulating the pressure of fuel to be injected into an internal combustion engine 102. The control system includes an electronic fuel pressure regulator 104, an electronic control unit (ECU) 106 and a pressure sensor 108.

Regulation of fuel pressure is mainly controlled by employing the fuel pressure regulator 104, which is electronically controlled by the ECU 106. The ECU 106 is aided by the pressure sensor 108 that monitors the pressure of the fuel from a fuel pump 110 entering into a fuel injector 112.

The fuel pump 110 pumps the fuel from the fuel tank 100 into the fuel injector 112 and the fuel pressure regulator 104. The fuel, pumped by the fuel pump 110, is at a certain pressure called as forward fuel pressure. Subsequently, when fuel approaches the fuel injector 112, it experiences a backward fuel pressure due to the closed state of the injector 112. The fuel with a pressure equal to the difference in the forward and backward fuel pressures enters the fuel pressure regulator 104.

The pressure sensor 108 is provided in line between the fuel pump 110 and the fuel injector 112 to constantly monitor the pressure of fuel entering the fuel injector 112. Whenever the pressure of fuel entering the fuel injector 112 exceeds a certain predetermined threshold value, the pressure sensor 108 alerts the ECU 106. On receiving the alert signals from the pressure sensor 108, the ECU 106 communicates with the fuel pressure regulator 104. Depending upon the magnitude of rise in fuel pressure beyond the threshold value, the fuel pressure regulator 104 allows the excess fuel to drain into the fuel tank 100. This leads to the reduction of the back fuel pressure, thereby reducing the pressure of fuel entering the fuel injector 112. The fuel pressure regulator 104 along with the fuel tank 100 and the fuel pump 110 forms a closed loop to achieve the desired fuel pressure which constantly varies according to the operating conditions, such as engine speed and engine load, of the vehicle.

FIG2 shows a sectional view of the fuel pressure regulator 104 of the variable pressure fuel injection system of the vehicle according to a first embodiment of the present subject matter. The fuel pressure regulator 104 is hydraulically connected to a fuel inlet line 200 and a fuel outlet line 202. The fuel pressure regulator 104 of the present embodiment is configured as a solenoid valve. The fuel pressure regulator 104 includes a housing 204 having an inlet chamber 206, an outlet chamber 208 and a passage connecting the inlet chamber 206 and the outlet chamber 208. The inlet chamber 206 is connected to the fuel inlet line 200 whereas the outlet chamber 208 is connected to the fuel outlet line 202. In the present embodiment, the housing 204 is a two piece assembly having a cap 210 and a mounting block 212. However, in another embodiment, the housing 204 can be a single piece in structure. The fuel pressure regulator 104 further comprises an actuator assembly having a coil 214 and a movable armature 216 enclosed within the coil 214. The movable armature 216 is provided within the passage connecting the inlet chamber 206 and the outlet chamber 208 and controls the flow of fuel from the inlet chamber 206 to the outlet chamber 208.

The fuel pressure regulation is achieved by energizing the coil 214 placed within the cap 210. When the pressure in the line between the fuel pump 110 and the fuel injector 112 raises above the threshold value, the pressure sensor 108 measures this pressure and immediately sends corresponding signals to the ECU 106. The ECU 106, on receiving signals from the pressure sensor 108 energizes the coil 214, thereby resulting in reciprocating movement of the movable armature 216. The reciprocating movement of the movable armature 216 leads to opening of the passage between the inlet chamber 206

and the outlet chamber 208, thereby leading to draining of fuel with excess pressure back into the fuel tank 100.

FIG.3 shows a perspective view of the fuel pressure regulator 104 of the variable pressure fuel injection system of the vehicle according to the first embodiment of the present subject matter. As shown in Fig. 3, the fuel inlet line 200 is disposed at the cap 210 whereas the fuel outlet line 202 is disposed at the mounting block 212.

FIG.4 shows a sectional view of the fuel pressure regulator 104 of the variable pressure fuel injection system of the vehicle according to a second embodiment of the present subject matter. In the present embodiment, the fuel pressure regulator 104 is configured as a stepper motor 400. The stepper motor 400 is electronically controlled by the ECU 106. The fuel pressure regulator 104 includes a housing having a fuel chamber 402 and an actuator chamber 404 separated by a diaphragm 406. The fuel inlet line 200 and the fuel outlet line are provided in the fuel chamber 402 of the fuel pressure regulator 104. The movable armature 216 is disposed in the actuator chamber 404 and is coupled to a pressure plate assembly 408. The pressure plate assembly 408 is disposed in the fuel chamber 402 and controls the flow of fuel from the fuel inlet line 200 to the fuel outlet line 202

Fuel enters the fuel chamber 402 through the fuel inlet line 200 and is obstructed by the pressure plate assembly 408. In case the pressure of the fuel in the fuel inlet line exceeds a certain predetermined value, the pressure sensor 108 senses this pressure rise and sends certain signals to the ECU 106. The ECU 106 then regulates the pressure of the fuel at an optimum level by energizing the coil 214 thereby causing the reciprocating movement of the movable armature 216. This causes the pressure plate assembly 408 to

move up with the movable armature 216, leading to the opening of the fuel outlet line 202, thereby bleeding the excess fuel to the fuel tank 100.

FIG.5 shows a sectional view of the fuel pressure regulator 104 of the variable pressure fuel injection system of the vehicle according to a third embodiment of the present subject matter. In the present embodiment, the movable armature 216 is integrated with a metering needle 500. The metering needle 500 has a tapered end 502. The tapered end 502 of the metering needle 500 characterizes the closing for the fuel outlet line 202. The rise in pressure of the fuel above the threshold value causes the stepper motor 400 to lift the metering needle 500. The position of the tapered end 502 of the metering needle 500 determines the size of the aperture created for bleeding the fuel out to the fuel tank 100.

The previously described versions of the subject matter and its equivalent thereof have many advantages, including those, which are described below. The present subject matter proposes a solution to maximize the fuel efficiency of the vehicle. In addition to high fuel economy, low emission rate is also achieved by effectively and efficiently varying the pressure of the fuel according to different operating conditions of the vehicle. Variation of fuel pressure according to the operating conditions of the vehicle leads to proper atomization of the fuel. This results in proper burning of the fuel which consequently leads to increase in fuel economy and reduction in the emission rates.

Although the subject matter has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are also possible. As such, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiment contained therein.