GB2571752A

GB2571752A - Fuel injection equipment

Info

Publication number: GB2571752A
Application number: GB1803668.1A
Authority: GB
Inventors: Male Andrew
Original assignee: Delphi Technologies IP Ltd
Current assignee: Delphi Technologies IP Ltd
Priority date: 2018-03-07
Filing date: 2018-03-07
Publication date: 2019-09-11
Also published as: GB201803668D0

Abstract

Fuel injection equipment, a method of controlling said equipment and a command unit (ECU) are disclosed. The fuel injection equipment 10 comprises a transfer pump 22 for passing fuel from a fuel tank 20 to a compression pump 14 from which fuel is passed to a common rail 26. A pressure sensor 28 on the reservoir 26 delivers a signal S3 to an ECU 23 relevant to the actual pressure in the rail. An inlet metering valve (IMV) 24 arranged upstream of the feed pump 22 limits the quantity of fuel entering the pump. The IMV may be controlled by the ECU. The method comprises the steps of determining the rail pressure based on the sensor signal, determining a target rail pressure and adjusting the IMV orifice as a function of these pressures. The equipment removes the need for a pressure regulator as the output flow of the transfer pump is better matched to the inlet flow of the compression pump.

Description

TECHNICAL FIELD

The present invention relates to a fuel injection equipment and, more particularly to the arrangement of an inlet metering valve in said system.

BACKGROUND OF THE INVENTION

A known fuel injection equipment of an internal combustion engine, is controlled by a command unit (ECU) adapted to determine the fuel pressure and fuel quantity to be injected in said engine in order to fulfil the engine power demand. In the fuel injection equipment, the fuel flows from a tank to a transfer pump (TP) then to an inlet metering valve (IMV) controlled by the ECU for limiting the fuel quantity flow to a high pressure (HP) pump to the flow needed. The HP pump delivers pressurized fuel to a HP reservoir, known as a common rail, which stores and delivers said HP fuel to fuel injectors.

In conventional diesel fuel systems the HP pump outlet flow is controlled by the IMV located between the TP and the inlet to the HP Pump.

The output flow of the TP is typically not well matched to the inlet flow requirements of the HP pump and therefore the pressure can vary with maybe a range from 1 to 15 bar. The IMV cannot control flow to the HP pump with a large pressure range and it is typically maintained in the range 5 to 7 bar by a pressure regulator.

The TP flow is unregulated which means it must have an output that is higher than that of the HP pump. This means that flow must be spilt from the TP outlet flow in order to control pressure in the range that is acceptable for the IMV. This results in wasted energy and parasitic power consumption which causes higher vehicle fuel consumption than would otherwise be required.

The requirement for a pressure regulator causes complexity and cost.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to resolve the above mentioned problems in providing a fuel injection equipment of an internal combustion engine, the equipment being controlled by a command unit (ECU) adapted to determine the fuel pressure and the quantity to be injected in said engine in order to fulfil the engine power demand. The equipment comprises a tank for storing fuel at low pressure (LP), a transfer pump for sucking said LP fuel and delivering it to a compression pump that compresses and delivers high pressure (HP) fuel to a common rail. A pressure sensor is adapted to deliver to the ECU a signal relevant to the actual pressure inside the common rail and, an inlet metering valve (IMV) is arranged upstream of the transfer pump for limiting to the quantity required to fulfil the engine needs the fuel entering the transfer pump. Moreover, the IMV may be controlled by the ECU.

The invention further extends to a method of control of a fuel injection equipment described above, the method comprising the steps of:

a) determining the actual rail pressure based on a signal received from the pressure sensor;

b) determining a targeted rail pressure;

c) adjusting the IMV orifice as a function of the output of steps a) and b). The adjusting step c) leads to:

c2) increasing the IMV orifice if the targeted pressure determined at step b) is inferior to the actual pressure determined at step a);

c3) maintain unchanged the IMV orifice if the targeted pressure determined at step b) is equal to the actual pressure, step a);

c4) reducing the IMV orifice if the targeted pressure determined at step b) is superior to the actual pressure, step a).

The invention further extends to a command unit, (ECU), adapted to control a fuel injection equipment or execute a method as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now described by way of example with reference to the accompanying drawings in which:

Figure 1 is a fuel injection equipment as per the invention.

Figure 2 a diagram of a method for controlling the equipment of figure 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In reference to figure 1 is described a diesel fuel injection equipment 10 of an internal combustion engine (ICE). In the example the ICE has six cylinders but the invention can be used with ICE having more or less cylinders.

The equipment 10 is controlled by a command unit 12, hereafter ECU 12, that receives inputs signals SI, S4 from the engine and the vehicle, inputs from which the ECU computes output command signals S2, S3 sent to the equipment 10 to fulfil the torque and power requirements from said ICE.

The equipment 10 comprises a low pressure side and a high pressure side, in between which, a compression pump 14 receives LP fuel via a controlled inlet 16 and delivers pressurised fuel via a controlled outlet 18.

The LP fuel stored in a tank 20 is sucked by a transfer pump 22 and sent to said pump controlled inlet 16. An inlet metering valve 24, hereafter IMV 24, arranged upstream of the transfer pump 22 limits the fuel quantity flowed and delivered by the transfer pump 22 to the quantity needed to fulfil said ICE torque and power requirements. Said IMV 24 defines a controlled orifice which opening section is controlled by the ECU 12. To reduce the fuel quantity entering the transfer pump 22 the ECU sends a command signal S3 to the IMV to reduce the section of said orifice and, to increase said fuel quantity the command signal S3 requests to enlarge said section.

Whichever it is, the fuel quantity is sent to the compression pump 14 wherein it is compressed in a compression chamber prior to be expelled via the outlet 18 and delivered to a HP reservoir 26, well known as a common rail 26. The actual internal rail pressure APR is measured by a sensor 28 connected to the ECU 12 and sending to the ECU a relevant signal S4. Figure 1 sketches a possible embodiment where the sensor is connected onto the common rail. Other locations of the sensor are possible, for instance at an end of the rail or in another place of the equipment HP side. Fuel injectors 30 are connected in parallel to the common rail, receiving fuel pressurized to the rail pressure APR, said injectors 30 being commanded by the ECU 12 for selectively injecting pressurized fuel in the cylinders of the ICE.

Upstream and downstream of the transfer pump 22, the equipment 10 further comprises filters for protecting the equipment from damages due to particles that may be present in the fuel.

Also, the equipment may be provided with a return line connecting upstream the controlled inlet 16 and going back to the tank 20. Said line, present on many production systems, is used for purging air from the low pressure system. The orifice of the return line is small enough to prevent excessive loss of flow of pressurised fuel, in order to keep the low pressure pump size small and avoid excessive power consumption, but big enough to quickly purge air that may be trapped.

In reference to the diagram of figure 2, to fulfil the engine needs in terms of fuel to be injected, based on the input signals SI, S4, the ECU 12 computes a targeted rail pressure TPR, compares it to the actual rail pressure APR, and determines signal S3.

If the targeted pressure TPR is superior to the actual pressure APR, the rail pressure has to be increased, and the command signal S3 sent by the ECU to the IMV requests to enlarge the section of the IMV orifice. This is shown in figure 2 by TPR > APR; S3, 24 and an arrow upwardly oriented.

If the targeted pressure TPR is inferior to the actual pressure APR, the rail pressure has to be decrease, and the command signal S3 sent by the ECU to the IMV requests to reduce the section of the IMV orifice. This is shown in figure 2 by TPR < APR; S3, 24 and an arrow downwardly oriented.

If the targeted pressure TPR is equal to the actual pressure APR, the rail pressure must not change, and the command signal S3 sent by the ECU to the IMV requests to maintain unchanged the section of the IMV orifice. This is shown in figure 2 by TPR = APR; S3, 24 and an horizontal arrow.

A major interest in locating the IMV upstream the transfer pump 22 is to generate fuel economy by limiting the quantity of fuel flow to the needs of the ICE. In the prior art, the IMV being between the transfer pump and the compression pump, the transfer pump had to be set to flow more fuel than required and, the IMV returned to the tank the quantity in excess. Said tuning of the fuel flow enables fuel economy.

LIST OF REFERENCES input signal command signal sent to the injectors command signal sent to the IMV input signal from the sensor to the ECU

APR actual rail pressure

TPR targeted rail pressure fuel inj ection equipment - FIE command unit - ECU compression pump controlled inlet controlled outlet tank transfer pump inlet metering valve - IMV

HP reservoir - common rail sensor injectors

100 method

Claims

1. Fuel injection equipment (10) of an internal combustion engine, the equipment being controlled by a command unit 12 (ECU 12) adapted to determine the fuel pressure and quantity to be injected in said engine in order to fulfil the engine power demand, the equipment (10) comprising a tank (20) for storing fuel at low pressure (LP), a transfer pump (22) for sucking said LP fuel and delivering it to a compression pump (14) that compresses and delivers high pressure (HP) fuel to a common rail (26), a pressure sensor (28) adapted to deliver to the ECU (12) a signal (S3) relevant to the actual pressure (APR) inside the common rail and, an inlet metering valve (24) (IMV 24) arranged upstream of the transfer pump (22) for limiting the fuel quantity entering the transfer pump to the quantity required to fulfil the engine needs.

2. Fuel injection equipment (10) as claimed in the preceding claim wherein the IMV (24) is controlled by the ECU (12).

3. Method (100) of control of a fuel injection equipment (10) as claimed in any of the preceding claims, the method comprising the steps of:

a) determining the actual rail pressure (APR) based on a signal (S3) received from the pressure sensor (28);

b) determining a targeted rail pressure (TPR);

c) adjusting the IMV (24) orifice as a function of the output of steps a) and b).

4. Method (100) as claimed in claim 3 wherein the adjusting step c) leads to: c2) increasing the IMV orifice if the targeted pressure (TPR) determined at step b) is inferior to the actual pressure (APR), step a);

c3) maintain unchanged the IMV orifice if the targeted pressure (TPR) determined at step b) is equal to the actual pressure (APR), step a);

c4) reducing the IMV orifice if the targeted pressure (TPR) determined at step b) is superior to the actual pressure (APR), step a).

5. Command unit 12, ECU 12, adapted to execute a method (100) as claimed in any one of the claims 3 or 4 for controlling a fuel injection equipment (10) as claimed in any one of the claims 1 or 2.