EP1319829A1 - Fuel feeding system for an internal combustion engine - Google Patents

Abstract

This system for supplying a device with fluid comprises a circuit (14) for admitting fluid into the device comprising a pump for supplying an injection system (22) connected, on the one hand, to a fluid reservoir and, on the other hand, to means (20) for injecting fluid into the device, a circuit (26) for returning excess fluid to the reservoir, which extends between a portion of the circuit d inlet located downstream of the pump and the reservoir, and means (24, 28) for regulating the pressure acting on the flow of fluid in the fluid return circuit to regulate the pressure of the fluid in the injection means. The pressure regulation means are arranged in the excess fluid return circuit and include means for measuring a characteristic representative of the pressure level prevailing downstream of the pump, and control means (24) controlling the pump. injection (22) according to the value of said characteristic. <IMAGE>

Description

The present invention relates to power systems of a fluid device.

More particularly, the invention relates to a system supplying a device with fluid, of the type comprising a circuit fluid intake in the device comprising a pump supply connected, on the one hand, to a fluid reservoir, and, on the other hand, to means for injecting fluid into the device, a excess fluid return circuit to the reservoir extending between a portion of the intake circuit located downstream of the pump and the tank.

A particularly interesting application of this type of fuel system is the fuel supply of a vehicle automobile equipped with an internal combustion engine.

As we know, one of the main concerns of motor vehicle manufacturers is decreasing the fuel consumption.

The energy consumed by the injection pump has an influence not negligible on the total consumption of the vehicle, as well as on carbon dioxide emissions.

The energy consumed by the supply pump being proportional to the fuel flow multiplied by the pressure supplied, flow limitation results in energy savings not negligible.

So some fuel systems for motor vehicles are provided with means for regulating pressures intended to regulate the pressure of the fluid in the means injection.

These regulation means act as a switch in shutting off the fuel return circuit when the pressure level supplied by the pump is insufficient or, on the contrary, by opening this fuel return system when the pressure level supplied by the pump is greater than a predetermined threshold value.

The open or closed state of the switch also provides indication of the fuel pressure level prevailing in the intake circuit, downstream of the pump.

This information can be used to stop feeding fuel injectors and stop the engine before dry breakdown, which prevents damage to the engine and for the exhaust system, in particular when it has a catalytic converter.

This type of feeding system nevertheless presents a major drawback relating to the fact that its operation is accompanied by a significant increase in consumption for the engine. Also, the object of the invention is to overcome this disadvantage.

According to the invention, a system is therefore proposed. supplying a device with fluid, comprising a circuit fluid intake in the device comprising a pump supply system of an injection system connected, on the one hand, to a fluid reservoir and, on the other hand, to means for injecting fluid in the device, an excess fluid return circuit to the tank, which extends between a portion of the intake circuit located downstream of the pump and the reservoir, and means for regulating pressure to regulate the pressure of the fluid in the means injection.

According to one aspect of this feeding system, the means of pressure regulators are arranged in the fluid return circuit in excess and include means for measuring a characteristic representative of the pressure level prevailing downstream of the pump, and control means controlling the injection pump as a function of the value of said characteristic.

The pressure prevailing downstream of the pump is therefore regulated, on the one hand, by controlling the flow of fluid in the return circuit of fuel, and, on the other hand, by acting on the operating regime of the pump, which significantly reduces the level of overall engine consumption.

According to one embodiment of this system, the means of regulation have a diaphragm forming a valve, which is mounted in a housing provided with a fluid return channel, which communicates with the intake circuit, and one free end of which constitutes a seat for the membrane, the membrane being mounted so displaceable in the casing under the effect of the pressure prevailing in the intake circuit, between a first closing position of the fluid return circuit in which it rests in abutment against the seat and a second position for opening the return circuit of fluid in which it is spaced from said seat.

According to an advantageous characteristic of this system, said measuring means include means for measuring resistance electrical portion of an electrical circuit comprising the valve and the fluid return channel.

For example, the membrane delimits in the housing a first chamber in which is placed a return spring and a second chamber in which the fluid circulates.

According to a particular embodiment, the casing comprises two housing elements made of electrically conductive material between which is placed the membrane, one of the housing elements being connected to the control means and internally delimiting the first chamber, the other housing element, which delimits internally the second chamber, being provided with said return channel of fluid and being connected to ground, the membrane being made of electrically insulating material carrying an electrically element conductor suitable for bringing electrical elements of housing when the membrane is in the first position.

The fluid return channel is made of material electrically conductive.

The invention also relates to the use of a system as defined above for the supply of fuel from an internal combustion engine.

• la figure 1 est une vue schématique d'un système d'alimentation conforme à l'invention, pour l'alimentation en carburant d'un moteur à combustion interne de véhicule automobile ; et
• la figure 2 est une vue en coupe transversale des moyens de régulation de pression du système d'alimentation de la figure 1.

Other objects, characteristics and advantages of the invention will emerge from the following description, given solely by way of nonlimiting example, and made with reference to the appended drawings, in which:

• Figure 1 is a schematic view of a supply system according to the invention, for the supply of fuel to an internal combustion engine of a motor vehicle; and
• FIG. 2 is a cross-sectional view of the pressure regulation means of the supply system of FIG. 1.

In Figure 1, there is shown a supply system of a fluid device, designated by the general reference 10.

In the embodiment shown, this system 10 is intended to supply fuel to an internal combustion engine 12 of a motor vehicle. However, other applications may also be considered mutatis mutandis.

The system 10 essentially comprises a circuit 14 fuel intake to engine 12. This intake circuit is in communication, through one of its ends 16, with a reservoir of fuel (not shown) and, by its opposite end 18, with electro-injectors 20 controlled by an electronic control unit- motor which determines the opening time of the different injectors and thus the amount of fuel injected into the engine cylinders.

The intake circuit 14 is provided with a pump 22 supply system for an injection system controlled by a central unit 24, so as to regulate the fuel pressure in the circuit intake.

Furthermore, the supply system includes a circuit 26 return fuel intended to reinject excess fuel into The reservoir.

According to the invention, this circuit 26 for returning fuel is provided with a pressure regulator 28 ensuring, part, the pressure regulation around a set point of predetermined pressure corresponding to an average value of pressure to obtain nominal pump operation 22, without overheating, and, on the other hand, a measurement of the pressure level prevailing in the fuel intake circuit 14, downstream of the pump 22 or regulator discharge flow level.

We will now describe, with reference to FIG. 2, the regulator structure 28.

As seen in this figure, the regulator has a casing 30 made of electrically conductive material comprising a first housing element 32 and a second housing element 34, each having a generally cylindrical side wall, and assembled with each other with the interposition of a membrane 36 in the form of disc and elastically deformable and electrically insulating material, by means of a crimp 38 made of an electrically material insulating.

The first housing element 32 delimits, jointly with the membrane 36, a first chamber 40 in which is placed a spring 42, resting, on the one hand, against the bottom of the first element of housing 32, and, on the other hand, on a seat 43 made of a material electrically conductive and which is fixed on the membrane 36 at the by means of a rivet 44, also made of material electrically driver.

Regarding the second housing element 34, it internally defines, jointly with the membrane 36, a second chamber 45 in which the fuel circulates. It is provided of a connector 46 for its connection to the circuit 14 of admission of fuel and a channel 48 made of electrically material conductor, for example come of matter with the second element of housing 34, which projects into the internal volume of the second housing element 34 and which opens, outside, towards the tank, via the fuel return circuit 26.

In the equilibrium position, the membrane 36 is supported, by through the rivet 44, against the end edge 50 of the channel 48.

We finally see in Figure 2, that the second element of box 34, in which the fuel circulates, is connected to earth, while the first housing element 32 is connected to the unit control center 24 via a conductor 52.

In operation, as long as the fuel pressure prevails in the intake circuit 14, downstream of the pump 22, is less than a predetermined threshold value, which corresponds to the force applied by the spring 42 on the membrane 36, the latter remains in support against the end edge 50 of channel 48, via the rivet 44.

Therefore, the conductor 52 is connected to ground by through the spring 42, the seat 43, the rivet 44, and the channel 48.

As soon as the pressure prevailing downstream of the pump 22 and in the first chamber 40 is such that it exerts a force on the membrane 36 greater than that exerted by the spring 42, this membrane 36 is offset from the end edge 50 of channel 48.

Therefore, channel 48 is open and allows a return of fuel in the circuit 26 for returning fuel to the tank and this, with a flow all the more important as the value of the pressure prevailing downstream of the pump 22 is important.

At the same time, the voltage level present on the conductor 52 depends on the electrical resistance of the portion of the electrical circuit constituted, in particular, by the spring 42, the seat 43, the rivet 44, the fuel blade L located between the rivet 44 and the end edge 50 from channel 48, and through channel 48 itself.

As can be seen, the thickness and therefore the value of the resistance of the fuel blade L depends on the pressure level prevailing in the second housing element 34, and therefore the flow in channel 48. The control unit is thus provided with means, of the type conventional, able to measure the value of the resistance of this blade L of fuel.

This information is used by the control unit 24 to regulate the operation of pump 22 accordingly.

So when the resistance value is zero, which corresponds to a situation in which the membrane is in support against channel 48, the leakage rate in the fluid return circuit is zero. The flow of fuel supplied by the pump 22 is then insufficient and should be increased. The control unit 24 then controls the pump 22, accordingly.

On the contrary, when the resistance of the fuel blade L is very high, which means that the pressure value downstream of pump 22 is important, the leakage rate in the return circuit fluid 26 is important. The control unit 24 then controls the pump 22 so as to reduce the flow rate.

As will be appreciated, the invention which has just been described, which uses a pressure regulator to reduce the pressure prevailing in a fuel intake circuit, on the one hand, mechanically, increasing the fuel flow in the circuit return of excess fuel and, in a controlled manner, by controlling the injection pump accordingly, allows a significant reduction fuel consumption.

It should also be noted that this regulation is totally independent of the nature of the fuel supplying the engine, and the pump supply voltage. This feeding system is by therefore capable of regulating independently, without the need for a specific sensor.

Finally, note that the regulator of the power system which has just been described can advantageously be positioned in the tank, which significantly reduces the cost and the size of the power system.

Finally, it should be noted that the invention is not limited to the mode of realization described.

Indeed, while in the example described with reference to Figures 1 and 2, the regulator consists of a pressure regulator simple, that is to say that the first box element is isolated from the rest of the supply system, it is also possible, as a variant, to arrange the regulator in the form of a pressure regulator differential controlled by the pressure prevailing in the distributor engine intake 12.

In this case, the first element of the regulator case is provided with a conduit for communicating its volume internal with the intake manifold.

Claims (7)

System for supplying a fluid device, comprising a circuit for admitting fluid into the device comprising a pump for supplying an injection system (22) connected, on the one hand, to a fluid reservoir and, on the other hand, to means (20) for injecting fluid into the device, a circuit (26) for returning excess fluid to the reservoir, which extends between a portion of the intake circuit located downstream of the pump and the reservoir, and pressure regulating means (28, 24) for regulating the pressure of the fluid in the injection means, characterized in that the pressure regulating means are arranged in the circuit return of excess fluid and comprise means for measuring a characteristic representative of the pressure level prevailing downstream of the pump, and control means (24) controlling the injection pump as a function of the value of said characteristic. Supply system according to claim 1, characterized in that the regulating means comprise a diaphragm (36) forming a valve, which is mounted in a housing (30) provided with a channel (48) for return of fluid, which communicates with the intake circuit and one free end of which forms a seat for the diaphragm, the diaphragm being movably mounted in the casing under the effect of the pressure prevailing in the intake circuit, between a first closed position of the fluid return circuit (26) in which it rests in abutment against the seat and a second open position of the fluid return circuit in which it is spaced from said seat. System according to claim 2, characterized in that said measuring means comprise means for measuring the electrical resistance of a portion of the electrical circuit comprising the valve (36) and the channel (48) for return of fluid. Supply system according to one of claims 2 and 3, characterized in that the membrane defines in the housing a first chamber (40) in which is disposed a return spring (42) and a second chamber (35) in which circulates the fluid. System according to claim 4, characterized in that the casing comprises two housing elements (32, 34) of electrically conductive material between which the membrane (36) is placed, one of the housing elements being connected to the control means ( 24) and internally delimiting the first chamber, the other housing element, which internally delimits the second chamber, being provided with said fluid return channel (48) and being connected to ground, the membrane being made of electrically insulating material and carrying an electrically conductive element (44) suitable for bringing the housing elements into electrical contact when the membrane is in the first position. System according to claim 5, characterized in that the fluid return channel is made of electrically conductive material. Use of a feeding system according to one any of claims 1 to 6, for the fuel supply an internal combustion engine.

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