FR2931877A3 - Fuel i.e. petrol, supply line for road motor vehicle, has disconnection injector e.g. multi-point injection type petrol injector, disconnecting controlled fuel flow and with end fitting realizing fluid connection between injector and line - Google Patents

Abstract

The invention relates to a fuel supply line (10) adapted to be connected at one end to a feed pump (3) and to the other end to a fuel introduction device (4) in a exhaust line (2), said feed line (10) comprising a controlled fuel flow cutoff means characterized in that the breaking means is a cutoff injector (6).

Description

The present invention relates generally to the field of the depollution of combustion engines internal combustion equipping road vehicles, including diesel engines. More particularly, the invention relates to a fuel supply line adapted to be connected to a first end to a feed pump and to the other end to a fuel introduction device in an exhaust line, the said feed line comprising a controlled fuel flow cutoff means. In order to reduce the allowable thresholds for the emission of gaseous pollutants from motor vehicles, gas after-treatment systems are arranged in the exhaust line. Some of these systems operate discontinuously or alternatively, that is to say that in normal operation they trap pollutants but treat them only during regeneration phases. This is the case of particulate filter (FAP) or particle traps (Nox-Trap) post-treatment systems. A method of regeneration of these post-treatment systems consists in introducing, during the regeneration phases, a suitable quantity of fuel by a device for introducing fuel into the exhaust line upstream of the after-treatment devices in order to raise the temperature and burn the trapped pollutants. Generally, the introduction device is supplied with fuel from a low pressure stage of a high pressure fuel pump supplying the injectors opening into the combustion chamber of the engine, so that the introduction device is fed by a pressure of the order of a few bars, varying for example from 5 to 7 bars. However, the introduction devices opening into the exhaust line at the engine outlet, are subjected to severe conditions of use due to contact with hot and corrosive exhaust gases, which can lead to malfunctions of the device. introduction. A failure that can be observed is the blocking in the open / passing position of the introduction device leading to an uncontrolled amount of fuel introduced into the exhaust line. This excess fuel introduced into the exhaust line can then lead to a deterioration of the after-treatment systems by an uncontrolled rise in temperature.

In this context, the present invention aims to provide a fuel introduction device in an improved exhaust line, and more particularly that avoids the deterioration of the after-treatment systems. This invention finds application in post-processing systems of the FAP or Nox-Trap type.

To this end, the introduction device according to the invention also complies with the generic definition given in the preamble defined above, is essentially characterized in that the breaking means is a cutoff injector. The invention therefore allows the metering of the fuel introduced into the exhaust line when the fuel introduction device is defective by blocking in the open / passing position.

The cutoff injector then performs the function of the introduction device by dosing and limiting the amount of fuel introduced into the exhaust line, the fuel introduction device then being seen as a simple restriction.

It can be ensured that the cutoff injector is a gasoline type fuel injector and more particularly the MPI multi-point injection type, which reduces the cost of the system. It is possible for the cut-off injector to have a hydraulic end-piece capable of making a fluid connection between the injector and the feed-line on the introduction device, which makes it possible to limit the flow losses in the feeder.

It is possible to ensure that the cut-off injector has a first open / on state and a second closed / block state, which makes it possible to simplify its piloting and to limit the pressure drops introduced by the cut-off injector into the d-line. supply if the pilot passed through a gradient of state of openings.

It can be ensured that the cut-off injector is kept in an open / passing state during the regeneration phases, which then allows this cut-off injector to be transparent from a hydraulic point of view in the line of power supply when the fuel introduction device connected to it functions properly. It can be ensured that the cut-off injector is maintained in a closed / blocking state outside the regeneration phases, which makes it possible to increase the operating safety of the supply line. When the introduction device is faulty and blocked in the open / passing position, the cutoff injector then makes it possible to block the arrival of fuel towards the introduction device. It can be arranged that the cut-off injector is controlled by a frequency control, and more particularly by pulse-width modulation (PWM), which makes it possible to precisely control the cut-off injector during the time of operation. long opening. It can be ensured that the fuel introduction device in the exhaust line is a fuel injector and more particularly a fuel type fuel injector, which reduces the cost of the system, because of the use of a component with proven technology, and a reduction in diversity, by reusing the same component for two different functions.

It can be arranged that the supply line comprises a pressure limiter arranged downstream of the feed pump, which makes it possible to reduce the pressure oscillations and to maintain the pressure in the supply line at a predetermined value. . The invention also relates to a fuel introduction system in an exhaust line comprising an introduction device opening into an exhaust line fed by a low pressure pump of a fuel supply system. an internal combustion engine via a feed line according to the invention. Other characteristics and advantages of the invention will emerge clearly from the description which is given below, by way of indication and in no way limitative, with reference to the single appended figure which represents the fuel introduction system in a line d exhaust according to the invention. As previously announced and presented in the single figure, the invention relates to a fuel introduction system 1 in an exhaust line 2 which comprises post-processing means 20 to be regenerated. This fuel introduction system 1 comprises a feed pump 3 and a feed pipe 10 for transporting the fuel expelled by the pump 3 to a fuel introduction device 4 opening into the exhaust line 2 in This fuel introduction device 4 is often placed as close as possible to the outlet of the exhaust manifold in order to take advantage of the thermal energy generated in the combustion chamber of the engine to vaporize. the introduced fuel which is then transported in the flow of the exhaust gas to the post-processing means to regenerate. In the embodiment shown in the figure, the feed pump 3 is constituted by the mechanical booster pump of the low pressure stage of a fuel pump for a common rail injection system for supplying the chamber with fuel combustion. The typical pressure at the outlet of the low pressure stage is of the order of ten bars, and more often between 5 and 7 bars.

However, it is also conceivable that the feed pump 3 is a specific electric pump, separate from one of the fuel pumps for common rail injection system. A pressure limiter 5 is provided in the feed line 10 downstream of the feed pump 3 to limit and stabilize the fuel pressure downstream thereof. This limitation can be obtained either by a calibrated restriction or by a pressure regulator type clipper without return. According to the embodiment shown, the introduction device 4 is a fuel injector whose nozzle opens into the exhaust duct. This injector can be a gasoline injector, and more particularly a multi-point fuel injector type MPI.

According to the embodiment shown, a cutoff injector 6 is arranged upstream of the feed device 4 and downstream of the feed pump 3. The inlet of the cutoff injector 6 is connected to the feed line. supply 10 on the supply pump side 2, and the output of the cut-off injector 6 is connected to the feed pipe 10 on the introduction device side 4. This cut-off injector 6 is a gas injector, and more particularly a essence injector MPI type. The cut-off injector 6 has a hydraulic nozzle in place of an injection nozzle, so as to minimize the pressure drops in the supply line 10.

When the fuel introduction device 4 is in working order, the cut-off injector 6 is kept in the open / pass position only when the system 1 is in a regeneration phase and as long as the fuel introduction device 4 works correctly. The cutoff injector 6 is controlled by a computer 7, for example an electronic control unit, better known by its acronym ECU. The cut-off injector 6 has two states, a first open / on state during the regeneration phases and a second closed / block state outside of regeneration phases. Due to the maintenance of the cut-off injector 6 in an extended open / extended position during the regeneration phases, the computer 7 controls the cut-off injector 6 by a pulse width modulation (PWM) type frequency control. ), also known by its acronym PWM. A ratio of the pulse width over the important period, that is to say greater than 95% and preferably of the order of 99.5%, is used, as well as a low frequency, ie to say of the order of 1Hz. When the introduction device 4 is faulty, and more particularly when the latter is blocked in an open / passing position, the cut-off injector 6 is controlled by the computer 7 so as to selectively inject fuel into the exhaust duct. 2. The cut-off injector 6 can then be driven according to the same control method of the introduction device 4. The operation of the fuel introduction system 1 in the exhaust duct 2 is then ensured. In the event of failure of the introduction device 4, the cut-off injector 6 is in a closed / blocking state outside of regeneration phases and in an open / on state during the regeneration phases. However, the cut-off injector 6 can also be maintained at times in a closed / blocking state during the regeneration phases in order to modulate the quantity of fuel introduced into the exhaust pipe 2. In the case of the use of two MPI gasoline injectors, the system is economically advantageous, since it combines an injector with proven technology, an MPI fuel injector, and a reduction of diversity, reusing for two different functions the same component, at the hydraulic end near .

Claims (10)

CLAIMS1) Fuel supply line (10) adapted to be connected at one end to a feed pump (3) and at the other end to a fuel introduction device (4) in a line of fuel. exhaust (2), said feed line (10) comprising a controlled fuel flow cutoff means characterized in that the breaking means is a cutoff injector (6). 2) Supply line (10) according to the preceding claim characterized in that the cutoff injector (6) is a gasoline type fuel injector and more particularly of the type MPI. 3) Supply line (10) according to one of the preceding claims characterized in that the cutoff injector (6) has a hydraulic endpiece adapted to perform a fluid connection between the injector (6) and the line feeding device (10) on the introduction device (4). 4) Supply line (10) according to one of the preceding claims characterized in that the cutoff injector (6) has a first open / on state and a second closed / blocking state. 5) Supply line (10) according to the preceding claim characterized in that the cutoff injector (6) is maintained in an open / passing state during the regeneration phases. 6) Supply line (10) according to one of claims 4 or 5 characterized in that the cutoff injector (6) is maintained in a closed / blocking state outside the regeneration phase. 7) Supply line (10) according to one of the preceding claims characterized in that the cutoff injector (6) is controlled by a frequency control, and more particularly by a pulse width modulation (PWM) . 8) Supply line (10) according to one of the preceding claims characterized in that the fuel introduction device (4) in the exhaust line (2) is a fuel injector and more particularly a fuel injector. fuel type. 9) Supply line (10) according to one of the preceding claims characterized in that a pressure limiter (5) is disposed downstream of the feed pump (3). 10) Fuel introduction system (1) in an exhaust line (2) characterized in that it comprises an introduction device (4) opening into the exhaust line (2) fed by a low pump pressure (3) of a fuel supply system of an internal combustion engine via a feed line (10) according to one of the preceding claims.