FR3056640A1 - SYSTEM AND METHOD FOR DECREASING VALVES FROM AN INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

The invention relates to a system for slopping valves and / or cylinder head ducts of an internal combustion engine comprising a calculator and a set of low-pressure injectors fluidly connected to a first reservoir containing a detergent fluid, each injector being implanted in an intake or exhaust duct of the cylinder head and having a series of holes for projecting the detergent fluid on a valve and / or on walls of the duct. The invention also relates to a process using such a scrubbing system.

Description

Technical area

The invention relates to the field of motor vehicles. More particularly, the invention relates to a system and method making it possible to overcome fouling of valves and internal conduits of a cylinder head during the repeated phases of regeneration of a nitrogen oxide trap.

State of the art

The recent evolution of the regulatory standards of depollution requires the installation of treatments making it possible to limit the emissions of nitrogen oxides, in particular on the Diesel engines which function in lean mixture and produce much of it.

One known method consists in using a nitrogen oxide trap (NOX trap according to English terminology) installed on the exhaust line. During the normal operation of the engine with a lean mixture, the nitrogen oxides (NOx) present in the combustion gases of the engine are stored in the trap without being treated there. Then, by periodic regenerations of the trap which consist in switching the operation of the engine into a rich mixture, the NOx are reduced to harmless molecules, for example of N2.

To carry out these regenerations, unburnt hydrocarbons are supplied, for example, by carrying out late injections of fuel into the engine cylinders while allowing air to enter the engine intake duct so as to degrade the efficiency of combustion and increase the richness of the air-fuel mixture, for example to a value close to 1.05. Nevertheless, the regeneration cycles fairly quickly cause fouling of the valves mainly due to degraded combustion. This causes compression losses because some valves remain blocked in the partially open position due to deposits of soot and oil on their seats and inside the cylinder head conduits. Thus, in the compression phase, an air leak can be created, which can result in engine instabilities, which can go as far as the extinction of one or more cylinders, or even in some cases, stopping complete with engine.

The object of the invention is to provide an efficient means for cleaning the valves and conduits of a cylinder head of an internal combustion engine, in particular following a regeneration of the nitrogen oxide trap mounted at the engine exhaust. .

Description of the invention

To this end, the invention relates to a system for cleaning the valves and / or cylinder head conduits of an internal combustion engine, characterized in that it comprises a computer and a set of low pressure injectors fluidly connected to a first reservoir containing a detergent fluid, each injector being located in an intake or exhaust duct of the cylinder head and having a series of holes making it possible to project the detergent fluid onto a valve and / or onto the walls of the duct .

The cleaning system according to the invention therefore makes it possible to spray a detergent fluid whose action makes it possible to dissolve and eliminate the residues of soot and oil accumulated in the valves and on the internal walls of the intake and exhaust ducts. exhaust from the cylinder head.

Advantageously, the series of holes comprises a first row of holes having a first ply angle making it possible to spray the detergent fluid onto a valve stem and a second row of holes having a second ply angle making it possible to spray the detergent fluid onto the walls of the duct, on the lowest part of the valve guide and of the valve seat.

Advantageously but optionally, the system also comprises a second reservoir, containing a non-stick fluid, to which all of the injectors are fluidly connected. The non-stick fluid limits the soot and oil deposits on the valves and on the walls of the cylinder head ducts.

Advantageously but optionally, the system includes a three-way valve making it possible to select a projection of detergent fluid or of non-stick fluid. This valve makes it possible to connect the two tanks to the same pipe, itself connected to all of the injectors.

The invention also relates to a method of descaling valves and / or internal conduits of a cylinder head of an internal combustion engine during repeated phases of regeneration of a nitrogen oxide trap, the method implementing the cleaning system according to the invention as described above, and successively comprises:

a step 100 while which the calculator checked than the number of regenerations is equal at an NI number predetermined; then, - a step 200 while which the calculator checked than 1 injection of fuel is cut r then, - a step 300 while which the calculator

check that the valves are closed; then,

a step 400 during which the computer controls a spraying of detergent fluid by the low pressure injectors.

The number NI is for example equal to 10.

Advantageously but optionally, steps 200 to 400 are repeated a number N2 times, for example 5 times.

Advantageously but optionally, the method successively comprises, following step 400:

a step 500 during which the computer verifies that the fuel injection is cut off; then,

a step 600 during which the computer verifies that the valves are closed; then,

a step 700 during which the computer controls a spraying of non-stick fluid by the low-pressure injectors.

Advantageously but optionally, steps 500 to 700 are repeated a number N3 of times, for example 5 times.

The invention also relates to a motor vehicle comprising a scouring system and / or a scouring method as described above.

Other characteristics and / or advantages will appear on reading the following description, of a preferred embodiment, given by way of nonlimiting example, in relation to the appended drawings, among which:

- Figure 1 is a schematic view of a preferred example of a cleaning system according to the invention;

- Figure 2 is a sectional view showing the location of a low pressure injector according to the invention in the cylinder head;

- Figure 3 is a flow diagram representing the process according to the invention for the projection of a detergent fluid; and

- Figure 4 is a flowchart showing the additional steps for the projection of a non-stick fluid.

A scouring system shown in FIG. 1 comprises a set of low pressure injectors 3 mounted on a cylinder head 5. The injectors 3 are fluidly connected by a line 6 to a three-way valve 7, itself connected by two other lines 61, 62 respectively to a first reservoir 8 comprising a detergent fluid and to a second reservoir 9 comprising a non-stick fluid.

The injectors 3 and the three-way valve 7 are electrically connected to a computer 10 controlling the cleaning system, respectively by two connections 11 and 12.

The location of a low pressure injector 3 in the cylinder head 5 is shown in FIG. 2. The injector 3 is installed in the cylinder head 5 so that one of its ends 31 opens into an intake duct or d exhaust 51 of the cylinder head 5 and facing a valve 1. At the end 31, the injector 3 has a series of holes 32 of which a first row, comprising for example between 4 and 8 holes, has a ply angle "a" centered on the bottom of the rod 11 of the valve 1 when the latter is closed. The angle "a" is for example between 10 ° and 40 °. This angle “a” makes it possible to project the detergent fluid directly onto the rod 11 of the valve 1. This makes it possible to avoid the accumulation of traces of coking and of combustion deposits which could cause aerodynamic dysfunctions in the cylinder head.

The second row, for example comprising between 8 and 16 holes, has an angle “b”, for example, between 60 ° and 140 ° making it possible to spray the detergent fluid on the wall 52 of the conduit 51 and on the lowest part valve guide 2 and valve seat 4.

Its purpose is to maximize the efficiency of the system regarding the scouring of the seat and the valve seat in order to eliminate traces of coking and combustion deposits.

In other exemplary embodiments not shown, the values of the angles “a” and “b” may be different from the values presented above. In particular, the value of the angles “a” and “b” can vary according to the geometry of the engine, the diameter of the rod and of the valve seat.

Advantageously but optionally, the attachment of the injector 3 is ensured by a flange 33.

The operating steps of the previously described scouring system are illustrated by FIGS. 3 and 4 according to a preferred embodiment of the method.

According to the illustrated embodiment, the system successively performs a spraying of a detergent fluid followed by a spraying of a non-stick fluid according to the following steps:

In step 100, the computer verifies that the number of regenerations of the nitrogen oxide trap is equal to 10.

As the number of regenerations of the Nox trap is a function of the use of the vehicle, for example driving in town or on motorway, the system is put in phase with the computer 10 to know the occurrences of regeneration. For example, in this exemplary embodiment, an algorithm of the computer 10 determines the triggering of the scrub at the end of the 10 ^th regeneration of the Nox trap. This number of regeneration may however be different in other embodiments.

In step 200, the computer verifies that the fuel injection is cut off. The detergent is sprayed during the fuel injection cut-off phases so as not to disturb combustion, for example, when the driver releases the accelerator pedal.

- In step 300, the computer checks that the valves are closed, in order to ensure optimum spraying on the seat and the valve stem and the cylinder head duct.

In step 400, the computer controls a projection of detergent fluid by the low pressure injectors.

According to this exemplary embodiment, steps 200 to 400 are repeated 5 times, however the number of repetitions may be different in other exemplary embodiments.

Thereafter, once the detergent fluid has been sprayed 5 times, the three-way valve 7 switches over to the reservoir comprising the non-stick fluid and the process continues according to the steps illustrated in FIG. 4.

- In step 500, the computer verifies that the fuel injection is cut, so as not to disturb the combustion, as for the projection of the detergent fluid.

- In step 600, the computer also verifies that the valves are closed, in order to ensure optimum spraying on the seat and the valve stem and the cylinder head duct.

In step 700, the computer controls a projection of non-stick fluid by the low pressure injectors.

The steps 400 to 700 forming a cycle are also repeated 5 times, according to this exemplary embodiment of the method. However, the number of repetitions can also be different in other exemplary embodiments.

The composition of the detergent fluid is, for example, based on a dosage of kerosene, naphthalene and ethylhexyl nitrate. The percentage of each component is chosen to allow optimum efficiency while ensuring the mechanical strength of the moving parts.

The composition of the non-stick fluid is, for example, a silicone lubricant having virtues of high thermal resistance, in particular for projections made on the exhaust face.

Claims (11)

1. Clogging system for valves and / or cylinder head conduits of an internal combustion engine 5 characterized in that it comprises a computer and a set of low pressure injectors fluidly connected to a first reservoir containing a detergent fluid, each injector being located in an intake or exhaust duct of the cylinder head and having a series of holes allowing 10 spray the detergent fluid onto a valve and / or onto the walls of the duct. 2. A cleaning system according to claim 1, characterized in that the series of holes comprises a first 15 row of holes having a first ply angle for spraying the detergent fluid on a valve stem and a second row of holes having a second ply angle for spraying the detergent fluid on the walls of the conduit and on the most low of a valve guide 20 and a valve seat. 3. A cleaning system according to one of claims 1 and 2, characterized in that it further comprises a second reservoir, containing a non-stick fluid, 25 which is fluidly connected to all of the injectors. 4. cleaning system according to claim 3, characterized in that it comprises a three-way valve for selecting a projection of detergent fluid 30 or non-stick fluid. 5. A method of deslagging valve and / or conduits internal of a cylinder head of an internal combustion engine during repeated regeneration of a trap to ¹⁰ nitrogen oxide phases, the method implementing a deslagging system according to one of claims 1 to 4, characterized in that the method successively comprises: - a step (100) during which the computer 5 verifies that the number of regenerations is equal to a predetermined number NI; then, - a step (200) during which the computer verifies that the fuel injection is cut off; then, - a step (300) during which the computer 10 checks that the valves are closed; then, - A step (400) during which the computer controls a projection of detergent fluid by the low pressure injectors. 15 6. A cleaning process according to claim 5, characterized in that the number NI is equal to 10. 7. A cleaning process according to one of claims 5 and 6, characterized in that the steps (200) 20 to (400) are repeated an N2 number of times. 8. A cleaning process according to claim 7, characterized in that the number N2 is equal to 5. 25 9. Process scrub according to one of claims 5 to 8, characterized by what, the system of scrub being according to one of claims 3 to 4, the process comprises successively, following step (400): a step (500) during which the computer 30 verifies that the fuel injection is cut off; then, - a step (600) during which the computer verifies that the valves are closed; then, - a step (700) during which the computer controls a spraying of non-stick fluid by the low-pressure injectors. 10. A cleaning process according to claim 9, characterized in that the steps (500) to (700) are repeated a number N3 times. 11. A cleaning process according to claim 10, characterized in that the number N3 is equal to 5. 12. Motor vehicle comprising a scouring system according to one of claims 1 to 4, and / or a scouring method according to one of claims 5 to 11. ECU; 12 r-13 i Cylinder head li Z ^ cteui ^ low pressure BYPASS