EP3169890B1 - Fuel injektor - Google Patents

Description

TECHNICAL AREA

The present invention relates to a fuel injector and more particularly to an arrangement allowing a closed-loop control of an injection system.

BACKGROUND OF THE INVENTION

On today's common rail fuel injectors, the quantity of fuel injected and the opening and closing times of the injector are dependent on the capacity of the industrial production means to produce the injectors while respecting the parameters. keys of the injector. Therefore, dispersions exist. In addition, during fuel injector operating cycles, some parameters drift due to wear of the components. The drift and rise times of the control valve as well as those of the injection nozzle needle can be cited as drift. Strategies for monitoring the movements of the needle exist, in particular by measuring the variation of a current injected through the injector, the position of the needle causing this current to vary. This type of solution requires the arrangement in the injector resistive coatings and electrical connections to achieve a known electrical path of the injected current. The establishment in the injector of electrical connections for diagnosing the position of the needle by current injection is an industrial obstacle. The problems of reliability of the connections during the life cycle of the injector, as well as the productivity problems related to the assembly time of such an injector have slowed down the implementation of this type of control strategies on the injectors of the injector. fuels. It is therefore important to propose a new solution solving these problems. Injectors comprising means for detecting the movement of the needle are known from DE10201222215777 A1 and DE102005019806 A1 . EP2713040 A1 shows an example of electrical contact in an injector.

SUMMARY OF THE INVENTION

An internal combustion engine fuel injector according to claim 1 and a method of assembling such an injector according to claim 3. A fuel injector for an internal combustion engine comprises: an injector body in which are arranged an actuator, a control valve, and a needle guide. The actuator actuates the control valve, the control valve controlling a sliding injection needle in its guide between an open position in which injection is permitted and a closed position in which fuel injection is prohibited.

The injector further comprises a first electrical connection extending from the needle guide to intermediate electrical connection means internal to the injector, and also comprises a second electrical connection extending from said connection means. intermediate to a connector pin accessible externally to the injector, so that an electrical signal representative of the position of the needle can be transmitted from the needle guide to the connector pin and thus be accessible to an external electronic calculator.

The internal intermediate connection means may consist of a metal strip. The first electrical connection may be in contact with the metal strip by a spring system arranged in termination of the first electrical connection. The guide of the needle may comprise on its radial surface a hole receiving a termination of the first electrical connection thus allowing their electrical contact. The second electrical connection is integrated with the coverslip. The internal intermediate connection means may comprise a metal ring arranged on the actuator.

A method of assembling a fuel injector, comprises the following steps: the establishment of a metal ring having a first metal extension substantially perpendicular to the ring and integrated with the ring by overmolding on the cylindrical periphery of the actuator; the positioning of the actuator in the housing of the body of the injector; connecting the first metal extension with a connector pin of the injector; inserting a second metal extension into a housing of the valve body having a recess opposite the ring, the termination of the second metal extension being arranged with a spring system lodging in the recess; assembly of the control valve with the actuator, the second metal extension passing through the body of the control valve; and assembling the needle guide with the control valve, the second end of the second metal extension arranged with another spring system housed in a hole located on the radial surface of the needle guide in contact with the control valve.

The step of placing the ring on the actuator can be done by inserting the ring in a groove of the body of the actuator.

BRIEF DESCRIPTION OF THE DRAWINGS

• La figure 1 est une représentation d'un injecteur de carburant selon un premier exemple ne faisant pas partie de l'invention.
• La figure 2 est une représentation partielle d'un injecteur de carburant selon un exemple de mode de réalisation de la présente invention.
• La figure 3 est une représentation partielle d'un injecteur de carburant selon un exemple de mode de réalisation de la présente invention.
• La figure 4 est une représentation d'une méthode d'assemblage d'un injecteur de carburant de la présente invention.

Other features, objects and advantages of the invention will appear on reading the detailed description which follows, and with reference to the accompanying drawings, given by way of non-limiting example and in which:

• The figure 1 is a representation of a fuel injector according to a first example not forming part of the invention.
• The figure 2 is a partial representation of a fuel injector according to an exemplary embodiment of the present invention.
• The figure 3 is a partial representation of a fuel injector according to an exemplary embodiment of the present invention.
• The figure 4 is a representation of a method of assembling a fuel injector of the present invention.

DESCRIPTION OF PREFERRED EXAMPLES AND EMBODIMENTS

According to figure 1 , which represents an example not forming part of the invention, a fuel injector 10 extending longitudinally along the axis A is an assembly of metallic components comprising fixed components and moving components.

The injector comprises an injector body 12 in several parts, an upper part 23 and a lower part 25 or nut.

A substantially cylindrical solenoid actuator 14 is arranged in the upper part 23 of the body of the injector 12. A control valve 21 cooperating with the actuator 14 is arranged below the actuator 14 in the lower part 25 of the body of the the injector 12, so that the upper radial surface of the control valve is in contact with the upper part 23 of the The actuator 14 is controlled by two control wires 15 connected to its coil 19 and joining a connector 17. The actuator 14 comprises a return spring 16 positioned longitudinally along the axis A, said spring return biasing the control valve 21.

The control valve 21 comprises a valve body 20 in which is arranged a frame 36 integral with a rod 18. According to the figure 1 and when the coil 19 of the actuator is not energized, the return spring 16 of the actuator 14 pushes the armature 36, the latter driving the rod 18 of the control valve 21 in its seat 22.de so that the control valve 21 is in the closed position. When the coil 19 of the actuator is energized, the armature 18 is attracted magnetically towards the actuator 14 as far as the stop driving with it the stem 18 of the control valve out of its seat 22 so as to open the valve of control 21.

A guide 24 of an injection needle 38 is arranged in the lower part 25 of the body of the injector 12. The guide 24 of the needle has a radial surface in contact with the control valve 21 and a bore in which the injection needle 38 is arranged. The injection needle 38 whose upper part is in connection with a control chamber 28 is movable back and forth along the longitudinal axis A of the injector 10. The ceiling 30 of the control chamber 28 is in contact directly with the body 20 of the control valve 21 and the wall 32 of the control chamber is in contact with the body of the guide 24 of the needle 38.

A nozzle body 26 is arranged in the lower part 25 of the body of the injector 12. The injection needle 38 moves back and forth in the middle portion of the nozzle body 26 so that when the needle Injection seat 38 is in its seat 34, thus preventing the injection of fuel, the injector is said in closed position.

The essential fixed components of the injector 10 comprise the injector body 12, the actuator 14, the control valve body 20, the guide of the injection needle 24, the injection nozzle 26, the chamber 28 and the seat of the injection needle 34.

The moving components of the injector comprise in particular the rod 18 of the control valve 21, the armature 36 of the control valve 21 integral with the rod 18 of the control valve 21 and the injection needle 38.

The control wires 15 of the actuator make it possible to control the moving components of the injector 10.

The surfaces of the injector components in contact with each other are referred to as contact surfaces S.

For a good understanding of these different contacts, there will be mentioned for example the contact surface S1 between the body 20 of the control valve 21 and the guide of the needle 24, and also the contact surface S2 between the guide of the needle 24 and the body of the injection nozzle 26. For example, the contact surfaces S3 between the injection needle 38 and its seat 34, and also the contact surfaces S4 between the injection needle are also mentioned. 38 and the ceiling of the control chamber 30.

The injector further comprises a first electrical connection 42 extending from the guide of the needle 24 to a metal strip 40, and also a second electrical connection 44 extending from the metal strip 40 to a pin 46 of the connector 47, so that an electrical signal representative of the position of the injection needle 38 can be accessible to an external electronic computer by this external connection means.

During operation of the injector 10, there are several phases.

In a first phase, during the supply of the actuator 14 by the control wires 15, the armature 36 is attracted against the actuator 14 driving with it the rod 18 of the control valve 21. The control valve 21 and open, causes a pressure drop in the control chamber 28. This pressure drop causes the displacement of the injection needle 38 to the limit with the ceiling 30 of the control chamber 28. The needle injection 38 is no longer in its seat 34. This phase is called fuel injection phase.

In a second phase, when the actuator 14 is no longer powered by its control son 15, the armature 36 is pushed by the holding spring 16 driving the rod 18 of the control valve 21 in its seat 22. The control valve 21 thus closed, causes an increase in pressure in the control chamber 28. This increase in pressure causes the displacement of the injection needle 38 in abutment in its seat 34. The injector 10 thus closed is said in non-injection phase.

The contact between the injection needle 38 and its seat 34 is established during the non-injection phases. The injection needle 38 is in the closed position. The contact between the injection needle 38 and the ceiling of the control chamber 30 is established when the injection needle 38 is in the high stop position, that is to say at the end of the upstroke during the fuel injection. The injection needle 38 is also in permanent contact with the guide of the needle 24 in which it moves back and forth. This movement implies that neither the contact of the injection needle 38 with the ceiling of the control chamber 30 nor the contact of the injection needle 38 with its seat 34 are established during this race.

In order to ensure the operation of the device allowing the electrical signal to represent the position of the injection needle 38, the contact surfaces S1 between the guide of the injection needle 24 and the body 20 of the control valve 21, as well as the contact surfaces S2 between the needle guide 24 and the body of the nozzle 26, as well as the contact surfaces S5 between the needle guide 24 and the body of the injector 12 are coated. The contact surfaces S3, S4 between the movable elements of the injector 10, namely between the injection needle 38 and its seat 34, as well as between the needle injection 38 and the ceiling of the control chamber 30 are coated with a coating having a non-zero resistivity, for detecting a potential difference due to the flow of a detectable electric current through the coating, this detection being carried out by calc external electronic ulcer. The external computer and the body of the injector 12 are interconnected by an electrical ground.

To detect the position of the injection needle, an electric current is injected into the injector by the pin 46 of the connector, reaching the body of the guide of the injector 24 by taking the electrical path composed of the second electrical connection. connected to the metal part 40, the metal strip 40 being connected to the first electrical connection 42.

When the needle 38 is in contact with its seat 34, the injector 10 being in the closed position, the electric current continues its path from the guide of the needle 24 to the needle 38, then from the needle 38 to the seat 34, seat 34 being of material with the nozzle 26, the nozzle 26 being in contact with the body of the injector 12. The electronic calculator then detects a first voltage drop due to the resistivity of the path traveled.

When the needle 38 is in contact with the ceiling of the control chamber 30, the electric current continues its path from the guide of the needle 24 to the needle 38, then from the needle 38 to the body 20 of the control valve 21, the control valve 21 being in contact with the ceiling of the control chamber 30, then the current continues its way to the body of the injector 12. The electronic computer then detects a second voltage drop due the resistivity of the second path traveled.

When the needle 38 travels between the seat 34 and the ceiling of the control chamber 30, the injected current can not flow, the guide of the needle 24 being electrically isolated from all possible paths to the body of the In this case, no voltage drop is detected.

According to figure 2 , the internal intermediate connection means 40 to the injector 10 comprise a closed metal ring 40 positioned around the actuator 14 of the injector 10. The first electrical connection 42 is formed by an overmolded wire 42, a termination of which is arranged with a spring system 48 ensuring electrical contact with the metal ring 40. The spring system 48 is of the curved leaf spring type 48. The spring system 48 is housed in a recess 54 of the body of the injector 12 positioned vis-à- screw of the metal ring 40 so that the curved spring blade 48 is supported on the metal ring 40 thus making it possible to have an electrical contact between the curved spring blade 48 and the ring 40. More specifically, the domed central portion of the spring blade 48 bears on the metal ring 40.

The other end of the overmolded wire 42 is arranged with another spring system 50 which can be housed in a hole 52 located on the radial surface of the guide 24 of the needle 24 thus ensuring their electrical contact. The other spring system 50 is of torsion spring type so that when arranged in the hole 52, the spring comes into contact with the side walls of the hole 52 to thereby ensure electrical contact between the needle guide. 24 and the overmolded wire 42

The overmolded wire 42 extends longitudinally from the curved spring blade 48 positioned vis-à-vis the metal ring 40 to the hole 52 located on the radial surface of the guide 24 of the needle. In order to allow passage of the overmolded wire 42, the upper part 23 of the body of the injector 12 has a bore 43 from the recess 54 and opening onto another bore 45 formed on either side of the body 20 of the control valve. 21 and opening on the hole 52. The overmolded wire thus allows the indexing of the needle guide 24 with the control valve 21 and also the control valve 21 with the body of the injector 12. A shoulder 56 on the inner face of the body of the injector 12, located near the control valve 21, keeps the other spring system 50 arranged with the overmolded wire 42 in the hole 52 of the needle guide. The second electrical connection 44 is integrated with the ring 40, the end of this second electrical connection 44 being electrically connected to the pin of the connector 46.

According to figure 3 the metal ring 40 is open. The second electrical connection 44 is a wire welded at its end with the ring 40. The ring has an angular sector of the order of 40 degrees. The second electrical connection 44 extending longitudinally A on the actuator 14. The metal ring 40 is advantageously fixed on the cylindrical periphery of the body of the actuator 14. The metal ring 40 is inserted in a groove of the body of the actuator 14. The ring 40 is split and elastic. The end 48 of the overmolded wire 42 in contact with the metal ring 40 is of the spring pin type 48.

Alternatively, the opening of the ring 40 may have many angular sector values, this value being dependent on the attachment means of the ring with the component of the injector 10 to which it is fixed. By way of non-limiting example, the ring may have an angular sector of the order of 200 degrees allowing it to be easily overmolded in the body of the actuator 14, this making it possible to avoid contact of this ring 40 with the body of the injector 12. In other embodiments, the ring 40 may have a width of at least 3 mm, its angular sector may be between 40 degrees and 360 degrees. Alternatively, the ring 40 can simply completely and circularly surround the body of the actuator 14.

Alternatively, the end 48 of the overmolded wire 42 in contact with the metal ring 40 may have all kinds of protuberances allowing said contact with the ring 40.

The actuator may be of different types, such as for example and non-limiting, of the solenoid actuator type or alternatively of the piezoelectric actuator type.

Alternatively, the first electrical connection 42 and the second electrical connection 44 may each be of different types such as, for example, conducting wires, rigid lamellae or any other electrical conductor making it possible to conduct an electrical signal from the guide of the injection needle. 24 to the pin of connector 46.

Also alternately and in a nonlimiting manner, the two terminations 48, 50 of the first electrical connection 42 may each be, independently of one another, of the spring pin type, or of the domed spring type, or of the spring type torsion.

• mise en place 102 de la bague métallique 40 comportant la première extension métallique 44 substantiellement perpendiculaire à la bague 40 et intégrée avec la bague 40 par surmoulage sur le pourtour cylindrique de l'actionneur 14.
• positionnement 104 de l'actionneur 14 dans le logement du corps de l'injecteur 12.
• connexion 106 de la première extension métallique 44 avec la broche du connecteur 46 de l'injecteur 10.
• insertion 108 de la deuxième extension métallique 42 dans le logement du corps de vanne 12 présentant un évidement 54 en vis-à-vis de la bague 40, la terminaison de la deuxième extension métallique 42 étant agencée avec le système ressort 48 se logeant dans l'évidement 54.
• assemblage 110 de la vanne de contrôle 21 avec l'actionneur 14, la deuxième extension métallique 42 passant au travers du corps 20 de la vanne de contrôle21.
• assemblage du guide 112 de l'aiguille 24 avec la vanne de contrôle 21, la deuxième extrémité de la deuxième extension métallique 42 agencée avec l'autre système ressort 50 se logeant dans le trou 52 localisé sur la surface radiale du guide de l'aiguille 24 en contact avec la vanne de contrôle 21.

According to figure 4 an assembly method 100 of a fuel injector 10 as described above may comprise the following steps:

• placing 102 of the metal ring 40 including the first metal extension 44 substantially perpendicular to the ring 40 and integrated with the ring 40 by overmoulding on the cylindrical periphery of the actuator 14.
• positioning 104 of the actuator 14 in the housing of the body of the injector 12.
• connection 106 of the first metal extension 44 with the pin of the connector 46 of the injector 10.
• insertion 108 of the second metal extension 42 in the housing of the valve body 12 having a recess 54 opposite the ring 40, the termination of the second metal extension 42 being arranged with the spring system 48 housed in the recess 54.
• assembly 110 of the control valve 21 with the actuator 14, the second metal extension 42 passing through the body 20 of the control valve.
• assembly of the guide 112 of the needle 24 with the control valve 21, the second end of the second metal extension 42 arranged with the other spring system 50 housed in the hole 52 located on the radial surface of the needle guide 24 in contact with the control valve 21.

Alternatively, the step of placing 102 of the ring 40 on the actuator 14 is done by insertion of the ring 40 into a groove of the body of the actuator 14.

Claims (4)

1. Fuel injector (10) for an internal combustion engine comprising an injector body (12) in which there are positioned an actuator (14), a control valve (21), a needle guide (24); the actuator (14) actuating the control valve (21), the control valve (21) controlling an injection needle (38) sliding in its guide (24) between an open position in which injection is permitted and a closed position in which the injection of fuel is prevented, characterized in that the injector (10) comprises:

   a metal ring (40) including a first metal extension (44) substantially perpendicular to the ring (40) and integrated with the ring (40), said ring (40) and the first metal extension (44) being over molded onto the cylindrical circumference of the actuator (14), the first metal extension (44) being connected to a connector pin (46) of the injector (10);

   a second metal extension (42) inserted into a housing of the valve body (12) having a recess (54) facing the ring (40),

   the first termination of the second metal extension (42) being provided with a spring system (48) accommodated in the recess (54) so as to ensure an electrical contact with the ring (40), and wherein the second metal extension (42) is positioned through the body (20) of the control valve (21).
2. Fuel injector (10) according to the preceding claim, according to which the second extremity of the second metal extension (42) is provided with another spring system (50) accommodated in a hole (52) situated on the radial surface of the guide (24) for the needle in contact with the control valve (21) so as to ensure an electrical contact with the guide (24) for the needle.
3. Method of assembly (100) of a fuel injector (10) as described in Claim 2 comprising the following stages:

   putting in place (102) of a metal ring (40) including a first metal extension (44) substantially perpendicular to the ring (40) and integrated with the ring (40) by overmolding onto the cylindrical circumference of the actuator (14);

   positioning (104) of the actuator (14) in the housing of the body of the injector (12);

   connection (106) of the first metal extension (44) to a connector pin (46) of the injector (10);

   insertion (108) of a second metal extension (42) into a housing of the valve body (12) having a recess (54) facing the ring (40), the termination of the second metal extension (42) being provided with a spring system (48) accommodated in the recess (54);

   assembly (110) of the control valve (21) with the actuator (14), the second metal extension (42) passing through the body (20) of the control valve (21);

   assembly (112) of the guide (24) for the needle with the control valve (21), the second extremity of the second metal extension (42) provided with another spring system (50) accommodated in a hole (52) situated on the radial surface of the guide (24) for the needle in contact with the control valve (21).
4. Method of assembly (100) of a fuel injector (10) as described in Claim 2 comprising the following stages:
   putting in place (102) of putting the ring (40) in place on the actuator (14) takes place by insertion of the ring (40) into a groove in the body of the actuator (14)
   positioning (104) of the actuator (14) in the housing of the body of the injector (12);
   connection (106) of the first metal extension (44) to a connector pin (46) of the injector (10);
   insertion (108) of a second metal extension (42) into a housing of the valve body (12) having a recess (54) facing the ring (40), the termination of the second metal extension (42) being provided with a spring system (48) accommodated in the recess (54);
   assembly (110) of the control valve (21) with the actuator (14), the second metal extension (42) passing through the body (20) of the control valve (21);
   assembly (112) of the guide (24) for the needle with the control valve (21), the second extremity of the second metal extension (42) provided with another spring system (50) accommodated in a hole (52) situated on the radial surface of the guide (24) for the needle in contact with the control valve (21).

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