JP3167288U - Fuel injector for internal combustion engine - Google Patents

Abstract

A seal member is molded directly on a valve body to ensure stable and accurate position adjustment and an effective seal. A fuel injector 1 for an internal combustion engine houses an injection control valve 4 and a valve body 17 that defines an annular chamber 30 together with the injector body 2 in its own hollow injector body 2. The annular chamber 30 is designed to receive fuel under pressure and is liquid-tightly isolated by a seal member 51 made of a plastic material supported by the valve body 17. [Selection] Figure 1

Description

  The present invention relates to a fuel injector for an internal combustion engine.

  In particular, the present invention relates to an injector of the type that includes a hollow injector body, the injector body having its own axis and defining a seat for receiving an injection control valve. The valve then includes a tubular valve body which is inserted into the seat of the injector body coaxially with the aforementioned axis by screwing in a ring nut manner into the seat of the injector body. Then, the outer flange of the valve body is pressed against the inner shoulder of the injector body itself. The valve includes an opening / closing member that is pressed against the head surface of the valve body by an elastic thrust member, and an electric actuator. The electric actuator is operated in the opposite direction to the action of the elastic member, and the opening / closing member is Arranged along the aforementioned axis so that it can be spaced from the head surface. An annular chamber is obtained between the valve body and the injector body, into which is piped a pipe for supplying fuel under pressure to be injected. The chambers share the aforementioned axis and are defined axially by two shoulders facing each other, one of the shoulders being supported by the injector body and the other being supported by the valve body. For the purpose of preventing fuel leakage between the injector body and the valve body, a ring seal made of an elastomer material is disposed on the shoulder portion of the injector body. On the shoulder of the valve body, the pressure of the fuel contained in the annular chamber acts or is used to produce an axial thrust towards the ring nut.

  Although known injectors of the type described above are generally used, when the injection is performed regularly with particular control of the stroke or lift of the opening and closing member, it is not efficient and reliable at all. Not at all satisfactory.

  What has been described above is that due to the particular form of the annular seat that receives fuel under pressure, the fuel itself produces an axial thrust on the valve body, as opposed to the elastic thrust on the opening and closing member by the elastic body. Basically based on that. The thrust is proportional to the pressure at which the fuel is introduced and elastically deforms the valve body without applying a load from the ring nut to the injector body. Therefore, during operation of the injector, the opening and closing member and the electric actuator are placed in a relative position that is different from the concept in the design phase, that is, in the activated state, the effective lift of the opening and closing member is different from the concept. .

  Furthermore, since the elastic deformation of the valve body is usually on the order of a few microns and is strictly related to the instantaneous value of the pressure of the fuel in the annular chamber, it does not represent a constant offset with respect to a static state where there is no pressure, Therefore, no compensation can be made at the stage of placing the injector.

  The object of the present invention is to provide a fuel injector which, by virtue of its structure, can solve the above-mentioned problems in a simple and economically advantageous manner.

  In accordance with the present invention, an injector body having a seat, and an injection control valve including a valve body disposed in the seat for defining an annular chamber designed to receive fuel under pressure; First and second liquid-tight means disposed on the opposite side of the annular chamber in the axial direction for liquid-tightly isolating the chamber, wherein the second liquid-tight means includes the injector body and An internal combustion engine comprising: a seal member disposed between the valve body; and the injector includes first and second liquid-tight means, wherein the seal member is supported by the valve body. A fuel injector for an engine is provided.

  In the above-described injector, the seal member is preferably a main body made of a plastic material.

1 is a cross-sectional view of a fuel injector made in accordance with the teachings of the present invention with parts removed for simplicity. FIG. 2 is a cross-sectional view of a first modification of the member represented in FIG. 1. FIG. 4 is a partial sectional view of a second modification of the member shown in FIG. 2.

  The present invention will now be described with reference to the accompanying drawings, which illustrate non-limiting examples of embodiments.

  In FIG. 1, reference numeral 1 indicates the whole fuel injector for the internal combustion engine E, which is schematically shown by a broken line in FIG.

  The injector 1 comprises a tubular injector body 2 having an axis 3, a servo valve 4 housed in a seat 5 of the injector body 2, and a tube 7 for supplying fuel at a pressure exceeding 1000 bar. A connector 6 for connecting the injector 1 and a rod 8 that is partially disposed on the seat 9 of the servo valve 4 and is movable in a direction D1 parallel to the axis 3 are provided.

  As a result of this process, reference numeral 3 refers to both the axis of the injector body 2 and the axis of the injector 1 which are in fact coincident.

  The injector body 2 has a substantially cylindrical side wall 10, and a seat portion 5 is formed on the inside thereof. The side wall 10 has two cylindrical axial end extensions, indicated by 11 and 12, which extend sharing the same axis 3, and the extension 11 is more diameter than the extension 12. Is big. The extensions 11 and 12 are fitted to each other by a radial shoulder 13 perpendicular to the axis 3. Provided in the elongated portion 12 is a circumferentially annular recess 15 that communicates with the supply pipe 7 through a passage 16 formed in the elongated portion 12.

  Referring again to FIG. 1, the servo valve 4 includes a T-shaped valve body 17 and has its own head portion 17 a attached to the injector body 2 by the ring nut 18. The head 17a is pressed against the shoulder 13 of the injector body 2 to provide a fluid tight connection. The servo valve 4 further includes an actuator device 20 that is coaxial with the rod 8 and is provided with an electromagnet 21. The servo valve 44 further has a fan-shaped configuration and can be slid in the axial direction within the elongated portion 11 under the action of the electromagnet 21, and is surrounded by the electromagnet 21 and attracted by the electromagnet 21 itself. Comprises a preloaded spring 24 which exerts a thrust action on the anchor 22 in the opposite direction.

  Again, as shown in detail in FIG. 1, the chamber 9 is axially defined between the end face 25 of the portion 26 of the rod 8 and the end disk 27, the end disk 27 being In the chamber 5 of the injector body 2, it is accommodated in a predetermined position between the actuator device 20 and the head 17 a of the valve body 17.

  The chamber 9 is in permanent communication with the tube 7 to receive fuel under pressure through a radial calibration duct 29 formed in the valve body 17 and an annular chamber 30. The chamber 30 is formed at a predetermined position adjacent to the head portion 17a, and is defined by a recess 15 on one side and a cylindrical portion in the middle of the valve body 17 itself.

  The chamber 9 is further in communication with another chamber 33 via a calibration duct 32 that shares the axis 3, which also shares the same axis 3 as well as the disk 27 itself and the actuator device. 20 is formed in a distribution body 35 arranged at an intermediate axial position between 20 and 20.

  The body 35 includes a base portion 36, which is formed by screwing the ring nut 18 into the inner surface of the extension portion 11 and axially coupling the ring nut 18 so that the ring nut 18 presses the outer annular portion of the base portion 36. The disc 27 is tightly packed in the axial direction in a liquid-tight manner and at a predetermined position. The body 35 further includes a shaft or pin 37, which extends from the base 36 along the axis 3 on the side of the base 36 opposite the disk 27, the outer side being defined by a cylindrical surface 39, Also, it consists of a single part with a base 36.

  Referring again to FIG. 3, the chamber 33 extends through a portion of the base 36 and shaft 37, sharing the axis 3, and on the opposite side 180 °, each radial formed in the shaft 37. It communicates with the hole 41. The bore 41 extends into an annular chamber 42 dug along the surface 39 at an axial location adjacent to the base 36.

The chamber 42 defines an annular gap or port at a radially outer position, which is designed to be opened and closed by an opening and closing element, which is defined by a sleeve 43 that is adjustable. Actuated by the actuator device 20 to change the pressure in the chamber 9, thus adjusting the axial movement of the rod 8.
The sleeve 43 is a single piece with the anchor 22 and has an inner cylindrical surface that is axially between the end advancement position and the end retraction position. To the surface 39 in a substantially liquid-tight manner.

  In particular, in the advanced end movement position, the sleeve 43 is coupled to push the conical shoulder 45 at one end 44 of the end, thereby closing the outer annular gap of the chamber 42 and A shaped shoulder 45 connects the surface 39 of the shaft 37 to the base 36. In this position, since the pressure in the chamber 42 acts radially on the inner cylindrical surface of the sleeve 43 itself, the axial thrust force applied by the fuel becomes zero, and no force is applied to the sleeve 43.

  In the retracted end travel position, the end 44 of the sleeve 43 is spaced from the shoulder 47 and defines a gap for flowing fuel to the annular channel 48, which is a ring nut. 18 and the sleeve 43 itself. An annular channel 48 communicates with each exhaust or recirculation pipe (not shown) through a cavity 49 in the injector body 2.

  Referring again to FIG. 1, the valve body 17 includes a cylindrical hollow shaft 17 b having an axis 3 in addition to the head portion 17 a. The hollow shaft 17 b extends in the extension portion 12 of the seat portion 5 and has an annular groove. The annular groove 50 is formed on the intermediate extension of the shaft 17b disposed below the annular chamber 30 and spaced axially from the annular chamber 30. An annular seal body 51 is engaged in the groove 50, and this annular seal body 51 is PTFE with a suitable plastic material, preferably copper filler, or the trade name “Turcite®” or Adjacent to the annular chamber 30 made of a material known as “Turcon®” and protruding from the outer periphery of the shaft 17b in a cantilevered manner by pressing it or providing liquid tightness It cooperates with a suitable shoulder mounted on the valve body 17 by making a radial connection with a portion of the elongate portion 12 that does. The body 51 is conveniently molded directly on the shaft 17b so as to be integrated with the valve body by depositing the material forming the body 51 itself directly into the groove 50.

  Alternatively, according to what is shown in FIG. 2, the body 51 is replaced with a helical body 53, which has one complete winding and two end turns with the ends cut off. It is preferable. The spiral body 53 is formed separately from the valve body, and is then coupled to the valve body by being inserted into the seat portion 50.

  In another variant shown in FIG. 3, the shaft 17b has no external grooves, has a straight busbar and is inserted so as to be axially mounted to support an additional support body 55, on which An annular body 56, which also extends beyond the periphery of the shaft 17b and the additional body 33 so as to provide fluid tightness.

  In use, fuel under pressure introduced into the annular chamber 30 axially thrusts the body 51, 53 or 56 downward, i.e., toward a nebulizer member (not shown). The thrust does not reach the valve body because the body is supported by the valve body. Since the valve head 17a is joined to the shoulder 13 for sealing, the thrust direction is opposite to the direction in which pressure is applied to the valve body itself. Therefore, the valve body is subjected to two thrusts acting in opposite directions and having substantially the same size, and is thus substantially balanced. Said balancing prevents the displacement and / or local elastic deformation of the valve body itself in the direction of the actuator device 20, and in this way the geometrical shape of the valve body does not substantially change, It is ensured that the various parts are always moved and arranged relatively independently of the fuel pressure.

  By molding the seal body directly on the valve body, the seal body can be permanently blocked on the valve body. Instead, the use of a helical seal body and / or an additional support body simplifies and speeds up the installation of the seal body on the valve body, while at the same time providing a stable and accurate position. Adjustment and effective sealing are guaranteed.

  From the foregoing, it will be apparent that variations and modifications may be made to the injector 1 described herein without departing from the scope of protection defined by the following claims. In particular, the seal body supported by the valve body can be formed using a different material than that shown here and different from that described merely as an example.

Claims (11)

A fuel injector (1) for an internal combustion engine,
An injector body (2) provided with a seat (5);
An injection control valve (4) comprising a valve body (17) disposed in the seat (5) and defining an annular chamber (30), designed to receive fuel under pressure;
A first liquid-tight means (13, 17a) and a second liquid-tight means (51, 53,) arranged on the opposite side in the axial direction of the annular chamber (30) and for isolating the annular chamber in a liquid-tight manner. 56), wherein the second liquid tight means includes seal means (51, 53, 56) disposed between the injector body (2) and the valve body (17). One liquid-tight means (13, 17a) and the second liquid-tight means (51, 53, 56);
With
The fuel injector, wherein the seal member (51, 53, 56) is supported by the valve body (17).   The injector according to claim 1, characterized in that the sealing member (51, 53, 56) is a body made of a plastic material.   The injector according to claim 1 or 2, wherein the sealing member (51, 53, 56) is arranged at a predetermined position spaced axially from the annular chamber (30). .   The seal members (51, 53, 56) cooperate by pressing the axial shoulder (50), and the axial shoulder (50) is supported by the valve body (17), The injector according to any one of claims 1 to 3, characterized in that it is radially coupled to a portion of the injector body (2) adjacent to the annular seat (30).   The said valve body (17) contains an outer peripheral seat part (50), The said sealing member (51, 53) is accommodated partially in the said outer peripheral seat part (50), The injector according to any one of 1 to 4.   The injector according to claim 5, wherein the outer circumferential seat portion is a circumferential seat portion.   The injector according to any one of claims 1 to 6, wherein the seal member (51) is integrated with the valve body (17).   The injector according to claim 7, wherein the seal member (51) is directly molded on the valve body by depositing material in the groove (50).   The injector according to any one of claims 1 to 6, wherein the seal member (53) is separated from the valve body and has a spiral shape.   The injection according to any one of claims 1 to 4, wherein the sealing member (56) is coupled to a support body (55) separate from the valve body and is firmly connected to the valve body. vessel.   11. The injector according to claim 10, wherein the support body (55) is attached to the valve body.

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