JP6787687B2 - Electromagnetic fuel injection device with an annular recess located in the welded area of the extension - Google Patents

Description

The present invention relates to an electromagnetic fuel injection device.

An electromagnetic fuel injection device (such as the electromagnetic fuel injection device described in the specification of a patent document) usually functions as a fuel duct and is operated by an electromagnetic actuator. It comprises a cylindrical tubular support body with a central supply duct that is terminated by an injection jet controlled by a valve (see, eg, Patent Document 1). The injection valve is equipped with a plunger, which moves between the closed and open positions of the injection port by the action of an electromagnetic actuator against the action of a closing spring that pushes the plunger toward the closed position. Be done.

This electromagnet is made of a ferromagnetic material that is tightly connected to the plunger and mounted so that it can move inside the support body, with a coil that is located on the outside and in a fixed position around the support body. Movable armatures made and fixed armatures made of ferromagnetic material and located inside the support body within the area of the coil and designed to magnetically attract the movable armature. And. The fixed armature has a central through hole that serves to allow fuel to flow towards the injection port. Inside the center hole of the fixed armature is a closing spring, which pushes the movable armature and therefore the plunger integrated with the movable armature towards the closing position of the injection valve. It is compressed between a perforated striker body fitted therein and a movable armature.

A metal extension is partially located inside the support body at a fixed position and just above the upper fixed armature, which allows fuel to flow towards the injection port. Has a central hole for Since the upper portion of this extension is located outside the support body, the extension is only partially located inside the support body. This extension is mechanically constrained to the support body by an annular weld, which is formed within the area of the upper end of the support body and begins at the upper wall of the support body.

Manufacturers of Otto cycle heat engines (ie, ignition controlled engines) can improve the mixing of fuel with oxidants (ie, the air sucked into the cylinder) and (improper combustion). Increasing the fuel supply pressure (higher than 70-80 Mpa) to reduce the generation of black smoke (showing) and injecting a small amount of fuel to separate the fuel injection into different forms of injection operation (so) By doing so, both to increase the dynamic performance of the electromagnetic injector (and thus gradually increase the reaction rate of the electronic injector) so that the generation of contaminants during combustion is reduced). I need.

Increased fuel supply pressure (higher than 70-80 Mpa) cracks in the support body in or near the annular weld that mechanically constrains the armature fixed to the support body or other types of structural It causes an increase in the frequency of failure of the fuel injection device due to the occurrence of defects. To solve this problem, manufacturers have tried to increase the thickness of the support body, but the solution is (increased amount of material used and increased manufacturing complexity). Increased manufacturing costs of fuel injectors (due to both) and increased diameters of fuel injectors (thus, especially in the case of internal combustion engines with small displacements, within the crown end of the cylinder). It has the unavoidable drawback of making it more difficult for the fuel injector to be housed).

A specification of a patent document describes a fuel injection device 100 (see, for example, Patent Document 2), the fuel injection device 100 for adjusting the injection port and the flow of fuel through the injection port. An injection valve 239 equipped with a movable plunger 266 and an electromagnetic actuator for moving the plunger 266 between the closed and open positions of the injection valve 239, the electromagnet with the coil 310 and the fixed armature 220. And an electromagnetic actuator equipped with a movable armature 262 mechanically connected to the plunger 266, a closing spring 270 that pushes the plunger 266 toward the closing position, and a tubular shape and fixed armature. A support body 240, with a central conduit that partially accommodates the 220 and totally accommodates the movable armature 262, and is located entirely outside the support body (ie, spaced from the support body 240). Includes an extension 210 that is located on the fixed armature 220 and is mechanically constrained to the fixed armature 220 by an annular weld.

European Patent Application Publication No. 1619384A2 U.S. Patent Application Publication No. 2002084362A1

An object of the present invention is to provide an electromagnetic fuel injection device that is not adversely affected by the above-mentioned drawbacks and can be easily manufactured at low cost at the same time.

The present invention provides the electromagnetic fuel injection device described in the appended claims.

Hereinafter, the present invention will be described with reference to the accompanying drawings showing non-limiting embodiments of the present invention.

It is a vertical sectional view of the fuel injection apparatus according to this invention. The detailed part of FIG. 1 is enlarged and shown. The detailed part of FIG. 2 is further enlarged and shown. The detailed part of FIG. 3 is further enlarged and shown. The injection valve of the injection device of FIG. 1 is shown. The detailed part of FIG. 5 is enlarged and shown.

In FIG. 1, number 1 indicates the fuel injection device as a whole, and the fuel injection device has cylindrical symmetry about the vertical axis line 2 and has a cylinder combustion chamber (not shown). It is designed to be operated to inject fuel through an injection port 3 that leads directly into it. The injection device 1 includes a support body 4, which has a tubular cylindrical shape with a variable cross section along the vertical axis 2 and supplies pressurized fuel to the injection port 3. A supply conduit 5 extending along the entire length of the support body 4 is provided for this purpose.

The support body 4 houses the electromagnetic actuator 6 in the area above it and the injection valve 7 (which can be seen more appropriately in FIG. 5) in the area below it. In use, the injection valve 7 is actuated by an electromagnetic actuator 6 to regulate the flow of fuel through the injection port 3 obtained within the area of the injection valve 7.

In FIGS. 2 and 3, the electromagnetic actuator 6 comprises a pair of twin electromagnets 8 (an upper electromagnet and a lower electromagnet, respectively), and these electromagnets are actuated together to operate simultaneously. When each electromagnet 8 is excited, the action of a single common closing spring 10 that pushes each movable armature 9 made of a ferromagnetic material toward the closing position of the injection valve 7. It is designed to move the injection valve 7 from the closed position to the open position along the axis 2 against the above. Each electromagnet 8 is powered by an electronic control unit (not shown) and has a coil 11 attached to the outside of the support body 4 and a fixed armature 12 made of a ferromagnetic material. The fixed armature 12 is housed in a fixed position inside the support body 4 and has a central hole 13 to allow fuel to flow towards the injection valve 3.

The metal extension portion 14 is partially located inside the support body 4 at a fixed position and just above the upper fixed armature 12 (ie, the upper fixed armature 12 of the electromagnet 8). And, the extension portion 14 has a central hole 15 for allowing fuel to flow toward the injection port 3. The extension portion 14 is arranged only partially inside the support main body 14 because the upper portion of the extension portion 14 is arranged outside the support main body 4. In particular, as can be clearly seen in FIG. 1, the maximum portion of the extension portion 14 is arranged outside the support main body 4. A striker body 16 is attached at a fixed position inside the central hole 15 of the extension portion 14, and the striker body 16 is used to allow fuel to flow toward the injection port 3 (if necessary). It has a cylindrical tubular shape (opening along the generatrix) and the closing spring 10 presses against the upper movable armature 9 (ie, against the upper magnet 8 movable armature 9). It is designed to maintain its condition.

Each coil 11 is wound directly inside an annular slot 17 of its own, which is obtained by removing material from the outer surface of the support body 4. Each coil 11 consists of an enamel wire, which has a self-bonding layer and is kept small along the axial size (ie, along the vertical axis 2) to minimize dispersion flux. (Measured size). Within the area of the coil 11, a protective body 18 made of ferromagnetic material is connected around the support body 4, and this protective body 18 ensures proper mechanical protection of the coil 11. In order to allow the streamline of magnetic flux generated by the coil 11 to be closed, and within the area of structural fragility inevitably caused by the presence of the slot 17 of the support body 4. Used to increase mechanical durability.

The movable armature 9 is a part of a mobile device, which further comprises a shutter or plunger 19, the shutter or plunger 19 having an upper portion integral with the movable armature 9 and fuel toward the injection port 3. It has a lower portion that cooperates with the valve seat 20 (shown in FIG. 5) of the injection valve 7 to regulate the flow of the injection valve 7 in a known manner.

In the user, when the electromagnet 8 is not excited, each movable armature 9 is not attracted by its fixed armature 12, and the elastic force of the closing spring 10 pushes the movable armature 9 downward with the plunger 19. In this situation, the injection valve 7 is closed. When the electromagnet 8 is excited, each movable armature 9 is magnetically attracted by its fixed armature 12 against the elastic force of the closing spring 10, and the movable armature 9 together with the plunger 19 is the injection valve 7. Move upwards to determine the opening of.

In order to accurately determine the upward stroke of the plunger 19, the upper movable armature 9 (ie, the upper movable armature 9 of the electromagnet 8) is replaced by the lower movable armature 9 (ie, the lower electromagnet 8 of the movable armature 9). ) Has a shorter usable stroke than the usable stroke. Thus, when the electromagnet 8 is excited, it is always the upper movable armature 9 that is in contact with the fixed armature 12 and moves so as to collide with the fixed armature 12, regardless of unavoidable assembly tolerances. That is, only the movable armature 9) of the upper electromagnet 8. In order to limit the usable stroke of the upper movable armature 9 (ie, the upper movable armature 9 of the electromagnet 8), the lower surface of the upper fixed armature 12 or the upper surface of the upper movable armature 9 is hard and non-rigid. It is covered with a layer of ferromagnetic metal material, preferably a layer of chromium. Thus, the thickness of the chromium layer determines the reduction in the usable stroke of the upper movable armature 9 (ie, the upper movable armature 9 of the electromagnet 8). Yet another function of this chrome layer is to increase the durability of the area against impact and, in particular, the ferromagnetic material and upper fixation of the upper movable armature 9 (ie, the upper movable armature 9 of the electromagnet 8). It is to avoid the magnetic adhesion phenomenon caused by the direct contact of the armature 12 with the ferromagnetic material. In other words, this chrome layer defines a gap, which is the magnetic force generated by the residual magnetism between the upper movable armature 9 (ie, the upper movable armature 9 of the electromagnet 8) and the upper fixed armature 12. Prevents reaching an excessively high value, that is, a value greater than the elastic force generated by the closing spring 10.

Further, precision machining is performed so that only the upper movable armature 9 (ie, the upper movable armature 9 of the electromagnet 8) has an adjusted outer diameter approximately equal to the inner diameter of the supply conduit 5 (obviously rounded down). receive. In contrast, the lower movable armature 9 (ie, the lower movable armature 9 of the electromagnet 8) has an unadjusted outer diameter that is always smaller than the inner diameter of the supply conduit 5. Thus, only the upper movable armature 9 (ie, the upper movable armature 9 of the electromagnet 8) serves as an upward guide for the plunger 19 to control the axial sliding of the plunger 19 along the vertical axis 2. This assembly solution reduces manufacturing costs by the manufacturer, as very high cost precision machining only needs to be done on the upward movable armature 9 (ie, the movable armature 9 on the upper electromagnet 8). Make it possible.

In FIG. 5, the valve seat 20 is defined within a sealing element 21 made in the form of an integral part, which closes the supply conduit 5 of the support body 4 on the lower side and is traversed by the injection port 3. Has been done. In particular, the sealing element 21 comprises a disc-shaped plugging element 22, which seals the supply conduit 5 of the support body 4 on the lower side and is crossed by the injection port 3. There is. The guide element 23 protrudes from the obstruction element 22 and has a tubular shape and accepts the plunger 19 inside so as to define a lower guide for the plunger 19 itself, and the pressurized fuel flows through it. It has an outer diameter that is smaller than the inner diameter of the supply conduit 5 of the support body 4 so as to define the outer annular conduit 24 that is possible.

Within the lower portion of the guide element 23, there is a supply through hole (not shown in FIG. 5) that reaches the valve seat 20 to allow the pressurized fuel to flow towards the valve seat 20. Has been obtained. The supply holes are staggered relative to the vertical line 2 so that they do not converge toward the vertical line 2 and do not cause vortex movements of the respective fuel flows during use. It is possible, or this supply hole can converge towards vertical line 2. In the embodiment shown in the accompanying drawings, the supply hole appears to be tilted at an angle of 80 ° (more generally, an angle in the range of 70 ° to 90 °) with respect to vertical line 2. Is located in. In another embodiment not shown here, the supply holes form an angle of 90 ° with respect to the vertical line 2.

The plunger 19 terminates in the form of a shutting head 25 having a generally spherical shape, the closing head 25 being designed to rest on and seal the valve seat 20. There is. As an alternative, the closed head 25 may have a shape that is essentially cylindrical and may have a single collision area with a spherical shape. Further, the closing head 25 is mounted on the inner surface of the guide element 23 in a sliding manner so that its movement is guided along the vertical axis line 2. The injection port 3 is defined by a plurality of injection through holes (not shown), and these injection through holes are obtained in a form starting from an injection chamber 26 arranged downstream of the valve seat 20.

As described above, the upper movable armature 9 (that is, the upper movable armature 9 of the electromagnet 8) has an outer diameter substantially the same as the inner diameter of the corresponding portion of the supply conduit 5 of the support body 4. Thus, the upper movable armature 9 can slide relative to the support body 4 along the vertical axis line 2, but in the transverse direction with respect to the vertical axis line 2 with respect to the support body 4. It is impossible to move. Since the plunger 19 is tightly coupled to the upper movable armature 9 (ie, the upper movable armature 9 of the electromagnet 8), apparently the upper movable armature 9 further serves as an upward guide for the plunger 19. .. Therefore, the plunger 19 is guided by the upper movable armature 9 (that is, the movable armature 9 of the upper electromagnet 8) on the upper side and by the guide element 23 on the lower side.

In FIGS. 2 and 3, the lower surface of the upper movable armature 9 (that is, the upper movable armature 9 of the electromagnet 8) is connected to the hydraulic braking device, and in this hydraulic braking device, the plunger 19 opens the injection valve 7. The movement of the plunger 19 is braked (decelerated) both when the plunger 19 moves from the closed position to the closed position and when the plunger 19 moves from the closed position to the open position of the injection valve 7.

The plunger 19 has a cylindrically symmetrical stem, to which a substantially spherical closing head 26 is connected by an annular weld. On the other hand, this stem is connected to each movable armature 9 by an annular weld.

In FIG. 3, the lower fixed armature 12 (that is, the fixed armature 12 of the lower electromagnet 8) can be a spot weld 27 (or an annular weld) that constrains the lower fixed armature 12 to the support body 4. Is mechanically fixed to the fixed position inside the support body 4 by the above. Preferably, the support body 4 has a central hole, which is made within the area of the lower fixed armature 12 (ie, the fixed armature 12 of the lower electromagnet 8) and is welded inside. Accommodates 27. The welds 27 are directionally arranged in the radial direction (ie, perpendicular to the vertical line 2) and, therefore, along the radial direction (ie, perpendicular to the vertical line 2). Extends from the outside to the inside. Because the weld 27 is completely located inside the support body 4 (which means that the weld 27 does not have to withstand the hydraulic stresses caused by the pressure of the fuel). And, since this weld 27 is not subject to mechanical stress (as described above, only the upper movable armature 9 hits the upper fixed armature 12 at the end of the open stroke of the plunger 19). The welded portion 27 is not significantly subjected to mechanical stress.

In FIG. 3, the upper fixed armature 12 (that is, the upper fixed armature 12 of the electromagnet 8) is mechanically fixed at a fixed position inside the support main body 4 by the annular welded portion 28, and the annular welded portion is fixed. 28 constrains the upper fixed armature 12 to the extension portion 14. The annular weld 28 between the upper fixed armature 12 (ie, the fixed armature 12 of the upper electromagnet 8) and the extension portion 14 inserts the upper fixed armature 12 and the extension portion 14 together into the support body 4. It is made on the outside of the support body 4 before it is done. In other words, the upper fixed armature 12 and the extension portion 14 are connected (preassembled) to each other by the outer annular weld 28 of the support body 4 and then with the upper fixed armature 12 connected to each other. Both the extension portions 14 are inserted into the support body 4. The annular weld 28 is directionally arranged in the radial direction (ie, perpendicular to the vertical line 2) and therefore upward along the radial direction (ie, perpendicular to the vertical line 2). Extends between the fixed armature 12 and the extension portion 14. The annular weld 28 is made under ideal conditions (ie, on the outside of the support body 4) and therefore has good mechanical durability. Further, the annular weld 28 is completely located inside the support body 4 (this means that the annular weld 28 does not have to withstand the hydraulic stresses caused by the fuel pressure. And (when the upper movable armature 9 hits the upper fixed armature 12 at the end of the open stroke of the plunger 19), the annular weld 28 acts only in the form of compression. It does not suffer much mechanical stress.

The upper fixed armature 12 (ie, the fixed armature 12 of the upper electromagnet 8) does not exert a direct mechanical constraint on the support body 4, which causes the upper fixed armature 12 to directly relative to the support body 4. It must be pointed out that it means that they are not mechanically connected. In practice, the upper fixed armature 12 is kept stationary inside the support body 4 only via the annular weld 28 that mechanically constrains the fixed armature 12 to the extension portion 14.

In FIG. 3, the extension portion 14 is mechanically restrained to the support main body 4 by the annular welded portion 29, and the annular welded portion 29 is formed in the area of the upper end portion of the support main body 4 and the support main body. It starts from the wall above 4. The annular weld 29 is axially arranged (ie, parallel to the vertical axis 2) and, therefore, along the axial direction (ie, parallel to the vertical line 2) of the support body 4 Extends between and the extension portion 14. The annular weld 29 is formed between materials that are ideally (ie, outside the support body 4) and have high mechanical durability (the extension 14 is unaffected by magnetic flux and is unaffected by magnetic flux. Therefore, it is made of non-ferromagnetic steel with high mechanical performance, and the support body 4 is also made of steel with high mechanical performance), so it has excellent mechanical durability. Since the annular weld 29 is markedly mechanically stressed, it is important that the annular weld 29 has high mechanical durability. The annular weld 29 must ensure sealing above the support body 4 and, therefore, withstand the hydraulic stress caused by the pressure of the fuel, as well as the open stroke of the plunger 19. At the end of, when the upper movable armature 9 hits the upper fixed armature 12, the annular weld 29 must withstand the shear stress.

In FIG. 4, the support body 4 has an annular recess 30, which is obtained starting from the inner surface of the support body 4 (ie, in an extension portion 14 located inside the support body 4). (Opposite) and (immediately) below the annular weld 29 (ie, below the root of the annular weld 29). The annular recess 30 is arranged below the annular weld 29 at a very short distance from the annular weld 29 itself. Basically, the starting point of the annular recess 30 is adjacent to the annular weld 29 (ie, the root of the annular weld 29) (ie, flush with the annular weld 29). As an alternative, the annular recess 30 can also partially overlap the annular weld 29 (ie, the root of the annular weld 29). In a preferred non-limiting embodiment, the annular recess 30 has a semi-circular shape in the cross section. Further, in a preferred non-limiting embodiment, the annular recess 30 has an axial length equal to or longer than the axial length of the annular weld 29. The annular recess 30 functions to protect the root of the annular weld 29 from mechanical stress. Obviously, the mechanical stress cannot pass through the empty annular recess 30, and therefore the mechanical stress travels from the support body 4 to the extension portion 14 and passes through the annular recess 30. And, it must proceed to the extension portion 14 which diffuses relatively far from the root of the annular weld 29. In other words, the annular recess 30 provides that the root of the annular weld 29 (there is tension concentration within this area of the annular weld 29) is released from tension and that the annular weld provides a more uniform stress distribution in the weld area. Allows the root of 29 to have. In summary, the presence of the annular recess 30 causes a crack in the root area of the annular weld 29 (the most vulnerable area and, therefore, the area most at risk of breakage within the annular weld 29). Alternatively, the likelihood of rift formation can be greatly reduced, and further, the welded area can act in a more uniform and dispersed manner.

In FIG. 4, the extension portion 4 has an annular recess 31, which is obtained starting from the outer surface of the extension portion 14 and is (ie, annular) above (immediately) above the annular weld 29. It is located above the base of the weld 29). In other words, the annular recess 31 is located above the annular weld 29 at a very short distance from the annular weld 29 itself. Briefly, the axial distance between the annular recess 31 and the annular weld 29 is non-zero (ie, greater than zero) and less than 50% of the axial length of the annular weld 29. (It must be pointed out that the axial distance between the annular recess 31 and the annular weld 29 can also be equal to zero). In a preferred non-limiting embodiment, the annular recess 31 has a rectangular shape with rounded vertices in its cross-sectional view. Further, in a preferred non-limiting embodiment, the annular recess 31 has an axial length equal to or longer than the axial length of the annular weld 29. In the annular recess 31, the mechanical stress transmitted between the support body 4 and the extension portion 14 passes through the annular recess 31 and diffuses relatively far from the outer surface (tension concentration area) of the annular welded portion 29. It serves to direct its mechanical stress so that it allows the welded area to act in a more uniform and dispersed manner. In other words, the presence of the annular recess 31 can cause the annular weld 29 to work better and thus greatly reduce the likelihood of cracks or crevices forming in the area of the outer surface of the annular weld 29. It is possible. It should be pointed out that the two annular recesses 30, 31 act in a synergistic manner. The two annular recesses 30, 31 are located above and below the annular weld 29 to ensure large changes in the direction of mechanical stress, and this mechanical stress is the most vulnerable area. And thus diffuse away from both tension concentration points (root and outer surface) in the weld, forming the area most at risk of breakage in the annular weld 29. If only one of the annular recesses 30 and 31 is present, the stress state at the root and the outer surface of the annular weld 29 cannot be reduced at the same time, and conversely, only one of the annular recesses 30 and 31 is present. It will be released from stress in a way that damages others.

Possible errors to obtain high accuracy in the length of the axial stroke of the upper movable armature 9 (ie, the upper electromagnet 8 movable armature 9) and and therefore due to unavoidable assembly tolerances. The upper fixed armature 12 together with the extension portion 14 (as already mentioned above, the upper fixed armature 12 is pre-welded to the extension portion 14 by the annular weld 28) to compensate for the support body 4 Inserted into and collided with the upper movable armature 9 and then correlated with the desired axial stroke of the upper movable armature 9 and compensated for shrinkage after welding. A distance away from the upper movable armature 9 (in particular, this distance can be greater than or less than the desired axial stroke to accommodate post-welding shrinkage). It is pulled in the axial direction. Finally, the extension portion 14 is secured to its final position by an annular weld 29 that constrains the extension portion 14 (integral with the upper fixed armature 12) to the support body 4.

In a preferred embodiment shown in the accompanying drawings, a portion of the support body 4 and a portion of the extension portion 14 are covered with a plastic coating 32, and the plastic coating 32 is overmolded. In addition, it functions to protect a part of the support main body 4 and a part of the extension portion 14 from external causes.

In a preferred embodiment shown in the accompanying drawings, the extension portion 14 is also used to connect the fuel injection device 1 to the pressurized fuel supply pipe. For this purpose, the upper portion of the extension portion 14 is threaded so that it is connected to the pressurized fuel supply pipe by screwing.

In FIGS. 5 and 6, the sealing element 21 is mechanically attached to the support body 4 by an annular weld 33 formed in the area of the lower end of the support body 4 and starting from the lower wall of the support body 4. Being restrained. The annular weld 33 is axially arranged (ie, parallel to the vertical line 2), and therefore the annular weld 33 is along the axial direction (ie, relative to the vertical line 2). Extends between the support body 4 and the extension portion 14). The annular weld 33 is made under ideal conditions (ie, on the outside of the support body 4) and between materials with high mechanical durability (sealing element 21 and support body). Since both of 4 are made of steel with high mechanical performance), the annular weld 33 has good mechanical durability. Since the annular weld 33 is subject to a large mechanical stress, it is important that the annular weld 33 has high mechanical durability. On the one hand, the annular weld 33 must ensure the sealing below the support body 4, and therefore the annular weld 33 must withstand the hydraulic stress created by the pressure of the fuel. And, on the other hand, the annular weld 33 is located inside the cylinder and therefore suffers from all the mechanical stresses of the combustion cycle.

In FIGS. 5 and 6, the support body 4 has an annular recess 34, which is obtained starting from the inner surface of the support body 4 (ie, facing the sealing element 21) and annular. It is located (immediately) above the weld 33 (ie, above the root of the annular weld 33). The annular recess 34 is located above the annular weld 33 at a very short distance from the annular weld 33. Basically, the starting point of the annular recess 34 is adjacent to (ie, flush with) the end of the annular weld 33 (ie, the base of the annular weld 33). Alternatively, as an alternative, the annular recess 34 can further partially overlap the annular weld 33 (ie, the root of the annular weld 33). In a preferred non-limiting embodiment, the annular recess 34 has a semi-circular shape in its cross-sectional view. Further, in a preferred non-limiting embodiment, the annular recess 34 has an axial length equal to or shorter than three times the axial length of the annular weld 33. The annular recess 34 serves to protect the root of the annular weld 33 from mechanical stress. Naturally, the mechanical stress cannot pass through the empty annular recess 30, and therefore this mechanical stress travels from the support body 4 to the extension portion 14 through the annular recess 34. It passes through and disperses relatively far from the root of the annular weld 33. In other words, the annular recess 34 allows the root of the annular weld 33 (tension concentration area) to be released from tension and that the root of the annular weld 29 has a more uniform stress distribution in the weld area. To. In summary, the presence of the annular recess 34 causes a crack or crack in the root area of the annular weld 33 (the most vulnerable area and therefore the area most at risk of breakage in the annular weld 33). It is possible to greatly reduce the likelihood of rift formation and, in addition, allow the welded area to act in a more uniform and dispersed manner.

The fuel injection device 1 described above has many advantages.

First of all, in the fuel injection device 1 described above, even when the fuel injection device 1 operates at a high fuel supply pressure (higher than 70-80Mpa), within the area of the annular welds 28, 29, 30. Alternatively, the frequency of failures caused by cracks in the support body 4 or other types of structural defects in the vicinity thereof is low.

Further, the fuel injection device 1 described above has a difference that is inexpensive, easily manufactured, and easily generated as compared with a known similar fuel injection device.

The fuel injection device 1 described above is arbitrary in an internal combustion engine operated by an Otto cycle (that is, by controlled ignition of the mixture) or by a diesel cycle (that is, by spontaneous combustion of the mixture). It must be pointed out that it can be used for the injection of types of fuel.

1 Fuel injection device 2 Vertical line 3 Injection port 4 Support body 5 Supply conduit 6 Electromagnetic actuator 7 Injection valve 8 Electromagnet 9 Movable armature 10 Closed spring 12 Fixed armature

Claims (13)

The fuel injection device (1)
Injection port (3) and
An injection valve (7) provided with a movable plunger (19) to regulate the flow of fuel through the injection port (3).
An electromagnetic actuator (6) for moving the movable plunger (19) between a closed position and an open position of the injection valve (7), the at least one including a first coil (11). An electromagnetic actuator (6) including a first electromagnet (8), a first fixed armature (12), and a first movable armature (9) mechanically connected to the movable plunger (19). ,
A closing spring (10) that pushes the movable plunger (19) toward the closing position,
A support body (4) having a tubular shape, wherein the first fixed armature (12) and the first movable armature (9) are generally arranged inside the support body (4). As described above, the support body (4) including the central conduit (5) that accommodates the first fixed armature (12) and the first movable armature (9) as a whole.
The extension portion (14), said on the first fixed armature (12), such that the lower wall of the extension portion (14) is in contact with the upper wall of the first fixed armature (12). Partially disposed inside the support body (4), before the first fixed armature (12) and the extension portion (14) are inserted together into the support body (4). the has is and independently separated from the first fixed armature (12), said support body (4) in extension which is mechanically restrained by the first annular weld (29) (14) In the fuel injection device (1) provided with
The support body (4) has a first annular recess (30), and the first annular recess (30) is obtained in a form starting from the inner surface of the support body (4), and the first annular recess (30) is obtained. A fuel injection device (1), which is arranged below the annular weld (29). The start point of the first annular recess (30) is adjacent to the end of the first annular weld (29), or the first annular recess (30) is the first annular weld (29). The fuel injection device (1) according to claim 1, which partially overlaps (1). The fuel injection device (1) according to claim 1 or 2, wherein the first annular recess (30) has a semicircular shape in the cross-sectional view thereof. The extension portion (14) has a second annular recess (31), the second annular recess (31) is obtained in a form starting from the outer surface of the extension portion (14), and the first. The fuel injection device (1) according to any one of claims 1 to 3, which is arranged above the annular welded portion (29) of 1. The fuel injection device (1) according to claim 4, wherein the second annular recess (31) is arranged in the vicinity of the first annular weld (29). The fuel injection device (1) according to claim 4 or 5, wherein the second annular recess (31) has a rectangular shape in the cross-sectional view thereof. The first annular weld (29) is formed in the area of the upper end portion of the support body (4), and any one of claims 1 to 6 starting from the upper wall of the support body (4). The fuel injection device (1) according to claim 1. The first fixed armature (12) is mechanically placed at a fixed position inside the support body by a second annular weld (28) that constrains the first fixed armature (12) to the extension portion (14). The fuel injection device (1) according to any one of claims 1 to 7, which is fixed to the fuel injection device (1). The first fixed armature (12) is not directly mechanically constrained to the support body (4), and the first fixed armature (12) is mechanically attached to the extension portion (14). The fuel injection device (1) according to claim 8, wherein the fuel injection device (1) is kept stationary inside the support main body (4) only by the second annular welded portion (28) that is constrained. The extension portion (14) has a central hole (15), which allows fuel to flow toward the injection port (3) and provides the closing spring (10). Partially housed
A striker body (16) is fitted in a fixed position inside the central hole (15) of the extension portion (14), and the striker body (16) has a cylindrical tubular shape. The fuel according to any one of claims 1 to 9, which is designed to keep the closing spring (10) pressed against the first movable armature (9). Injection device (1). The electromagnetic actuator (6) includes a second electromagnet (8) arranged below the first electromagnet (8) and having a second coil (11), and a second fixed armature (12). ) And a second movable armature (9) mechanically connected to the movable plunger (19).
The first movable armature (9) has a usable stroke shorter than the usable stroke of the second movable armature (9).
The second fixed armature (12) is mechanically fixed to a fixed position inside the support main body (4) by a third welded portion (27), and the third welded portion (27). Claims 1 to 10, wherein the second fixed armature (12) is directly constrained to the support body (4) and extends inward from the outside of the support body along the radial direction. The fuel injection device (1). The support body (4) has a counterbore, the counterbore such that the third weld (27) can be formed within the second fixed armature (12). The fuel injection device (1) according to claim 11, which is obtained in the area of the second fixed armature (12). The fuel injection device (1) according to any one of claims 1 to 12, wherein the extension portion (14) has an upper threaded portion for connection to a supply pipe for pressurized fuel. ..