JP3996109B2 - Fuel injection valve - Google Patents

Description

  The present invention relates to a fuel injection valve using an electromagnetic actuator for injecting and supplying fuel into a cylinder of an internal combustion engine.

  As a fuel injection valve for directly injecting and supplying fuel into a cylinder of an internal combustion engine as used in a common rail system, for example, a type of fuel injection valve disclosed in Patent Document 1 is known. This fuel injection valve causes the control chamber in the injection valve body to communicate with the fuel low pressure portion by energizing the electromagnetic actuator, thereby removing the back pressure of the valve piston and lifting the nozzle needle to start fuel injection. After a predetermined time has elapsed, the electromagnetic actuator is de-energized to release the communication state between the control chamber and the fuel low pressure part, and a predetermined back pressure is applied to the valve piston to depress the nozzle needle, thereby fuel injection Is configured to terminate.

In the electromagnetic actuator for fuel injection control used in the fuel injection valve having the above-described configuration, the valve body for controlling the communication state between the control chamber and the fuel low-pressure portion in accordance with on / off of energization It is necessary that the lift amount of the armature plate for driving is a predetermined value. This is because when the lift amount of the armature plate changes, the lift amount (stroke amount) of the valve body also changes, causing a change in the fuel injection amount, and the performance of the internal combustion engine changes. This is because deterioration will occur. For this reason, conventionally, the error in the lift amount of the armature plate is managed to be within a few μm, for example.
JP-A-7-310621

  By the way, in this type of fuel injection valve, the valve body is housed in the injector housing, and the valve body is fixed by tightening a nut screwed to the injector housing. In this fixing, a nut with a thread groove on the outer peripheral surface is screwed into a thread groove on the inner peripheral surface of the recess of the injector housing that houses the valve body, and the head of the valve body is brought into the recess by tightening the nut. I'm going to hold it down. For this reason, there exists a tendency for the deformation | transformation by tightening of a nut to arise around the recessed part of an injector housing.

  However, the upper end surface of the recess is overlaid with an armature holder, an armature lift adjustment shim, and the like, and serves as a reference surface for setting the lift amount of the armature plate. Therefore, there has been a problem that the level of the upper end surface is deviated from the planned level due to deformation around the concave portion generated when the nut is tightened, and the lift amount of the armature plate is deviated from the predetermined value accordingly.

  The objective of this invention is providing the fuel injection valve which can solve the above-mentioned problem in a prior art.

  In order to solve the above problems, according to the invention of claim 1, the valve body accommodated in the recess of the injector housing is fastened and fixed by a nut screwed to the inner peripheral surface of the recess, In a fuel injection valve in which an electromagnetic actuator cooperating with the valve body is assembled on an upper end surface, at least one protrusion for providing an assembly reference surface of the electromagnetic actuator is provided on the upper end surface of the recess. A fuel injection valve is proposed.

  By providing a protrusion for giving the assembly reference surface, it is possible to avoid the influence of the deformation of the upper end surface of the recess due to the tightening of the nut on the assembly reference surface, so that the deformation due to the tightening of the nut occurs. However, the relative positional relationship between the electromagnetic actuator and the valve body can be accurately set to the required positional relationship.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a sectional view showing an example of an embodiment of a fuel injection valve according to the present invention. Reference numeral 1 denotes a fuel injection valve used in a common rail system for injecting and supplying fuel to a diesel internal combustion engine. The fuel injection valve 1 is assembled in a cylinder of a diesel internal combustion engine (not shown), and is for directly injecting and supplying a required amount of high-pressure fuel supplied from a common rail (not shown) into the cylinder at a required timing. The nozzle 3 is fixed to the tip of 2 by a retaining nut 4, and an electromagnetic actuator 5 is provided at the rear end of the nozzle holder 2.

  The nozzle holder 2 has an injector housing 22 in which a guide hole 21 is formed in its axial direction, and a valve piston 23 is disposed in the guide hole 21 so as to be movable in the axial direction by the guide hole 21. . A spring chamber 25 of the injector housing 22 accommodates a spring spring 25, and a nozzle needle 32 (described later) is elastically biased toward the nozzle hole 35 by the spring spring 25. What is indicated by reference numeral 26 is a passage provided in the injector housing 22 for supplying high pressure fuel from a common rail (not shown) to the nozzle 3.

  The nozzle 3 has a nozzle body 31 and a nozzle needle 32, and the nozzle needle 32 is supported and guided so as to be movable in the axial direction by a through-hole 33 formed coaxially in the nozzle body 31. The tip 32A of the nozzle needle 32 is aligned with the through hole 33 and extends into a cylinder 34 provided in the nozzle body 31, and the tip of the nozzle needle 32 functions as a valve body for opening and closing the nozzle hole 35. It has a configuration.

  Therefore, when the nozzle needle 32 is held at a position where the nozzle hole 35 is closed, fuel is not injected from the fuel injection valve 1. On the other hand, when the nozzle needle 32 is retracted and the nozzle needle 32 is held at a position where the nozzle hole 35 is opened, fuel is injected from the fuel injection valve 1.

  In the nozzle body 31, an oil sump 37 is formed in which high-pressure fuel from the passage 26 is introduced through the passage 36 and holds the high-pressure fuel. On the other hand, the nozzle needle 32 is formed with a tapered portion 38 for applying a force in a direction in which the nozzle needle 32 is separated from the injection hole 35 by the pressure of the high-pressure fuel in the oil sump 37.

  A valve body 24 constituting a drive mechanism for driving the nozzle 3 in combination with the valve piston 23 is accommodated in the rear end portion of the injector housing 22. The valve body 24 is formed by integrally forming a lower cylindrical portion 24 </ b> A and an upper flange portion 24 </ b> B, and is accommodated in a recess 27 for accommodating the valve body 24 provided at the rear end portion of the injector housing 22.

  The concave portion 27 is a hole portion having a shape substantially corresponding to the outer shape of the valve body 24, communicates with the guide hole 21 at the bottom portion of the concave portion 27, and the upper end portion 23A of the valve piston 23 enters the lower cylindrical portion 24A. . The space between the outer peripheral surface of the valve piston 23 and the inner peripheral surface of the lower cylindrical portion 24A is in an oil-tight state.

  In order to fix the valve body 24 at a predetermined position in the recess 27, a nut 28 is screwed into the opening side of the recess 27. Here, the screw groove 28a formed on the outer peripheral surface of the nut 28 is engaged with the screw groove 27a on the inner peripheral surface of the opening side of the concave portion 27, and the nut 28 is tightened toward the valve body 24, whereby the valve body 24 is inserted into the injector. It is fixed to the housing 22.

  The valve piston 23 and the valve body 24 are assembled to the injector housing 22 as described above, and a drain chamber 41, a radial supply conduction path 43, and an axial drain conduction path 44 are disposed at the rear end of the injector housing 22. A communication chamber 45 that is in communication is formed. The supply conduction path 43 communicates with the intake tool 47 via a radial conduction path 46 in the injector housing 22, and the bottom of the control chamber 45 is formed on the upper surface of the valve piston 23.

  The armature bolt 51 of the electromagnetic actuator 5 is fixed with a ball 52 that functions as a valve body that constitutes a valve mechanism that controls the communication state between the control chamber 45 and the fuel low pressure portion. The armature bolt 51 is elastically urged toward the drain conduction path 44 by the force of a valve spring (not shown), and the ball 52 is pressed against the open end of the drain conduction path 44 to block the drain conduction path 44. ing.

  Therefore, when the electromagnetic actuator 5 is not energized, the open end of the drain conduction path 44 is blocked by the ball 52, so that the control chamber 45 is filled with high-pressure fuel. The nozzle needle 32 closes the nozzle hole 35 and fuel injection is not performed. When the electromagnetic actuator 5 is energized, the ball 52 is separated from the open end of the drain conduction path 44, the high-pressure fuel in the control chamber 45 escapes to the fuel low-pressure part, and the pressure in the control chamber 45 drops, so fuel injection is performed. Is called. When the electromagnetic actuator 5 is de-energized, the nozzle needle 32 is returned to the position where the nozzle hole 35 is closed again, so that fuel injection ends.

  FIG. 2 is a cross-sectional view of a main part for illustrating the assembled state of the electromagnetic actuator 5 at the rear end portion of the injector housing 22.

  In FIG. 2, 53 is an armature plate fixed to the armature bolt 51, 54 is an armature guide for guiding the armature bolt 51, 55 is an electromagnetic unit combined with the armature plate 53, 56 is a shim for armature lift adjustment, These parts are assembled on the upper end surface 27A of the recess 27 of the injector housing 22 to constitute the electromagnetic actuator 5.

  On the upper end surface 27 </ b> A of the recess 27, a protrusion 70 is provided for providing an assembly reference surface for assembling the electromagnetic actuator 5. Here, the protrusion 70 is formed as an annular protrusion provided on the upper end surface 27A. The protrusion 70 is formed integrally with the injector housing 22, and the upper surface 71 of the protrusion 70 is an assembly reference surface.

  That is, an armature guide 54, an armature lift adjusting shim 56, and an electromagnetic unit 55 are stacked and assembled in this order in the concave portion 27 at the rear end of the injector housing 22, and the lowermost armature guide 54 is assembled. The level of the bottom surface 54 </ b> A matches the upper surface 71 of the protrusion 70.

  The armature plate 53 is spring-biased in the direction of the nozzle holder 2 by an armature spring (not shown). The armature plate 53 overcomes this spring-biasing force by an electromagnetic attractive force generated by energizing the electromagnetic unit 55, and stops the electromagnetic unit 55. It moves until it contacts the surface 55A.

  The armature lift adjusting shim 56 is a member for adjusting the level of the stopper surface 55 </ b> A to a predetermined level with respect to the upper surface 71 of the protrusion 70. By adjusting the thickness of the shim 56 for adjusting the armature lift, the maximum lift position of the armature plate 53 relative to the valve body 24 can be set.

  The protrusion 70 that provides the assembly reference surface (upper surface 71) used to set the maximum lift position of the armature plate 53 is the upper end surface 27A of the recess 27, as shown in FIG. A distance from the end edge 27B is provided. Therefore, even if the tightening stress acts near the inner peripheral edge 27B of the recess 27 by tightening the nut 28, and the deformation occurs near the inner peripheral edge 27B, the protrusion 70 may be affected by this deformation. Absent.

  Therefore, the protrusion 70 is not deformed by tightening the nut 28, and the upper surface 71 of the protrusion 70 can give a predetermined assembly reference surface to the bottom surface 54 </ b> A of the armature guide 54. As a result, the armature guide 54, the armature lift adjusting shim 56, and the electromagnetic unit 55 are simply stacked and assembled in this order in the recess 27, so that the maximum lift level of the armature plate 53 can be set to a predetermined value.

  In the above-described embodiment, the case where only one protrusion 70 that is an annular protrusion is provided has been described. However, the protrusion that provides the assembly reference surface is not limited to this, but by tightening the nut 28. Any other configuration can be used as long as it is configured to avoid the influence of the deformation of the upper end surface 27A of the recess 27 on the assembly reference surface.

  For example, it is good also as a stepping stone form which divided | segmented the protrusion 70 into two or arbitrary numbers. Alternatively, in order to avoid the influence of the deformation of the upper end surface 27A of the concave portion 27 due to the tightening of the nut 28 on the assembly reference surface, a cylindrical shape having a plane that gives the assembly reference surface, a prismatic shape, or other appropriate A member that protrudes from the upper end surface 27A of the concave portion 27 may be provided on the upper end surface 27A. In any case, it is preferable that the member having a flat surface that provides the assembly reference surface is provided at a distance from the inner peripheral edge 27B of the upper end surface 27A.

Sectional drawing which shows an example of embodiment of the fuel injection valve by this invention. The principal part sectional view for showing the attachment state of the electromagnetic actuator in the rear end part of an injector housing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel injection valve 2 Nozzle holder 3 Nozzle 5 Electromagnetic actuator 22 Injector housing 23 Valve piston 24 Valve body 27 Recessed part 27A Upper end surface 28 Nut 53 Armature plate 55 Electromagnetic unit 55A Stopper surface 56 Shim 70 for armature lift adjustment Projection 71 Upper surface

Claims (1)

The valve body housed in the recess of the injector housing is fastened and fixed by a nut screwed onto the inner peripheral surface of the recess, and an electromagnetic actuator that cooperates with the valve body is assembled on the upper end surface of the recess. In the fuel injection valve consisting of
The fuel injection valve according to claim 1, wherein at least one protrusion for providing an assembly reference surface of the electromagnetic actuator is provided on an upper end surface of the recess.

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