EP1530680A1

EP1530680A1 - Method for the production of a module with a moving insert for an injection valve and injection valve

Info

Publication number: EP1530680A1
Application number: EP03762417A
Authority: EP
Inventors: Heinz Lixl
Original assignee: Siemens AG
Current assignee: Continental Automotive GmbH
Priority date: 2002-07-02
Filing date: 2003-06-24
Publication date: 2005-05-18
Anticipated expiration: 2023-06-24
Also published as: EP1518050A1; WO2004005704A1; EP1518050B1; WO2004005699A1; EP1530680B1

Abstract

A method for the production of a module with a moving insert for an injection valve is disclosed, whereby the insert is arranged such as to move within the module and the module and the insert comprise contact surfaces on a common side. According to the invention, the insert and/or the module are pre-tensioned and whilst in the pre-tensioned state the contact surfaces of the module and the insert are ground to a plane. By applying the pre-tensioning, a tensioning is simulated during the plane grinding which occurs during application of the module in an injection valve. A precise matching of the end surfaces to each other can thus be achieved.

Description

description

Method of manufacturing a module with a movable insert for an injector and injector

The invention relates to a method for producing a module with a movable insert for an injection valve according to the preamble of patent claim 1 and an injection valve with a module and an insert according to the preamble of patent claim 7.

Depending on the embodiment of the injection valve, an injection valve has a module with a movable insert. The movable insert is used, for example, to transmit an actuator deflection to an injection needle. If piezoelectric actuators are used, precise adjustment of the movable insert with respect to an actuator is required, since piezoelectric actuators can only achieve a small movement stroke and, on the other hand, due to different thermal expansion coefficients between an injection valve housing and the piezoelectric actuator, a defined idle stroke between - See the piezoelectric actuator and an actuator to be controlled must be observed.

Modules with movable inserts, which are clamped in a housing of the injection valve, are used to construct an injection valve. For a precise setting, both the module and the movable insert have a flat surface. For example, the module rests on another module and the movable insert is in turn controlled by an actuator. In both cases, a precise definition of the height of the module or the length of the movable insert is advantageous.

From DE 19 822 503 Cl a control valve for a fuel injection valve is known which is a module with a valve body having. The valve body has a surface which is assigned to a tappet which is operatively connected to a piezoelectric actuator. An idle stroke is preset between the end of the tappet and the closing member, which is formed in the closed position of the valve body and when the piezoelectric actuator is not energized. For a precise adjustment of the idle stroke, it is necessary to precisely define the area of the valve body.

The object of the invention is to provide a method for producing a module with a movable insert for an injection valve, the insert and the module having contact sides which are worked flat in a fixed relationship to one another.

The object of the invention is achieved by the method according to the feature of claim 1. An essential advantage of the method according to the invention is that the module and the insert are held in a form-fitting manner with one another, • that the module and / or the insert are subjected to a pretensioning force and that the module and the insert are applied while the pretensioning force is being applied a plan side to be worked on.

By introducing the pretensioning force, a pretensioning force acting on the module and / or the insert during actual operation of the injection valve is simulated during face grinding. A determination of the contact sides of the module in relation to the contact side of the insert is thus adapted to the clamping forces prevailing in the injection valve

In a preferred application of the procedure according to the invention is as a module Rens and an actuator housing as an insert a AK- ^■ gate, in particular a piezoelectric actuator, used with a bottom plate. The actuator is positively connected to the actuator housing in an upper area. In the top A prestressing force is introduced in the region of the actuator housing, while the actuator housing is clamped in a holding bearing in an opposite region. While the pretensioning force is present, the actuator housing is machined, in particular ground, in the area of a bearing surface in which the base plate is arranged. In addition, when the pretensioning force is present, the base plate with the contact surface is also machined, in particular ground flat. In this way, a uniform level is obtained for the bearing surfaces of the actuator housing and the base plate under prestress.

The pretensioning force is preferably at least in the range of the pretensioning force with which an injection valve is clamped in a cylinder head. In this way, it is achieved that the underside of the base plate lies on the same level with the support surface of the actuator housing in relation to the clamping situation. In this way, an improved adjustment of the base plate with respect to further actuators is possible in an injection valve.

An idle stroke distance is preferably also simulated with the preload force, which must be arranged so that the base plate is set back in relation to the bearing surface of the actuator housing. Thus, by means of the grinding method according to the invention, the required idle stroke distance for the base plate can be set at the same time by introducing a suitable pretensioning force. Additional adjustment, for example with shims, is therefore not necessary.

In a further preferred embodiment, the method according to the invention is applied to a valve plate as a module and a closing element as an insert. The closing element is pressed against a sealing seat of the valve plate, a pin part of the closing element protruding through a drain opening of the valve plate. The closing element is pressed against the sealing seat with a pre-tensioning force. Gender biasing force the pin part and the surface of the valve plate surrounding the pin part are worked to a height, in particular ground flat. The situation prevailing in the injection valve is simulated again by the introduction of the pretensioning force on the closing member. In the installed state, the closing member is assigned to a control chamber in the injection valve, in which a predetermined maximum control pressure prevails. The maximum control pressure exerts a prestressing force on the closing element. Since the pretensioning force acting on the closing element in real operation was already taken into account when grinding the valve plate and the pin part of the closing element, the top of the valve plate and the surface of the pin part are in use in the injection valve on one level. This results in an optimal adjustment of the surface of the pin part in relation to the surface of the valve plate for operation in the injection valve.

An injection valve, which has a module with an insert, which were produced in accordance with the method according to claim 1, have a precise adjustment of contact surfaces of the module and the insert relative to one another, which is determined for use in the injection valve. This provides an improved adjustment.

The invention is explained in more detail below on the basis of an exemplary embodiment. Show it

1 schematically shows a structure of an injection valve,

Fig. 2 shows a cross section through a valve plate with a

Closing member,

Fig. 3 shows a cross section through an actuator housing with a piezoelectric actuator and

Fig. 4 is an enlarged view of a cross section through the valve plate and the bottom plate.

Fig. 1 shows a cross section through an injection valve with an actuator housing 1, in which an actuator 2 is inserted. The Actuator housing 1 is screwed to a clamping nut 3. The clamping nut 3 clamps a nozzle body 4, a guide plate 11 and a valve plate 5 against the actuator housing 1. The nozzle body 4 rests with an upper end surface on a lower end surface of the guide plate 11. The guide plate 11 in turn abuts an upper end surface on a lower end surface of the valve plate 5. The valve plate 5 in turn rests with an upper end surface on a lower end surface of the actuator housing 1.

0 The actuator 2 is clamped between a base plate 7 and a head plate 9 via a spring sleeve 8. The top plate 9 is firmly connected to the actuator housing 1. The base plate 7 is movably arranged in relation to the actuator housing 1. The base plate 7 has a control mandrel 16 which is assigned to a pin part 23 of a closing element 6. The closing member 6 is arranged in a drain opening 17 of the valve plate 5. The drain opening 17 is essentially cylindrical and tapers in the upper area in a. a conical shape. The conical area of the drain opening 17 0 represents a sealing seat for the closing element 6. Between the closing element 6 and the valve plate 5 there is arranged a plate spring 25 which prestresses the closing element 6 on the associated sealing seat. The closing member 6 is essentially cylindrical in shape and also tapers 5 in the upper region via a conical shape into the pin part 23. The drain opening 17 is connected to an inlet channel 10 via an inlet bore 18 which is introduced into the guide plate 11 is guided in the actuator housing 1 and represents a fuel connection. Between the inflow

30 bore 18 and the drain opening 17, an inlet throttle 19 is arranged. The drain opening 17 is in hydraulic connection with a control chamber 20 which is introduced into the guide plate 11 and is delimited by a movably mounted control piston 21. The control piston 21 is operatively connected

55 fertilizer with a valve needle 12, the tip of which is assigned to an injection opening 14. Around the injection opening 14 is a Sealing seat designed for the tip of the valve needle 12. A fuel chamber 13 is formed between the valve needle 12 and the nozzle body 4 and is also connected to the inlet channel 10. For this purpose, corresponding fuel bores are made in the nozzle body 4, in the guide plate 11 and in the valve plate 5.

The injection valve works in the following way: in the non-activated state of the piezoelectric actuator 2, the control pin 16 is a fixed idle stroke distance from the stiff part of the closing element 6. The inlet anal 10 is connected to a fuel reservoir that holds fuel at a high pressure. Consequently, there is fuel at high pressure in the fuel chamber 13, the control chamber 20 and the drain opening 17. Due to the high fuel pressure, the closing member 6 is pressed into the associated sealing seat and closes the drain opening 17. At the same time, the valve needle 12 is closed by the high fuel pressure, which prevails in the control chamber 20, pressed downward over the control coils 21 onto the sealing seat of the injection opening 14. As a result, the injection opening 14 is closed and there is no injection.

If the piezoelectric actuator 2 is now energized, the piezoelectric actuator 2 expands and thereby presses the base plate 7 down and thus the control pin 16 against the pin part 23 of the 'closing member 6. As a result, this

Closing member 6 is lifted from the associated sealing seat. As a result, the drain opening 17 is opened and fuel flows out of the control chamber 20. The fuel pressure in the control chamber 20 thus drops, since less fuel flows in via the inlet throttle 19 than flows out via the outlet opening 17. Since the valve needle 12 has a pressure shoulder 15 in the area of the fuel chamber 13, the high fuel pressure prevailing in the fuel chamber 13 lifts the valve needle 12 from the sealing seat of the injection opening 14. Thus the Spray opening 14 is opened and fuel is dispensed from the fuel chamber 13 via the injection opening 14.

For a precise functioning of the injection valve, it is necessary to set the idle stroke distance between the control pin 16 and the closing element 6 precisely. A precise setting of the idle stroke distance is essentially determined by the relative arrangement of the lower contact surface of the actuator housing 1 to the lower contact surface of the control pin 16 and by the relative position of the upper contact surface of the valve plate 5 to the upper contact surface of the pin part 23 of the closing element 6 when the drain opening 17 is closed.

Fig. 2 shows a cross section through a valve plate 5 and a closing member 6, wherein the valve plate 5 is pressed with an upper contact surface against a grinding plate 22. In addition, the closing member 6 is pressed against the sealing seat with an additional prestressing force F. As a result, the pin part 23 is pushed out further over the contact surface of the valve plate 5. The grinding plate 22 grinds the upper contact surface of the valve plate 5 and the upper contact surface of the pin part 23 flat on one level. Instead of a grinding process, other machining methods can also be selected with which a uniform height between the pin part 23 and the valve plate 5 is set. Due to the prestressing force additionally applied to the closing member 6, the pin part 23 is ground down shorter than would be the case without the additional prestressing force. The additional pretensioning force is preferably selected in such a way that the pretensioning force is simulated which acts on the closing element 6 when the drain opening 17 is closed. In this way, the end face of the pin part 23 becomes precise in one

Level aligned with the end surface of the valve plate 5.

FIG. 3 shows a cross section through the actuator housing 1 and the actuator 2 with the base plate 7. The base plate 7 has the control mandrel 16. For precise adjustment of the Lying surface of the control pin 16, with which the control pin 16 comes into contact with the pin part 23, and the contact surface of the actuator housing 1, with which the actuator housing 1 rests on the valve plate 5, the actuator housing 1 is in the area of the contact surface against a stop 24 clamped. In addition, the actuator housing 1 is biased against the stop 24 with a defined biasing force. In this way, the actuator housing 1 is preloaded with respect to the actuator 2 and the base plate 7. The pretensioning force is preferably selected in such a way that the pretensioning force corresponds to the pretensioning force which is exerted on the actuator housing 1 when the injection valve is clamped in a cylinder head. An additional prestressing force is preferably exerted on the actuator housing 1, which corresponds to a displacement of the base plate 7 with respect to the actuator housing 1 by a desired idle stroke between the contact surface of the control pin 16 and the contact surface of the pin part 23. Depending on the circumstances, somewhat varied preload forces can also be used.

If, for example, the injection valve is not clamped, then only a preload force that corresponds to the idle stroke is selected. If the idle stroke is set using shims, the preload is selected according to the clamping force with which the injector is clamped in the cylinder head using clamps. The forces are in the range of 3 to 12 kN for clamping in the cylinder head and in the range of 0.5 to 5 kN for setting the idle stroke.

During the introduction of the pretensioning force, the contact surfaces of the actuator housing 1 and the contact surface of the control mandrel 16 are brought to one level, preferably ground and finished with a grinding plate 22. Experiments have shown that when a preload force of 100 N is applied, the idle stroke changes during housing manufacture by +0.25 μm. Through the described procedure a precise setting of the desired position of the control mandrel 16 in relation to the actuator housing 1 is achieved.

Fig. 4 shows an enlarged view of the fit of the actuator housing 1, which rests with a lower contact surface on an upper contact surface of the valve plate 5. In addition, the control pin 16 is assigned to the pin part 23 of the closing element 6. An idle stroke is formed between the contact surface of the pin part 23 and the contact surface of the control mandrel 16. If the injection valve is not clamped in the cylinder head, the idle stroke is significantly greater than the desired idle stroke. A desired idle stroke is in the range of preferably 0.5 to 5 μm. However, if the injection valve is clamped in the cylinder head, the actuator housing 1 is preloaded according to FIG. 3 and the idle stroke between the pin part 23 and the control pin 16 is thus reduced. However, the optimum idle stroke has not yet been achieved, since the closing member 6 is not yet pressed against the sealing seat by the fuel pressure prevailing in the control chamber. If the closing member is pressed against the sealing seat by the fuel pressure, the optimal and desired idle stroke is finally set.

The method according to the invention was explained using selected examples for a module and an insert, the method according to the invention being able to be used for every module and every insert in which it is advantageous to produce contact surfaces of the insert and the module precisely on one another taking into account clamping forces.

The injection valve according to the invention is not limited to the injection valve type according to FIG. 1, but rather can be used with any type of injection valve type.

Claims

claims

1. Method for machining contact surfaces of a module (1, 5) and an associated insert (2, 6) of an injection valve, the module (1, 5) and the insert (2, 6) having contact surfaces arranged on one side are characterized in that the module (1, 5) and the insert (2, 6) are positively held together, that a preload force is applied to the module (1, 5) and / or the insert (2, 6) that the contact surfaces on the same side are worked to the same height under the pre-tensioning force.

2. The method according to claim 1, characterized in that the module is designed as an actuator housing (1) and the use as an actuator (2) with a base plate (7), that the actuator (2) in a first end region with the actuator. Housing (1) is connected, ^■ that the base plate (7) is arranged in the region of an actuator housing opening, that the actuator (2) is arranged in the actuator housing (1), that the actuator (2) is variable in length, so that the position of the Base plate (7) can be moved relative to a contact surface which surrounds the actuator housing opening, that a pretensioning force is introduced into the actuator housing (1) in the longitudinal direction of the actuator (2), and that when the pretensioning force is applied, the base plate (7) and the The contact surface of the actuator housing (1) can be processed on one level.

3. The method according to claim 2, characterized in that the biasing force is at least in the range of the clamping force with which an injection valve is clamped in a cylinder head of an internal combustion engine.

4. The method according to any one of claims 2 or 3, characterized in that the pretensioning force is selected or increased so that the base plate (7) is displaced outwards by an idle stroke with respect to the bearing surface of the actuator housing (1).

5. The method according to claim 1, characterized in that as a module, a valve plate (5) and as. Use a closing member (6) that the closing member (6) has a pin part (23) which projects into an outlet opening (17) which is formed in the valve plate (5) in such a way that a sealing seat surrounds the outlet opening (17) that the closing member is pressed against the sealing seat with a pretension, that when the pretensioning force is applied, the pin part (23) and the surface of the valve plate (5) which surrounds the drain opening are worked to one height.

6 "Method according to claim 5, characterized in that the pretensioning force is selected in accordance with the magnitude of the pretensioning force which, in operation in the injection valve, acts on the closing element (6) in the closing position in which the closing element (6) lies against the sealing seat ,

7. Injector with a module (1, 5) and an insert (2, 6), which were processed according to claim 1.