JP4072172B2 - Fuel injection valve - Google Patents

Description

【Technical field】
[0001]
The present invention relates to a fuel injection valve according to the superordinate concept of claim 1.
[0002]
EP-A-0477400 discloses an apparatus for adaptive mechanical error compensation acting in the stroke direction for a displacement actuator of a piezoelectric actuator for a fuel injection valve. In this case, the stroke of the actuator is transmitted through the hydraulic chamber. The hydraulic chamber has a predetermined leak portion having a predetermined leak rate. The stroke of the actuator is introduced into the hydraulic chamber via the master piston and transmitted to the element to be driven via the slave piston. This element is, for example, a valve needle of a fuel injection valve.
[0003]
A slave piston is guided in the master cylinder. The slave piston also closes the master cylinder, thereby forming a hydraulic chamber. A spring is disposed in the hydraulic chamber. This spring presses the master cylinder and the slave piston away from each other. When the actuator transmits a stroke motion to the master cylinder, the stroke motion is transmitted to the slave piston by the pressure of the hydraulic fluid in the hydraulic chamber. This is because the hydraulic fluid in the hydraulic chamber is not compressed and only a small portion of the hydraulic fluid escapes from the ring gap during a short stroke. In the idle phase when the actuator does not apply pressure to the master cylinder, the slave piston is pushed out of the cylinder by the spring, and the hydraulic medium enters the hydraulic chamber through the ring gap due to the resulting non-pressure and refills the hydraulic chamber. As a result, the hydraulic coupler is automatically adjusted to the length extension and to the expansion of the fuel injection valve based on the pressure. The hydraulic medium is sealed by a seal ring.
[0004]
A fuel injection valve for sealing a hydraulic medium with a bellows-like or bellows-like sealing member is also known from the prior art.
[0005]
The disadvantage of this known prior art is that the return force is only loaded by the spring. For example, a change in spring characteristics due to aging greatly affects the return force, so the coupler characteristics are also affected. Furthermore, the constituent size of the spring is increased.
[0006]
On the other hand, in the fuel injection valve according to the present invention having the features of claim 1, the coupler can be manufactured easily and inexpensively, is formed at a small cost, and reliably withstands long-term use. The characteristic has the advantage that it is almost independent of the operating period.
[0007]
The features of the dependent claims result in an advantageous further configuration of the fuel injection valve of claim 1.
[0008]
In a first advantageous configuration, the compensation chamber is connected to the throttle via a transverse hole and / or the compression spring is spirally formed. This makes the coupler particularly easy to form.
[0009]
By forming the first slave section of the slave piston partially limiting the coupler volume by the bottom surface in the shape of a cup, or by guiding the first slave section in the master piston in the axial direction with guide play The coupler is particularly compact and simply inexpensive, by partially enclosing the first slave section in a cup shape with a master piston, or by placing a throttle on the bottom surface of the cup-shaped first slave section can do.
[0010]
In another configuration, the stop has a stop sphere guided with a stop gap in the aperture. This makes it possible to easily configure the throttle, and the compression spring is supported by a surface that limits the coupler volume of the master piston via the throttle ball. This further provides a simple and compact configuration format.
[0011]
A compact and simple flexible section can be fixed by means of a plate-like structure with holes and a sleeve-like structure with axial and radial sections.
[0012]
The fixing of the simple, reliable and particularly airtight flexible section is advantageously done by engaging the end formed in the radial section with a second notch formed in the slave piston and / or axially The end formed in the section is obtained by engaging a notch arranged in the master piston. This is further improved by the notch being formed in a recess, by clamping the end, or by making the end thick.
[0013]
In yet another configuration, the end of the flexible section is bent inward, in which case this end forms a recess. Advantageously, in this case, the end engages the notch in a gas-tight manner. Advantageously, the internal pressure of the compensation chamber is thereby used so that the end of the flexible section is pressed against the notch in a fluid-tight manner by pressure transmission via the hydraulic medium, and thus reliably and continuously sealed.
[0014]
Drawings Embodiments of the invention are shown in the drawings briefly and are described in detail below.
[0015]
FIG. 1 shows a schematic cross-sectional view of a fuel injection valve according to the prior art,
FIG. 2 shows a schematic partial cross-section showing the region of a coupler of a fuel injection valve according to the prior art similar to the fuel injection valve shown in FIG.
FIG. 3 shows an embodiment of a fuel injection valve according to the invention in the area of the coupler,
FIG. 4 shows another embodiment of the fuel injector according to the invention in the area of the flexible section of the coupler.
[0016]
Description of Examples Next, examples of the present invention will be described.
[0017]
Before describing the advantageous configuration of the present invention in detail, the main components of the prior art fuel injector are briefly described with reference to FIGS. 1 and 2 for a better understanding. In this case, the same components are denoted by the same reference numerals in a plurality of drawings.
[0018]
The fuel injection valve 1 shown in FIG. 1 is formed as a fuel injection valve 1 for a fuel injection device of a mixture compression type spark ignition internal combustion engine. The fuel injection valve 1 is particularly suitable for directly injecting fuel into a combustion chamber (not shown) of an internal combustion engine.
[0019]
The fuel injection valve 1 has a casing 2, and a piezoelectric or magnetostrictive actuator 4 having an actuator-coated injection molding portion 3 is disposed in the casing 2. A voltage is supplied to the actuator 4 through an electrical line 5. In the electrical line 5, an electrical connection portion 6 protruding from the casing 2 can be formed. The actuator 4 is supported on the master piston 9 of the hydraulic coupler 7 on the inflow side, and is supported on the actuator head 8 on the outflow side. The hydraulic coupler 7 further includes one slave piston 10, a compression spring 11 that loads the hydraulic coupler 7 with a predetermined preload, and a compensation chamber 12 filled with a hydraulic medium. Yes. The fuel is supplied to the center via the inflow portion 14.
[0020]
A detailed description of the coupler 7 and its function will be described with reference to FIG.
[0021]
An operating body 15 is disposed on the outflow side of the actuator head 8, and this operating body 15 acts on the valve needle 16. The valve needle 16 has a valve closing body 17 at the end on the outflow side. The valve closing body 17 forms a seal seat portion in cooperation with the valve seat surface 18 formed in the nozzle body 19. The return spring 20 loads the valve needle 16 so that the fuel injection valve 1 remains closed when the actuator 4 is not energized. The return spring 20 further serves to return the valve needle 16 after the injection phase.
[0022]
The nozzle body 19 is fixed to the inner casing 22 by a welding seam 21, and the inner casing 22 seals the actuator 4 against fuel. The fuel flows from the supply section 14 between the casing 2 and the inner casing 22 to the seal seat.
[0023]
FIG. 2 shows a coupler 7 formed similar to the coupler 7 shown in FIG.
[0024]
The hydraulic coupler 7 provided on the fuel injection valve 1 is usually designed in part to convert the stroke movement of the actuator 4 into the stroke movement of the valve needle 16, and in part, It is formed in order to compensate for the length change based on the temperature of the actuator 4 and the casing 2. Such compensation is performed by a coupler 7 formed as a two-media coupler as shown in the embodiment. The coupler 7 has a hydraulic medium that does not contact the fuel. In this case, the hydraulic medium fills the compensation chamber 12 and the coupler volume 23 formed between the master piston 9 and the slave piston 10. The coupler volume 23 is connected to the compensation chamber 12 via a diaphragm 24.
[0025]
The compensation chamber 12 is disposed inside and outside the slave piston 10. In this case, both parts are connected to each other by a lateral hole 31, and the part located outside the compensation chamber 12 is made into the fuel flowing through the fuel injection valve 1 by the flexible section 13 formed as a bellows seal member. Sealed against.
[0026]
When the temperature changes, the hydraulic medium between the coupler volume parts 23 is exchanged with that of the compensation chamber 12 via the restriction 24. In this case, the necessary filling pressure is applied via the compression spring 11 arranged in the slave piston 10 in the pressure accumulating chamber 32. The pressure accumulating chamber 32 is disposed between the first closing body 25 and the second closing body 26. In this case, the first closing body 25 has a groove 27 in which a seal ring 28 for sealing the coupler chamber 12 is disposed.
[0027]
For example, the hydraulic medium is filled into the coupler 7 at the time of manufacture via the passage 29. This passage can be closed by a closed sphere 30 fitted with a press, for example.
[0028]
FIG. 3 shows an embodiment of a coupler 7 for a fuel injection valve 1 constructed according to the invention. The slave piston 10 is a cup-shaped first slave section 34 and engages a hollow cylindrical master piston 9 closed on one side. The slave piston 10 or the first slave section 34 is guided by a guide gap 38 so as to be axially movable within the master piston 9. The guide gap 38 is relatively small, and in this case, the amount of hydraulic medium flowing through the guide gap 38 is very small. In another embodiment, the guide gap 38 has a throttling function.
[0029]
In this embodiment, the slave piston 10 comprises a first slave section 34, a second slave section 35 and a connection section 33. The first slave section 34 is a closed end and forms a coupler volume 23 with the bottom surface of the master piston 9. Centered on the closed end of the first slave section 34 is a stop 24. The diaphragm 24 comprises an opening 36 centered on the bottom surface of the cup-shaped first slave section 24 and a diaphragm sphere 39 guided by a diaphragm gap 37 in the opening.
[0030]
The open end of the first slave section 34 opposite the coupler volume 23 is closed by a connection section 33. The connecting section 33 is in this case partly engaged with the first slave section 34 and is joined to the first slave section 34 in a relatively immovable manner, for example by press fitting or welding. A compression spring 11 preloaded in a spring chamber 45 arranged in the first slave section 34 is arranged between the end of the connection section 33 engaged with the first slave section 34 and the throttle sphere 39. Has been.
[0031]
The compression spring 11 has a coil shape, and presses the throttle sphere 39 through a spring receiver 40. In this case, the throttle sphere 39 is supported on the bottom surface of the master piston 9 in the coupler volume 23. The upper ends of the first slave section 34 and the master piston 9 on the side opposite to the coupler volume 23 are located at substantially the same height. In this case, the connection section 33 is a flange 44, which rests on the upper end of the first slave section 34 and partially projects from the first slave section 34. The flange 44 has approximately the same diameter as that of the first slave section 34.
[0032]
Compensation chamber 12 is limited by flexible section 13, connection section 33, flange 44, master piston 9, and first slave section 34, and compensation chamber 12 includes lateral hole 31, spring It is connected to the diaphragm 24 through the chamber 45. The flexible section 13 is elastic, for example made of elastomer or steel.
[0033]
In this embodiment, the flexible section 13 includes an axial section 46 extending axially toward the direction of movement of the slave piston 10 and a radial section extending radially relative to the direction of movement of the slave piston 10. It is divided into 47. Thus, the edge part of the flexible division 13 formed in plate shape and sleeve shape is made thick. The flexible section 13 is located at the end formed in the radial section 47 and in the second notch 43 formed on the opposite side of the flange 44 from the coupler volume 23 and is in the axial section. The end formed at 46 is located in a first notch 42 disposed on the outer surface of the upper end region of the master piston 9. The notches 42 and 43 are hollow.
[0034]
The thick end formed in the radial section 47 is placed on the connection section 33 and is brought into the second notch 43 by the second slave section 35 partially engaged with this connection section 33. It is pushed in airtight and fixed here. The end formed in the axial section 46 of the flexible section 13 is hermetically pushed into the first notch 42 by the sleeve 41 partially surrounding the master piston 9 and is fixed here.
[0035]
This sleeve 41 closely surrounds the axial section 46 and the transition to the radial section 47, so that the sleeve 41 acts as an expansion limiting member. The sleeve is reduced in diameter behind the axial section 46 and extended upwards, in which case it closely surrounds the second slave section 35 at least partly with little play in the radial direction.
[0036]
For example, due to the force applied to the coupler 7 in the axial direction over a long period of time, which occurs when the actuator 4 is extended based on temperature, the hydraulic medium passes through the throttle 24 from the coupler volume 23, and the spring chamber 45 and the lateral hole 31. As a result, the coupler volume portion 23 is reduced. The compensation chamber 12 is partially limited by an elastic, diaphragm-like flexible section 13. Due to the preloading of the flexible section 13 and the compression spring 11, a pressure that expands the coupler volume 23 is applied to the hydraulic medium. In this case, the compression spring 11 presses the master piston 9 and the slave piston 10 away from each other only through a rigid component without acting via the hydraulic medium.
[0037]
The compression spring 11 may be disposed outside the spring chamber 45.
[0038]
The dynamic stiffness of the coupler 7 is determined in particular by the size and shape of the throttle gap 37 and possibly the size and shape of the guide gap 38.
[0039]
FIG. 4 shows another embodiment of the fuel injector 1 according to the invention as an embodiment similar to FIG. 3 in the region of the flexible section 13 of the coupler 7. The difference from the embodiment of FIG. 3 is that both ends of the flexible section 13 are bent inward. Thereby, a recess 48 is formed on the end of the flexible section 13 on the side facing the compensation chamber 12. The outer surface of the end portion abuts against the notches 42 and 43 in an airtight manner. The shape of the recess 48 can in this case be formed, for example, as a semicircle, a triangle, an ellipse or a polygon.
[0040]
The present invention is not limited to the illustrated embodiment, and is suitable for any configuration of the fuel injection valve 1, particularly for the fuel injection valve 1 for a self-igniting internal combustion engine and / or for an inner opening type fuel injection valve. Yes. The features described generally can be arbitrarily combined with each other.
[Brief description of the drawings]
[0041]
FIG. 1 is a schematic cross-sectional view of a fuel injection valve according to the prior art.
2 is a schematic partial cross-sectional view showing a region of a coupler of a fuel injection valve according to the prior art similar to the fuel injection valve shown in FIG. 1;
FIG. 3 is a view showing an embodiment of a fuel injection valve according to the present invention in the region of a coupler.
FIG. 4 is a view showing another embodiment of the fuel injection valve according to the present invention in the area of the flexible section of the coupler.

Claims (22)

A fuel injection valve is provided piezoelectric or magnetostrictive actuator (4) is, the actuator is a valve closing body which forms a sealing seat cooperates with a valve seat surface (18) (17 ), And a hydraulic coupler (7) is provided. The coupler (7) includes a master piston (9), a slave piston (10), and a coupler volume formed therebetween. And the coupler volume (23) is connected to the compensation chamber (12) via the restriction (24), and the elastic and flexible section (13) is the compensation chamber (12). ) At least partly, in which the coupler volume (23), the throttle (24) and the compensation chamber (12) are filled with a hydraulic medium,
A flexible section (13) applies pressure to the hydraulic medium by preloading, directly to the slave piston (10) and / or the master piston (9) and / or via a rigid component (40, 39). The preload of the force of the compression spring (11) supported in this way is directed in a direction in which this force expands the coupler volume (23), and the throttle (24) has a throttle ball (39), a fuel injection valve characterized that you have been guided in the narrowed sphere with throttle gap (37) opening (36).   2. The fuel injection valve according to claim 1, wherein the compensation chamber (12) is connected to the throttle (24) via a transverse hole (31).   The fuel injection valve according to claim 1 or 2, wherein the compression spring (11) is helical.   4. The fuel injection valve according to claim 1, wherein the compression spring (11) is arranged on the slave piston (10) in the spring chamber (45).   The slave piston (10) has a cup-shaped first slave section (34), the bottom surface of the slave section (34) partially limiting the coupler volume (23). The fuel injection valve according to any one of 1 to 4.   6. The fuel injection valve according to claim 5, wherein the first slave section (34) is guided in the master piston (9) in the axial direction with guide play (38).   7. The fuel injection valve according to claim 5, wherein the master piston (9) partially surrounds the first slave section (34).   8. The fuel injection valve according to claim 5, wherein the throttle (24) is arranged on the bottom surface of the cup-shaped first slave section (34). A compression spring (11) is supported via a throttle ball (39), a fuel injection valve of any one of claims 1 to 8. The fuel injection valve according to any one of claims 1 to 9 , wherein the compression spring (11) is supported by the throttle ball (39) via a spring plate (40). Stop ball (39) is a master piston (9) is supported on a surface to restrict coupler volume (23), a fuel injection valve of any one of claims 1 to 10. Compensation chamber (12), a flexible section (13) and the slave piston (10) and is limited by the master piston (9), the fuel injection valve of any one of claims 1 to 11. Flexible section (13), axial segment extending in the axial direction with respect to the direction of movement of the slave piston (10) and (46), radial portion extending radially with respect to the direction of movement of the slave piston (10) ( 47) and a fuel injection valve of any one of claims 1 to 12. 14. The fuel injection valve according to claim 13 , wherein the flexible section (13) is in the form of a plate with a hole and in the form of a sleeve. An end formed in the radial section (47) engages a second notch (43) formed in the slave piston (10) and / or an end formed in the axial section (46) The fuel injection valve according to claim 13 or 14 , wherein the fuel injection valve engages a first notch (42) arranged in the master piston (9). The fuel injection valve according to claim 15 , wherein at least one of the notches (42, 43) is recessed. A second notch (43) is disposed between the connection section (33) of the slave piston (10) and the second slave section (35) of the slave piston (10), and the connection section (33 ) Is disposed at the end of the first slave section (34) opposite the coupler volume (23), and the second slave section (35) is mounted on the connection section (33). that is location, claim 15 or 16 fuel injection valve according. 16. The fuel injection valve according to claim 15 , wherein the end of the radial section (47) is clamped or airtightly clamped. The end of the axial section (46) is clamped between the outer surface of the master piston (9) and the sleeve (41) which at least partly surrounds the master piston (9), in particular airtightly clamped The fuel injection valve according to any one of claims 15 to 18 . The fuel injection valve according to any one of claims 1 to 19 , wherein the end of the flexible section (13) is thickened. At least one of the ends of the flexible section (13), but is bent inwardly, thereby recess (48) forms a fuel injection according to any one of claims 16 to 20 valve. 22. The fuel injection valve according to claim 21 , wherein at least one bent end of the flexible section (13) is located in the notch (42, 43) hermetically on its outer surface.

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