EP2813698B1 - Fuel injector valve - Google Patents

Description

State of the art

The invention relates to a fuel injection valve, in particular an injector for fuel injection systems of internal combustion engines. Specifically, the invention relates to the field of injectors for fuel injection systems of air compressing, self-igniting internal combustion engines.

From the DE 10 2009 046 332 A1 a control valve arrangement for a control chamber of a fuel injector is known. In this case, the control valve arrangement can be actuated by an electromagnetic actuator. The control valve assembly has a sleeve-shaped closing body, which is tensioned by a closing spring against a concentric seat. A control chamber pressure of the control chamber is removed by means of a guide rod on a transmission, the electromagnetic parameters of the solenoid assembly changed such that the closing times of a nozzle needle can be detected by appropriate evaluation of the electric current-voltage curve of a magnetic coil. Thus, in addition to its actuator function, the solenoid assembly also assumes sensor functions, and in addition to its guide function for the closing body, the guide rod has the task of modifying parameters of the electromagnet arrangement.

By a control valve assembly, as is known from the DE 10 2009 046 332 A1 is known, can be exploited that the control chamber pressure and thus also a valve chamber pressure at the time of injection end experiences a characteristic, rapid increase. In this case, the fact can be used that the guide rod is thus acted upon on its lower end face with the valve space pressure and above it is guided such that the guide is simultaneously a seal. Consequently, the guide rod is biased with an axial force that is proportional to the valve chamber pressure.

This axial force can be introduced, for example, in a piezoelectric sensor, which then emits a charge or voltage which is proportional to this biasing force and therefore proportional to the valve chamber pressure.

The from the DE 10 2009 046 332 A1 known control valve arrangement has the disadvantage that the application is limited and must be met for the operation certain conditions. Even with a servo valve, which is actuated by a piezoelectric actuator, there is a relationship between the time courses of a nozzle needle stroke and a control chamber pressure, wherein the reaction of opening and closing of the nozzle needle is clearly visible on the control chamber pressure. However, with an inwardly opening valve, the valve space pressure acts only on the switching valve seat and the surfaces otherwise bounding the valve space. The attachment of a pressure sensor in this area thus requires its sealing against the high pressure and the introduction of additional electrical contacts. Therefore, it is better for the piezo-controlled servo valve to analyze the actuator voltage signal to a typical resonant vibration, which is stimulated among other things by the closing of the nozzle needle. The excitation takes place here on the one hand via the switching chain by the rapid increase of the valve chamber pressure at the moment of valve closing and on the other hand by acoustic transmission through the holding body, which is stimulated by the rapid increase of the nozzle seat force at the moment of the needle closing. In contrast to a design, as they are from the DE 10 2009 046 332 A1 is known, but this is not a targeted detection of the valve space pressure curve, but only the detection of a parasitic excited by the needle closing vibration possible. It is conceivable that only a very narrow frequency signal is taken from the input signals and modulated with a gain of significantly less than 1 of the actuator force. In particular, in this case the DC components of both the control chamber pressure and the nozzle seating force are already filtered out in the mechanical transmission chain, so that the significant changes of these two variables at the moment of nozzle needle closing have only a small transient effect on the Aktorspannungssignal. Specifically, there is this problem when the actuator, which is used as a sensor, is installed very far from the actual power flow line and is excited only by a parasitic coupling out of these power flow lines to vibrate. Thus, the detection method for the injection end in a piezoelectrically actuated servo valve is much less robust and much more susceptible to interference than in an electromagnetically actuated control valve assembly, as shown in DE 10 2009 046 332 A1 is known. As a result, one in the fuel pressure load level is essential smaller functional area for the detection of an injection end at the piezo injector in comparison to a solenoid valve injector.

Disclosure of the invention

The fuel injection valve according to the invention with the features of claim 1 has the advantage that an improved design is possible. In particular, in an embodiment in which the piezoelectric actuator is provided, a portion can be coupled into a biasing force of the piezoelectric actuator, which depends on the pressure in the valve chamber and in particular is proportional to the pressure in the valve chamber.

The measures listed in the dependent claims advantageous developments of the fuel injection valve specified in claim 1 are possible.

The force transmission element is arranged at least in sections in the valve closing body. In particular, the force transmission element may be guided at least in sections in the valve closing body. This is particularly advantageous in a possible embodiment in which the force transmission element is designed as a rigid force transmission element. The force transmission element can then be formed, for example, from a metal or a metallic alloy. In another possible embodiment, the force transmission element may also be formed of a fuel-resistant, elastic plastic or based on a fuel-resistant, elastic plastic.

The force transmission element transmits the force which results from the application of pressure to the end face of the force transmission element to the pressure in the valve space, at least indirectly to the actuator. In practice, the transmission in practice will regularly be a lossy transmission. The transmission losses will usually arise in embodiments in which the force transmission element is formed of a fuel-resistant, elastic plastic. However, such transmission losses can be accommodated by appropriate adjustments. In particular, this can be realized structurally by means of a suitable adaptation with regard to the configuration, in particular the size, of the end face, which is acted upon by the pressure in the valve chamber.

The power transmission element is configured in a possible embodiment as a rigid power transmission element. For example, the force transmission element can be configured as a pin-shaped force transmission element. As a result, it is also possible for the force transmission element to transmit the force which results from the application of pressure to the end face of the force transmission element to the pressure in the valve space, at least substantially unattenuated to the actuator.

It is advantageous that the actuator actuates the valve closing body by means of a mechanical transmission device and that the force transmission element transmits the force to the actuator by means of the mechanical transmission device. About the mechanical transmission device, the force can be transmitted indirectly from the power transmission element to the actuator. In this case, the transmission device can also achieve a force transmission or displacement transmission between the actuator and the valve closing body. Conversely, then results in a power transmission from the power transmission element to the actuator by means of the mechanical transmission device. In the embodiment with the mechanical transmission device, a biasing force or an additional biasing force can be exerted on the actuator in an advantageous manner, which depends on the pressure in the valve chamber.

It is also advantageous that the actuator is designed as a piezoelectric actuator. Specifically, the actuation of the actuator, which depends on the pressure in the valve chamber, for piezoelectric actuators, to use the actuator in this case as a sensor with a good resolution is suitable. As a result, it is possible, in particular, to realize a detection of oscillations that occur in the case of needle closure with improved resolution.

In a correspondingly modified embodiment, it is likewise advantageous that the actuator actuates the valve closing body by means of a hydraulic transmission device and that the force can be transmitted to the actuator by a mechanical bridging of the hydraulic transmission device from the force transmission element. In a hydraulic transmission device, a transfer of the dynamic Aktorhubs can be achieved on the nozzle needle in an advantageous manner. However, in the quasi-static case, there is the problem that a force acting permanently on the hydraulic transmission device would displace a piston of the hydraulic transmission device into an end position due to the intended leakage or an intended throttling action, so that the transmission of the Force that results from the application of the pressure to the end face of the force transmission element in the valve chamber would end in the region of the hydraulic transmission device and does not reach the piezoelectric actuator. Due to the mechanical bridging of the hydraulic transmission device, this force can still be transmitted from the power transmission element to the actuator. Thus, the actuator can be applied to a certain extent with a DC component, although the hydraulic transmission device can only transfer alternating parts. Specifically, the hydraulic transmission device can be designed as a hydraulic coupler. In this case, the actuator can be designed as a piezoelectric actuator in a corresponding manner.

In this case, it is also advantageous that the hydraulic transmission device has a coupler space and a coupler body, that a low-pressure space is provided, that between the low-pressure space and the valve space, a sealing seat formed by the valve closing body is predetermined, that an actuator-side end of the coupler body limits the coupler space a valve-closing body-side end face of the coupler body bears against the valve closing body and that the force transmission element and / or at least one further force transmission element are guided through the coupler body. In this way, a mechanical power transmission from the power transmission element can be effected at least indirectly on the actuator, which bridges the hydraulic transmission device. Here, a seal is realized in a suitable manner. In this case, there is the advantage that the dynamic actuation by the actuator leads to a relatively short pressure increase in the coupler space, which considerably simplifies the sealing.

Here, it is further advantageous that the coupler body has a through hole and that the at least one further force transmission element is guided at least substantially continuously along the through hole of the coupler body. In this embodiment, at least one further force transmission element is provided, wherein a certain seal between the at least one further force transmission element and the through hole is realized to allow the pressure increase in the coupler space. In this case, a transfer of the DC component of the pressure in the valve chamber to the actuator is possible via the at least one further force transmission element.

In a correspondingly modified embodiment, it is also advantageous that the coupler body has a through-bore extending through the coupler body, that the at least one further force-transmitting element in an extended Guiding portion of the through hole of the coupler body is guided and that extends the extended guide portion of the through hole to the actuator-side end face of the coupler body. Thus, sufficient sealing can be ensured between the further force transmission element and the coupler body in the region of the guide section in order to enable a dynamic pressure increase in the coupler space. As a result, an advantageous actuation of the control valve by the actuator is possible. Furthermore, the actuator can be acted upon by the DC component of the pressure in the valve chamber.

It is also advantageous that the force transmission element rests against the further force transmission element in the area of the valve closing body-side end face of the coupler body. As a result, on the one hand, the force transmission element can be guided on the valve closing body of the control valve. On the other hand, the further power transmission element can be guided independently of the force transmission element in the coupler body. This prevents over-determination.

It is advantageous that the valve closing body has a through hole in which the force transmission element is guided. As a result, on the one hand a simple embodiment of the valve closing body is possible, wherein the bore can be configured in particular as an axial bore with respect to the valve closing body.

In a modified embodiment, it is advantageous that the valve closing body has a blind hole in which the force transmission element is guided, that an end face of the force transmission element in the blind hole delimits a pressure chamber and that the valve closing body has at least one lateral connection bore, which the pressure chamber with the valve chamber combines. As a result, for example, an embodiment of the control valve can be realized with a bypass or the like. In particular, a side facing away from the pressure-relieved space end face of the valve closing body can be acted upon at least temporarily or in response to a switching position of the control valve by a pressure which differs from the pressure in the valve chamber, with which the end face of the force transmission element is acted upon. In addition, this may be due to throttles, bypasses or the like occurring in the valve chamber, local pressure fluctuations and / or pressure increases and / or pressure reductions are at least partially eliminated by a suitable design of the lateral connecting holes in terms of their effect on the actuation of the actuator.

It is also advantageous here that a low-pressure chamber is provided, that between the low-pressure chamber and the valve chamber a sealing seat formed by the valve closing body is provided and that a remote from the low pressure chamber end face of the valve closing body in a valve sleeve, in which the valve closing body is guided, a pressure relieved Subspace separated from the valve chamber. As a result, a force-balanced or pressure-balanced design of the control valve is possible. As a result, an actuating force that has to be applied by the actuator for adjusting the valve closing body can be reduced.

Thus, the power transmission element, which is preferably guided in the valve closing body, for example, be designed as a rigid pin, which enables the generation of a force and their forwarding to a piezoelectric actuator when pressurized. Here, a purely mechanical coupling or a hydraulic coupling between the valve closing body and the actuator can be provided. The seal between the force transmission element and the valve closing body of the control valve can be realized via a tight guide play. However, this form of sealing entails that in this guide a permanent leakage occurs, which additionally heats the low-pressure region of the fuel injection valve and requires a correspondingly enlarged dimensioning of the high-pressure pump of the fuel injection system.

In a further possible embodiment, the sealing between the force transmission element and the valve closing body of the control valve via sealing elements, as they come in a corresponding manner in other components of a motor vehicle, for example in anti-lock braking systems (ABS) or ESP systems used. Then, a leakage in the leadership of the power transmission element can be avoided. However, the presence and the installation of the sealing elements leads to additional costs.

For the two above-mentioned possibilities of sealing also applies that the power transmission element in the practical implementation may be very small and consequently the bore (guide bore) in the valve closing body in which the power transmission element is guided, a small diameter, for example of at most 1 mm. With these small dimensions, the realization of a defined guide clearance or the installation of separate sealing elements may be difficult.

The difficulties just mentioned, which can occur with a rigid force transmission element, in particular a metallic force transmission element in the form of a guided pin, however, if they are relevant in the particular application, can be solved in an advantageous manner, as further explained below. Thereby, the occurrence of a permanent leakage on the leadership of the power transmission element in the valve closing body can be avoided with simple, inexpensive means. Thus, the scope can be increased.

An advantageous solution of the problems just mentioned is not to carry out the force transmission element of a rigid material, such as a metal, but from a fuel-resistant, elastic plastic. Particularly suitable for this purpose is a silicone material. If such a force transmission element is subjected to an axial force, then it shortens and at the same time expands in the radial direction. As a result, the force transmission element engages positively against an inner wall of the guide bore and thus seals this guide completely.

Thus, there are several advantages. Due to the transverse expansion of the existing of this plastic force transmission element a permanent leakage in the guide is completely prevented. Instead of producing the power transmission element as a separate component, this can also be injected directly into its guide bore. To avoid extrusion of the force transmission element due to the optionally high axial force at its support point on its other end face, which faces away from the pressurized end face, simple measures can be taken. These may consist of a targeted narrowing of the extrusion gap by a metallic component between the force transmission element and the subsequent component or element and / or the reinforcement of the plastic material by higher-strength materials such as glass or carbon fibers or metal particles.

It is therefore advantageous that the force transmission element is at least partially formed from a material which is based on a fuel-resistant, elastic plastic. In this case, it is also advantageous that the material has reinforcing elements and that the plastic is reinforced by the reinforcing elements. Thus, the Permanent leakage can be avoided on the leadership of the power transmission element. In this case, with respect to the respective application, a sufficient durability with respect to the size of the force occurring during operation, which results from the application of the pressure to the end face of the force transmission element in the valve chamber, can be achieved by optionally provided reinforcing elements in the plastic.

The reinforcing elements may in this case be configured advantageously as glass fibers and / or carbon fibers and / or metal particles. By the number of reinforcing elements per unit volume and the selection of suitable reinforcing elements in this case an adaptation to the particular application is possible.

It is also advantageous that the force transmission element is at least partially inserted into a bore of the valve closing body and that the force transmission element when loading the end face of the force transmission element with the pressure in the valve chamber form fit to an inner wall of the bore of the valve closing body, in which the force transmission element is arranged invests. Thus, the power transmission element during assembly can first be introduced into the bore of the valve closing body. When pressure is then achieved by the generated axial force and the resulting transverse strain, the positive application of the force transmission element to the inner wall of the bore. This results in a simple assembly and the power transmission element can be configured geometrically simple. Specifically, the force transmission element may be configured cylindrical before the first pressurization.

In a modified embodiment of the fuel-resistant, elastic plastic, which is optionally reinforced, are also injected into the bore of the valve closing body to design in this way a connected to the valve closing body power transmission element.

It is also advantageous that a dimensionally stable sealing element is at least partially disposed in the bore of the valve closing body, that the sealing element on the further end face of the force transmission element, which faces away from the end face of the force transmission element, and that the force transmission element, the force on the sealing element at least indirectly transfers to the actor. The dimensionally stable sealing element can in particular be designed as a metallic sealing element be. As a result, a targeted narrowing of the extrusion gap is possible in order to prevent extrusion of the elastically deformable force transmission element.

Brief description of the drawings

• Fig. 1 ein Brennstoffeinspritzventil in einer auszugsweisen, schematischen Schnittdarstellung entsprechend einem ersten Ausführungsbeispiel der Erfindung;
• Fig. 2 den in Fig. 1 mit II bezeichneten Ausschnitt des Brennstoffeinspritzventils in einer auszugsweisen, schematischen Schnittdarstellung entsprechend einem zweiten Ausführungsbeispiel der Erfindung;
• Fig. 3 den in Fig. 1 mit II bezeichneten Ausschnitt des Brennstoffeinspritzventils in einer auszugsweisen, schematischen Schnittdarstellung entsprechend einem dritten Ausführungsbeispiel der Erfindung;
• Fig. 4 eine Brennstoffeinspritzventil in einer auszugsweisen, schematischen Schnittdarstellung entsprechend einem vierten Ausführungsbeispiel der Erfindung;
• Fig. 5 ein Brennstoffeinspritzventil in einer auszugsweisen, schematischen Schnittdarstellung entsprechend einem fünften Ausführungsbeispiel der Erfindung;
• Fig. 6 ein Diagramm zur Erläuterung der Funktionsweise entsprechend einer möglichen Ausgestaltung der Erfindung;
• Fig. 7 den in Fig. 1 mit II bezeichneten Ausschnitt des Brennstoffeinspritzventils in einer auszugsweisen, schematischen Schnittdarstellung entsprechend einem sechsten Ausführungsbeispiel der Erfindung im Neuzustand vor einer erstmaligen Druckbeaufschlagung;
• Fig. 8 den in Fig. 7 dargestellten Ausschnitt des Brennstoffeinspritzventils entsprechend dem sechsten Ausführungsbeispiel der Erfindung nach der erstmaligen Druckbeaufschlagung;
• Fig. 9 den in Fig. 1 mit II bezeichneten Ausschnitt des Brennstoffeinspritzventils in einer auszugsweisen, schematischen Schnittdarstellung entsprechend einem siebten Ausführungsbeispiel der Erfindung und
• Fig. 10 ein Brennstoffeinspritzventil in einer auszugsweisen, schematischen Schnittdarstellung entsprechend einem achten Ausführungsbeispiel der Erfindung.

Preferred embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawings, in which corresponding elements are provided with identical reference numerals. Show it:

• Fig. 1 a fuel injection valve in an excerpt, schematic sectional view according to a first embodiment of the invention;
• Fig. 2 the in Fig. 1 labeled II section of the fuel injection valve in a partial, schematic sectional view according to a second embodiment of the invention;
• Fig. 3 the in Fig. 1 labeled II section of the fuel injection valve in a partial, schematic sectional view according to a third embodiment of the invention;
• Fig. 4 a fuel injection valve in a partial, schematic sectional view according to a fourth embodiment of the invention;
• Fig. 5 a fuel injection valve in a partial, schematic sectional view according to a fifth embodiment of the invention;
• Fig. 6 a diagram for explaining the operation according to a possible embodiment of the invention;
• Fig. 7 the in Fig. 1 with II designated section of the fuel injection valve in a partial, schematic sectional view according to a sixth embodiment of the invention in the new state before a first pressurization;
• Fig. 8 the in Fig. 7 illustrated section of the fuel injection valve according to the sixth embodiment of the invention after the initial pressurization;
• Fig. 9 the in Fig. 1 Designated II section of the fuel injection valve in a partial, schematic sectional view according to a seventh embodiment of the invention and
• Fig. 10 a fuel injection valve in an excerpt, schematic sectional view according to an eighth embodiment of the invention.

Embodiments of the invention

Fig. 1 shows a first embodiment of a fuel injection valve 1 in a partial, schematic sectional view. The fuel injection valve 1 can serve in particular as an injector for fuel injection systems of air-compressing, self-igniting internal combustion engines. A preferred use of the fuel injection valve 1 is for a fuel injection system with a common rail, the diesel fuel under high pressure leads to a plurality of fuel injection valves 1. However, the fuel injection valve 1 according to the invention is also suitable for other applications.

The fuel injection valve 1 has a partially illustrated housing 2, a throttle plate 3 and a valve piece 4. Furthermore, a nozzle body 5 is provided, which is connected in a suitable manner, in particular via a nozzle retaining nut, with the housing 2. The throttle plate 3 and the valve piece 4 are disposed within the housing 2 and the nozzle body 5.

In the housing 2, a piezoelectric actuator 6 is arranged with a protective sleeve 7. An actuator head attached to the piezoelectric actuator 6 is connected to the protective sleeve 7 via a deformable membrane 9. As a result, the piezoelectric actuator 6 is sealed off from a pressure-relieved space (low-pressure space) 10, via which a reflux of fuel takes place during operation. Furthermore, a control unit 11 is provided, which is connected to the piezoelectric actuator 6.

Between the throttle plate 3 and the nozzle body 5, a fuel chamber 12 is formed, which is filled via a fuel line 13, which is partially guided by the throttle plate 3, in operation with fuel. In the fuel chamber 12, a nozzle needle 14 is arranged, which cooperates with a valve seat surface 15 to a sealing seat. An end face 16 of the nozzle needle 14, which faces the throttle plate 3, defines a control chamber 17, which is formed within a sleeve 18. The nozzle needle 14 is in this case guided in the sleeve 18. The sleeve 18 is acted upon by a spring 19 against the throttle plate 3, so that the control chamber 17 is separated from the fuel chamber 12.

During operation, the control chamber 17 is filled with fuel via an inlet throttle 20 configured in the throttle plate 3.

When the pressure in the control chamber 17 falls below a certain value, then there is an actuation of the nozzle needle 14, wherein the sealing seat formed between the valve seat surface 15 and the nozzle needle 14 is opened and Fuel via injection holes 21, 22, which are configured in the nozzle body 5, is injected into the combustion chamber of an internal combustion engine. If then the pressure in the control chamber 17 is increased above a certain value, then the nozzle needle 14 is again in the in the Fig. 1 shown reset closed position.

The pressure in the control chamber 17 is controlled by a control valve 30. The actuation of the control valve 30 takes place here by the piezoelectric actuator 6. The control valve 30 has a valve closing body 31 which is at least partially disposed in a valve chamber 32. In this embodiment, a valve seat surface 33 is formed on the valve piece 4. The valve closing body 31 cooperates with the valve seat surface 33 to form a sealing seat. Here, the valve closing body 31 is acted upon by a valve spring 34 against the valve seat surface 33. When the sealing seat is closed, the valve chamber 32 of the control valve 30 is separated from the pressure-relieved space 10. When the sealing seat is open, a connection between the valve chamber 32 and the pressure-relieved space 10 is established, so that a pressure p _v in the valve chamber 32 drops. As a result, fuel flows through an outlet throttle 35, which is configured in the throttle plate 3, from the control chamber 17 into the valve chamber 32. This causes a pressure drop in the control chamber 17, which allows actuation of the nozzle needle 14.

The valve closing body 31 of the control valve 30 is indirectly actuated by the actuator 6 in this embodiment. Here, the actuator 6 actuates the valve closing body 31 by means of a transmission device 36. In this embodiment, the transmission device 36 is designed as a mechanical transmission device 36, which converts the stroke of the piezoelectric actuator 6 in a corresponding stroke of the valve closing body 31. Depending on the design of the mechanical transmission device 36, this can also be a path translation or force transmission.

In addition, a power transmission element 37 is provided. The valve closing body 31 has a through bore 38, in which the force transmission element 37 is guided. The force transmission element 37 has an end face 39 with an effective area A. The force transmission element 37 is guided along an axis 40 of the valve-closing body 31, which in this embodiment is also the axis 40 of the through-bore 38. The end face 39 is in this embodiment in a plane which is oriented perpendicular to the axis 40. Thereby, the area of the end face 39 is equal to the effective area 39A. In a modified embodiment, the effective area A results as a projection of the end face 39 in such a plane which is oriented perpendicular to the axis 40.

In the valve chamber 32 there is a pressure p _v . This pressure p _v acts on the end face 39 a. Due to the through bore 38 of the valve closing body 31 is configured so that the end face 39 of the power transmission element 37 is acted upon by the pressure p _v in the valve chamber 32, so that the force transmission element 37, a force F acts. The force F results from the loading of the end face 39 with the pressure p _v in the valve chamber 32. The force F results here as a product of the effective area A and the pressure p _v . In particular, the force F is thus proportional to the pressure p _v in the valve chamber 32.

The valve closing body 31 has a sleeve-shaped extension 41, which extends through the pressure-relieved space 10 to the transmission device 36. In a starting position, in this case, a small distance between the sleeve-shaped extension 41 and a contact surface 42 of the transmission device 36 may be provided in order to allow a reliable closing of the valve closing body 31 with respect to possible tolerances, temperature-related expansions and the like. From a preferably small stroke of the actuator 6, it then comes to operate the Valve-closing body 31, in which the sleeve-shaped extension 41 is then in contact with the contact surface 42 of the transmission device 36.

The force transmission element 37 is axially movable in the through bore 38 and is always on the contact surface 42 of the transmission device 36 at. In this case, the force transmission element 37 transmits the force F dependent on the pressure p _v in the valve space 32 to the piezoelectric actuator 6 by means of the mechanical transmission device 36.

The mechanical transmission device 36 may be designed as a rigid transmission device 36. However, the transmission device 36 may also be designed as a mechanical switching chain for force and displacement transmission between the actuator 6 and the valve closing body 31. The mechanical transmission device 36 transmits the DC component of a force, so that the force transmission element 37 can be supported directly on the transmission device 36 in order to transmit the axial force F. The through hole 38 extends axially and centrally in the valve closing body 31. In this case, the through hole 38 preferably has a small diameter. In a modified embodiment, an embodiment of the through bore 38 with a center offset is possible. Furthermore, an only approximately axial guidance of the force transmission element 37 may be sufficient. The seal between the force transmission element 37 and the through bore 38 can be done by a small guide clearance and / or by suitable sealing elements, as they come for high pressure systems, especially high pressure pumps or the like used.

Thus, a force P proportional to the pressure p _v in the valve chamber 32 can be permanently introduced into the transmission device 36 and thus transmitted to the actuator 6.

The control unit 11 can use the piezoelectric actuator 6 as a sensor to detect vibrations emanating from the nozzle needle 14. This results in the advantage that a broad frequency band of the pressure p _v in the valve chamber 32, including its DC component, is transmitted to the biasing force of the piezoelectric actuator 6. This is made possible by the force transmission element 37. For example, the increase of the pressure in the control chamber 17 and thus also the increase of the pressure p _v in the valve chamber 32 at the end of an injection leads to a correspondingly constant increase of the actuator voltage and a nearly exact mapping of the pressure p _v in the actuator voltage. This allows a much more accurate detection of an end of an injection process, which in addition is allowed to a much larger area of a fuel pressure load range. Since the Aktorvorspannung is significantly increased by the transmission of the pressure p _v in the valve chamber 32 proportional force F on the actuator 6, especially at high pressures, and serving as a spring sleeve 7 protective sleeve 7 can be biased lower. A weaker and cheaper design of the protective sleeve (spring sleeve) 7 is made possible. Since caused by the pressure p _v force F is constantly applied to the actuator, ie in its not yet controlled state, and 13 greatly decreases when you open the control valve 13 for actuating the nozzle needle 14, this solution also contributes to the power relief of the control valve 13 and a reduction the voltage requirement of the actuator 6 at.

Fig. 2 shows the in Fig. 1 labeled II section of the fuel injection valve 1 in an excerpt, schematic sectional view according to a second embodiment. In this embodiment, the valve closing body 31 has a blind hole 43 in which the force transmission element 37 is axially guided. The end face 39 of the force transmission element 37 limits this in the blind hole 43 a pressure chamber 44. In addition, the valve closing body 31 has lateral connection bores 45, 46, which connect the pressure chamber 44 with the valve chamber 32.

In this embodiment, the application of the end face 39 of the force transmission element 37 thus does not take place with its effective area A from a bottom 47 of the valve closing body 31, as in the case of the Fig. 1 described embodiment of the case, but of a lateral surrounding area of the valve closing body 31 in the valve chamber 32. The lateral surrounding area 48 encloses the valve closing body 31 in this case circumferentially. This embodiment is advantageous, inter alia, when the underside 47 of the valve closing body 31 is flowed through a bypass bore and is itself part of a throttle arrangement, so that at least temporarily below the valve closing body 31 a locally different pressure deviates from the actual pressure p _v in the valve chamber 32 pending. Thus, the control valve 30 can be made robust against such influences.

In this embodiment, the bottom 47 is designed as a closed end 47.

Fig. 3 shows the in Fig. 1 With II designated section of the fuel injector 1 in a partial, schematic sectional view corresponding to a third

Embodiment. In this embodiment, the control valve 30 is designed as a pressure-relieved control valve 30. Here, the power transmission element 37 is guided in the blind hole 43. The configured in the blind hole 43 pressure chamber 44 is connected via the lateral connection bores 45, 46 with the valve chamber 32, so that in the pressure chamber 44, the pressure p _v acts as in the valve chamber 32.

In addition, the valve closing body 31 in this embodiment, a guide portion 49 which extends from the bottom (front side) 47 in the axial direction. Furthermore, the control valve 30 has a valve sleeve 50, in which the valve closing body 31 is axially guided with its guide portion 49. Adjoining the underside 47 of the valve closing body 31 is a partial space 51, which is separated from the valve space 32, in which the pressure p _v prevails, by the valve sleeve 50. The subspace 51 is connected via a connection 52 with the pressure-relieved space 10. The pressure-relieved space 10 is a low-pressure space 10, in which a much lower pressure than in the valve chamber 32 prevails when the sealing seat between the valve closing body 31 and the valve seat surface 33 is closed.

This embodiment has the advantage that the actuation force for opening the sealing seat formed between the valve closing body 31 and the valve seat surface 33 is reduced.

Depending on the configuration of the control valve 30 may also be provided a Fülldrossel 53, which serves as a bypass, for example, to allow faster closing of the nozzle needle 14. In this case, the pressure from the valve chamber 32 can be increased faster via the filling throttle 43. Optionally, it can also lead to an opposite flow through the outlet throttle 35, wherein the control chamber 17 is at least temporarily filled not only via the inlet throttle 20, but also on the outlet throttle 35, which is made possible by the filling of the control chamber 32 via the Fülldrossel 53.

Fig. 4 shows a fuel injection valve 1 in an excerpt, schematic sectional view according to a fourth embodiment. In this embodiment, the valve closing body 31, the through hole 38, in which the power transmission element 37 is axially guided. Furthermore, the transmission device 36 is configured in this embodiment as a hydraulic transmission device 36. The actuator 6 actuates the valve closing body 31 for opening the nozzle needle 14 in this embodiment by means of the hydraulic Transmission device 36. This can be done Hubübersetzung or force transmission.

The hydraulic transmission device 36 has a coupler space 60, a coupler body 61 and a further coupler body 62, the coupler bodies 61, 62 being guided in a coupler housing 59. In this case, the piezoelectric actuator 6 mechanically actuates the further coupler body 62. The stroke of the actuator 6 thus directly effects a stroke of the further coupler body 62. The displacement of the fuel in the coupler space 60, which takes place through the stroke of the further coupler body 62, then leads to a hydraulically transmitted movement of the Coupler body 61. In this case, an actuator-side end face 77 of the coupler body 61 limits the coupler space 60. The coupler body 61 in turn acts on the valve closure body 31.

In order to transmit the force F dependent on the pressure p _v to the actuator 6, the coupler body 61 can not simply be acted upon in this case, since an application of the constant force of the coupler body 61 to the coupler body 61 results in an empty-pressing due to a functionally required throttled leakage of the coupler space 60 until the coupler body 61 rests against the further coupler body 62. As a result, the operation of the hydraulic transmission device 36 would no longer be guaranteed, since in this movement of the coupler body 61 and the contact between the contact surface 42 on the coupler body 61 and the sleeve-shaped extension 41 of the valve closing body 31 is released. For the operation of the transmission device 36, however, it is necessary that is filled by a certain pressure of the fuel in the low-pressure space 10 of the coupler chamber 60 with fuel until the coupler body 61 rests against the sleeve-shaped extension 41 of the valve closing body 31, but without the sealing seat between the valve closing body 31 and the valve seat 33 to open. Because then the operation of the actuator 6 already at the Hubanfang to open the sealing seat. A compensation of tolerances, temperature-induced changes in length or the like is thus ensured by the operation of the hydraulic transmission device 36.

In this embodiment, another power transmission member 63 is provided which extends through a through hole of the coupler body 61. In this embodiment, the through-hole 64 is designed as an axial through-hole 64. Further, the through hole 64 is centered through the coupler body 61. The other power transmission member 63 is continuously guided along the through hole 64 of the coupler body 61. The coupler body 61 is between the coupler space 60 and the low pressure space 10 is arranged. Thus, the further force transmission element 63 extends on the one hand through the coupler space 60 and on the other hand it is led to the low-pressure space 10. The further coupler body 62 has a side 65 adjacent to the coupler space 60. The further force transmission element 63 has an end face 66. With the end face 66, the further force transmission element 63 abuts on the side 65 of the further coupler body 62.

In this exemplary embodiment, the contact surface 42 is designed as a valve closing body-side end face 42 of the coupler body 61. In the area of the valve closing body-side end face 42 of the coupler body 61, the force transmission element 37 rests with its end face 67 against an end face 68 of the further force transmission element 63. The end face 68 of the further force transmission element 63 is in this case facing away from the end face 66. By this embodiment, a tolerance compensation, in particular a radial tolerance compensation, allows. This avoids over-determination.

Due to the pressure p _v in the valve chamber 32, the force F, which acts on the force transmission element 37 against the further force transmission element 63 is formed. The force F is thus forwarded by the further force transmission element 63 to the further coupler body 62. The force is introduced into the piezoelectric actuator 6 via the further coupler body 62. Thus, it comes in this embodiment, a bias of the actuator 6 with the force F. Thus, the force F, which depends on the pressure p _v in the valve chamber 32, by a mechanical bridging of the hydraulic transmission device 36 of the power transmission element 37 and the other Power transmission element 63 to the actuator 6 transferable.

In a correspondingly modified embodiment of the fuel injection valve 1, the through-bore 64 can also be designed in other ways. In particular, the through-bore 64 may also extend eccentrically through the coupler body 61. Furthermore, the through-bore 64 may also be designed as a guide bore only on a part of its length. In this case, a seal or a sufficiently large throttling effect is ensured in a suitable manner in order to allow the pressure build-up in the coupler space 60 required for the functioning of the hydraulic transmission device 36. The seal along the guide of the further force transmission element 63 in the through hole 64 can be done by a small guide clearance or by sealing elements.

Further, the end faces 67, 68 of the power transmission element 37 and the further force transmission element 63 are designed so that an advantageous power transmission is possible and at the same time a certain distance to the contact surface 42 of the coupler body 61 or to the sleeve-shaped extension 41 is guaranteed to snag on the Coupler body 61 or the sleeve-shaped extension 41 to prevent. Thus, in an axial movement, the force F is advantageously forwarded by a contact with the coupler body 61 or the sleeve-shaped extension 41 in the region of the end faces 67, 68 is avoided. Thus, a mutual influence of the hydraulic transmission device 36 and the bridging of the hydraulic transmission device 36, which is mediated by the force transmission elements 37, 63, prevented.

Fig. 5 shows the fuel injection valve 1 in an excerpt, schematic sectional view according to a fifth embodiment. In this embodiment, the further power transmission element 63 has a larger diameter portion 69 and a smaller diameter portion 70. Furthermore, the through-bore 64 is designed as a stepped bore 64. Here, the through-hole 64 has an extended guide portion 71 extending to the actuator-side end face 77 of the coupler body 61, and a portion 72 having a diameter smaller than a diameter of the extended guide portion 71. In the extended guide section 71, the further force transmission element 63 is sealingly guided at its portion 69. In the section 72 of the through-hole 64, an annular gap 73 is formed between the section 70 of the further force-transmitting element 63 and the section 72 of the through-hole 64. The sealing of the coupler space 60 with respect to the low-pressure chamber 10 thus takes place in the region of the extended guide section 71 of the through-bore 64. The through-bore 64 thus functions only in the guide section 71 as a guide in this exemplary embodiment.

In a modified embodiment, it is also conceivable that the further force transmission element 63 is guided on one or more sections of the through bore 38 of the valve closing body 31.

Fig. 6 shows a diagram for explaining the operation of the fuel injection valve 1 according to a possible embodiment of the invention. In this case, a signal, in particular a voltage signal U, is plotted on the ordinate, which describes an actuator voltage on the piezoelectric actuator 6. The abscissa shows the time. The Control unit 11 can detect the actuator voltage 6. Further, for actuating the fuel injection valve 1, a suitable voltage can be applied to the piezoelectric actuator 6. At the time t ₁ , the actuator 6 is acted upon by an actuating voltage. This admission ends at time t ₂ . The signal here is very large, which is illustrated by arrows 74, 75. The voltage swing between the times t ₁ and t ₂ is therefore only shown in a hint. After the time t ₂ , the closing of the nozzle needle 14 occurs. In the course of this closing, a characteristic pattern 76 occurs in the signal curve U (t). Because when closing the nozzle needle 14, there is a typical, excited by the nozzle needle closing vibration 76. This vibration 76 follows the closing of the nozzle needle 14, so that the end of the injection can be determined at the time t ₃ . For from the time t ₃ , the oscillation occurs in the form of the characteristic pattern 76. Between the times t ₂ and t ₃ , the oscillation initially decreases, as it corresponds, for example, to a typical attenuation, while after the time t ₃ an oscillation with now greater amplitude occurs again. Thus, the vibration characterized by the pattern 76 is an additional excited vibration due to needle closure.

By acting on the actuator 6 with the force F, a weakening of the oscillation 76 in the transmission path from the sealing seat between the nozzle needle 14 and the valve seat surface 15 to the actuator 6 is reduced. In particular, not only a narrow frequency band from the valve chamber pressure signal is coupled out and transmitted to the actuator, but it is implemented a wide frequency band including the DC component of the valve chamber pressure in a force acting on the actuator biasing force. The time t ₃ , which indicates the end of the injection, can thus be clearly recognized from the signal U (t) of the actuator voltage of the piezoelectric actuator 6.

Thus, in the fuel injection valves 1 according to the described embodiments, an injection end detection can be realized in an advantageous manner. The fuel injection valve 1 can thus be designed in particular when using a piezoelectric actuator 6 so that a specific suitability for detecting an end of an injection process, as shown in the Fig. 6 is illustrated by the time t ₃ exists.

Fig. 7 shows the in Fig. 1 Section II of the fuel injection valve 1 in a partial, schematic sectional view corresponding to a sixth Embodiment when new before a first pressurization. In this embodiment, the control valve 30 has a valve closing body 31 with an axial, continuous bore 38. In the through hole 38, the power transmission element 37 is introduced. The power transmission element 37 is formed in this embodiment of a material based on a fuel-resistant, elastic plastic. The power transmission element 37 is in this case designed cylindrical in the new state. By contrast, the through bore 38 in this exemplary embodiment is not exactly cylindrical. For in the field of power transmission to the contact surface 42 of the transmission device 36, an annular gap 81 is formed between an inner wall 80 of the through bore 43 and the cylindrical force transmission element 37. Furthermore, a further end face 67 of the power transmission element 37, which is remote from the pressurized in operation end face 39 of the power transmission element 37, in the new state, a slight distance of the power transmission element 37 to the contact surface 42 of the transmission device 36 and / or the other end face 82 is not accurate be designed plan.

Then, the pressure p _{v is established} in the valve chamber 32 during startup, so that the control valve 30 is applied for the first time with the pressure p _v . The resulting influence on the force transmission element 37, in particular the elastic plastic of the force transmission element 37, is based on the Fig. 8 described in more detail below.

Fig. 8 shows the in Fig. 7 shown section of the fuel injection valve 1 according to the sixth embodiment in the state with pressurization. By the pressurization of the end face 39 of the force transmission element 37, the axial force F is generated. Due to the resulting axial force F on the force transmission element 37, this deforms elastically, wherein it is shortened in the longitudinal direction and expands in the radial direction. At high pressure, a partial plastic deformation of the force transmission element 37 is possible and permissible. As a result, existing cavities between the power transmission element 37 and the inner wall 80 of the bore 38 and between the power transmission element 37 and the contact surface 42 of the transmission device 36 are completely filled. For example, the annular gap 81 is filled up by the deformation of the force transmission element 37, so that it disappears, at least for the duration of the pressurization. Thus lays down the force transmission element 37 evenly against the inner wall 80 of the through bore 38 at.

When the force transmission element 37 is acted upon by the axial force F, it thus presses against the inner wall 80 of the bore 38 of the valve closing body 31 in a form-fitting manner due to its transverse expansion, thereby sealing it completely. As a result, the requirements for the accuracy of the design of the bore 38 of the valve-closing body 31 of the control valve 30 and the accuracy of the outer contour of the force transmission element 37 are significantly reduced. Thus, in this way, a particularly simple embodiment with the force transmission element 37 can be realized from the fuel-resistant, elastic plastic.

As a fuel-resistant, elastic plastic advantageously a thermoplastic or an elastomer can be used. It is particularly advantageous if a silicone is used as the elastic plastic. The power transmission element 37 is wholly or partly formed from the material, which is based on the fuel-resistant, elastic plastic.

In order to avoid the emergence of a closed pressure chamber between the force transmission element 37 and the contact surface 42 of the transmission device 36 to the actuator 6, the contact surface or contact line between the other end face 67 of the force transmission element 37 and the contact surface 42 is preferably not closed circumferentially, but executed interrupted. This can be realized, for example, by means of small grooves or notches in at least one of the two surfaces, that is to say on the end face 39 and / or on the contact surface 42. However, in the concrete case of application, this may involve the risk that the force transmission element 37 may be extruded at high loads through such grooves or notches and thus ultimately damaged or destroyed. To avoid this, a dimensionally stable sealing element 83 can be introduced above the force transmission element 37 in the bore 38, as it is based on the Figures 9 and 10 is described in more detail. Additionally or alternatively, to avoid extrusion of the force transmission element 37 due to the high axial force at its support point on its other end face 67, a reinforcement of the material, which is based on the elastic plastic, be provided by reinforcing elements of higher-strength materials. For this purpose, the material which is based on the fuel-resistant, elastic plastic, reinforcing elements, wherein the plastic is reinforced by the reinforcing elements. For the reinforcing elements Glass fibers, carbon fibers or metal particles and suitable mixtures of such fibers and / or particles can be used.

Fig. 9 shows the in Fig. 1 labeled II section of the fuel injector 1 in a partial, schematic sectional view according to a seventh embodiment of the invention. In this exemplary embodiment, the dimensionally stable sealing element 83 is arranged between the further end face 67 of the force transmission element 37 and the contact surface 42 of the transmission device 36. In this case, the further end face 67 has a configuration adapted to the surface 84 of the sealing element 83. In this embodiment, the further end face 67 is designed partially spherical and concave. In this way, the sealing element 83 can be partially inserted into the force transmission element 37, wherein it bears against the further end face 67.

The dimensionally stable sealing element 83 is preferably made of metal and has a guide clearance to the inner wall 80 of the bore 38, in which it is at least partially inserted. On the one hand, the guide play is large enough to ensure easy production of the through bore 38 of the valve closing body 31 and of the dimensionally stable sealing element 83, and on the other hand is small enough to reliably prevent extrusion of the force transmission element 37 through the guide gap. For example, the guide clearance of the sealing element 83 in the bore 38 may be on the order of 10 μm. In order to increase the upper limit for this guide play and to improve the robustness of the control valve 30, the material for the power transmission element 37, which is based on the elastic plastic, can be stabilized by said reinforcing elements. For this purpose, for example, glass fibers, carbon fibers or metal particles in question.

The dimensionally stable sealing element 83 is designed in this embodiment as a spherical sealing element. In a modified embodiment, the dimensionally stable sealing element 83 may also be designed as a cylindrical sealing element 83. Furthermore, other modifications with respect to the configuration of the sealing element 83 are possible. The further end face 67 of the force transmission element 37 may in this case be adapted to the surface 84 of the sealing element 83 in its respective configuration.

Fig. 10 shows a fuel injection valve 1 in a partial, schematic sectional view according to an eighth embodiment of the invention. In In this exemplary embodiment, the control valve 30 is connected to the piezoelectric actuator 6 via a transmission device 36 designed as a hydraulic coupler 36. The hydraulic coupler 36 acts as a high pass and thus can not transmit stationary forces. Therefore, the force F is transmitted in this embodiment via the further power transmission element 63 to the other coupler body 62. The basic principle corresponds to the fourth embodiment, which is based on the Fig. 4 is described, or the fifth embodiment, based on the Fig. 5 is described. Since the power transmission element 37 in the now using the Fig. 10 described eighth embodiment is at least partially formed of the material, which is based on the fuel-resistant, elastic plastic, it may in a possible embodiment in which the force transmission element 37 acts directly on the further force transmission element 63, at the contact point between the force transmission element 37 and further force transmission element 63 in the respective application to an extrusion of the force transmission element 37 come. In such applications, in which there is a risk that the power transmission element 37 extruded in direct transmission to the further force transmission element 63, the dimensionally stable sealing element 83 is additionally provided, as shown in the Fig. 10 is shown.

The dimensionally stable sealing element 83 is in this case arranged between the force transmission element 37 and the further force transmission element 63. Thus, the power transmission member 37 is prevented from extruding at the contact point to the other power transmission member 63. Thus, the potential scope can be increased.

Thus, the power transmission element 37 may advantageously be at least partially formed of a material based on a fuel-resistant, elastic plastic. In a modified embodiment, it may also be particularly advantageous not to manufacture the power transmission element 37 separately and to insert it into the bore 38 of the valve closing body 31, but to inject it directly into the through bore 38 of the valve closing body 31. In one embodiment, in which a dimensionally stable sealing element 83 is provided, the dimensionally stable sealing element 83 can already be inserted into the bore 38 before the material for the force transmission element 37 is injected into the bore 38. In this way, the finished valve closing body 31 can be easily made with the power transmission element 37 and the dimensionally stable sealing element 83.

Thus, advantageous embodiments of the control valve 30 are possible in which the dimensionally stable sealing element 83 bears against the further end face 67 of the force transmission element 37, wherein the force transmission element 37 transmits the force F via the sealing element 83 at least indirectly to the actuator 6.

The invention is not limited to the described embodiments.

Claims (9)

1. Fuel injection valve (1), in particular injector for fuel injection systems of air-compressing, autoignition internal combustion engines, having an actuator (6) and having a control valve (30), wherein a valve closing body (31) of the control valve (30) can be at least indirectly actuated by the actuator (6), wherein a force-transmitting element (37) is provided, in that the force-transmitting element (37) is guided at least in sections in the valve closing body (31), in that the valve closing body (31) is designed such that a face side (39) of the force-transmitting element (37) can be acted on by a pressure (p_v) in a valve chamber (32) of the control valve (30), and in that the force-transmitting element (37) at least indirectly transmits to the actuator (6) a force (F) arising from the action of the pressure (p_v) in the valve chamber (32) on the face side (39) of the force-transmitting element (37), characterized in that
   the actuator (6) actuates the valve closing body (31) via a hydraulic transmitting device (36), and in that the force (F) can, by way of mechanical bypassing of the hydraulic transmitting device (36), be transmitted from at least the force-transmitting element (37) to the actuator (6), wherein the actuator (6) is in the form of a piezoelectric actuator (6).
2. Fuel injection valve according to Claim 1,
   characterized
   in that the actuator (6) actuates the valve closing body (31) via a mechanical transmitting device (36), and in that the force-transmitting element (37) transmits the force (F) to the actuator (6) via the mechanical transmitting device (36).
3. Fuel injection valve according to Claim 1,
   characterized
   in that the hydraulic transmitting device (36) has a coupler chamber (60) and a coupler body (61), in that a low-pressure chamber (10) is provided, in that, between the low-pressure chamber (10) and the valve chamber (32), there is provided a sealing seat formed by the valve closing body (31), in that an actuator-side face side (77) of the coupler body (61) delimits the coupler chamber (60), in that a valve closing body-side face side (42) of the coupler body (61) bears against the valve closing body (31), and in that the force-transmitting element (37) and/or at least one further force-transmitting element (63) are/is guided through the coupler body (61).
4. Fuel injection valve according to Claim 3,
   characterized
   in that the coupler body (61) has a passage bore (64), and in that the at least one further force-transmitting element (63) is guided in at least substantially continuous fashion along the passage bore (64) of the coupler body (61).
5. Fuel injection valve according to Claim 3,
   characterized
   in that the coupler body (61) has a passage bore (64) which extends through the coupler body (61), in that the at least one further force-transmitting element (63) is guided in a widened guide section (71) of the passage bore (64) of the coupler body (61), and in that the widened guide section (71) of the passage bore (64) extends to the actuator-side face side (77) of the coupler body (61).
6. Fuel injection valve according to Claim 4 or 5,
   characterized
   in that the force-transmitting element (37) bears, in the region of the valve closing body-side face side (42) of the coupler body (61), against the further force-transmitting element (63).
7. Fuel injection valve according to one of Claims 1 to 6,
   characterized
   in that the valve closing body (31) has a continuous bore (38) in which the force-transmitting element (37) is guided.
8. Fuel injection valve according to one of Claims 1 to 6,
   characterized
   in that the valve closing body (31) has a blind bore (43) in which the force-transmitting element (37) is guided, in that, in the blind bore (43), the face side (31) of the force-transmitting element (37) delimits a pressure chamber (44), and in that the valve closing body (31) has at least one lateral connecting bore (45, 46) which connects the pressure chamber (44) to the valve chamber (32).
9. Fuel injection valve according to Claim 8,
   characterized
   in that a low-pressure chamber (10) is provided, in that, between the low-pressure chamber (10) and the valve chamber (32), there is provided a sealing seat which is formed by the valve closing body (31), and in that, in a valve sleeve (50) in which the valve closing body (31) is guided, a face side (47), averted from the low-pressure chamber (10), of the valve closing body (31) separates a pressure-relieved sub-chamber (51) from the valve chamber (32).

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