WO2018046204A1 - Fluid injector for a motor vehicle - Google Patents

Abstract

A fluid injector (1) for a motor vehicle comprises an actuator (3), a nozzle needle (9) and a valve plate (30) which has a first and a second recess (31, 32), which forms a hydraulic coupling between the actuator (3) and the nozzle needle (9). The fluid injector (1) also comprises a control valve (20) and a pressure-regulating valve (10), part of which is arranged in the valve plate (30) and which, in a first state, closes a cut-off channel (14) in the valve plate (30) and prevents fluid flowing through the cut-off channel (14) and, in a second state, allows fluid to flow through the cut-off channel (14). A fluid pressure in the fluid injector (1) can be regulated in this manner by means of the pressure-regulating valve (10) interacting with the actuator (3).

Description

description

Fluidinj ector for a motor vehicle The invention relates to a Fluidinj ector for a motor vehicle, which is inexpensive to manufacture and provide an ^¬ reliable operation and a precise metering of fluid possible. Internal combustion engines are often designed to produce high torques requiring large injection quantities. On the other hand, legal regulations regarding the permissible pollutant emissions of internal combustion engines, which are arranged in motor vehicles, require various measures to be taken by which pollutant emissions are kept low. One

The starting point here is to be able to meter a fluid required as fuel as accurately as possible and to reduce the pollutant emissions generated by the internal combustion engine. The reduction of pollutant emissions from internal combustion engines and accurate metering of a metered fluid are in the construction of Fluidinj injectors a great challenge. It is necessary to take into account a variety of parameters in order to enable reliable and precise operation of the fluid injector.

It is an object of the invention to provide a Fluidinj ector for a motor vehicle, which is inexpensive to produce and which allows reliable operation and precise metering of fluid and which helps to minimize pollutant emissions in an internal combustion engine ^¬ . The problem is solved by the features of independent Pa ^¬ tentanspruchs. Advantageous embodiments are specified in the subclaims. According to a first aspect of the invention, a fluid injector for a motor vehicle comprises an actuator which is designed to axially move a nozzle needle relative to a longitudinal axis of the fluid injector. The fluid injector further comprises a valve plate having a first and a second recess, which form a hydraulic coupling between the actuator and the nozzle needle. The fluid injector further comprises a control valve, which is arranged within the first recess of the valve plate and is coupled to the actuator in order to translate a movement of the actuator into a movement of the nozzle needle. In addition, the Fluidinj ector comprises a pressure control valve which is at least partially in the valve plate at ^¬ arranged and which closes in a first state a diversion conduit in the valve plate and in an operation of the Fluidinj ector fluid flow through the spill channel un- terbindet. In a second state of the pressure control valve, a fluid flow is released through the Absteuerkanal, so that by means of the pressure control valve in cooperation with the actuator, a fluid pressure in the fluid injector is regulated. The described Fluidinj ector allows reliable operation and precise metering of fluid in a combustion chamber of an internal combustion engine and contributes to

Keep pollutant emissions in the engine low. In particular, due to the integrated pressure in the valve plate pressure control valve, a controlled pressure reduction of the fluid pressure in the fluid injector is possible, which can be advantageous to the functionality of the injectors Fluidinj and precise metering of an injection quantity to be injected. By means of the described Fluidinj ector and arranged in the Ven ^¬ tilplatte pressure regulating valve can be saved ector zusätz ^¬ Liche, separate actuators for pressure reduction of fluid pressure in a Fluidinj. Such additional

Actuators cause besides their own component costs further costs, which are due to an extension of a leakage line, an associated control electronics and a required electrical connection to a respective control unit. Such costs can be saved by means of the described fluid injector, since a reliable and useful valve function for pressure control of the fluid pressure in the fluid injector is realized in a simple and cost-effective manner by the pressure regulating valve arranged in the valve plate.

In this way, by means of the pressure control valve of the fluid injector a controlled rules of a predetermined fluid pressure within the fluid injector can be realized, which is fed starting from a storage or rail space in the Fluidinj ector. In particular, a reliable and reliable pressure reduction of an increased fluid pressure in the fluid injector is therefore also possible with a rapid load reduction of an associated internal combustion engine. In addition, a construction-related idle stroke of the actuator for a controlled pressure reduction is specifically made use of by means of the described Druckrege ^¬ ment valve of the fluid injector. Such Leerhub is given for example in indirectly driven Fluidinj ectors with piezoelectric actuator to ensure a safe closing of the control valve. Such an idle stroke represents a gap between the discharged actuator and the control valve and is for example a few microns. According to a development ector of Fluidinj the pressure ^¬ control valve is arranged and designed such that it is evident with respect to a longitudinal axis of the spill channel in a direction from a first axial end of the spill channel to a second axial end of the spill channel, said first axial end of the nozzle needle facing and the second axial end of Dü ^¬ sennadel facing away.

The fluid injector is realized, for example, as a servo-piezoelectric fluid injector, in which the pressure regulating valve forms an outwardly opening valve in the valve plate of the fluid injector in addition to the inwardly opening control valve. In this context, the terms "inwardly" and "outwardly" designate an opening direction of the respective valves, which faces the nozzle needle ("inward") or avoids ("outwards").

In other words, has an associated fluid channel, which is controlled by the respective valve, based on a

Longitudinal axis of the fluid channel on an axially upper and an axially lower end. Viewed in terms of flow technology, the upper end of the fluid channel faces away from the nozzle needle and faces the lower end of the nozzle needle. The inwardly opening control valve thus opens in a direction from the upper to the lower end of the associated fluid channel, which is realized in the described construction of the fluid injector by the first recess of the valve plate. The outwardly opening pressure regulating valve accordingly opens in a direction opposite to the control valve from the lower end to the upper end of the associated fluid passage formed by the discharge passage. According to a development of the Fluidinj ector, the STEU ^¬ erventil a valve body with a penetrating recess which forms the spill channel of the pressure control valve. The pressure regulating valve is integrated according to such a development in the control valve, so that by means of a simple and inexpensive modification of the control valve forming the pressure control valve can be realized.

According to one embodiment, the valve plate has a further penetrating recess which the Absteuerkanal of the

Pressure control valve forms. Also, adjusting the Ven ^¬ tilplatte means forming a further recess realizes a simple and inexpensive way, the pressure Rege ^¬ lung beneficial valve for pressure reduction in the fluid pressure in the Fluidinj to mold ector. In this way, existing components of the Fluidinj ectors can be modified to allow in addition to their previous task, the function of the pressure control ^¬ valve. In further embodiments, the fluid injector can also comprise two or more pressure control valves, so that, for example, as described above, a

Pressure control valve is integrated in the control valve and another is formed in the valve plate.

According to a further development of the fluid injector, the pressure regulating valve comprises a valve lever, which is coupled with respect to the longitudinal axis of the fluid injector on the one hand with the actuator and on the other hand with the pressure regulating valve. By means of the valve lever, a movement of the actuator is translatable into a movement of the pressure control valve, so that in the interaction of the actuator and the valve lever, a fluid pressure in the fluid injector can be regulated.

According to a further development of the fluid injector of the valve lever is based on the longitudinal axis of the fluid injector on the one hand with the Actuator and on the other hand coupled to the pressure control valve and the control valve. In this way, by means of the actuator and the valve lever, a control of the control valve and the pressure control valve, so that a beneficial Absteuerung the fluid pressure in the Fluidinj ector is possible.

Embodiments of the invention are explained in more detail below with reference to the schematic drawings. In the drawings: Figure 1 an embodiment of a Fluidinj ector in a schematic sectional view showing an embodiment of a pressure control valve of the Fluidinj ector, a further embodiment of a pressure control passage ^¬ lung valve of Fluidinj ector, various curves for the functionality of a Fluidinj ector piezoelectric actuator depending on a piezoelectric voltage, and a piezoelectric charge.

Elements of the same construction or function are identified across the figures with the same reference numerals. For reasons of clarity, not all of the illustrated elements may be indicated in all figures with associated reference numerals.

Figure 1 illustrates in a schematic sectional view of an embodiment of a fluid injector 1, which comprises an injector body 63 and a nozzle body 68, which is coupled to the injector 63. Within a recess of the injector body 63, which along a longitudinal axis L of the Fluidinj ector 1 is bounded by a wall of the injector body 63, a piezoelectric actuator 3 is arranged, which is coupled to a nozzle needle 9 to move axially relative to the longitudinal axis L and in a closed position of the nozzle needle 9 a fluid flow through the Fluidinj ector 1 to stop and otherwise release.

The piezoelectric actuator 3 is coupled to an electrical connection 60 of the fluid injector 1, which is designed for the energetic supply and control of the actuator 3. The Fluidinj ektor 1 further comprises a pressure control valve 10 and a control valve 20 which are at least partially integrated in a Ven ^¬ tilplatte 30. As will be explained with reference to the following figures 2 to 4, by means of the pressure control valve 10 is a reliable and safe operation of the Fluidinj ector 1 and a precise metering of fluid in a combustion chamber of an internal combustion engine reali ^¬ sierbar. Among other things, this is a contribution to a cost-effective design of the Fluidinj ector 1 and for keeping low pollutant emissions in an internal combustion engine.

In addition, a high-pressure bore 64 of the Fluidinj ector 1 is illustrated, which couples the Fluidinj ektor 1 with a storage or rail space and which allows supplying the Fluidinj ector 1 with fluid.

Figure 2 illustrates the dashed line in Figure 1 marked area in which the pressure control valve 10 and the STEU ^¬ erventil 20 are arranged. The valve plate 30 has a first and a second recess 31 and 32 which, in cooperation with associated recesses 51 and 52 of a throttle plate 5, a hydraulic coupling between the piezoelectric actuator 3 and the nozzle needle 9 form. Relative to the longitudinal axis L of Fluidinj ector 1, the throttle plate 5 between the Ven ^¬ tilplatte 30 and the nozzle needle 9 is disposed so that the first groove 51 of the throttle plate 5 adjoins the first recess 31 of the valve plate thirtieth Analog connects the second recess 52 from ^¬ the throttle plate 5 to the second recess 32 of the valve plate 30, which is coupled, for example, with the high-pressure range or the high-pressure bore 64 of the Fluidinj ector. 1

The control valve 20 is disposed within the first recess 31 of the valve plate 30 and allows a translation of a movement of the actuator 3 in a movement of the nozzle needle 9. In the first recess 31, a biasing member 26 is also arranged, which a predetermined force on the control valve 20 in the direction of the actuator 3 exerts and presses a valve body 20 of the control valve 20 against an inner wall of the valve plate 30, which limits the first recess 31. The pressure regulating valve 10 has a discharge channel 14 and a valve element 12 and is partially disposed in the valve plate 30. According to the example shown in Figure 2 ^¬ execution example, the pressure control valve 10 is integrated in the control valve 20th The valve body 22 of the control valve 20 has a penetrating recess 24, which forms the Absteuerkanal 14 of the pressure control valve 10.

The pressure regulating valve 10 is designed to close the bypass duct 14 in the valve plate 30 in a first state and to prevent fluid flow through the bypass duct 14. This is done by controlling the actuator 3, which presses the valve element 12 of the pressure control valve 10 against the valve body 22 of the STEU ^¬ erventils 20 by means of a piston 7 and thereby closes the discharge channel 14. Preferably, a top of the valve body 22 is adapted to a shape of a bottom of the valve member 12 so that the top of valve body 22 forms a valve seat for the Ven ^¬ tilelement 12th

In a second state, the pressure regulating valve 10 is opened and a fluid flow through the diversion channel 14 is released. By means of the pressure regulating valve 10, a fluid pressure in the fluid injector 1 can be regulated in cooperation with the actuator 3, so that a controlled pressure reduction of the fluid pressure in the fluid dinjektor 1 can be realized.

 The pressure regulating valve 10 is preferably designed and arranged so that a construction-related idle stroke of the actuator 3 is specifically made use of for controlled pressure reduction. Such an idle stroke is realized as a gap between the discharged actuator 3 and the control valve 20 and is designed to ensure a safe closing of the control valve 20. According to the embodiment of the fluid injector 1 illustrated in FIG. 2, such an idle stroke is related to the longitudinal axis L between the valve element 12 of FIG

Pressure control valve 10 and the valve body 22 of the control ^¬ valve 20 is formed.

The pressure regulating valve 10 forms, in addition to the inwardly opening control valve 20, an outwardly opening valve in the valve plate 30 of the fluid injector 1. The terms "inwardly" and "outwardly" ^¬ a Publ voltage direction of the respective valves, that is, the nozzle needle 9 faces ( "inward") or away ( "outward"). In other words, the pressure regulating valve 10 is arranged and configured to be apparent in a direction from a first axial end of the spillway 14 toward a second axial end of the spillway 14 with respect to a longitudinal axis A of the spillway 14. Here is the first axial end ₁

the Absteuerkanals 14 of the nozzle needle 9 fluidly facing and the second axial end of the Absteuerkanals 14 of the nozzle needle 9 facing away. The inwardly opening control valve 20 thus opens in a direction towards the throttle plate 5 from the second to the first axial end of the Absteuerkanals 14. An opening of the control valve 20 by means of energization of the actuator 3 against the spring force of the biasing member 26. The outwardly opening pressure - Corresponding valve 10 opens in a direction opposite to the control valve 20 toward the actuator 3 from the first to the second axial end of the diversion channel 14th

The described Fluidinj ektor 1 thus comprises an inwardly opening control valve 20 and an outwardly opening pressure control valve 10, which e ^¬ an advantageous pressure compensation ^¬ the fluid pressure within the Fluidinj ektor ^¬ possible and reliable operation and a cost-effective design of the Fluidinj ectors. 1 contribute.

FIG. 3 illustrates a further exemplary embodiment for configuring the pressure regulating valve 10, in which the Absteu ^¬ erkanal 14 is formed as part of a further recess 34 which penetrates the valve plate 30. To the further recess 34 includes a third recess 33 of the valve plate 30, which hydraulically couples the pressure control valve 10 to the high-pressure region.

According to this embodiment, the valve body 12 functions of the pressure control valve 10 with an upper wall of the Ven ^¬ tilplatte 30 together. Preferably, therefore, an upper side of the valve plate 30 in the region of the pressure regulating valve 10 and the further recess 34 is adapted to a shape of an underside of the valve element 12, so that the wall of the valve plate 30 relative to the longitudinal axis L of the fluid injector 1 in the axially upper region of the recess 34 forms a valve seat for the valve element 12. Analogous to the idle stroke according to Figure 2 between the valve element 12 and the valve body 22, an idle stroke between the valve ^¬ element 12 and the wall of the valve plate 30 is formed in this embodiment. The control valve 20 and the valve body 22 of the

Control valve 20 is formed in this embodiment without penetrating recess.

Compared to the embodiment of Figure 2, the pressure control valve 10 in this embodiment, a further element in the form of a valve lever 16, which is arranged between the piston 7 and the valve element 12 and the valve element 22. The valve lever 16 implements a lever ratio to the control valve 20 and the pressure ^¬ control valve 10, in which a Absteuern a fluid pressure directly from the high-pressure region before the throttles of the fluid dinjektors 1 can be done. The throttles are realized for example by the first and second recesses 51 and 52 of the throttle plate. By positioning the point of attack on the valve lever 16 also a degree of freedom for the design of the fluid injector 1 is created. By actuating the actuator 3, a force is exerted on the valve lever 16, which causes a movement of the control valve 20 and the pressure regulating valve 10. Thus, the inward-opening control valve 20 is opened while the outward-opening pressure regulating valve 10 is placed in a closing state. In this way, a controlled

Pressure control of the fluid pressure in the Fluidinj ektor 1 can be achieved, which is advantageous for driving and operation of the Fluidinj ector 1 and a precise metering of fluid in a combustion chamber of an internal combustion engine made ^¬ light.

Both concepts for pressure control by means of the pressure control valve 10 according to the illustrated embodiments of Figure 2 and 3 has in common that a prevailing in the Fluidinj ektor 1 fluid pressure, which emanates from an associated rail or Sepicherraum, causes opening of the pressure control valve 10. The valve element 12 of the pressure regulating valve 10 is pushed against the piston 7 and this to the bottom plate of the piezoe ^¬ lektrischen actuator 3. In a de-energized state of the actuator 3, the system of Fluidinj ector 1 is thus leakage ^¬ afflicted. To close the pressure control valve 10, the actuator 3 is loaded to a predefined partial stroke, so that the existing idle stroke is compensated. Such a forward stroke of the piezoelectric actuator 3 allows a hydraulic Ab ^¬ densities of the high-pressure system in the Fluidinj ektor 1, which is in terms of efficiency and pressure-holding capacity of importance.

In order to selectively reduce the fluid pressure in the fluid injector 1, the fluid injector is completely or partially discharged from the set partial stroke of the actuator 3. In this way, the pressure regulating valve 10 can be opened in a controlled manner and the fluid pressure can be reduced by the diversion channel 14 and fed to a leakage path.

In Figure 4 are different gradients V_DV, V_PA and V_PAo the functionality of a Fluidinj ector 1 as a function of a piezoelectric voltage U _P i _{e Z o} and a piezoelectric

Charge E _{P ezozo} qualitatively represented. These gradients V_DV, V_PA and V_PAo illustrate a Druckregelungs- and injection ^¬ function of Fluidinj ector. 1 The course V_DV represents a flow through the pressure regulating valve 10 as a function of the piezoelectric charge E _P i _{ezo of} the actuator 3. Between a starting position PO of the fluid injector 1 and a position PI, which represents a throttle start by the pressure regulating valve 10, is the

Flow almost constant. From the throttle start in position PI, the flow decreases continuously with increasing charge E _{P ezo of} the actuator 3 until the pressure control valve 10 is closed (position P2). In this first functional area I of the Fluidinj ector 1, a force build-up takes place by pressure build-up in the spring chamber, which is located in the region of the biasing element 26 in the first recess 31 of the valve plate 30.

The course V_PA represents the piezoelectric voltage Upi _ezo as a function of the piezoelectric charge E _P i _{ezo of} the actuator 3. The piezoelectric voltage U _P i _e z _o increases with zu ^¬ taking piezoelectric charge E _{P ezo ezo of} the actuator 3 to a position P3, at which the control valve 20 is opened by means of the actuator 3. From then on, the piezoelectric voltage Upi _{ezo decreases} with increasing piezoelectric charge E _{P ezo of} the actuator 3. In the marked second functional area II of the fluid injector 1, a further force build-up takes place by opening the control valve 20, while in the third functional area III of the fluid injector 1 a force reduction by relieving the spring space is achieved by opening the control valve 20. The course V_PAo represents the sole piezoe ^¬ lectric voltage Upi _ezo as a function of the piezoelectric charge E _{P ezo ezo of} the actuator 3 without additional hydraulic power.

In addition, various functionalities of the fluid injector 1 are indicated in Figure 4 with the arrows F_D and F_F, which can be assigned to the corresponding functional areas. F_D represents the range of the pressure control function for Pressure reduction of fluid pressure within the fluid injector 1 by means of the pressure control valve 10. F_F represents a further functionality of the fluid injector 1 among other things for opening the control valve 20 and the nozzle needle 9 for injecting a predetermined injection quantity into a combustion chamber of an internal combustion engine.

According to the relationships illustrated in FIG. 4, a robust algorithm can be used to enable detection of the idle stroke between the valve body 12 of the pressure regulating valve 10 and the control valve 20 or the valve plate 30. For example, if the control valve 20 and the pressure regulating valve 10 are closed, the system of the fluid injector 1 has no permanent leakage. By means of energization of the piezoelectric actuator 3, a force is induced, which increases upon further charging of the actuator 3. Such an increase in force correlates with the closing of the pressure regulating valve 10.

Reference sign list

fluid injector

 actuator

 throttle plate

 first recess of the throttle plate

 second recess of the throttle plate

 piston

 nozzle needle

 Pressure control valve

 valve element

 spill channel

 valve lever

 control valve

 Valve body of the control valve

 Recess of the valve body

 biasing member

 valve plate

 first recess of the valve plate

 second recess of the valve plate

 further recess of the valve plate

 electrical connection

 Inj ector body

 High-pressure bore

 nozzle body

A longitudinal axis of the diversion channel

Epi _ezo charge of the piezoelectric actuator

 F_D Functionality of the pressure regulating valve for pressure control F_F Functionality of the fluid injector

L longitudinal axis of the fluid injector

 P (i) different positions of the functionality of the fluid injector

Upiezo voltage of the piezoelectric actuator V_DV Course of the flow through the pressure regulating valve for pressure control

 V_PA Course of the piezoelectric voltage as a function of the piezoelectric charge of the actuator

V_PAo Course of the piezoelectric voltage as a function of the piezoelectric charge of the actuator without additional force

Claims

Fluid injector (1) for a motor vehicle, comprising:  an actuator (3) which is designed to move a nozzle needle (9) axially with respect to a longitudinal axis (L) of the fluid injector (1),  a valve plate having first and second recesses forming a hydraulic coupling between the actuator and the nozzle needle;  - A control valve (20) which is disposed within the first recess (31) of the valve plate (30) and for translating a movement of the actuator (3) in a movement of the nozzle needle (9) is coupled to the actuator (3), and  - A pressure control valve (10) which is partially disposed in the valve plate (30) and which is adapted to close in a first state, a Absteuerkanal (14) in the valve plate (30) and a fluid flow through the Absteuerkanal (14) stop and in a second state to release a fluid flow through the Absteuerkanal (14), so that by means of the pressure control valve (10) in cooperation with the actuator (3), a fluid pressure in the Fluidinj ector (1) is adjustable. A fluid injector (1) according to claim 1, wherein the pressure regulating valve (10) is arranged and configured to move in a direction from a first axial end of the diversion passage (14) with respect to a longitudinal axis (A) of the diversion passage (14) second axial end of the Ab ^¬ control passage (14) is apparently, wherein the first axial end of the nozzle needle (9) facing away and the second axial end of the nozzle needle (9) facing away. Fluid injector (1) according to claim 1 or 2, wherein the control valve (20) has a valve body (22) with a penetrating recess (24) forming the Absteuerkanal (14) of the pressure regulating valve (10). Fluid injector (1) according to one of claims 1 to 3, wherein the valve plate (30) has a further penetrating recess ^¬ (34), which forms the Absteuerkanal (14) of the pressure control valve (10). Fluid injector (1) according to one of claims 1 to 4, wherein the pressure regulating valve (10) comprises a valve lever (16) which is coupled on the one hand with the actuator (3) and on the other hand with the pressure regulating valve (10) and by means of a movement of the actuator (3) in a movement of the Pressure control valve (10) can be translated, so that by means of the valve lever (16) in cooperation with the actuator (3), a fluid pressure in the Fluidinj ector (1) is adjustable. Fluid injector (1) according to claim 5, wherein the valve lever (16) on the one hand with the actuator (3) and on the other hand with the pressure control valve (10) and the control valve (20) is ge ^¬ coupled.