EP2726723B1 - Fuel injection valve - Google Patents

Description

State of the art

The invention relates to a fuel injection valve according to the preamble of claim 1, and an electrical circuit and a method according to the independent claims.

Switching elements, such as relays or solenoid valves, which are used in particular as injection valves of an internal combustion engine are exposed to high demands during operation and are therefore frequently monitored. This monitoring is done for example by an evaluation of currents and / or voltages of an actuator of the switching element. In particular, sensors can serve for this purpose, which detect physical variables and convert them into electrical variables. The transmission of these quantities to a control unit or the like is generally associated with an increased expense in terms of the number of electrical lines.

In solenoid valves for gasoline direct injection of internal combustion engines electrical control variables of the magnetic circuit can be used to determine the closing time of a nozzle needle of the injection valve when the magnetic circuit actuates the nozzle needle directly. In this case, additional measuring lines or the like are often unnecessary. In contrast to this - for example for diesel injection - there are versions of injection valves, in which the magnetic circuit additionally actuates a servo valve, which subsequently controls a nozzle needle-operated high-pressure hydraulics. The closing time of the nozzle needle can not be determined from the movement of a magnet armature of the solenoid valve.

From the DE 10 2010 063 681 a method is known in which a measuring state is produced in which at least one connection of the actuator is at least temporarily decoupled from a reference potential and / or from a source controlling the actuator substantially. In the measuring state, at least one signal of at least one sensor of a sensor device is determined from at least one electrical potential at at least one connection of the actuator. Advantageously, lines to the actuator and the sensor device can be saved.

Disclosure of the invention

The problem underlying the invention is solved by a fuel injection valve according to claim 1 and by an electrical circuit and a method according to the independent claims. Advantageous developments are specified in the subclaims.

Characterized in that the sensor device comprises a sensor and a series resistor connected in series with the sensor and in a first phase in the control of an actuator, the current is limited by the sensor, a disturbance or damage of the sensor is advantageously prevented. The series resistor connected in series with the sensor also offers advantages with regard to the design of the sensor. The sensor may, for example, have a high capacity, without resulting in detrimental effects on the activation of the actuator. In particular, high-capacity piezoelectric sensors can thereby be used. The capacitance of the sensor and the series resistor form a first low-pass first order, which advantageously reduces the above-described load on the sensor in the control of the actuator.

In an advantageous development, the ohmic resistance of the series resistor is substantially greater than the ohmic resistance of the actuator. In the first phase much more power is supplied to the actuator than the sensor device. In the event of a short circuit of the sensor, the series resistor advantageously ensures that the actuator can continue to operate despite the short circuit.

An electrical circuit advantageously comprises a capacitor between the one terminal of the actuator, to which the sensor device is connected. In a third phase, a signal of the sensor of the sensor device is determined as a function of the electrical potential at the capacitor of the electrical circuit. In the third phase, the sensor has voltage source character. The series resistor and the capacitor of the electrical circuit form a second low-pass filter. Accordingly, high-frequency noise can be filtered out and the electrical potential at the capacitor of the electrical circuit is advantageously smoothed and thus there is an improved signal quality. The second low pass consisting of the series resistor of the sensor device and the capacitor of the electrical circuit is advantageously dimensioned such that the sensor signal is attenuated only slightly.

In an advantageous development, the capacitance of the sensor is greater than the capacitance of the capacitor of the electrical circuit. Thus, the time constant of the first low-pass filter is greater than the time constant of the second low-pass filter, which advantageously determines the scanning accuracy predominantly only from the first low-pass filter.

In an advantageous embodiment, the actuator is substantially decoupled from the reference potential and / or from the driving source in a second phase before the third phase and after the first phase. Due to the decoupling, the sensor signal is not degraded via the low-impedance actuator and the sensor signal can be measured.

In an advantageous embodiment, an error of the sensor is determined as a function of the electrical potential or a profile of the electrical potential at the capacitor of the electrical circuit. Depending on the detected error, an error signal is generated by the electrical circuit. Advantageously, it can thereby be taken into account, for example in the case of further operation of the actuator, despite the error that the electrical potential at the capacitor is no longer valid or defective. The electrical potential at the capacitor can thus be advantageously ignored or ignored in the activation of the actuator. A faulty sensor thus does not lead to a faulty operation of the actuator. The error signal can For example, the driver or Werkstattmitarbeiter be displayed, for example, to perform the replacement of the fuel injection valve or perform.

Features which are important for the invention can also be found in the following drawings, wherein the features, both alone and in different combinations, can be important for the invention, without being explicitly referred to again.

Figur 1

eine teilweise Schnittdarstellung eines Servoventils eines Kraftstoffeinspritzventils mit einem magnetischen Schaltglied und einem Ventilstück;

Figur 2

ein Zeitdiagramm eines Steuerraumdrucks und eines Hubs eines als Ventilnadel ausgebildeten Ventilelements des Servoventils von Figur 1;

Figur 3

ein vereinfachtes Schema eines Ausführungsbeispiels zum Anschluss eines Sensors und einer Spule in einem Gehäuse eines Kraftstoffeinspritzventils;

Figur 4 und 5

jeweils ein schematisches Schaltbild mit einem Kraftstoffeinspritzventil und einer elektrischen Schaltung zur Ansteuerung des Kraftstoffeinspritzventils;

Figur 6

ein schematisches Schaltbild einer Sensoreinrichtung des Kraftstoffeinspritzventils in einer ersten Phase; und

Figur 7

ein weiteres schematisches Schaltbild des Kraftstoffeinspritzventils und der elektrischen Schaltung in einer dritten Phase.

Hereinafter, exemplary embodiments of the invention will be explained with reference to the drawings. In the drawing show:

FIG. 1

a partial sectional view of a servo valve of a fuel injection valve with a magnetic switching member and a valve piece;

FIG. 2

a time chart of a control chamber pressure and a stroke of a formed as a valve needle valve element of the servo valve of FIG. 1 ;

FIG. 3

a simplified schematic of an embodiment for connecting a sensor and a coil in a housing of a fuel injection valve;

FIGS. 4 and 5

in each case a schematic circuit diagram with a fuel injection valve and an electrical circuit for controlling the fuel injection valve;

FIG. 6

a schematic diagram of a sensor device of the fuel injection valve in a first phase; and

FIG. 7

another schematic diagram of the fuel injection valve and the electrical circuit in a third phase.

The same reference numerals are used for functionally equivalent elements and sizes in all figures, even in different embodiments.

FIG. 1 shows a partial sectional view of a servo valve 10 of a fuel injector 11 of an internal combustion engine, which is not further illustrated in detail. The servo valve 10 is essentially rotationally symmetrical about a longitudinal axis 12. In an upper portion of the drawing, a fixed to a (not shown) housing support plate 14 is shown in a vertically central region, a magnetic switching member 16 is shown, and in a lower portion is a housing-fixed valve member 18 with a hydraulic control chamber 20 and a shown on a valve needle, not shown, of the fuel injection valve 11 or firmly connected with such a valve needle valve piston 22.

The support plate 14 has in the region of the longitudinal axis 12 a support piston 24, with which a force-sensitive transducer 26 is operatively connected. The force-sensitive transducer 26 is in turn supported in the direction of the longitudinal axis 12 on the support plate 14. In the drawing above the non-positive converter 26, two openings (without reference numerals) are arranged, through which lines for contacting the terminals 70a and 70b of a sensor device 70 are guided. The arrangement of the two openings is in the FIG. 1 merely exemplified.

The magnetic switching member 16 includes a coil 30 which is embedded in a magnetic core 32, wherein the magnetic core 32 is pressed by a plate spring 34 against an annular anchor stop 36. The armature stop 36 is in turn pressed by the diaphragm spring 34 by means of the magnetic core 32 against a diameter jump (no reference numeral) of a sleeve 38 fixed to the housing. Along a central region of the longitudinal axis 12, there is arranged an armature bolt 40 mounted in a play-like manner along the longitudinal axis 12 but held radially, on which an armature 42 is displaceably arranged in the direction of the longitudinal axis 12. An in FIG. 1 lower end portion 44 of the armature 42 may rest on a valve seat forming a sealing portion 46 of the valve member 18. The end portion 44 forms in this respect a valve element of the servo valve 10. The magnetic switching member 16 is like the other elements of the servo valve 10 in Essentially designed rotationally symmetrical, but only the right in the drawing half of a sectional view is shown. A guide diameter of the armature 42 and a seat diameter in the region of the sealing portion 46 are approximately equal.

The valve member 18 defines the hydraulic control chamber 20 and the valve piston 22. The valve piston 22 is displaceable in the valve member 18 in the direction of the longitudinal axis 12 and, as already mentioned above, with a valve element, not shown (nozzle or valve needle) fixedly coupled. In the drawing above the control chamber 20 this is connected via an outlet throttle 48 with a valve chamber 50. In the drawing right of the control chamber 20, an inlet throttle 52 is arranged, through which the control chamber 20 can be fed with a high pressure fluid 54. The fluid 54 is provided, for example, by a common-rail fuel system (not shown). A fluid space 56, in which the armature 42 and the anchor bolt 40 are arranged, is connected to a low-pressure region, not shown.

As long as the coil 30 is not energized, the end portion 44 is pressed by a valve spring, not shown, against the sealing portion 46, the servo valve 10 is thus closed. Due to the pressure conditions in the control chamber 20, the valve piston 22 is pressed down in the drawing, so that the (not shown) valve needle closes. If the coil 30 is energized, the armature 42 is moved by magnetic force in the direction of the magnetic core 32 against the anchor stopper 36. As a result, fluid flows from the control chamber 20 to the fluid chamber 56 out, so that the pressure in the control chamber 20 decreases and the valve needle with the valve piston 22 in FIG. 1 can move up and open. The fuel injection begins. To close the energization of the coil 30 is terminated. By the valve spring, the end portion 44 is again pressed against the sealing portion 46, the servo valve 10 thus closes, and the outflow of fluid from the control chamber 20 is terminated. Since fluid continues to flow via the inlet throttle 52 into the control chamber 20, the valve piston 22 and with it the valve needle in FIG. 1 pressed down in the closing direction. The fuel injection ends.

The closing time of the fuel injection valve 11 can be determined by the course of the force exerted by the anchor bolt 40 against the force-sensitive transducer 26, is evaluated. By such a force or force change, a voltage is built up in the latter or generates a current pulse or there is a change of a passive parameter of the sensor, for example its resistance or its capacitance, whereby a sensor signal is generated. The sensor signal can by means of electrical circuits, as described below in the FIGS. 4 and 5 be described.

The force-sensitive transducer 26 may also be embodied as a sensor which alternatively or additionally detects a force and / or pressure of the fluid 54 and / or structure-borne noise of the support plate 14 or of a housing of the fuel injection valve 11, so that the opening times and / or closing times of the servo valve 10 can be determined. Force sensitive transducer 26 will therefore be generically referred to as sensor 26 below.

FIG. 2 shows a temporal relationship between the pressure 160 in the valve chamber 50, the pressure 60 in the control chamber 20 and the stroke 62 of the valve piston 22 and the associated valve needle. In an upper diagram of the FIG. 2 the pressure 60 in the control chamber 20 and the pressure 160 in the valve chamber 50 are plotted on the ordinate, and the stroke 62 of the valve piston 22 is plotted on the ordinate in a lower diagram. The pressure 60 is shown by a solid line, the pressure 160 by a dashed line. In the present case, a stroke 62 of zero means a closed injection valve. Both diagrams have on the abscissa an equal time scale t.

It can be seen that both at the beginning of the opening movement of the valve piston 22 at a time ta and at the end of the closing movement at a time tb, the course of the pressure 60 experiences clearly visible changes. Immediately before opening at time ta, there is a sudden pressure drop, and when closing at time tb, there is a sudden increase in pressure. The pressure 160 in the valve chamber 50, which is identical with the pressure 60 in the control chamber 20 when the servo valve 10 is closed, acts on the anchor bolt 40 on the force-sensitive transducer 26, and thus can be converted into a sensor signal, so that the changes in the pressure 160 are reflected in the sensor signal and thus can be evaluated for determining, for example, the closing time.

FIG. 3 shows a simplified schematic embodiment for connecting the sensor device 70 and an actuator 80 in a housing 64 of the fuel injection valve 11. The actuator 80, the FIG. 1 explained coil 30 include, but other or further elements. In particular, the actuator 80 may be a part of a magnetic or piezo valve or else a magnetostrictive valve. The described methods are therefore also applicable to other actuator types. The terminals HS and LS of the actuator 80 are isolated out of the housing 64 of the fuel injection valve 11 out. The terminal 70a of the sensor device 70 is electrically conductively connected to the terminal HS of the actuator 80, the further terminal 70b of the sensor 26 is electrically conductively connected to an electrically conductive portion 66 of the housing 64 low impedance. The housing 64 in turn is electrically conductively connected to a reference potential 88, which in the present case is a ground potential of a motor vehicle containing the fuel injection valve 11. This is done by means of the mechanical attachment of the fuel injection valve 11, which is screwed, for example, in an engine block. This is not shown in the drawing.

The sensor 26 determines according to the representation of FIG. 2 the pressure 160 in the valve chamber 50 of the servo valve 10. Via the terminal HS or LS of the actuator 80, a signal of the sensor 26 can be determined by an electrical potential at the terminal HS and LS of the actuator is detected. The arrangement of the sensor 26 within the housing 64, the signal detection is particularly robust and insensitive to interfering electromagnetic couplings.

FIG. 4 shows a schematic circuit diagram with the fuel injection valve 11 and an electric circuit 100 for driving the fuel injection valve 11. The sensor device 70 includes the sensor 26 and a series resistor 90 which is connected in series with the sensor 26. The terminal 70a of the sensor device 70 is connected to the terminal HS of the actuator 80 electrically connected. Alternatively, the terminal 70a of the sensor device 70 may also be connected to the terminal LS of the actuator 80. The other terminal 70b of the sensor device 70 is electrically conductively connected to the reference potential 88. Both connections HS and LS of the actuator 80 are not connected to the reference potential 88, but operating states are conceivable in which the connection HS or LS is at least temporarily connected to the reference potential 88. Of course, the reference potential does not necessarily have to be connected to the vehicle ground, but can refer to another potential level.

Two drive lines 76 and 78 connect the terminals HS and LS of the actuator 80 to the electrical circuit 100. This electrical circuit 100 serves on the one hand for driving the actuator 80 and includes a driver circuit not explained in more detail. Furthermore, the electrical circuit 100 serves for determining a signal of the sensor 26, for which purpose an evaluation circuit, which is not explained in greater detail, is contained in the electrical circuit 100. For controlling the actuator 80 is a non-illustrated source, in particular a DC voltage source. The electrical circuit 100 and thus also the source is supplied via a potential or a supply voltage U _v .

Of course, another resistor may be located between the terminal 70a and the sensor 26. It is also self-evident that between the connection HS or LS of the actuator 80 and the connection 70a as well as between the connection 70b and the reference potential 88 there are further components, such as resistors, coils or capacitors.

In a first phase of the actuator is connected by means of the electrical circuit 100 to the above-mentioned source, that is, connected to the source low resistance. In the first phase of the actuator 80 is thus energized and can, for example, the servo valve 10 from the FIG. 1 into a working position.

In a second phase, the actuator 80 is decoupled from the driving source by means of the electrical circuit 100. The current in the actuator 80 is ideally to zero, and thus, for example, the servo valve 10 of the FIG. 1 go into his rest position.

In a third phase, a measurement state is established to evaluate the signal from the sensor 26. The third phase can also be initiated when, for example, residual energy is present in the actuator 80. The electrical circuit 100 now detects a potential U _{76 of} the control line 76 against the reference potential 88 in order to determine a voltage signal or current signal generated by the sensor device 70 or by the sensor 26. If the connection 70a of the sensor device 70 is connected to the connection LS of the actuator 80, the electrical circuit 100 determines an electrical potential U _{78 of} the control line 78 against the reference potential 88 to generate a voltage signal or voltage generated by the sensor device 70 or by the sensor 26 To determine current signal.

The area between the vertical lines 82 and 84 represents a wiring harness that includes, among other things, the drive lines 76 and 78. The connection 98 between the vertical lines 82 and 84 represents the connection in FIG FIG. 3 between the terminal 70b of the sensor device 70 and the reference potential 88 via the housing 64 and other components.

In the FIG. 4 to the right of the line 84, the electrical circuit 100 is arranged. The electrical circuit 100 is connected to the reference potential 88 and is supplied by a power supply, not shown, with the potential U _v .

Furthermore, the electrical circuit 100 generates a signal 92, which is determined as a function of the potential U ₇₆ or U ₇₈ , wherein the potential U ₇₆ or U _{78 is influenced} by the signal of the sensor 26.

Due to the series resistor 90, which is connected in series with the sensor 26, more power is supplied to the actuator 80 in the control of the actuator 80 by means of the electrical circuit 100 in the first phase than the sensor device 70. For this purpose, the ohmic resistance of the series resistor 90th or the entire sensor device 70 is greater than the ohmic resistance of the actuator 80. In particular, the ohmic resistance of the series resistor 90 is essential greater than the ohmic resistance of the actuator 80, in particular at least by a factor of 5 greater, in particular at least by a factor of 10 larger.

The electrical circuit 100 includes one in the FIG. 4 Not shown capacitor C ₁₀₀ between the one terminal HS and LS, where the sensor device 70 is connected to the terminal 70a, and the reference potential 88. In the third phase, the signal of the sensor 26 of the sensor device 70 from the electrical potential U _76th or the electrical potential U ₇₈ determined.

The sensor 26 is in particular a capacitive sensor and essentially represents a capacitor. A capacitance of the sensor 26 is designated by the reference symbol C ₂₆ . The capacitance C _{26 of} the sensor 26 is greater than the capacitance C _{100 of} the capacitor of the electrical circuit 100.

The electrical circuit 100 can determine a short circuit of the sensor 26 as a function of the electrical potential U ₇₆ or U ₇₈ or the course of the electrical potential U ₇₆ or U ₇₈ . In particular, as a function of the determined short circuit of the sensor 26, the electrical circuit 100 generates an error signal 94.

FIG. 5 shows a schematic circuit diagram with the fuel injection valve 11 and the electric circuit 100 for driving the fuel injection valve 11. Die FIG. 5 essentially corresponds to the FIG. 4 , wherein only the position of the sensor 26 and the series resistor 90 in the sensor device 70 are reversed. Furthermore, the sensor device 70 with its connection 70a can also be connected to the connection LS of the actuator 80.

FIG. 6 shows a schematic diagram of the sensor device 70 of the fuel injection valve 11 in the first phase, regardless of the respective interconnection of the sensor device 70 with the actuator 80. A potential U _A drops at the series circuit of the series resistor 90 and the sensor 26 from. A potential U _B drops at the sensor 26. In the first phase of the actuator 80 is driven. The ohmic resistance of the series resistor 90 and the capacitance C _{26 of} the sensor 26 form a first first order low-pass filter with respect to the transfer function U _B / U _A. A first time constant T _{1 of} this first Low pass results from the product of the ohmic resistance of the series resistor 90 and the capacitance C _{26 of} the sensor 26. By the series resistor 90, the current through the sensor 26 is limited in the first phase.

FIG. 7 shows another schematic diagram of the fuel injection valve 11 and the electric circuit 100 in the third phase. In the third phase, the actuator 80 is substantially decoupled from the reference potential 88 and / or from the driving source. In the third phase, the signal of the sensor 26 via the potentials U ₇₆ and U _{78 is} detected. In the figure to the right of a line 86 is an equivalent circuit diagram of the electrical circuit 100 in the third phase. On the left of the vertical line 86 is an equivalent circuit diagram of the fuel injection valve 11 in the third phase.

The capacitance C _{26 of} the sensor 26 was charged in the first phase by the source and represents in the third phase, a voltage source. The sensor 26 thus generates a potential U _C and a profile of the potential Uc which is detected by the electrical circuit 100 , The ohmic resistance of the series resistor 90 and the capacitance C _{100 of} the capacitor of the electrical circuit 100 form a second first-order low-pass filter. At the series circuit consisting of the series resistor 90 and the capacitor of the electrical circuit 100, the potential U _C drops. At the capacitance C ₁₀₀ drops a potential U _D. The second low pass relates to the transfer function U _D / U _C. A second time constant T _{2 of} the second low-pass filter results from the ohmic resistance of the series resistor 90 and the capacitance C _{100 of} the electrical circuit 100. The second time constant T _{2 of} the second low-pass filter is substantially equal to or smaller than the first time constant T _{1 of} the first low-pass filter , In particular, the capacitance C _{26 is} greater than the capacitance C _{100 of} the capacitor of the electrical circuit 100.

In the case of the implementation of the sensor 26 as a piezo sensor, it does not matter if the sensor 26 has been loaded or not. Even if the piezo sensor has not been charged, it generates a voltage under mechanical stress due to charge transfer.

Claims (14)

1. Fuel injection valve (11) comprising an actuator (80) and a sensor device (70), wherein a first connection (70a) of the sensor device (70) is connected to a connection (HS; LS) of the actuator (80), and wherein a further connection (70b) of the sensor device (70) is connected to a reference potential (88), and the sensor device (70) comprises a sensor (26) and a series resistor (90) connected in series with the sensor (26), characterized in that the further connection (70b) of the sensor device (70) is electrically conductively connected to at least one electrically conductive section (66) of a housing (64) of the fuel injection valve (11).
2. Fuel injection valve (11) according to Claim 1, wherein the resistance of the series resistor (90) is substantially greater than the resistance of the actuator (80), in particular at least by a factor of 5 greater, in particular at least by a factor of 10 greater.
3. Electrical circuit (100) for operating the fuel injection valve (11) according to either of Claims 1 and 2, wherein, in a first phase, the actuator (80) is actuable by a source of the electrical circuit (100), characterized in that the electrical circuit (100) comprises a capacitor between the one connection (HS; LS) of the actuator (80) to which the sensor device (70) is connected and the reference potential (88), and in that, in a third phase, a signal (92) is determinable depending on an electrical potential (U₇₆; U₇₈) at the capacitor of the electrical circuit (100).
4. Electrical circuit (100) according to Claim 3, wherein, in the third phase, the actuator (80) is not actuated.
5. Electrical circuit (100) according to Claim 3 or 4, wherein a capacitance (C₂₆) of the sensor (26) is greater than the capacitance (C₁₀₀) of the capacitor of the electrical circuit (100).
6. Electrical circuit (100) according to one of Claims 3 to 5, wherein, in a second phase, prior to the third phase and after the first phase, the actuator (80) is substantially decoupled from the reference potential (88) and/or from the actuating source.
7. Electrical circuit (100) according to one of Claims 3 to 6, wherein a fault of the sensor (26) is determinable by the electrical circuit (100) depending on the electrical potential (U₇₆; U₇₈) or the profile of the electrical potential (U₇₆; U₇₈), and a fault signal (94) can be generated by the electrical circuit (100) depending on the determined fault.
8. Electrical circuit according to Claim 7, wherein the fault is a short circuit of the sensor (26).
9. Method for operating the fuel injection valve (11) according to either of Claims 1 and 2, wherein, in a first phase, the actuator (80) is actuated by a source of an electrical circuit (100), characterized in that the electrical circuit (100) comprises a capacitor between the one connection (HS; LS) of the actuator (80) to which the sensor device (70) is connected and the reference potential (88), and in that, in a third phase, a signal (92) is determined depending on an electrical potential (U₇₆; U₇₈) at the capacitor of the electrical circuit (100).
10. Method according to Claim 9, wherein the resistance of the series resistor (90) is substantially greater than the resistance of the actuator (80), in particular at least by a factor of 5 greater, in particular at least by a factor of 10 greater, and wherein, in the first phase, substantially more current is supplied to the actuator (80) than to the sensor device (26).
11. Method according to Claim 9 or 10, wherein a capacitance (C₂₆) of the sensor (26) is greater than the capacitance (C₁₀₀) of the capacitor of the electrical circuit (100).
12. Method according to one of Claims 9 to 11, wherein, in a second phase, prior to the third phase and after the first phase, the actuator (80) is substantially decoupled from the reference potential (88) and/or from the actuating source.
13. Method according to one of Claims 9 to 12, wherein a fault of the sensor (26) is determined by the electrical circuit (100) depending on the electrical potential (U₇₆; U₇₈) or the profile of the electrical potential (U₇₆; U₇₈), and a fault signal (94) is generated by the electrical circuit (100) depending on the determined fault.
14. Method according to Claim 13, wherein the fault is a short circuit of the sensor (26).

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