CN104775926B

CN104775926B - Method and circuit arrangement for actuating an injection valve of an internal combustion engine, in particular of an externally ignited internal combustion engine

Info

Publication number: CN104775926B
Application number: CN201510008351.1A
Authority: CN
Inventors: H.哈梅多维奇; H.拉普
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2014-01-09
Filing date: 2015-01-08
Publication date: 2020-03-03
Anticipated expiration: 2035-01-08
Also published as: CN104775926A; DE102014200184A1

Abstract

The invention relates to a method and a circuit arrangement for actuating an injection valve of an internal combustion engine, in particular of an externally ignited internal combustion engine. In a method and a circuit arrangement for actuating at least one injection valve, in particular of an externally ignited internal combustion engine, the at least one injection valve is actuated by means of an electrical actuating voltage (102, 107, 112, 117), wherein the actuating voltage is generated by a temporal synchronization of a supply voltage (140), and wherein the temporal synchronization is in particular performed until the at least one injection valve is completely opened or closed.

Description

Method and circuit arrangement for actuating an injection valve of an internal combustion engine, in particular of an externally ignited internal combustion engine

Technical Field

The invention relates to a method and a circuit arrangement for actuating an injection valve of an internal combustion engine, in particular of a spark-ignition engine, according to the preambles of the respective independent claims.

Background

In the field of fuel intake manifold injection, cost-effective solenoid valves are mostly used for gasoline engines of motor vehicles, with injection pressures of the order of a few bar. For the duration of the actuation, a supply voltage, typically a vehicle electrical system voltage of the motor vehicle, is applied to the solenoid of the respective injection valve in a time-synchronized manner, thereby opening the valve and releasing the injection process. At the end of the actuation period, the solenoid is disconnected from the supply voltage. The magnetic field passing through the magnet coil is rapidly reduced by means of a ziner diode which acts as a "protective diode" and generates a negative coil voltage (the so-called "quenching voltage"), as a result of which the spring-biased magnet valve is again brought into the starting position and the injection process is terminated.

The solenoid valve operates in a manner known per se by means of an armature driven by the solenoid coil and a valve needle driven by the armature, which valve needle has a sealing seat in the home position. When the two end positions of the valve needle are reached, the armature and the valve needle accordingly cause high-frequency noise pollution, which is perceived by the vehicle driver as reducing comfort, for example.

This reduction in noise pollution can be achieved by the generation of a braking pulse, wherein the actuation process is interrupted shortly before the armature reaches its lift stop (Hubanschlag) when open, so that the current flowing through the magnet coil and thus the magnetic force drops briefly. In the closing case, on the other hand, a brief additional actuation pulse can be interrupted before the valve needle reaches its sealing seat.

The action of such brakes is strongly dependent on the temporal accuracy of the actuation of the brake pulses mentioned and on the magnitude of the vehicle circuit voltage or the battery voltage, the fuel temperature or the solenoid temperature. The movement of the valve needle is also subject to sample-dependent deviations, for example, depending on the closing spring force or the valve lift. If the temporal position and duration of the brake pulse are erroneously or inaccurately controlled, injection interruptions or additional injections may occur, which have a great influence on the driving behavior of the motor vehicle and on the combustion-induced emission of pollutants from the internal combustion engine.

Disclosure of Invention

As a starting point for the present invention, the following is utilized: the injection valve concerned here is designed in such a way that it also has a complete functional reliability even when operating a conventional vehicle circuit voltage (also referred to below as "battery voltage" or "supply voltage") with a voltage of less than 13V, for example at approximately 10V. The invention is based on the special recognition that: the noise generated by the impact of the armature when opening the magnetic valve described at the outset is significantly reduced with a decreasing actuation voltage, in particular during operation of the valve supply voltage specified as the minimum voltage.

According to the method according to the invention for actuating an injection valve associated therewith, the actuation process is carried out at least during the opening phase of the injection valve with an effective actuation voltage value that is lower than the vehicle circuit voltage and, more precisely, with a specific duty cycle by means of a temporal synchronization. Such synchronization can be provided, for example, by means of switching elements, such as transistors or MOSFETs (metal oxide semiconductor field effect transistors). The effective voltage value of the actuation voltage is thus preferably in the range of the minimum voltage mentioned for which the injection function is still ensured. In the case of a magnetic valve, the opening phase mentioned represents the attraction phase of the armature. In particular, the switching elements for actuating the injection valves are operated synchronously until the injection valves are fully opened or closed. In the case of a magnetic valve, the synchronization is carried out until the armature of the magnetic valve has reached its lift stop. The switching element can then be permanently switched on for the remaining actuation duration.

The line arrangement according to the invention for actuating the injection valves associated in this case, which is comparatively easy to construct and therefore can be implemented cost-effectively, comprises means for actuating at least one injection valve in a timely and synchronized manner.

The invention makes it possible to open and close the injection valve concerned here in a defined and therefore reliable manner with significantly reduced noise pollution due to the switching noises mentioned, but without the need for cumbersome and error-prone application algorithms, such as are required for setting the parameters for the brake pulses mentioned. The method according to the invention and the line arrangement are robust both with respect to fluctuations of external parameters, as mentioned at the outset, and with respect to the mentioned sample deviations of the valve. The invention also requires no additional overhead or only a small overhead of the measurement technique. In addition, the sensitivity of the opening times and thus of the injection quantities with respect to the vehicle circuit voltage or the supply voltage is significantly reduced, so that the compensation algorithm associated therewith can either be significantly simplified or even completely eliminated.

The method according to the invention can be designed such that, after the start of the actuation of the injection valve, the switching element is first permanently electrically conductive for a time interval, which is preferably empirically predefined, and is operated synchronously only after the end of this time interval. The duration of the time interval can be selected such that the injection valve is closed during the time interval.

In addition to the aforementioned actuation of the at least one injection valve, which is synchronized in time, the level of the quenching voltage mentioned at the outset can be reduced, by means of which the magnetic force is reduced as quickly as possible at the end of the opening actuation process. In a preferred embodiment, the quenching voltage is reduced to a value of zero.

In the case of an injection valve which is driven by a solenoid, the circuit arrangement according to the invention can be designed such that the switching state of the switching element is set by: the voltage applied to the solenoid coil is smoothed by means of a low-pass filter and the smoothed value is set to a target value.

The invention can be used with the advantages described therein, in particular when actuating the intake manifold injection valve of an internal combustion engine (gasoline engine) of a motor vehicle, which is ignited from an external source. In principle, however, the invention can also be used in other fields in which internal combustion engines are used, provided that the internal combustion engine has an injection valve with a valve needle or the like, the described noise pollution being produced by the movement of the valve needle or the like.

Further advantages and embodiments of the invention emerge from the description and the drawing.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination, but also in other combinations or alone without leaving the scope of the invention.

Drawings

Fig. 1 shows a circuit arrangement according to the prior art for an output stage for actuating four intake-injection valves, for which the method according to the invention can be used;

fig. 2 shows a voltage profile at the solenoid of an injection valve of a gasoline engine during the actuation according to the invention;

fig. 3 shows a first exemplary embodiment of the line arrangement according to the invention, in which the output stage shown in fig. 1 is supplemented with a measuring low-pass filter, which supplies the voltage UTP as a manipulated variable;

fig. 4 is a graph of the voltage applied to the solenoid of the injection valve, measured on the circuit arrangement according to fig. 3, with the voltage regulation according to the invention in the hysteresis band (hystereband);

fig. 5 shows a second exemplary embodiment of the circuit arrangement according to the invention, in which the output stage shown in fig. 1 additionally has a transistor and a self-oscillating diode;

fig. 6 is a graph of the voltage applied to the solenoid of the injection valve, measured on the line arrangement according to fig. 5, with the additional transistor being synchronized;

FIG. 7 is a voltage curve similar to that in FIG. 6, but with voltage regulation in the hysteresis band;

fig. 8 shows a third exemplary embodiment of the circuit arrangement according to the invention, in which the output stage shown in fig. 1 additionally has a linear voltage regulator; and is

Fig. 9 shows a fourth exemplary embodiment of the circuit arrangement according to the invention, in which the output stage shown in fig. 5 additionally has a linear voltage regulator.

Detailed Description

The circuit arrangement of the output stage, which is shown in fig. 1, is used in the present exemplary embodiment to actuate four intake manifold injectors. It goes without saying that the invention does not depend on the exact number of injection valves. The injection valves are solenoid valves, that is to say they are driven by

electromagnetic coils

100, 105, 110, 115, which

electromagnetic coils

100, 105, 110, 115 together with their respective

positive poles

120, 125, 130, 135 are connected to the positive pole of a vehicle electrical system supply voltage (Ubatt) 140. The

solenoid coils

100 and 115 are respectively loaded with actuation voltages (U1, U2, U3, U4) 102, 107, 112, 117. The

cathodes

145, 150, 155, 160 of the

solenoid coil

100 and 115 are connected to the vehicle Ground (GND) 185 via

semiconductor switches

165, 170, 175, 180, respectively. It should be noted that the invention can also be used in injection valves of other types of construction, for example in mechanical or hydraulic valves, as long as they have a valve needle or the like, the described noise pollution being caused by the movement of the valve needle or the like.

The

semiconductor switches

165 and 180 are embodied in this exemplary embodiment as MOSFETs, but instead of MOSFETs, switching means known per se, such as transistors or the like, can also be used. The respective mosfets (T1 to T4) 165-180 are switched off in the rest state of the injection valve. For the open actuation of the injection valve x (x =1, …, 4), the associated mosfet (tx) 165-. The resulting coil current causes the formation of a magnetic field, which opens the injection valve due to the magnetic force of the magnetic field. At the end of the actuation time, the mosfet (tx) 165 and 180 are switched off again, so that the injection valve is closed again.

In order to prevent electrical flashovers of the MOSFETs 165-.

When one of the solenoid valves is opened by means of one of the

solenoids

100 and 115, the valve needle (not shown here) is moved out of the valve seat. This movement takes place in an accelerated manner, since the magnetic flux and thus the magnetic force rises as a result of the applied vehicle circuit voltage (Ubatt) 140. Due to the corresponding acceleration of the armature, the armature impacts at a high speed on its lift stop. Tests have now shown that this stop is decisively involved in the generation of the switching noise mentioned at the outset, in particular to a significantly greater extent than the striking of the valve needle against the valve seat at the end of the injection when the injection valve closes.

Fig. 2 shows a diagram of the solenoid voltage 250 for a conventional vehicle circuit voltage Ubatt =13V, a zener voltage Uzener =20V and a (effective) setpoint voltage Uquer, soll =10V applied to the respective solenoid. The steering starts at t =0 μ in this embodiment. The exemplary embodiment of the method according to the invention shown in fig. 2 is based on the circuit arrangement shown in fig. 1. When actuating the injection valve, the transistor Tx (e.g. MOSFET) is no longer permanently switched on for the actuation time, but is synchronized with a duty cycle T, wherein the value is_TBetween 0 and 1. If it is not_TIf the voltage is less than 1, the voltage applied to the electromagnetic coil is reduced in a time method. For such medium voltages Uquer, Uquer = apply_T*Ubatt-(1-_T) Uzener. By aiming at the duty cycle

The control voltage of the solenoid can be reduced accordingly to the desired target value. It is particularly advantageous if, as setpoint value Uquer, a voltage value is to be selected for which the full functionality of the injection valve is ensured.

Fig. 3 shows an exemplary embodiment of the circuit arrangement (output stage) according to the invention, in which the switching state of the transistor (T1) 165 is set in the following manner: the voltage applied to the solenoid coil is smoothed by means of a low-pass filter, and the smoothed value is set to a nominal voltage value. It should be noted that functionally and/or structurally identical components are provided with corresponding reference numerals in fig. 3 and the remaining figures of the line arrangement.

The detection of the nominal voltage is carried out by tapping the capacitor voltage UTP at an RC element which is connected in parallel with respect to the solenoid coil and which in the present exemplary embodiment is formed by an effective resistor 300 and two capacitors 305, 310 and acts as a low-pass filter. Instead of the two capacitors C1 and C2, only one single capacitor (C1 or C2) may also be arranged. In order to operate such a circuit arrangement, the first switched-off transistor (T1) 165 can be switched on in an electrically conductive manner if the voltage (UTP) 315 falls below the target value UTP after subtracting half of the hysteresis band value Δ u. The corresponding measured curves for U400 and UTP405 are shown in fig. 4, with Ubatt =13V, Uzener =20V, Uquer, soll =10V, Δ U =0.2V and T =200 μ s being selected as parameters. As an alternative to the voltage UTP, the voltage difference (Ubatt-UTP) 320 can also be tapped, wherein the described method for operating the line arrangement is to be adapted accordingly.

The injection valves are actuated at least during the opening phase of the respective injection valve with a voltage value which is below the vehicle circuit voltage. This is achieved by the described temporal synchronization with a specific duty cycle and, more precisely, here by means of the transistor (T1) 165. For the present solenoid valve, the opening phase mentioned represents the attraction phase of the armature. In particular, transistor (T1) 165 is operated synchronously until the injection valve is completely opened or closed. In the case of the current solenoid valve, the synchronization is carried out until the armature of the solenoid valve has reached its lift stop. The transistor (T1) 165 is then permanently switched on for the remaining actuation duration.

The circuit arrangement shown in fig. 3 has the disadvantage that the energy from the magnetic circuit in the ziner diode Dlösch is converted into heat by the synchronization of the transistor (T1) 165 (or of the remaining

transistors

170, 175, 180), in particular in the switched-off state of the transistor 165, but in addition the zener voltage Uzener is significantly dependent on the temperature, to avoid these disadvantages, the voltage applied to the magnet coil is synchronized, according to the exemplary embodiment of the circuit arrangement according to the invention shown in fig. 5, not between the values Ubatt and Uzener, but between Ubatt and 0, for this purpose, the circuit arrangement of the present output stage has a high-voltage-side Transistor (THS) 500 and a free-running diode (DFr) 505, and in the operation of this circuit arrangement the following four possible switching states a) d are produced:

a) THS and Tx are conductive: ux = Ubatt;

b) THS cuts and Tx conducts: ux =0 (or Ux = -Uth, where Uth represents a turn-on voltage of DFr with approximately 0.7V);

c) THS conducts and Tx cuts: ux = -Uzener;

d) THS and Tx cut: ux = -Uzener.

As an alternative to the embodiment according to fig. 5, the anode of the ziner diode Dzener may be connected not to the source connection of the high-side Transistor (THS) 500 but to its Drain connection (Drain-anshluss) and thus to the positive pole of the vehicle electrical system. In this case, the voltage Ux = -Ubatt-Uzener-Uth occurs in the switching state d) THS and Tx off. Whereby another voltage level is again provided for a very rapid removal of the magnetic field when the valve is switched off.

In the operation of the circuit arrangement shown in fig. 5 (components corresponding to fig. 1 are not numbered), the transistors Tx and THS are switched on in an electrically conductive manner at the beginning of the actuation of the injection valve, so that the full vehicle electrical system voltage Ubatt is applied to the solenoid coil x. In order to reduce the medium or effective coil voltage Uquer according to the invention, the transistors Tx are not synchronized in this embodiment, but rather the transistors THS are synchronized. This results in Uquer =being generated as a medium voltage in this case_T*Ubatt-(1-_T) Uth. Fig. 6 shows a corresponding curve of the coil voltage 600 for the case of Ubatt =13V, Uth =0.7V and Uquer, soll = 10V.

The line arrangement shown in fig. 5 also offers the following possibilities: in the quenching phase which takes place at the end of the control, the voltage Uzener is not applied to the respective solenoid, but rather only the voltage Uth is applied completely or partially. This slows down the reduction of the magnetic field and thus of the magnetic force acting on the respective armature, thereby reducing the striking noise of the respective valve needle on its sealing seat.

Fig. 7 shows a measured curve of the coil voltage 700 on the line arrangement already shown in fig. 3. The actuation of the injection valve is carried out in this exemplary embodiment by adjusting the voltage (UTP) 705 across the capacitor of the low-pass filter. In this case, it is advantageous to arrange the RC low-pass filter between the common positive pole of the electromagnetic coils and the ground. The voltage curve 700 shown in fig. 7 for such a regulation is generated with the same voltage parameters and a low-pass filter time constant of T =200 μ s.

According to the exemplary embodiment shown in fig. 8, the coil voltage is reduced by means of a linear voltage regulator 800, which is arranged between the aforementioned common positive pole of the magnet coils and the positive pole of the vehicle electrical system voltage, and a capacitor 805 assigned to the voltage regulator 800 and connected in parallel therewith, the dc voltage applied to the respective magnet coil dropping at the capacitor 805. The voltage regulator may reduce its output voltage, which is equal to the input voltage 145 of the output stage line, to a fixed or programmable nominal value. If the transistor Tx is conducting, the resulting coil voltage Ux is equal to the value of the output voltage U0 of the voltage regulator.

The line arrangement can also provide a free-wheeling state if the Transistor (THS) 500 mentioned is arranged between the output of the linear voltage regulator 800 and the common anode of the magnet coil and additionally a Diode (DFR) 505 mentioned is inserted. Such an embodiment is shown in fig. 9.

If the vehicle electrical system voltage (Ubatt) 140 falls below the nominal voltage Uquer, soll, the synchronous operation is aborted and, in other words, the associated injection valve is supplied with a vehicle electrical system voltage which is already too low.

The described method can be implemented either in the form of a control program in an existing control unit for controlling the internal combustion engine or in the form of a corresponding control unit.

Claims

1. Method for actuating at least one injection valve, wherein the actuation of the at least one injection valve is performed by means of an electrical actuation voltage (102, 107, 112, 117) which is generated by means of a switching element (165) and 180, 500) by means of a temporal synchronization of a supply voltage (140), so that the switching element is no longer permanently switched on during the actuation time but is synchronized with a duty cycle during the actuation of the injection valve, characterized in that the temporal synchronization is performed until the at least one injection valve is completely opened or closed.

2. Method according to claim 1, characterized in that the value of the actuation voltage (102, 107, 112, 117) lies within a predetermined minimum voltage for which the at least one injection valve is also fully functional.

3. Method according to claim 1 or 2, characterized in that the temporal synchronization is carried out after the end of a predetermined time interval after the start of the actuation.

4. The method according to claim 1, characterized in that the temporal synchronization of the supply voltage (140) is carried out with a duty cycle between the values 0 and 1.

5. Method according to claim 1, characterized in that after the start of the actuation of the at least one injection valve, the switching element is first permanently electrically conductive for a predetermined time interval and is operated synchronously after the end of this time interval, wherein the duration of the time interval is selected such that the injection valve is closed in the time interval.

6. The method according to claim 1, characterized in that a quench voltage for closed actuation of the at least one injection valve is reduced in addition to the temporal synchronization of the supply voltage (140).

7. Method according to claim 1, characterized in that the actuation voltage (102, 107, 112, 117) is smoothed by means of a low-pass filter (300, 305, 310) and the smoothed value is set to a target value.

8. Method according to claim 1, characterized in that the control voltage (102, 107, 112, 117) is detected and converted into a digital signal, wherein the digital signal generated is smoothed by a digital filter having low-pass filtering properties and the smoothed value is set to a target value.

9. The method according to claim 7 or 8, characterized in that the smoothed value is set to the target value by: the switching state of the switching element (165) and 180 or 500) is predefined on the basis of the difference between the target value and the smoothed value, and this predefined measure is carried out in such a way that the smoothed value is held in a hysteresis band around the target value with a predefinable width.

10. The method of claim 1, wherein said injection valve is an injection valve of an externally fired internal combustion engine.

11. Line arrangement for actuating at least one injection valve, wherein the actuation of the at least one injection valve is performed by means of an electrical actuation voltage (102, 107, 112, 117) which is generated by means of a switching element (165) and 180, 500) by means of a temporal synchronization of a supply voltage (140), so that, during the actuation of the injection valve, the switching element is no longer permanently switched on for the actuation time but is synchronized with a duty cycle, characterized in that a control means is provided, by means of which the temporal synchronization of the supply voltage (140) is performed until the at least one injection valve is completely opened or closed.

12. Line arrangement according to claim 11, characterized in that the at least one injection valve can be actuated with a duty cycle between the values 0 and 1 by means of the switching element (165) and 180) by means of a temporal synchronization of the supply voltage (140).

13. A line arrangement as claimed in claim 11, characterized in that the switching state of the switching element (165, 180) is adjusted by: the control voltage (102, 107, 112, 117) is smoothed by means of a low-pass filter (300, 305, 310), and the smoothed value is set to a target value.

14. A line arrangement as claimed in any one of claims 11 to 13, characterized in that a high-side transistor (500) and a free-running diode (505) are provided, by means of which the control voltage (102, 107, 112, 117) can be synchronized between the value of the supply voltage (140) and the value zero.

15. A line arrangement as claimed in any one of claims 11 to 13, characterized in that a voltage regulator (800) is provided, by means of which the input voltage (145) can be regulated to a lower nominal value than the supply voltage (140).

16. The circuit arrangement of claim 11, wherein said injection valve is an injection valve of an externally fired internal combustion engine.