KR20190082292A - How to control solenoid valve of fuel injector - Google Patents

Abstract

The present invention relates to a method for controlling a solenoid valve of a fuel injector for injecting pressurized fuel into an internal combustion engine, the solenoid valve comprising: a solenoid coil; And a solenoid armature which can be raised by current supply to the solenoid coil for opening the fuel perfusion opening, wherein the solenoid valve is operable in a first operating mode (B ₁ ) and a second operating mode (B ₂ ) In each of these operating modes (B ₁ , B ₂ ), the solenoid coil is supplied with a pull-in current during a first time interval (Δt ₁ ) to raise the solenoid armature, Wherein the solenoid valve is first actuated in the first operating mode B _{1 and} is _switched from the first operating mode B ₁ to the second operating mode B ₁ according to one or more predetermined criteria T _S1 , B is converted to _2), the first operating mode (B ₁₎ a first time interval (Δt ₁₎ is the second operating mode (B ₂₎ longer, and / or the holding current than in the second operating mode (B ₂ ).

Description

How to control solenoid valve of fuel injector

The present invention relates to a method for controlling a solenoid valve of a fuel injector, as well as to a computation unit and a computer program for carrying out the method.

The injection system for the internal combustion engine transfers fuel from the tank into the combustion chamber of the internal combustion engine. In this case, the fuel is supplied from the high-pressure accumulator to the combustion chamber of the internal combustion engine by the fuel injectors.

In this case, the fuel injectors may include a solenoid valve that is supplied with current to the solenoid coil to raise the solenoid armature and open the fuel perfusion opening. In this case, many parts of the solenoid valve may be involved in setting the armature stroke. Also, the armature stroke is influenced by the fuel temperature and the fuel pressure.

In DE 10 2010 027 989 A1, the injection valves are switched to the boost voltage in the first stage of their control (boost phase) in order to shorten the switching time, so that the first highest value in the solenoid coil Fuel systems in which current is set are described. The boost phase most often characterizes the beginning of the armature motion, i.e., the initial acceleration of the armature. The boost voltage can be generated, for example, in a DC converter in a vehicle battery, and thus much higher than the battery voltage, thereby correspondingly flowing a relatively higher first current into the coil.

As a result, the armature of the solenoid valve can be accelerated relatively more strongly. The boost voltage is temporarily stored in the so-called boost capacitor. In the control phase (pull-in phase) immediately following the first current rise, the coil is switched to a battery voltage that is relatively lower than the boost voltage in order to perform the residual armature motion. The infeed phase provides armature movement until approximately the maximum armor stroke is reached. In general, the third phase (holding phase) is followed by the incoming phase. In this case, the coil is operated with a relatively small additional current as compared to the first and second steps. However, battery voltage is also used for control in the maintenance phase. The holding step causes the armature to be maintained in a substantially constant stroke.

At low temperatures, especially at low temperature, a rapid rise of the solenoid armature can be carried out with a higher current than is necessary for open holding, in order to block too little injection quantity. In this case, the coil can also be switched to a boost voltage that is relatively greater than the battery voltage during the lead-in phase. Such a method is known, for example, from DE 102 42 606 A1 and DE 10 2010 027 989 A1.

DE 10 2010 000 827 A1 includes, for example, injection nozzles controlled by a nozzle needle; And a control chamber communicating with the high pressure side and the low pressure side of the fuel injector and being switchable between a closing pressure and an opening pressure by a control valve assembly. The control chamber is assigned with a force sensor or a pressure sensor which detects the characteristic pressure variations upon closing and opening. The sensor is also referred to as a needle closing sensor (NCS sensor). The method implemented with the sensor is referred to as needle closure control (NCC). In this method, the control chamber pressure fluctuates significantly at the beginning and end of the fuel injector injection phase.

According to the present invention, a method for controlling a solenoid valve of a fuel injector, which has the features of the independent patent claims, and a calculation unit and a computer program for carrying out the method are proposed. Preferred embodiments are subject of the dependent claims and the following description.

A method according to the present invention includes: a solenoid coil; And a solenoid armature that can be raised by a current supply to the solenoid coil to open the fuel perfusion opening. The solenoid valve of the fuel injector injects pressurized fuel into the internal combustion engine. In this case, the solenoid valve can be used as a servo valve or a control valve for the fuel injector. In this case, the solenoid valve may be operated in the first operating mode and the second operating mode, and in each of these operating modes, the solenoid coil supplies a pull-in current for a first time interval to raise the solenoid armature And is then supplied with a holding current that is lower than the inrush current during the second time interval. In this case, the first time period may still include a boost current, as mentioned in the introduction, before the pull-in current. Now the solenoid valve is first controlled in the first operating mode and switched from the first operating mode to the second operating mode according to one or more predetermined criteria. In this case, the first time period in the first operating mode is longer than in the second operating mode, and / or the holding current is higher than in the second operating mode.

In this way, it is possible to achieve the maximum possible armature stroke and, correspondingly, to cope with as much fuel flow or seat throttle limit as possible, even at low temperatures where the rise of the solenoid armature is slowed, for example by the increased viscosity of the fuel . In this regard, preferably, when another temperature characteristic of the internal combustion engine at the start of the internal combustion engine, for example, the coolant temperature, is less than a preset temperature threshold, the solenoid valve is first controlled in the first operating mode. Alternatively, if the time interval over which the solenoid armature is raised by the predetermined value exceeds the preset stroke threshold, in other words, if the solenoid valve is opened too slowly, it is also preferable that the solenoid valve is first controlled in the first operating mode. The reason may be, for example, wear or increased friction.

Even if the stroke rate of the solenoid armature is now relatively slow, over a first time period in which the inrush current is relatively long and relatively longer than the second operating mode, which may be an operating mode for normal or normal operation, the solenoid armature So that the solenoid valve can be held in the open state by the subsequent holding current. On the other hand, if the first time period is too short, the solenoid armature does not rise sufficiently to keep it open by the magnetic force (which may be significantly smaller than the pull-in current) caused by the holding current, The coil may not reach close enough. As a result, the fuel flow rate may inadvertently decrease or, for example, in the case of a switching valve, the seat throttle limit may not be reached, which may result in very low flow rates. However, as with the relatively longer first time interval, the solenoid armature can rise relatively more due to the relatively higher holding current, thereby maintaining the solenoid armature continuously In some cases, only to a very small extent), relatively higher magnetic forces can be generated.

In this case, the pull-in current in the first operating mode, for example in the range of 14 to 18 A, can be generated, for example, via the battery voltage or the vehicle electrical system voltage. A subsequent holding current, for example in the range of 6 to 8 A (or in the range of 10 to 12 A if increased compared to the second operating mode, for example) may likewise be generated via battery voltage or vehicle electrical system voltage. Observing these current values, in particular a maximum current of, for example, about 18 A, no damage is expected in the control device supplying the inrush current. Values in the range of, for example, 450 to 900 占 퐏, and in particular in the range of 600 to 800 占 퐏 are taken into account as the first time interval in the first operating mode (at least at the start), while in the second operating mode the typical time duration Is 450 mu s, for example.

Preferably, the at least one criteria criterion is determined based on at least one predetermined or predetermined determination of the at least one predetermined operating period of the solenoid valve since the start of the first operating mode, and / Includes reaching or exceeding the value. Thereby, the first operating mode which requires a relatively higher load of the solenoid valve than the second operating mode may not be used unnecessarily long. For example, it can be assumed that the internal combustion engine is sufficiently warmed up after a predetermined operating period, so that the aforementioned disadvantages in the low temperature solenoid valve no longer occur. Likewise, temperatures may be used directly to initiate the conversion. In this case, in particular the at least one characteristic temperature may comprise the temperature of the fuel returning part and / or the temperature of the fuel tank and / or the temperature of the cooling water of the internal combustion engine, or a combination of two or more of these temperatures. A combination of one or more of the temperatures and the operating period is also possible.

Alternatively, or additionally, preferably one or more of the predetermined criteria may be reached or exceeded, respectively, of at least one predetermined value of the stroke of the solenoid armature during the second time interval, and / or the closing of the nozzle needle of the fuel injector Or at least one predetermined value of the voltage level of the sensor (which may be the NCS sensor referred to in the introduction) for detecting the voltage level. As already mentioned, the temperature of the internal combustion engine and hence the temperature of the fuel affect the stroke rate of the solenoid armature. The stroke of the solenoid armature during the second time period in which no further rise of the solenoid armature is generally carried out and only the reached stroke is maintained according to the stroke velocity and the first time interval is measured on a scale of the temperature of the fuel to be. Thus, the stroke can be used as a reference for switching to the second operating mode. Likewise, a measure for the stroke can be determined very simply by the NCS sensor mentioned in the introduction.

In this case, preferably, the arrival or the exceedance of at least one predetermined value of the stroke is determined according to the time curve of the stroke, and / or at least the predetermined value of the sensor's voltage level is reached or not, , Respectively, over a plurality of second time intervals. To this end, the respective stroke or voltage level can be determined, for example, in the defined measuring range during the second time interval (i.e. during the use of the holding current). Now, if the stroke increases over the second time intervals of the solenoid valve and the corresponding control processes, or if the voltage level decreases, this means that the temperature has risen. Correspondingly, it can be switched to the second operating mode (upon reaching or exceeding the predetermined value).

Likewise preferably, at least one predetermined value of the stroke is reached or exceeded, and / or at least a predetermined value of the voltage level of the sensor is reached or not, respectively, the reduced holding current and / I. E., During the first operating mode using the inrush current period. To this end, it is also possible, at predetermined spacing intervals, i.e. after a certain number of conventional control procedures using the first operating mode, to maintain a typical holding current and / A control process having a reduced holding current and / or a reduced first time interval as compared to a control process having a current period or a first time period can be performed. Now, it can be assumed that the temperature rises when the stroke of the solenoid armature reaches or exceeds the predetermined value, or when the voltage level reaches or falls below the predetermined value. In this case, particularly preferably, the holding current and / or the time interval in the second operating mode is used as the reduced holding current and / or the decreased first time interval. In this case, it is possible to immediately switch to the second operation mode as soon as possible.

In a preferred manner, the transition from the first operating mode to the second operating mode is performed through a gradual reduction of the first time interval and / or the holding current according to one or more criteria. Accordingly, in addition to immediate switching, it is also possible to switch stepwise between the two operating modes. For example, different values of one or more criteria and / or different criteria may be selected corresponding to each step for the stepwise conversion. The stepwise switching can achieve a relatively shorter operating period of the solenoid valve having a long first time interval for the entire incoming current. To this end, the first time period may be reduced to, for example, 50, 100, or 150 microseconds. These steps may be, for example, variable.

The control unit of a calculation unit, for example an automobile, according to the present invention is particularly adapted to perform the method according to the invention in a program description.

It is also desirable to implement the above method in the form of a computer program, since this approach results in particularly low costs, especially if the running-side control device is used for other tasks anyway. Storage media suitable for providing computer programs are, in particular, magnetic, optical and electronic memories such as hard disks, flash memories, EEPROMs, DVDs, and the like. It is also possible to download the program via a computer network (Internet, intranet, etc.).

Further advantages and embodiments of the present invention refer to the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated schematically in the drawings and with reference to the drawings in the following, in accordance with one embodiment.

1 is a schematic diagram of a solenoid valve in which the method according to the invention can be carried out.
2 is a graph of typical current characteristic curves and associated armature stroke characteristics curves in solenoid coils of solenoid valves at different temperatures.
Figure 3 is a graph of the solenoid coil current, associated injection rate, NCS signal characteristic curves, and characteristic curves of the armature stroke of a solenoid valve in a comparison between a method not in accordance with the present invention and a method according to the present invention in a preferred embodiment; to be.
4 is a graph showing different first time intervals of the incoming current with temperature in the application of the method according to the invention in one preferred embodiment.

1, there is shown schematically a solenoid valve 100 on which a method according to the present invention may be carried out. The solenoid valve 100 includes an electromagnet 110 having a solenoid coil 111 that may be formed, for example, in an annular shape. The current I flows in the solenoid coil 111, for example, when the voltage (U) is applied through the execution side calculation unit 180, for example, the control device.

There is also provided a solenoid armature 120 which is used to close or open the perfusion opening 150 of the solenoid valve 100. In this case, the solenoid armature 120 includes a component 122 that closes the perfusion opening 150. The component 122 is formed, for example, in the form of a bolt having an end that is partially conically narrowed in the direction of the perfusion opening 150.

The solenoid armature 120 also includes an armature blade 121 provided on the upper end of the solenoid armature 120, that is, on the end facing the direction of the solenoid coil 111. In this case, the armature blade 121 may be integrally formed with the component 122, or may be mechanically connected to the component 122.

It also acts on the solenoid armature 120 to provide a spring 130 that closes the perfusion opening by pressing the armature 120 into or through the perfusion opening 150 without supplying current to the solenoid coil 111, Is provided. The side of the spring 130, facing away from the solenoid armature, may be stationary in a suitable (not shown here) component of the solenoid valve 100.

A magnetic force is generated when a current is supplied to the solenoid coil 111 and the solenoid armature 120 is raised against the spring force of the spring 130 and pulled in the direction of the solenoid coil 111 or the electromagnet 110. At this time, the perfusion opening 150 is opened. Upon supply of the corresponding current to the solenoid coil, the solenoid armature 120 may rise until it stops at the adjusting ring 115 disposed in the electromagnet 110. In this case, the solenoid armature 120 is stopped at the radially outer end of the armature blade 121.

FIG. 2 schematically shows the characteristic curves of the armature stroke and the standard characteristic curves of the solenoid coil current of the solenoid valves at different temperatures. To this end, the current I and the armature stroke h are shown over time t.

After an optional short boost current not shown in detail in the figure, the pull-in current I _A can flow in the solenoid coil during the first time interval DELTA t ₁ . Then, the current can be reduced to the holding current I _H , which then flows during the second time period? T ₂ . The current characteristic curves shown here are common in normal control of solenoid valves, for example when the internal combustion engine is at operating temperature.

On the other hand, in the current characteristic curve shown, only three characteristic curves of the armature stroke are shown schematically in the direction of the arrow as the viscosity of the fuel flowing through the electromagnet valve increases. When the viscosity is low, a complete armature stroke is reached in a short time, whereas when the viscosity is slightly higher, a complete armature stroke is reached, but only after a relatively longer time. As the viscosity further increases, the armature stroke rate decreases much more and the solenoid armature no longer reaches a complete armature stroke, i. E., For example, the stop shown in FIG.

Now, Fig. 3, during a first mode of operation methods that do not conform to the present invention (characteristic curve I _1, R _1, S _1, h _1), and a preferred method according to the invention in the example (characteristic curve I ₂ , R ₂ , S ₂ , h ₂ ) of the solenoid coil of the solenoid valve are compared with each other to determine characteristic curves of the solenoid coil current I of the solenoid valve, the associated injection rates R, NCS signal characteristic curves (S) and armature stroke (h).

The NCS signal S is, for example, a voltage signal of a piezo sensor as already described in the introduction portion. From the characteristic curve of the NCS signal the armature stroke h can be derived or determined.

Current characteristic curve (I ₂₎ in the inlet, the other hand is used for ₍₁ and current characteristic curve (I ₁₎ in the incoming current time interval (Δt current time interval Δt), much shorter time period than ₁₎ (Δt ₁ ). In the case of a fuel having a high viscosity such as that which appears when the temperature of the internal combustion engine or solenoid valve is low, the longer first time period in which the inrush current is used now results in a greater amount of fuel flowing through the solenoid valve. This is confirmed at an increased injection rate (R ₂ ) relative to R ₁ .

In this case, the first time intervals are followed by a second time interval (? T ₂ or? T ' ₂ ) in which the holding current flows in the solenoid coil. In this case, the second time intervals are respectively selected in such a manner that the first and second time intervals are combined to derive the total control time of the solenoid valve.

Now, in the characteristic curves (S ₂ or h ₂ ), it can be seen that the longer the first time interval for the incoming current is, the larger the armature stroke is, which is consistent with the higher injection rate. Thus, through the selection of the longer first time period of the inrush current, the desired injection rate can be achieved even when the temperature is low and the fuel viscosity is high.

Herein, the first time interval (Δt _'1) or associated current characteristic curve (I ₂₎ is to be used for the first operating mode in the context of the process according to the invention On the other hand, the illustrated first time interval shown in ( Δt ₁₎ or associated current characteristic curve (I ₁₎ can be used for the second operating mode. As mentioned, the second operating mode is only used when a sufficiently high temperature is reached, so that a too low injection rate due to the high viscosity of the fuel no longer occurs.

4, there a preferred embodiment when applying the method according to the invention in the example, different first time interval of the current drawn according to the temperature of the fuel (T) (Δt ₁₎ is shown.

Here, it can be confirmed that the solenoid coil is controlled in the first operating mode B ₁ until the temperature T reaches the value T _S1 as a reference. In this case, the first time period is gradually decreased from the starting value to the value to be reached in the second operating mode (B ₂ ). In this case, the second operating mode B ₂ is used at the same time as the value T _S2 is reached.

As an additional or different criterion, for example, the arrival or exceedance of the predetermined value h _M of the armature stroke h; Or a predetermined value S _M of the voltage level or the voltage signal S can be used for a second time period? T ₂ or? T ' ₂ , as shown in Fig.

Claims (12)

A method for controlling a solenoid valve (100) of a fuel injector for injecting pressurized fuel into an internal combustion engine, the solenoid valve comprising: a solenoid coil (111); And a solenoid armature (120) which can be raised by supplying current to a solenoid coil (111) for opening a fuel flow opening (150), characterized in that the solenoid valve
The solenoid valve 100 may be operated in a first operating mode B ₁ and a second operating mode B ₂ and in each of these operating modes B ₁ and B _{2 the} solenoid coil 111 is connected to a solenoid armature the first time interval to raise the _{(120) (Δt 1, Δt} '1) being supplied to the incoming current (I _a) for, then the second time interval (Δt _2, Δt' ₂₎ during the pull current (I _a) Is supplied with a lower holding current I _H ,
The solenoid valve 100 includes a first, a first mode of operation and operative in the (B _1), at least one group determination reference (T _S1, T _S2), a first operating mode, the second mode of operation from (B ₁₎ in accordance with (B ₂ ),
A first operating mode the first time interval from _{(B 1) (Δt 1,} Δt '1) has a second operating mode (B ₂₎ longer, and / or the holding current than in the (I _H) is a second operating mode ( B ₂ ), wherein the solenoid valve control method further comprises: The method of claim 1, wherein the one or more criterion criteria comprises at least one of reaching or exceeding at least one predetermined operating period of the solenoid valve (100) after the start of the first operating mode (B ₁ ), and / Wherein at least one predetermined value (T _S1 , T _S2 ) of the temperature (T) is reached or exceeded. 3. The method of claim 2, wherein the at least one characteristic temperature (T) comprises a combination of two or more of the temperature of the fuel returning portion and / or the temperature of the fuel tank and / A method for controlling a solenoid valve of a fuel injector. 4. A solenoid valve according to any one of the preceding claims, wherein the one or more predetermined criterion references are selected such that during a second time interval (? T ₂ ,? T ' ₂ ) Comprising at least one predetermined value of the voltage level (S) of the sensor for detecting the arrival or the exceeding of the predetermined value, and / or the closing of the nozzle needle of the fuel injector, the solenoid valve control of the fuel injector Way. The method according to claim 4, characterized in that the arrival or the at least one predetermined value h _M of the stroke (h) is reached or exceeded according to the time curve of the stroke (h) and / Wherein the arrival or the inactivity of the determination value S _M is determined over a plurality of second time intervals? T ₂ and? T ' ₂ , respectively, in accordance with the voltage level S of the sensor. 5. The method according to claim 4, characterized in that the at least one predetermined value (h _M ) of the stroke (h) is reached or exceeded and / or the at least predetermined value (S _M ) Is determined according to test measurements during a first operating mode (B ₁ ) with a reduced holding current (I _H ) and / or a reduced first time interval (? T ₁ ), respectively. Claim 1 to gradual reduction of the method according to any one of claim 6, wherein the at least one criterion (T _S1, T _S2) the first time interval (Δt _1, Δt _'1) and / or the holding current (I _H) in accordance with the (B ₁ ) to the second operating mode (B ₂ ) via the first operating mode (B ₁ ). 8. The method according to any one of claims 1 to 7, wherein when the additional internal combustion engine characteristic temperature at startup of the internal combustion engine is less than a preset temperature threshold, the solenoid valve 100 is first operated in the first operating mode B ₁ And controlling the solenoid valve of the fuel injector. 9. The solenoid valve (100) according to any one of claims 1 to 8, wherein the solenoid armature (120) is raised by a predetermined value and the time interval exceeds a preset stroke threshold value, the solenoid valve (100) B ₁ ) of the solenoid valve. A computation unit (180) configured to perform the method according to any one of claims 1 to 9. A computer program which, when executed in the calculation unit (180), causes the calculation unit (180) to perform the method according to any one of claims 1 to 9. 12. A machine-readable storage medium having stored thereon a computer program according to claim 11.

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