KR102594622B1 - Method for controlling a magnetic actuator - Google Patents

Abstract

In the present invention, the armature 112 is operated by a magnetic coil 111 controlled by a pulse width modulation method, and the determination of control variables for pulse width modulation control generates a pulse width modulation signal for the magnetic coil 111. A control method of the magnetic actuator 100, performed within the ON-Phase of, and/or
The armature 112 is driven by a magnetic coil 111 controlled by pulse width modulation, and changes the current (I) in the magnetic coil 111 from a first value (I ₁ ) to a second value (I ₂ ). In order to do this, in the category of pulse width modulation control, the control variables (T', TG') for pulse width modulation control are different from the control variables (T, TG, TG") for the first value and the second value. It relates to a control method of a magnetic actuator (100) in which at least one cycle is used.

Description

{METHOD FOR CONTROLLING A MAGNETIC ACTUATOR}

The present invention relates to two methods for controlling magnetic actuators, such as those used in valves, and to a computer unit and computer program for carrying out the methods.

The invention belongs to the field of operation of magnetic actuators comprising a magnetic coil and an armature actuated by the magnetic coil, such as those used in internal combustion engines, in particular in proportional control valves. Diesel engines are mentioned here by way of example, for which typically the control elements in the fuel control system (in particular common rail systems) comprise magnetic actuators whose armature position can be varied in response to the drive current. In this regard, the invention relates, for example, to a so-called Metering Unit (MeUn) or a so-called Pressure Control Valve (PCV).

Typically, the magnetic actuators, or their magnetic coils, especially when used for proportional control valves, are controlled in a pulse-width modulation manner. In contrast, switching valves are typically controlled with a special current profile, which means increased complexity in the hardware.

According to the invention, two methods for controlling a magnetic actuator, each having the features of the independent patent claims, and a computer unit and a computer program for carrying out the methods are proposed. Preferred embodiments are the subject of the dependent claims and the description below.

A first method according to the invention is used to control a magnetic actuator whose armature is driven by a magnetic coil controlled in a pulse width modulation manner. In this case, determination of control variables for pulse width modulation control is performed within the ON-Phase of generation of the pulse width modulation signal for the magnetic coil. In this case, control variables mean period duration and/or duty factor, in particular in the scope of pulse width modulation control. In this case, the above-mentioned on phase relates to the phase or period within the cycle or cycle period during which the voltage is applied to the magnetic coil. In this case, the OFF-phase may, correspondingly, indicate a phase or period in which voltage is not applied to the magnetic coil. In this case, the duty cycle dictates the ratio between the on phase and the cycle period.

In many magnetic actuators, especially when used in proportional control valves, there is often a requirement for high dynamic behavior, ie to execute specific control commands as quickly as possible. However, this can usually be difficult in the scope of pulse width modulation control, since this usually involves, on the one hand, the determination or calculation of the control variables and, on the other, the generation of the pulse width modulation signal, i.e. the voltage to be applied to the magnetic coil. This is because it is not performed synchronously. This is usually performed in different units or modules within the computer unit, such as a control unit or control device. Therefore, a relatively higher duty cycle is now determined for subsequent cycles, but in practice a situation may arise where there is an immediate off phase. Therefore, the fluctuating duty cycle and the resulting fluctuating current can only be adjusted by the next period. This is particularly disadvantageous when the change in current is large.

However, now the determination (or calculation) of control variables for pulse width modulation control is carried out within the on phase, so that, for example, the already current on phase can be extended or stopped prematurely. Accordingly, much faster reactions and therefore higher dynamic behavior are possible.

Furthermore, in this connection, the determination of the control variables and the generation of the pulse width modulated signal are preferably carried out in time synchronization with each other. This can be done in particular at each arbitrary time within the ongoing cycle of the pulse width modulated signal. Thereby, particularly high dynamic behavior or particularly rapid responses can be achieved.

Preferably, the determined control variables are recorded in registers of a time control unit (also referred to as a timer unit) of the executing computer unit, which may in particular include a microcontroller. In this case, a time control unit is used for generation of pulse width modulated signals. This can be done through bypass or direct updating of the so-called shadow registers. The so-called shadow register of the timer unit is used to automatically perform an update of the pulse width modulated signal after the end of the cycle. Alternatively, the shadow register may be configured to perform an update immediately without waiting for the period of the pulse width modulation signal to end first.

In the second method according to the present invention, the armature is similarly used to control a magnetic actuator driven by a magnetic coil controlled in a pulse width modulation manner. In this case, in order to change the current in the magnetic coil from the first value to the second value, in the category of pulse width modulation control, control variables for pulse width modulation control include control variables for the first value and the second value. At least one different cycle is used. Here, control variables mean in particular a period period and/or a duty cycle in the category of pulse width modulation control.

In many magnetic actuators, especially when used in proportional control valves, there is often a requirement (as already mentioned) for high dynamic behavior, ie to execute specific control commands as quickly as possible. This is usually accompanied by high fluctuations in the current, that is, very large sudden changes in the target current. In the case of conventional pulse width modulation control, the period period is generally kept constant, and when the target current changes, the duty cycle is changed to change the current in the magnetic coil from a first value to a second value. A decrease in current means a decrease in duty cycle, and an increase in current means a corresponding increase in duty cycle.

Now, once a duty cycle suitable for the new target current is set, this generally means that there are alternating on and off phases, i.e. the voltage is applied or not applied alternately to the magnetic coil. In particular, if there are very rapid changes in current or target current, this means that the required value of current is not achieved by one subsequent cycle, but that multiple cycles are required, for example to increase or decrease the current even more fully. It can mean. However, this means that, with alternating on and off phases, if the current is to be substantially increased (in the off phase) the current is, for example, reduced for a short period of time, and if the current is to be substantially reduced (in the on phase) the current is reduced. It means that it increases in a short period of time.

But now, by using at least one period in which the control variables differ from the values normally used, the required target current can be achieved as quickly as possible without the disadvantages mentioned above. In this case, in said at least one period, in particular a period period and/or duty cycle different from the period period or duty cycle for the first and second values can be used. Thus, for example, a duty cycle of 1 or 100% (i.e., consecutive on phases within one cycle) is the cycle at which the required target current is exactly achieved (taking into account the on phases of subsequent cycles, as the case may be). Can be used by period.

In this case, depending on the respective implementation, one suitably selected period may be sufficient, but two or more of these periods may also be selected correspondingly.

By varying the cycle period, the frequency of the control is varied in a short time, but this variation does not have any effect on the hydraulic properties of, for example, the magnetic actuator or the corresponding valve during operation of the armature. The correct frequency is generally only important for steady-state operation, i.e. when the armature is held in a fixed position, to avoid friction problems. Accordingly, in case of (large) fluctuations in the target current, no corresponding problems occur.

A particularly desirable case is a combination of the two methods.

In both proposed methods, the magnetic actuator is preferably controlled by two-point control in the category of pulse width modulation control. Two-point control means that the current is increased or decreased depending on the respective actual value, ie the actual current, for example to control the current to the target current. For this purpose, the target variable, usually voltage, is switched back and forth between two values. By means of the proposed methods [which utilize not only the (at least approximately) time-synchronous determination of the control variables and the generation of signals, but also the variation of the control variables], it is possible to at least temporarily change the pulse width modulation control to a two-point control. .

In addition, in both proposed methods, preferably a magnetic actuator of a proportional control valve is used, in particular a magnetic actuator of a metering unit of a fuel control system of an internal combustion engine, or a magnetic actuator of a pressure control valve of an internal combustion engine. As mentioned in the introduction, pulse-width modulation control is usually used just for proportional control valves, and here it benefits in particular from the advantages mentioned. In the metering unit as well as in the pressure control valve, the pressure in the high-pressure accumulator of the internal combustion engine is regulated or controlled in closed-loop mode. That is, by the methods proposed here, pressure fluctuations in the high-pressure accumulator can be prevented, or at least reduced, even when load alternation is severe.

By the two proposed methods, it is possible to clearly enhance the dynamic behavior, i.e. rapid and large fluctuations in current, in a magnetic actuator where the magnetic coil is controlled by pulse width modulation.

In addition, it should be noted that the two proposed methods can be combined, that is, when controlling a magnetic actuator whose armature is driven by a magnetic coil controlled by pulse width modulation, the control variables for pulse width modulation control are changed. The decision may be performed within the on phase of generation of the pulse width modulated signal for the magnetic coil; In the scope of pulse width modulation control, at least one control variable for the pulse width modulation control is different from the control variables for the first value and the second value, in order to change the current in the magnetic coil from a first value to a second value. A cycle of can also be used. This also applies correspondingly to the preferred embodiments described above. Thereby, on the one hand, the dynamic behavior of the magnetic actuator can be increased even more, and on the other hand, the magnetic actuator (or corresponding valve) can be controlled or operated more flexibly.

A computer unit according to the invention, for example a control unit comprising a microcontroller, or a control device of an automobile, in particular program technology, is configured to perform the method according to the invention (one of the two proposed methods or a combination of the two methods). It is composed.

It is also desirable to implement the method of the present invention in the form of a computer program, since this incurs particularly low costs, especially if the execution-side control device exists anyway as it is also used for other tasks. am. Storage media suitable for providing computer programs are, for example, computer-readable recording media other than transmission media, especially magnetic, optical and electronic memories, such as hard disks, flash memories, EEPROMs, DVDs, etc. Additionally, it is possible to download programs through computer networks (Internet, intranet, etc.).

Further advantages and embodiments of the present invention are clearly set forth in the specification and accompanying drawings.

The invention is schematically illustrated in the drawings according to embodiments and is described below with reference to the drawings.

Figure 1 is a schematic diagram of a fuel injection system of an internal combustion engine comprising a high-pressure pump with an electric intake valve, in which the method according to the invention can be carried out.
Figure 2 is a schematic diagram of a magnetic actuator capable of carrying out the method according to the invention.
Figure 3 is a graph showing the characteristic curve of current during pulse width modulation control of a magnetic actuator.
Figure 4 is a graph showing a characteristic curve of current during pulse width modulation control of a magnetic actuator for explanation of the first method according to the present invention in a preferred embodiment.
Figure 5 is a schematic diagram of the sequence of the first method according to the invention in a preferred embodiment.
Figure 6 is a graph showing a characteristic curve of current during pulse width modulation control of a magnetic actuator for explanation of the second method according to the present invention in a preferred embodiment.

In Figure 1, an example of a fuel injection system 10 of an internal combustion engine 40 is schematically shown. The fuel injection system includes, by way of example, a fuel pump 14 (here electric), by which fuel is withdrawn from the fuel tank 12 via the fuel filter 13 to the high pressure pump 15. can be transported. Accordingly, the area upstream of the high pressure pump 15 forms a low pressure area. The high-pressure pump 15 is generally connected to the internal combustion engine 40 or a camshaft or crankshaft of the internal combustion engine at a certain transmission ratio and can thereby be driven.

The high-pressure pump 15 includes a metering unit 16, and the outlet of the high-pressure pump 15 is connected to a high-pressure accumulator 18, that is, a so-called rail, to which a plurality of fuel injectors 19 are connected. do. Fuel may be introduced into the internal combustion engine 40 again through the fuel injectors 19.

Additionally, on the high pressure accumulator 18 a pressure sensor 20 may be provided, configured to detect the pressure within the high pressure accumulator 18 . In addition, a pressure control valve 21 is provided, through which the pressure in the high-pressure accumulator can be controlled or adjusted (in addition to the use of a metering unit). Via the pressure control valve 21 , excess fuel can be returned into the fuel tank 12 . As is obvious, depending on the type of fuel injection system, only a metering unit or only a pressure control valve may be used for regulation or control of the pressure in the high pressure accumulator.

It is also designed as a control device, configured to control, for example, the internal combustion engine 40 or the fuel injectors 19, the high pressure pump 15 with metering unit 16, and the pressure control valve 21. A computer unit 80 is shown. Additionally, the control device 80 can for example read out signals from the pressure sensor 20 and thereby detect and process the pressure in the high pressure accumulator 18 .

In Figure 2 a magnetic actuator 100 is shown, with which the method according to the invention can be performed. In this case, the magnetic actuator 100, as previously described with reference to FIG. 1, may include, for example, a magnetic valve; or a metering unit of a fuel control system; Or it may be part of a proportional control valve, such as a pressure control valve of an internal combustion engine.

The magnetic actuator 100 includes a magnetic coil 111; and an armature 112 mounted to be movable in the x direction within the magnetic coil. The armature 112 is connected to a sealing member 113, such as a valve needle, etc., which interacts with the valve seat 114 to provide valve function.

The degree of opening of the valve, that is, the position (x) of the armature 112, can be controlled through the magnetic coil 111 by the current (I) output by the control device 80 when applying the voltage (U). there is. Obviously, control devices different from the control device shown in Figure 1 may also be used.

In Figure 3, a characteristic curve of the current during (conventional) pulse width modulation control of a magnetic actuator, for example as shown in Figure 2, is shown. Here, current (I) and voltage (U) are plotted over time (t).

In the category of pulse width modulation control, within the period (T) during the control period (Δt _on ), that is, in the on phase, a signal (S) as a voltage is first applied to the magnetic coil, as described with reference to FIG. 2, Subsequently, no voltage is applied during the control period (Δt _off ), that is, during the off phase.

Correspondingly, the current I first rises within the control period Δt _on and then falls again within the control period Δt _off , as is typical in the case of magnetic coils.

Additionally, the duty cycle, which is a control variable in the category of pulse width modulation control (in addition to the cycle period T), is shown as “TG”. In this case, the duty cycle indicates the ratio of the control period (Δt _on ) compared to the cycle period (T). In this case, via the duty cycle (TG), the (average) current in the magnetic coil can be adjusted.

In Figure 4, a current characteristic curve during pulse width modulation control of a magnetic actuator is now shown for illustration of the first method according to the invention in a preferred embodiment. As in Figure 3, here too current (I) and voltage (U) are plotted over time (t). In Figure 5, the corresponding sequence is schematically shown. In the following, FIGS. 4 and 5 are described collectively.

For the cycle shown in the center in Figure 4, two different times (t ₀ and t ₁ ) are shown. In the case of conventional pulse width modulation control, the determination of the control variables, namely the period period (T) and duty cycle (TG), is performed in time synchronization with the setting or sending of the signal (S) for energizing the magnetic coil. It doesn't work. That is, although the determination of the control variables may require an increase in the duty cycle, the determination is not carried out at time t ₀ , i.e. during the off phase, as seen in FIG. 4 . Therefore, the signal S with a new duty cycle, here referred to as TG"', can only be implemented by the next cycle, that is, from t _1. However, until then the current continues to drop.

In the scope of the proposed first method, the determination of the control variables, in particular the new duty cycle, is preferably time-synchronous with the setting or transmission of the signal S, here at the time point t ₁ shown, but nevertheless at least within the on-phase. is carried out in If, for implementation, the duty cycle (TG) and, if applicable, the cycle period (T) also have to be varied, the duty cycle and cycle period are stored in registers 82 of the time control unit 81 of the control device or computer unit 80. It is recorded directly within. Thereby, a response to the new duty cycle can still be made within the current cycle, i.e. the new duty cycle (TG"') can be set as quickly as possible. The dynamic behavior of the magnetic actuator is thereby significantly increased. .

In Figure 6, in a preferred embodiment, a current characteristic curve during pulse width modulation control of a magnetic actuator is shown for explanation of the second method according to the present invention. As in Figure 3, here too current (I) and voltage (U) are plotted over time (t).

The first of the three cycles shown includes control variables with a cycle period (T) and a duty cycle (TG). Accordingly, in the example shown, the first value I ₁ for the current I is achieved. In this case, the first value is given as an average value over the period T.

Subsequently, variable control variables are used, namely a cycle (shown in the middle) with cycle period T' and duty cycle TG', followed by again variable control variables, here again cycle period ( A cycle (shown third) with T) and duty cycle TG" is used. With duty cycle TG", the second value I ₂ for the current I in the illustrated example is reached. do. In this case, the second value, like the first value, is given as an average value over the period T.

For an intermediate cycle with an extended cycle period (T'), the duty cycle (TG") is either 1 or 100%. During this cycle, the current (I) (with the on phase of the subsequent cycle) is becomes normal again but the duty cycle continues to increase by varying subsequent periods such that the required second value (as an average value) can be reached.

But now (as may be the case with conventional pulse width modulation control), if said additional period, here the intermediate period, is omitted, that is, if only the duty cycle changes from TG to TG" when switching from one period to the next. , the current I may gradually rise, but not due to the already changed first cycle: on the contrary, in the meantime, through the off phase that appears in this case, the current may fall again.

In contrast, with additional cycles in which the control variables are varied, the current may increase or decrease very quickly, which obviously increases the dynamic behavior of the magnetic actuator.

As a matter of course, the control variables during the additional period can be selected so that, as desired, the required current value (with subsequent periods) remains the same. In this case, the cycle period can, if necessary, be shorter than for example in the normal state.

Claims (11)

delete delete delete A method of controlling a magnetic actuator 100 in which the armature 112 is driven by a magnetic coil 111 controlled by pulse width modulation,
In order to change the current (I) in the magnetic coil 111 from the first value (I ₁ ) to the second value (I ₂ ), in the category of pulse width modulation control, control variables (T) for pulse width modulation control are used. ', TG') is different from the control variables (T, TG, TG") for the first and second values. 5. The method of claim 4, wherein in the at least one period, a period period (T') and/or a duty cycle (T') that is different from the period period (T) or duty cycle (TG, TG") for the first and second values. TG') is used in the magnetic actuator control method. According to clause 4 or 5,
This is a control method of a magnetic actuator 100 in which the armature 112 is driven by a magnetic coil 111 controlled by a pulse width modulation method, and the determination of control variables (T, TG) for pulse width modulation control is performed using the magnetic actuator 100. A method of controlling a magnetic actuator, combined with a method of controlling a magnetic actuator, performed within the on phase (Δt _on ) of the generation of the pulse width modulated signal (S) for the coil (111). 6. Method according to claim 4 or 5, wherein the magnetic actuator (100) is controlled by two-point control in the category of pulse width modulation control. 6. The magnetic actuator (100) according to claim 4 or 5, wherein the magnetic actuator (100) is a magnetic actuator of a proportional control valve, a magnetic actuator of a metering unit (16) of a fuel control system of an internal combustion engine (40), or a magnetic actuator of a fuel control system (16) of an internal combustion engine (40). A magnetic actuator control method, wherein the magnetic actuator of the pressure control valve (21) is used. A computer unit (80) configured to perform the method according to claim 4 or 5. A computer program that, when executed in a computer unit (80), causes the computer unit (80) to perform the method according to claim 4 or 5, and is stored in a non-transitory machine-readable storage medium. A non-transitory machine-readable storage medium storing the computer program according to claim 10.

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