DE19746981A1 - Method of driving electromagnetic load, esp. a magnetic fuel injection valve for an internal combustion engine - Google Patents

Abstract

The method involves discharging the charge stored in a storage device into the load at the start of the drive process and increasing the charge by recharging between two injections. The injection process is divided into at least a first and a second partial injection process, and between two partial injections recharging is interrupted or stopped when certain conditions prevail. An Independent claim is also included for an arrangement for carrying out the method.

Description

State of the art

The invention relates to a method and a device to control at least one electromagnetic Ver user.

A device for controlling at least one electroma gnetic consumer is known from DE-OS 44 13 240. In this device, the one that is released when switching off Energy stored in a booster capacitor. When loading The stored energy begins at the next activation reloaded into the consumer.

Furthermore, devices are known in which, after the valve has been activated, the capacitor is additionally charged by briefly switching the current on and off. This process is commonly referred to as reloading or recharging. As a result of the recharging, the state of charge of the capacitor 145 and thus the voltage applied to it are increased. This reload time should be as short as possible, since there is usually very little time available. This is especially true at high speeds.

For injection systems in which the injection is in two Partial injections, the distance between the two partial injections are not chosen to be smaller, than the time it takes to set the capacitor on one to charge a sufficiently high voltage at which the successor switch-on takes place sufficiently quickly.

Object of the invention

The invention has for its object a Vorrich device for controlling an electromagnetic consumer shorten the distance between two partial injections, the switch-on process in the second partial injection should take place as quickly as possible.

Advantages of the invention

The device according to the invention with the features of unab pending claims has the advantage that the distance chosen between the two partial injections very short can be, although usually a very fast switching process possible with all partial injections is.

drawing

The device according to the invention is explained below with reference to the embodiments shown in the drawing. In the drawings Fig. 1 shows a circuit arrangement of the erfindungsge MAESSEN device, Fig. 2 different up over time transmitted signals and Fig. 3 is a flowchart.

Description of the embodiments

The device according to the invention is preferred at Brenn Engines, especially with self-igniting internal combustion machines, used. There is the fuel metering controlled by electromagnetic valves. This elec tromagnetic valves are referred to below as consumers designated. The invention is not for this application limits, it can be used wherever Fast switching electromagnetic consumers are required become.

When used in internal combustion engines, especially in self-igniting internal combustion engines, set the opening and Closing time of the solenoid valve the start of injection or the injection end of fuel in the cylinder firmly.

In Fig. 1 the most important elements of the device according to the Invention are shown. From the illustrated embodiment, it is a four-cylinder internal combustion engine. Each consumer is assigned an injection valve and each injection valve a cylinder of the internal combustion engine ne. If the number of cylinders of the internal combustion engine deviates, valves, switching means and diodes must be provided in a corresponding number.

Four consumers are shown at 100 , 101 , 102 and 103 . One connection each of the consumers 100 to 103 is connected via a switching means 115 and a diode 110 to a voltage supply 105 .

The diode 110 is arranged in such a way that its anode is connected to the positive pole and its cathode is connected to the switching means 115 . The switching means 115 is preferably a field effect transistor.

The second connection of the consumers 100 to 103 is connected to a resistance means 125 via a respective second switching means 120 , 121 , 122 and 123 . The switching means 120 to 123 are also preferably field effect transistors. The switching means 120 to 123 are referred to as low-side switches and the switching means 115 as high-side switches. The second connection of the resistance means 125 is connected to the second connection of the voltage supply.

A diode 130 , 131 , 132 and 133 is assigned to each consumer 100 to 103 . The anode connections of the diodes are each in contact with the connection point between the consumer and the low-side switch. The cathode connection is connected to a capacitor 145 and a further switching means 140 . The second connection of the switching means 140 is in contact with the first connections of the consumers 100 to 103 . The switching means 140 is also preferably a field effect transistor. This switching means 140 is also referred to as a booster switch. The second connection of the capacitor 145 is also connected to the second connection of the supply voltage 105 .

The high-side switch 115 is acted upon by a control unit 160 with a control signal AH. The switching means 120 is acted upon by the control unit 160 with a control signal AL1, the switching means 121 with a control signal AL2, the switching means 122 with a control signal AL3, the switching means 123 with a control signal AL4 and the switching means 140 with a control signal AC.

A diode 150 is connected between the second connection of the voltage supply 105 and the connection point between the switching means 115 and the first connections of the consumers 100 to 103 . Here, the anode of the diode is connected to the second connection of the voltage supply 105 .

The current flowing through the consumer can be determined by means of the resistor 125 .

With the arrangement shown, current measurement via the current measuring resistor 125 is only possible if one of the switching means 120 to 123 is closed. In order to be able to detect the current even when the low-side switches are open, the current measuring resistor can also be arranged elsewhere. For example, the second terminal of the capacitor 145 can be connected to the connection point between the current measuring means 125 and the switching means 120 to 123 . In this case, current measurement is also possible with the low-side switch locked. Furthermore, the Strommeßmit tel can be arranged between the voltage supply and the high-side switch or between the high-side switch and the consumers.

In Fig. 2a, the drive signal AC for the Boo ster switch 140 is applied. In Fig. 2b, the control signal AH for the high-side switch 115 is applied. Fig. 2c, the drive signal AL shows one of the low-side switch. In Fig. 2d the current flowing through the load current I and is shown in Fig. 2e the voltage present at capacitor 145 voltage UC plotted over time. Here, a control that corresponds to a partial injection is shown completely and a second partial injection is shown partially.

Different phases are distinguished for each partial injection. In a phase 0, before activating the consumer, the output stage is switched off. The control signals AC, AH and AL are at low potential. This means that the high-side switch 115 , the low-side switches 120 to 123 and the booster switch 140 block the current flow. No current flows through the consumers. The capacitor 145 is charged to its maximum voltage UC. For example, this assumes a value of approx. 80 volts, whereas the voltage of the power supply assumes a value of approx. 12 V.

In the first phase at the beginning of the control, which is referred to as booster operation, the low-side switch is activated, which is assigned to the consumer who is to measure the fuel. This means that the signal AL assumes a high level from the first phase. At the same time, a high signal is output on line AC, which controls switch 140 . The high-side switch 115 is not activated, it continues to lock. This control of the switching means causes a current to flow from the capacitor 145 via the booster switch 140 , the corresponding consumer, the low-side switch assigned to the consumer and the current measuring means 125 . In this phase, current 1 rises very quickly due to the high voltage at the consumer. The first phase ends when the sator 145 applied to the condensate exceeds a certain value U2 terschreitet un and / or the current that passes through the consumer a certain value.

In the second phase, which is referred to as starting current control, the inrush current is taken over by the high-side switch 115 and the booster switch is deactivated. In the second phase, the drive signal for the booster switch 140 is withdrawn, so that the switch 140 blocks. The control signals AH and AL for the high-side switch 115 and the low-side switch assigned to the consumer are set to a high level so that these switches release the current flow. Thus, a current flows from the voltage supply 105 via the diode 110 , the high-side switch 115 , the consumer, the corresponding low-side switch, the current measuring resistor 125 back to the voltage source 105 . By contacting the high-side switch, the current, which is detected by means of the current measuring resistor 125 , can be regulated to a predeterminable value for the starting current IA. This means that when the target current IA for the starting current is reached, the high-side switch 115 is activated in such a way that it blocks. If the level falls below another threshold, it is released again.

When the high-side switch 115 is blocked, a freewheeling circuit acts. The current flows from the consumer through the low-side switch, the resistor 125 and the free-wheeling diode 150 .

The second phase ends when the end of the tightening phase is output by the control unit 160 . This can e.g. B. be the case when a switching time detection recognizes that the solenoid valve armature has reached its new end position. He does not know the switching point detection within a predetermined time that the solenoid valve armature has reached its new end position, so an error is detected.

In the third phase, which is also referred to as the first quick extinguishing, the control signal for the corresponding low-side switch is withdrawn. This has the effect that a current flows from the respective consumer through the diode 130 to 133 assigned to the consumer in the capacitor 145 and the energy stored in the consumer is transferred to the capacitor 145 . The high-side switch 115 is controlled in the illustrated embodiment so that it remains closed. In this phase, the current drops from the starting current IA to the holding current IH. At the same time, the voltage across capacitor 145 rises to a value U3, which is, however, clearly below the value U1. The third phase ends when the setpoint IH for the holding current is reached. The energy released during the transition from the pull current IA to the holding current IH is stored in the capacitor. It is particularly advantageous here that the transition from the pull-in current to the holding current takes place quickly due to the rapid extinction.

The third phase is followed by the fourth phase, which is also referred to as holding current control. As in the second phase, the control signal for the low-side switch remains at its high level, i.e. the low-side switch assigned to the consumer remains closed. By opening and closing the high-side switch 115 , the current that flows through the consumer is regulated to the setpoint value for the holding current. When the high-side switch 115 is blocked, a freewheeling circuit acts. The current flows from the consumer through the low-side switch, the resistor 125 and the free-wheeling diode 150 . The fourth phase is finished when the injection process is completed.

In the subsequent fifth phase, which is also referred to as a second rapid extinction, the corresponding low-side switch is switched off and the high-side switch 115 is turned on . In this phase, the current flowing through the consumer also drops rapidly to zero. At the same time, the voltage U applied to capacitor 145 rises by a smaller value than in the third phase.

In the third and fifth phases, the setpoint for the current I changes from a high to a low value. In these phases, the low-side switch assigned to the consumer is controlled in such a way that it blocks the flow of current. The energy released is reloaded into the capacitor 145 . In these phases, quick deletion takes place. This causes the current to quickly reach its new set point.

In phases two and four, the current is regulated by touching the high-side switch. When the high-side switch is blocked, the freewheeling diode 150 is active. The current slowly drops in these phases. This leads to a lower switching frequency.

In the sixth phase, the output stage is inactive, which means that there is no fuel metering. This means that the control signal AC for the booster switch 140 , the control signal AH for the high-side switch and the control signal AL for the low-side switch all assume a low level and block all switches. The current flowing through the consumer remains at 0 and the voltage across capacitor 145 remains at its value.

In the seventh phase after the control, which is also referred to as clocking, recharging or recharging, the high-side switch 115 is brought into its conductive state by the control signal AH. By closing a low-side switch, a current flow in one of the consumers is initialized. The current flows back, for example, via the diode 110 , the switch 115 , the consumer 100 , the switching means 120 and the current measuring means 125 into the voltage source. When a setpoint for the current is reached, which is selected so that the solenoid valve does not yet react, the low-side switch is activated so that it opens. This in turn causes the current path to be quickly erased, consisting of the consumer, one of the diodes 130 to 133 and the capacitor 145 . As a result, the voltage across capacitor 145 rises.

As soon as the current falls below a certain value, the low-side switch 120 is activated again. This process is repeated until the voltage across the capacitor 145 gradually reaches the value U1 again. This process is known as recharging.

Then there is the eighth phase, in which all control signals withdrawn and all switches in their locked Condition. This phase corresponds to phase 0.

Then the next injection or part starts spraying with the first phase, followed by the second phase connects.

If it is provided that an injection is divided into at least one ste and a second partial injections, it can occur, especially at high speeds, that the distance between the two partial injections is not sufficient to fully charge the capacitor 145 to the voltage U1 . This means that the time available for phases 6 , 7 and 8 is too short to recharge the capacitor. At lower speeds, the seventh phase is too short to fully charge the capacitor so that the usual voltage U1 is applied to it.

This is particularly the case when the injection is in several partial injections is divided. These are before preferably a pre-injection before the actual Main injection, the main injection and one Post-injection after the actual main injection is done. Pre-injection is also possible Main injection and / or post-injection in others Subdivide partial injections.  

Post-injection is particularly problematic because of the Distance between the main injection and the post-injection tion must be very small to avoid unwanted effects can.

According to the invention it was recognized that the tolerances on occur when the booster capacitor is not fully charged is, with the post-injection only insignificantly on that Impact the behavior of the internal combustion engine. According to the invention it is provided that the reloading can be canceled. This be indicates that if certain conditions are met, the Nachla which is canceled, especially if the distance until the next injection and / or partial injection is less than a threshold. The reload was canceled is preferably done if it is the following Partial injection is a post-injection.

In particular, it can be provided that the reloading before Beginning of reloading is canceled. This means that Reloading in the seventh phase is completely eliminated. Erfin According to the reloading and thus the seventh phase before post-injection under certain conditions prevented or canceled. The seventh phase is opposite the other partial injections are shortened or completely eliminated constantly.

In Fig. 3, the procedure according to the invention is exemplified using a flow chart. The fifth phase takes place in step 300 . This means the partial injection, especially the main injection, ends. Inquiry 310 checks whether the duration of phases 6 , 7 and 8 is longer than a first threshold value SW1. If this is not the case, this means that the distance between the end of the partial injection and the subsequent partial injection is too short to recharge the booster capacitor, phase 0 immediately follows the subsequent partial injection, in particular the post-injection, in step 315 .

In one embodiment of the invention can also be provided be that an operating parameter is checked in such a way whether it takes on certain values. If this is the case, then also assumed that reloading was prevented and / or must be canceled. As operating parameters sizes that influence the distance between have the partial injections. It is particularly advantageous the use of the engine speed or egg ner size corresponding to the speed. This means that reloading is stopped or canceled when the Speed exceeds a threshold value.

If the duration of phases 6 , 7 and 8 is longer than a first threshold value SW1, this means that the distance between the end of the partial injection and the subsequent partial injection is not too short to recharge the booster capacitor, the seventh begins in step 320 Phase the reloading of the booster capacitor. The subsequent query 330 checks whether the remaining time RZ, which is still available for reloading, is less than a second threshold value SW2. If this is not the case, which means that there is still time until the start of the next partial injection, step 320 follows, that is to say the reloading is continued. If the remaining time RZ is less than the second threshold value SW2, the reloading is interrupted, which means that phase 0 follows immediately.

In a particularly simple embodiment of the invention, the recharging (phase 7 ) is interrupted when a signal is present that signals the start of the next partial injection.

As shown in FIG. 1, several consumers are seen before, especially if the number of consumers is greater than four, it is advantageous to divide the consumers into groups, with each group being assigned a capacitor 145 .

The device according to the invention was based on the example of a Internal combustion engine shown with four cylinders. The before is also on internal combustion engines with other Zy transferable number of people. There is a corresponding number for this of consumers, switching devices and other elements watch. It can also be provided that the consumer in a larger number of groups is divided. This is particularly useful with higher numbers of cylinders.

Claims (6)

1. A method for controlling at least one electromagnetic consumer ( 100 ), in particular a solenoid valve for controlling the injection of fuel into an internal combustion engine, the charge stored in a storage means ( 145 ) at the start of the control ( 1 ) in the consumer ( 100 ) is reloaded by reloading the storage means ( 145 ) between two injections to increase the loading state of the storage means, characterized in that the injection is divided into at least a first and a second partial injection, and that between two partial injections reloading Certain conditions are prevented or canceled. 2. The method according to claim 1, characterized in that in the partial injections between a pre-injection, a main injection or a post-injection under will be divorced. 3. The method according to any one of the preceding claims, characterized characterized in that the reloading before the post-injection is prevented or canceled. 4. The method according to any one of the preceding claims, characterized characterized in that reloading is prevented or canceled the distance between the two parts injections is less than a threshold.   5. The method according to any one of the preceding claims, characterized characterized in that reloading is prevented or canceled if the speed exceeds a threshold value tet. 6. Device for actuating at least one electromagnetic consumer ( 100 ), in particular a solenoid valve for controlling the injection of fuel into an internal combustion engine, with means that the charge stored in a storage means ( 145 ) at the start of the actuation ( 1 ) reload the consumer ( 100 ) and increase the loading state of the storage medium by reloading the storage medium ( 145 ) between two injections, characterized in that the injection is divided into at least a first and a second partial injection, and that means are provided that prevent or interrupt reloading between two partial injections when certain conditions exist.