DE19701471A1 - Method of exciting esp. vehicle IC engine solenoid fuel-injection valve while fuel is not injected and before first fuel injection - Google Patents

Abstract

The method controls the magnetic valve for controlling the injection of fuel in a combustion engine. Charge stored in a storage device is discharged into the load at the start of the control. The storage device is charged according to a condition in which there is no fuel injection, before a first fuel injection. Preferably the storage device is charged when a signal is applied which indicates a start process. Preferably the start signal is a rotation rate signal or a voltage applied to a clamp. Alternatively the storage device may be charged when a signal is applied which indicates the end of a push operation.

Description

State of the art

The invention relates to a method and a device to control an electromagnetic consumer.

A device for controlling an electromagnetic Consumer is known from DE-OS 44 13 240. At this Device, the energy released when switching off, stored in a booster capacitor. At the beginning of the the next time the stored energy is activated Reloaded consumers.

Furthermore, facilities are known in which during a Reload time after the actual activation of the valve by briefly switching the power on and off additional charge is charged into the capacitor. This Process is usually called reloading or recharging designated. The reload time should be as short as possible, because the time available, especially for large ones Speeds, can be very short.

After switching on the control unit using a The capacitor is usually not the ignition switch  loaded. The internal combustion engine has been in use for a long time in an operating state in which no injection take place, such as in overrun mode, is the The capacitor is usually also discharged. At a subsequent control can occur that the Valve does not open or only opens with a delay.

Object of the invention

The invention is based on the object Device for controlling an electromagnetic Consumers even when activated for the first time State in which there was no injection, a quick and to achieve precise switching of the consumer.

Advantages of the invention

The device according to the invention with the features of independent claims has the advantage that even the first metering after a state in which none Injection was carried out, the valve switched quickly and an accurate fuel metering is possible.

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 device according to the invention, Fig. 2 and 3 different over time applied signals, and Figs. 4 and 5 are respectively a flow chart.

Description of the embodiments

The device according to the invention is preferred at Brenn Engines, especially with self-igniting internal combustion machines, used. There are more electromagnetic Valves for controlling fuel metering. 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 will.

When used in internal combustion engines, especially in Auto-ignition 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. With higher numbers of cylinders of the internal combustion engine, more valves, switching means and diodes are to be provided accordingly.

With 100 , 101 , 102 and 103 four consumers are designated. In each case a first connection of the consumers 100 to 103 is connected to a voltage supply 105 via a switching means 115 and a diode 110 .

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 connection of the diodes is in each case 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 .

A control unit 160 applies a control signal AH to the high-side switch 115 . 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 control processes, among other things, the signal N of a speed sensor 180 , a sensor 195 indicating the accelerator pedal position FP and the voltage 190 applied to a terminal 50 . A voltage is present at the so-called terminal 50 when the starter is actuated. A voltage at terminal 50 indicates actuation of the starter or an imminent start of the internal combustion engine.

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 current measuring means can be arranged between the voltage supply and the high-side switch or between the high-side switch and the consumers.

The drive signal AC for the booster transistor 140 is plotted in FIG. 2a. The control signal AH for the high-side switch 115 is plotted in FIG. 2b. 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 applied across the capacitor 145 at opposite voltage UC over time. Here, a control that corresponds to a metering cycle is shown without pre-injection for a solenoid valve.

Different phases are distinguished in each metering cycle. In a phase 0, before the consumer is activated, 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 electricity flows through the consumers. The capacitor 145 is charged to its maximum voltage UC. This takes on a value of approx. 80 volts, for example, whereas the voltage of the power supply takes on a value of approx. 12 V.

In the first phase at the beginning of the activation, which is referred to as booster operation, the low-side switch is activated, which is assigned to the consumer who is to meter the fuel. This means that from phase 1 the signal AL assumes a high level. 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 actuation 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, the current I rises very quickly due to the high voltage at the consumer. Phase 1 ends when the voltage across capacitor 145 falls below a certain value U2.

In the second phase, also referred to as starting current control, the inrush current is taken over by the high-side switch 115 and the booster 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 a further threshold is undershot, 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 control unit 160 signals the end of the tightening phase. 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. If the switching point detection does not recognize within a predetermined time that the solenoid valve armature has reached its new end position, 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, that is to say 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 adjusted 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 . Phase 4 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 3rd and 5th phase, 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 driven in such a way that it blocks the flow of current. The energy released is reloaded into the capacitor 145 . Quick erasure occurs during these phases. 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 night clocking, the high-side switch 115 is brought back 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 a quick erase for the current path consisting of the consumer, one of the diodes 130 to 133 and the capacitor 145th As a result, the voltage applied to capacitor 145 increases.

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.

This is followed by phase 8 , in which all control signals are withdrawn and all switches are brought to their locked state. This phase corresponds to phase 0.

When the consumers are first activated after a state of the internal combustion engine, in which no injections take place, the capacitor 145 is discharged. In this case, the advantages of the capacitor cannot be used for the first activation. In particular, there is no accelerated switch-on process and no defined injection. Furthermore, when the internal combustion engine starts, the available voltage drops below the usual value.

To solve this problem it is provided that after a State in which no injections have taken place before the first time the fuel is loaded again becomes. By evaluating suitable signals, a imminent injection is recognized and the Charging of the capacitor initiated.  

Such a state in which no injections take place is that the internal combustion engine is at a standstill. The charging process is initialized when a signal is present that indicates an imminent starting process. A speed signal, the voltage at a terminal 50 and / or the voltage at a terminal 15 can in particular be used as the signal which indicates an imminent starting process.

Another state in which no injections take place is the overrun mode. The storage medium is loaded when there is a signal indicating the end of overrun operation displays. As a signal indicating the end of an overrun operation indicates, for example, an accelerator pedal position signal to serve.

To detect an impending start of the internal combustion engine, the output signal of the speed sensor and / or the terminal 50 is evaluated according to the invention. If the driver actuates the ignition key to start the internal combustion engine, the starter is energized, a voltage being present at terminal 50 . If the device detects that this voltage is present, the reloading process is started. The evaluation of terminal 15 is less suitable, since voltage is already applied to it if only the ignition is switched on. This can happen that the driver only switches on the ignition and only starts the internal combustion engine at a later time.

It is particularly advantageous if when the first occurs Impulse of the speed sensor the charging process is started. As a rule, segment encoders and / or Incremental encoder used on a regular basis Give impulses.  

In addition to these signals, other signals can also be evaluated to be an imminent start detect.

In Fig. 3 different signals are plotted against time. The voltage at terminal 15 is plotted in part 3a, and the voltage at terminal 50 is plotted over time t in part 3b. The partial figure 3c shows the pulses of the speed sensor 180 . The voltage U across the capacitor 145 is plotted in part 3d and the current I flowing through the consumer is plotted in part 3e.

In Fig. 3, the conditions when switching on before the first injection are shown. At time t0, the driver actuates the ignition key and the voltage at terminal 15 increases. At time t1, the starter is energized, which corresponds to a voltage increase at terminal 50 .

The first pulse of the speed sensor N occurs immediately after the time t1. At this time t1 or when the first speed pulse N occurs, the charging of the capacitor 145 is started according to the invention. This means that from time t1, the procedure is as shown in phase 7 of FIG. 2.

The result of this is that the current rises and falls again each time t2 and the voltage U increases gradually to the value U1. If this value is reached at time t2, the capacitor 145 is fully charged. This state corresponds to the state of the capacitor after an injection after phase 7 in FIG. 2.

At time t3, the first injection into the Internal combustion engine that lasts until time t4.  

Phases 1 to 5 are processed between times t3 and t4. This is followed by another recharging process to recharge the capacitor. The time sequence according to FIG. 2 is run through for each injection.

In FIG. 4, the procedure is shown in a flow chart. In a first step 400 it is recognized that the voltage at terminal 15 has risen. The subsequent query 410 checks whether a voltage is present at terminal 50 . If this is not the case, query 420 follows, which checks whether there is a speed pulse. If this is also not the case, query 410 follows again. If a voltage is present at terminal 50 and / or if the speed signal N is present, then the charging process for the capacitor follows in step 430 , as shown in FIG. 3 from time t1.

As shown, the two queries can both take place. But it can also be provided that only one of the two Queries is provided.

Monitoring the so-called terminal 15 is particularly advantageous. Voltage is applied to it when the driver actuates the ignition key. It is advantageous here that the reloading process takes place when evaluating terminal 15 before the starter is actuated, in which case the supply voltage is generally higher than after actuation of the starter. In this embodiment, step 430 occurs immediately after step 400 .

Another embodiment is shown in FIG. 5. In a first step 500 , it is recognized that there is an operating state in which no injection takes place. Such an operating state is, for example, in overrun mode. The coasting operation is recognized by evaluating the accelerator pedal and / or the speed. The subsequent query 510 checks whether the accelerator pedal is actuated. Pressing the accelerator pedal indicates an end of coasting. If there is no actuation of the accelerator pedal, query 510 follows again. If the accelerator pedal is actuated, the charging process for the capacitor follows as shown in FIG. 3 from time t1 in step 520 .

Claims (7)

1. A method for controlling an electromagnetic consumer, in particular a solenoid valve for controlling the injection of fuel into an internal combustion engine, the charge stored in a storage means being reloaded into the consumer at the start of the control, characterized in that after a state in which none Injections occur before the storage medium is loaded before a first injection. 2. The method according to claim 1, characterized in that the storage medium is loaded when a signal is present, that indicates an upcoming start-up. 3. The method according to any one of the preceding claims, characterized characterized that as a signal that an upcoming Starting process indicates, a speed signal is used. 4. The method according to any one of the preceding claims, characterized in that the voltage at a terminal ( 50 ) is used as a signal which indicates an upcoming starting process. 5. The method according to claim 1, characterized in that the storage medium is loaded when a signal is present, which indicates the end of a push operation. 6. The method according to claim 5, characterized in that as a signal indicating the end of overrun operation Accelerator pedal position signal is used. 7. Device for controlling an electromagnetic Consumer, in particular a solenoid valve for control the injection of fuel into an internal combustion engine, with means the charge stored in a storage means reload into the consumer at the start of control, characterized in that means are provided which according to a state in which no injections take place load the storage medium after a first injection.