JP2000046231A - Control method of electromagnetic load and control device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly distinguish an error and a normal operation from each other by detecting and evaluating voltage impressed on an energy accumulating element when fuel is injected, in a device using electric charge of the energy accumulating element for promoting input-connection of a load, in the case where a solenoid valve (an electromagnetic injector) is controlled. SOLUTION: In a four cycle internal combustion engine, each first terminal of electromagnetic injectors (a load) 100 to 103 arranged per cylinder is connected to a voltage supplying unit 105 through switch means 115 and a diode 110, and a second terminal is connected to a resistor 125 through switch means 120 to 123. Each load 100 to 103 is connected to a condenser 145 and switch means 140 through diodes 130 to 133. In a monitoring unit 165, current is measured through the current measuring resistor 125 only when one of the switch means 120 to 123 is closed, voltage applied on the condenser 145 is measured, and the whole of a system is monitored from those measured result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method and a control apparatus for an electromagnetic load, and more particularly to a control method and a control apparatus for an electromagnetic valve for controlling fuel adjustment to an internal combustion engine.

[0002]

2. Description of the Related Art Such a device and such a method for controlling electromagnetic loads are described, for example, in DE-OS 4413.
240 is known. There, energy that is freed when the load is cut off is stored in a capacitor, and is used to promote the connection of the load in the next connection process. Such loads are often used in injectors of internal combustion engines. Monitoring discrete quantities is necessary to identify the failure of individual components of such injectors.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to monitor the entire system in a method and a control device for controlling an electromagnetic load.

[0004]

This object is achieved by detecting and evaluating the voltage applied to the energy storage element between the end of an injection and the start of the next injection.

[0005]

DETAILED DESCRIPTION OF THE INVENTION By means of the invention, a simple and reliable monitoring of a system including an electromagnetic load is obtained. Especially in all operating areas, an exact distinction between error and normal operation is possible.

[0006] Advantageous developments and embodiments of the invention are described in the dependent claims.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The device according to the invention is advantageously used in self-igniting internal combustion engines. There, fuel metering is controlled by a solenoid valve. Hereinafter, this solenoid valve is referred to as a load. The present invention is not limited only to the application of the solenoid valve, and can be used anywhere where an electromagnetic load that turns on and off at a high speed is required.

When applied to an internal combustion engine, especially a self-ignition internal combustion engine, the opening and closing times of the solenoid valve determine the start or end of fuel injection into the cylinder.

FIG. 1 shows the main elements of the device according to the invention. In the illustrated embodiment, the engine is a four-cylinder internal combustion engine. Here, one injection valve is assigned to each load, and one cylinder of the internal combustion engine is assigned to each injection valve. If the internal combustion engine has a large number of cylinders, correspondingly more valves, switch means and diodes are provided.

According to 100, 101, 102 and 103,
Four loads are shown. All loads 100-10
Each of the first terminals 3 is connected to the voltage supply unit 105 via the switch means 115 and the diode 110. Switching means are also shown as upper switches.

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

The second terminals of the loads 100 to 103 are each connected to one switch means 120, 121, 12 respectively.
2 and 123 are connected to the resistor 125. The switching means 120 to 123 are likewise advantageously field effect transistors. The switch means 120 to 123 are shown as lower switches, and the switch means 115 is shown as an upper switch. A second terminal of the resistance means 125 is connected to a second terminal of the voltage supply unit.

Each load 100 to 103 has a diode 13
0, 131, 132, and 133 are assigned. The anode terminals of the diodes are each connected to a connection point between the load and the lower switch. The cathode terminal is connected to the capacitor 145 and another switch means 140. Switching means 140 is likewise advantageously a field effect transistor. This switch means 140 is also called a booster switch. The second of the capacitor 145
Are connected to the second terminal of the voltage supply unit 105 in the same manner.

A control signal AH is applied from a control circuit 160 to the upper switch 115. The control signal AL1 from the control unit 160 is supplied to the switch means 120, the control signal AL2 is supplied to the switch means 121, the control signal AL3 is supplied to the switch means 122, the control signal AL4 is supplied to the switch means 123, and the control signal AL4 is supplied to the switch means 140. The signal AC is applied.

A diode 150 is connected between a second terminal of the voltage supply unit 105 and a connection point between the switch means 115 and the first terminals of the loads 100 to 103. The anode of this diode is connected to the second terminal of the voltage supply unit 105.

The current flowing through the load can be detected by the resistor 125.

With the arrangement shown, current measurement via the current measuring resistor 125 is only possible when one of the switch means 120-123 is closed. The current measurement resistor can be located elsewhere to provide current detection when the lower switch is open. For example, the capacitor 14
5 can be connected to a connection point between the current measuring means 125 and the switch means 120 to 123. In this case, a current measurement is also possible when the lower switch is blocked. Furthermore, the current measuring means can be arranged between the voltage supply and the upper switch or between the upper switch and the load.

The configuration of the switching elements, loads, diodes and capacitors has been selected only by way of example. The means described below can be used even if the elements have other configurations.

The control unit 160 further includes a sensor 170
Is connected to Sensor is increment wheel 17
Scanning 5, the increment wheel is advantageously located on the camshaft and / or crankshaft.

Further, a monitoring unit 165 is provided, and this monitoring unit is connected to two terminals of the voltage supply unit 105. The monitoring unit 165 exchanges signals with the control unit 160. The voltage applied to the capacitor 145 is
5 as well.

When the control unit 160 and the monitoring unit 165
It is advantageous to form two structural units.

In controlling the load, different phases are distinguished. The first phase is also called a booster operation. In this phase, the closing of the switch means 140 and one of the switches 120 to 123 causes the corresponding load 10
Electric power is supplied to the electrodes 1 to 103 via the capacitor 145. Here, the current flowing through the load rises in a sinusoidal manner, and the capacitor 145 discharges. Phase 1 ends when the booster voltage measured at capacitor 145 falls below a predetermined threshold.

In an alternative embodiment, phase 1 may end when the current flowing through the load exceeds a predetermined value.

The second phase is also called an adsorption current control. In the second phase, the current flowing through the load is taken from the voltage supply unit 105 by opening the switch means 140 and closing the upper switch 115. Lower switches 120-123 remain in the closed position. When the adsorption target current is reached, the switch means 115 is blocked, and is closed again when the value falls below the hysteresis threshold. This realizes the adsorption current control during the phase 2. This control is adjusted over a predetermined duration until the load is reliably released.

The third phase is also called a first fast erase. When the load reaches its new end position, it can switch to a relatively small holding current. Here, the energy released by the inductance of the load is used for recharging the capacitor 145. For this purpose, the corresponding lower switches 120 to 123 are brought into their open state. The upper switch 115 remains in its closed state. Phase 3 ends when the current through the load falls below the holding current minus the hysteresis.

The subsequent fourth phase is called holding current control. In this phase, the upper switch 115 and one of the lower switches 120-123 are activated until the holding current is reached. Thereafter, the upper switch 115 is blocked until the current through the load drops below the holding current minus the hysteresis. Then, the upper switch 115
Is switched on again. This process is repeated many times. This phase ends when the injection process ends.

The fifth phase is called a second fast erase. In this phase, the energy still remaining in the load due to the holding current is used to recharge the booster capacitor 145 as well. Therefore, first, only the corresponding lower switches 120 to 123 are switched off. At this time, the upper switch 115 is kept closed. This phase ends when the current through the load has decreased substantially to a value of zero.

In the sixth phase, the output stage has no effect.
In this phase, the upper switch 115 is also shut off.

The seventh phase that follows is called post-clocking. Due to the loss in the load, the capacitor 145
Does not return to the original value even if the power is returned during and after the injection process. Therefore, it is necessary to recharge the booster capacitor. Here, the known method of the high-set regulator is applied, and the inductance of the load is used in the charging process.

First, current is supplied to at least one load by closing the upper switch 115 and at least one lower switch. When the recharge current is reached, the current is released by opening the lower switch to diodes 131 to 133.
To the booster capacitor 145.
The booster capacitor is thereby further charged.
When the current decreases, recharging is enabled. This process is repeated until the value of the voltage at the booster capacitor reaches the output voltage.

According to the present invention, by measuring and evaluating the booster voltage at the capacitor 145 at all times during the operation of the control unit, a so-called soft short circuit at the load,
Various faults of the components of the device shown in FIG. 1 can be monitored, as well as the injection function of the device, in particular the booster erase phase and the fast erase phase.

FIG. 4 plots various signals over time t. These signals are shown by way of example for a four cylinder internal combustion engine. FIG. 4a shows the various crankshaft segments that occur in the control unit. This crankshaft segment can be triggered, for example, by a segment wheel located on the crankshaft. The segment wheel has a number of teeth corresponding to the number of cylinders. 1 at each edge of the segment
Two revolution interrupts (DZI) are triggered.

FIG. 4 b plots the rotational speed signal NI generated by the sensor 170. Here, one pulse is preferably triggered for each 3 ° of the crankshaft angle. The signal also has one gap per engine revolution. FIG. 4c shows a time part EB, in which the control signal for the injection is calculated. FIG. 4d shows the time E for the start of the pre-injection and main injection
Are indicated by VE and HE, respectively.

FIG. 4e shows various interrupts IR. These are the rotation speed interrupt DZI and BOB
Interruption. Further, the top dead center of each cylinder is indicated by OT. FIG. 4f shows the level of the signal A. The signal A will be described with reference to FIG. FIG. 4g plots the signal ADC. During this signal, the voltage applied to capacitor 145 is converted to a digital signal.

FIG. 4h shows the signal UB by a dark black arrow.
Is plotted. This signal indicates the time for the voltage to jump.

The pre-injection and main-injection calculations shown in FIG. 4c are triggered by an angle-synchronous rotational speed interrupt DZI. Programming of the calculated injection start and injection duration is performed by another interrupt, a so-called BOB interrupt. This BOB interrupt is also triggered in the same manner as the angle. This BOB is triggered prior to the earliest injection start of the pre-injection.

At this point, the device for injection according to the invention must be ready. This means that the booster capacitor 145 must now be charged to a predetermined voltage. Therefore, this BOB interrupt is suitable for measuring the voltage UC of the booster capacitor 145.

However, depending on various conditions, the end of the preceding injection including the post-clocking (recharge phase) may exceed the BOB interrupt. For example,
The relatively low fuel pressure prolongs the injection time in so-called common rail systems. Supply voltage voltage U
If the bat is low, the recharge phase is extended. When the rotation speed of the internal combustion engine is high, the time interval between injections becomes short. When the injection amount is further large, the injection time is extended.

These conditions, individually or in combination, cause the voltage UC of the booster capacitor 145 to be measured at a point in time when the recharging process has not yet been completed. Therefore, an excessively low booster voltage is read by mistake. In order to avoid such a situation that may lead to a misdiagnosis, the monitoring of the booster voltage must be set in a worst case scenario. This may cause the entire monitor to fail. This is because a very small threshold value must be set.

This monitoring is improved by the present invention as follows. That is, a measurement time point that is advantageous for measuring the voltage UC is selected. Furthermore, it is advantageous to set the threshold value specifically for this voltage. It is particularly advantageous to carry out the various measures individually or in combination with one another.

FIG. 2 shows the details of the monitoring unit 165. The first comparator 200 outputs a signal indicating an error state or a normal operation of the output stage to the control unit 160. The signal “UCMIN3” is input to the input “a” of the comparator 200.
However, the signal UC is input to the input side b. The signal UC is generated by the voltage detector 210. The details of the voltage detector are shown in FIG.

The signal UCMIN3 is supplied to the first minimum value selector 2
20. The minimum value selection section 220 outputs the output signal UCMIN1 of the target value setting section 230 to the switch element 240
With the output signal of The switch element 240 is selectively connected to the output signal of the target value setting unit 230 or the connection point 250.
Is connected to the first minimum value selector 220. Junction point 250 combines the output signal of first characteristic map 260 with the output signal of second characteristic map 270. The first characteristic map 260 processes the output signal of the voltage detection unit 284 and the output signal of the time setting unit 282. The voltage detector 284 sends out a signal based on the battery voltage. The time setting section 282 sends out a signal TRE indicating the recharge duration time. The second characteristic map 270 processes the signal IRE of the current setting unit 280. Current setting unit 280
Sends out a signal corresponding to the recharge current IRE.

Further, the two input signals of the minimum value selector 220 are also sent to the inputs a and b of the second comparator 290. The second comparator 290 is likewise controlled by the control unit 16.
A signal representing the recharging process is supplied to 0.

The purpose of monitoring is to identify output stage or load faults. Normally, the booster voltage reaches the normal value UCSMIN1 after the recharging process. If the operating conditions are disadvantageous, the booster voltage has not yet reached its target value UCMN1 at the start of injection, even if the system is error-free. This occurs especially when the interval between injections is reduced at high rotational speeds and there is not enough time left for the complete recharging process.

It is an object of the present invention to find a different criterion between low booster voltage due to system failure and low booster voltage due to insufficient recharge time.

If the booster voltage is low due to a system failure, there is a serious error in the system. This must cause a corresponding error response.
As a result, a critical situation does not occur for the vehicle including the internal combustion engine or the passenger. Low booster voltages due to insufficient recharge time are less critical. Because of this,
This is because the injection amount is reduced at most.

The desired distinction is achieved according to the invention by detecting the achievable booster voltage taking into account any recharging conditions. By comparing the achieved booster voltage with this threshold, it can be estimated that the recharge time has been relatively reduced.

The achievable booster voltage is advantageously located in the control unit 160 and is detected on the basis of the instantaneous operating conditions required for controlling the internal combustion engine.

According to the present invention, it has been found that the achievable recharge voltage is substantially synthesized from two factors. The first factor is a function of the current IRE corresponding to the maximum current during the post-charging process by the load. Alternatively, the minimum value of the current can be used. The second factor is essentially the supply voltage Ubat and the duration TR of the post-charging process.
This is a function of E. The time TRE corresponds to the duration of the post-clocking.

In the present invention, the first factor is stored in the second characteristic map 270 as a function of the current IRE, and the second factor is stored in the first characteristic map 260 as the battery voltage UBat and the duration of the post-charging process. Filed depending on TRE. Subsequently, the two results are combined at the junction 250
Are advantageously multiplied to form the value UCMIN2.

The battery voltage Ubat is equal to the supply voltage 10
5 to monitor 165 and / or control unit 1
It is detected by evaluating by 60. Current IR
E is detected by the control unit depending on other operation characteristic quantities. The duration TRE of the recharging process can be determined from various injection parameters before the start and end of the pre-injection or main injection.

The target value setting section 230 stores a normal value UCMIN1 of the booster voltage. In the normal operation, the booster voltage value UCMIN2 dependent on the operating point, which is obtained by the connection point 250, is supplied to the minimum value selector 220. The minimum value selector has two values U CMIN1 and U
A relatively small value is selected from CMIN2 and supplied to the comparator 200 as a target value. When the comparator 200 identifies that the voltage UC measured at the booster capacitor at the moment is less than the target value UCMIN3, the comparator outputs a signal to the control unit 160 to indicate that an error exists.

The minimum value selector 220 considers the case where the achievable booster voltage UC decreases due to short recharge time.

Normally achieved booster voltage U CMIN1
And the threshold UC for the booster voltage, depending on the operating point
It is particularly advantageous to supply MIN2 to the comparator 290. The comparator then identifies a condition in which the recharge time is too short for a relatively long time and outputs a corresponding signal to the control unit 160.

The formation of the value UCSMIN2 has only been selected as an example. Other operating characteristic quantities can also be considered. It is also particularly advantageous to set the value UCMIN2, for example, as a function of the rotational speed.

In a simple embodiment, it is advantageous to set the threshold value UCMIN3 on the basis of at least one of the abovementioned quantities by means of a characteristic map and / or calculation.

FIG. 3 shows an example of instantaneous booster voltage detection.

The capacitor 145 is normally connected to the ground via the resistor R1. The second terminal of the capacitor can be connected to a load via the switching element 140. This second terminal is connected to ground via a voltage divider consisting of resistors R2 and R3. The connection point between the two resistors R2 and R3 is connected to the switch element 310 via the impedance converter 300. The impedance converter is connected to the storage means 320 via this switch element. The storage means 320 is configured as a capacitor in the illustrated embodiment, and one terminal is connected to the switch means 310 and the other terminal is connected to the ground. One terminal of the capacitor 320 is further connected to an AD converter ADC.
330. The AD converter 330 supplies the signal UC to the comparator 200 in FIG. The switch 310 is supplied with a control signal A from the flip-flop 340. To this end, the flip-flop 340 processes the signal E and the signal BOB of the control unit 160. Signal E indicates whether an injection, i.e., a pre-injection or a main injection, is present. The signal BOB is a BOB interrupt that usually triggers detection of an injection signal.

In the illustrated embodiment, the hardware circuit is substantially a sample-and-hold element, and includes an impedance converter 300, a flip-flop 340, and a switch element 3.
10 and a capacitor 320.

The function of this circuit will be described with reference to FIG. The flip-flop 340 outputs the control signal A immediately after the occurrence of the BOB interrupt. This means that the signal A goes high, which causes the switching element 31
0 means closed. This further means that the voltage applied to the voltage divider consisting of resistors R2 and R3 charges capacitor 320. That is, the voltage applied to the capacitor 320 is
Of the booster voltage. Therefore, the voltage UC applied to the A / D converter 330 corresponds to the booster voltage.

As soon as the injection starts, this is the signal E
And the signal A shifts to a low level. This means that the switch element 310 shifts to the open state. From this point on, the connection between the storage capacitor 320 and the booster capacitor 145 is cut off.

This is because the value of the booster voltage is stored in the capacitor 320 at this time immediately before the injection, and the AD value is stored at a later time.
This means that the data can be read out to the monitoring unit 200 via the converter.

The AD converter forms a digital signal based on the voltage applied to the capacitor 320, and this digital signal is processed by the monitoring unit 165. The AD conversion is performed within the time indicated by the ADC in FIG. The A / D conversion is advantageously triggered by a DZI interrupt. Further evaluation is performed during the DZI interrupt after the presence of the coarse value in FIG.
This is performed in the area UB indicated by UB in h.

This means that the voltage measurement takes place between the start of the calculation of the injection and the start of this injection. This furthermore means that the voltage detection takes place between the time immediately before the earliest possible injection start and the actual injection start time. The detection of the voltage is performed immediately before the injection. The voltage value detected immediately before the injection is evaluated at a later point in time.

In another configuration, the start and end of the voltage measurement can be controlled by different signals. For this purpose, instead of the signals E and BOB, corresponding signals are supplied to the flip-flops.

FIGS. 5 and 6 show another embodiment of the invention on the basis of a signal curve. The signals plotted in FIGS. 5 and 6 correspond to the signals shown in FIG.

The embodiment of FIG. 5 differs from the embodiment of FIG. 4 substantially in the following points. That is, the measurement of the voltage UC at the booster capacitor is started by the rotation speed interrupt DZI,
The process is terminated by a BOB interrupt. In the embodiment of FIG. 3, this means that switch 310 is closed at time DZI and opened at time BOB. The validity check UB is performed by the next rotation speed interrupt DZI.

This means that the voltage measurement takes place between the start of the injection calculation and the earliest start of the pre-injection.

The advantage of this measure is that the detection of the voltage UC is much simpler. Only the ADC converter 330 and / or the voltage dividers R2, R3 are required. When the rotation speed interrupt occurs, the AD converter 330 is active.

At time BOB, the last measured value for the booster voltage is selected and passed to the monitor 165.

Under worst-case conditions, the recharge can be interrupted by a new injection, so the threshold is read from the characteristic map as shown in FIG.

In a particularly advantageous configuration, the measured value and the booster voltage UC are simply compared with a threshold value UCMIN. This threshold value is determined based on the operating voltage Ubat from the characteristic map.
And a function of the engine speed N of the internal combustion engine.

FIG. 6 shows another embodiment. In this embodiment, only the main injection is performed. FIG. 6 shows FIG.
And corresponding signals are shown in FIG. In this embodiment, the value UC is measured during the speed interruption DZI,
It is evaluated during the next rotational speed interrupt DZI. This measure is selected when the speed exceeds a threshold.

This threshold value corresponds to the rotational speed at which the pre-injection no longer takes place. The advantage of pre-injection is usually obtained at low rotational speeds. Pre-injection does not work when the rotational speed is high. When switching to the operating state in which the pre-injection is not performed, it is particularly preferable to switch to the voltage detecting means shown in FIG. This measure is selected when no pre-injection takes place.

According to the invention, the evaluation of the voltage of the booster capacitor takes place between the end of the injection and the start of the next injection. The voltage detected within this time is compared with a predetermined threshold for monitoring. Based on this comparison, the device identifies an error to the system.

The advantage of this measure is that the detection of the voltage UC is much simpler. Only the AD converter 330 and / or the voltage dividers R2, R3 are required. If there is a rotation speed interrupt, the contents of the AD converter 330 are read out by the monitoring unit 165 and evaluated.

According to the invention, the detection of the voltage UC at the booster capacitor takes place in the region between the end of the injection and the start of the next injection. Particular preference is given to the time between the DZI and the BOB interrupt and / or between the BOB interrupt and the start of the injection. Triggering the detection with a DZI interrupt greatly simplifies the detection.

It is particularly advantageous to combine various means. This means, for example, that various means are switched depending on the operating state of the internal combustion engine. For example,
The measures shown in FIGS. 5 and 6 can be switched depending on whether a pre-injection is present or depending on the presence of an operating state with or without a pre-injection.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a circuit of the device of the present invention.

FIG. 2 is a block circuit diagram of a monitoring unit.

FIG. 3 is a block circuit diagram of voltage evaluation.

FIG. 4 is a diagram plotting various signals over time.

FIG. 5 is a diagram plotting various signals with respect to time.

FIG. 6 is a diagram plotting various signals with respect to time.

[Explanation of symbols]

 100, 101, 102, 103 Load 105 Voltage supply unit 160 Control unit 165 Monitoring unit 175 Increment wheel

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Christoph Hamel Germany Germany Schuttgart to Irastraße 10 (72) Inventor Andreas Werner Germany Reichenbach Weinbergstrasse 54 (72) Inventor Thomas Kroker Germany Republic Schuttgart Ferdhauser Strasse 8 (72) Inventor Ud Schulz Germany Feichingen / Enz Hexempfadere 7

Claims (10)

[Claims] 1. A method for controlling an electromagnetic load, the method comprising: an energy storage element, wherein the charge of the energy storage element is used to facilitate the loading connection of the load. A control method comprising: detecting and evaluating a voltage applied to the energy storage element between the start and the start. 2. The method according to claim 1, wherein a voltage applied to the energy storage element is monitored and compared to a predetermined threshold. 3. The method according to claim 2, wherein the threshold value is set as a function of the operating quantity of the internal combustion engine. 4. The method as claimed in claim 2, wherein the threshold value is set as a function of the supply voltage of the load and / or the speed of the internal combustion engine. 5. The method as claimed in claim 1, wherein the detection of the voltage takes place between the end of the injection and the start of the calculation of the next injection. 6. The method according to claim 1, wherein the detection of the voltage is performed between the start of the calculation of the injection and the start of the injection.
The method described in the section. 7. The method as claimed in claim 1, wherein the detection of the voltage is performed between a rotation speed interrupt and the start of the calculation of the injection. 8. The method according to claim 1, wherein the detection of the voltage is performed between the start of the earliest possible injection and the start of the actual injection.
The method according to any one of the preceding claims. 9. The method according to claim 1, wherein the detection of the voltage is performed by a rotation speed interruption above the rotation speed value. 10. A control device for an electromagnetic load, comprising an energy storage element, wherein the charge of the energy storage element is used for facilitating the closing connection of the load. A means for detecting and evaluating the voltage applied to the energy storage element between the start and the start of the control.