WO2012055668A1

WO2012055668A1 - Method for monitoring a control device for an injection system in a motor vehicle

Info

Publication number: WO2012055668A1
Application number: PCT/EP2011/067081
Authority: WO
Inventors: Jens-Holger Barth; Stefan Schempp; Erik Tonner; Boris Ostendorf
Original assignee: Robert Bosch Gmbh
Priority date: 2010-10-25
Filing date: 2011-09-30
Publication date: 2012-05-03
Also published as: CN103154477A; DE102010042844A1; CN103154477B; EP2633171A1; BR112013009685A2; DE102010042844B4; BR112013009685B1

Abstract

A method for monitoring a control device for an injection system in a motor vehicle is presented, in which, with respect to the running time of the control device, a maximum permissible actuation frequency for the control device is determined and monitored, wherein factors which limit the maximum actuation frequency are determined at a respective operating point of the control device, and said factors are included directly in the determination of the maximum permissible actuation frequency. In addition, a corresponding monitoring module and a control device with such a monitoring module are proposed.

Description

description

title

Method for monitoring a control unit for an injection system in a motor vehicle

The present invention relates to a method for monitoring a design of a control device for an injection system in a motor vehicle, in particular for solenoid valve and / or piezo valve injectors. Furthermore, the present invention relates to a suitable control module for carrying out the method proposed according to the invention and a control unit integrating such a control module.

PRIOR ART There are various restrictions or limitations with regard to an available maximum output power for injection output stages in control units for so-called common rail solenoid valve and piezo valve injectors. Limiting elements or factors are: a) a maximum output power of a DC-DC converter or DC / DC converter to be used as part of a respective control device or a capacity of a connected buffer capacitor (also referred to as a buffer capacitor). Such transducers are required for piezo valve injectors (PV) in order to build up a voltage required for charging an actuator (up to 245 volts), and for solenoid valve injectors to achieve a so-called booster voltage (about 45 volts). , Depending on the valve, the energy consumed per control depends on various parameters. In the case of piezo valve injectors, this is, for example, a so-called rail pressure, with solenoid valve injectors a respective injector temperature, which in turn leads to an extended booster phase. The converter itself depends in both cases on a corresponding battery voltage.

b) maximum RMS currents for which the respectively provided different components of the injection output stage are enabled in a corresponding control unit. By definition, the RMS current is the root of the mean square current through the respective component. The permissible maximum value for the respective RMS current is temperature-dependent. Depending on the component, it is largely constant in the low temperature range and decreases sharply above a certain temperature threshold. If the permissible current (maximum RMS current) is exceeded, the service life of the respective component is reduced. c) Power losses in the control unit and maximum, location-dependent cooling of the control unit, which essentially affect the temperature of the control unit, which must not exceed a maximum released value.

Ultimately, these limiting factors result in a maximum number of drives, generally indicated per cylinder and duty cycle, that can be performed by the controller without the controller suffering damage. The maximum number of drives is usually specified as a function of the so-called rail pressure and a speed of an engine to be controlled.

On the other hand, the requirements for the number of drives are getting bigger. By changing injection strategies, such as a split post-injection, or multiple pilot injections and additional functions that require controls without being injected, for example. In a so-called blankshot function with solenoid valve injectors without pressure loss (DRV) control units are now generally burdened to the limit of the possible. A performance of a corresponding control device is indeed in advance depending on various boundary conditions or limiting factors calculated very accurately by a corresponding module; However, a meaningful monitoring in the sense of a controller protection against overload does not yet exist. Only a so-called "buffer balance monitoring" prevents both solenoid valve injectors as well as piezo valve injectors that drop by arbitrarily injections by charge drops in the buffer capacitor of the respective injection output stage by too many controls. In addition, an application can be checked by a very complex offline method to find operating points at which a respective design of a control unit is not met. However, this can only be made meaningful after the application has been completed, ie at a point in time when possible measures are practically no longer possible.

The document DE 10 2004 012 428 A1 of Robert Bosch GmbH relates to a method and a control device for operating an internal combustion engine. This internal combustion engine comprises a plurality of cylinders, which are actuated by the control unit via individually assigned actuators. In this method, a destruction of the controller or a DC / DC converter located therein due to a thermal load to be avoided by a control device. This control device is designed to the required in the actuators of the internal combustion engine mean electric

Detecting power, and requesting a reduction of this power at a controller, when the power is greater than a predetermined target power, as represented by the control unit to the actuators deliverable rated power.

Another method for operating an internal combustion engine is described in the document DE 192 40 493 A1 of Robert Bosch GmbH. Here, at least one injection valve of the internal combustion engine is associated with a piezoelectric actuator, which is controlled by a control unit. It is provided that a control signal provided for this purpose is changed as a function of a drive power received by the piezoelectric actuator. As a result, inter alia, a loss of energy, which is converted into a power output stage of the controller, reduced, whereby the temperature of the controller decreases. From the document DE 10 2005 042 530 A1 of Denso Corp. a fuel injection system for an internal combustion engine is known. Here, a control unit controls a power supply to a solenoid of an electromagnetic actuator of a fuel injector. There is first the supply of a peak current and then the supply of a first and a second constant current. As a result, a setpoint value for the supply of the first constant current is set to a value which is significantly below a battery voltage, so that constant monitoring of the battery voltage is no longer necessary. This also results in a reduction in the load on the electronic control system.

Against the background of the cited prior art, it would now be desirable to provide a method which makes it possible to prevent more actuations being carried out by the control device during the operating time of the control device than the design of the respective control device permits.

DISCLOSURE OF THE INVENTION Against this background, a method for monitoring a control unit for an injection system in a motor vehicle with the features of claim 1, a control module with the features of claim 5 and a control unit with the features of claim 10 are presented. Further embodiments of the invention will become apparent from the dependent claims and the description.

According to the invention, a method is provided for monitoring a control unit for an injection system in a motor vehicle, in which a maximum permissible drive frequency for the control unit is determined and monitored during runtime of the control unit, wherein the maximum drive frequency determines limiting factors in a respective operating point of the control unit and directly into the determination of the maximum permissible activation frequency. By means of the method according to the invention, in particular a design of a corresponding control device can be monitored.

In this case, at least maximally permissible RMS currents of components integrated in the control unit, a maximum permissible control unit temperature, a maximum output power for at least one DC / DC converter to be used and an energy requirement per control are preferably determined as limiting factors and included in the determination of maximum permissible activation frequency involved.

The inventively provided method, which provides that in a corresponding control unit at runtime a maximum allowable drive frequency is calculated, allows to map exactly the limit that was used for the respective control unit design. In this way, it is ensured at each operating point of the control unit that no more activations are carried out than the design of the respective control unit permits. Exceeding the number of controls is prevented by a corresponding limitation and prioritization. Thus, the control unit can always be charged up to the permissible upper limit, but not beyond. On the other hand, therefore, no safety precaution or the like is needed, which would reduce the output power to an unacceptable degree.

Since, by means of the method according to the invention, in particular its design can be continuously monitored during runtime of the control device, ie already in an application phase of the respective control device, operating points in which an output power of the control device is exceeded are already noticeable at an early stage. Measures can be defined and carried out at an early stage.

It is achieved by the method according to the invention that a limitation of injections is strictly based on the respective control unit design. This ensures that all parameters relevant to the protection of the respective control unit are effectively monitored. Furthermore, there is no need for a costly offline check of a corresponding data, ie data implementation. By switching to broken rational calcula- tion of the maximum permissible drive frequency, an actual maximum can always be displayed without delay. This is particularly important for a "blank shot" pressure reduction function, since this pressure reduction function does not require "controls per load cycle" but "controls per unit time".

The method provided according to the invention is in principle largely uniform both for piezo-valve injectors and for solenoid valve injectors. This results in a greatly reduced care expenses in a particular development. The method also makes it possible, by incorporating a temperature sensor in the case of particularly critical components of the control unit, to place the respective design closer to the technically representable limit and also to comply with it.

It is conceivable that in the method according to the invention first the maximum permissible drive frequency for the control unit is determined, which is then converted with a speed-dependent factor into a maximum allowable number of drives per cylinder and load cycle.

Furthermore, the present invention relates to a control module, in particular for carrying out a method for monitoring a control device for an injection system in a motor vehicle, as has been described above. In particular, a design of the control unit can be monitored. The control module implements a function that is designed to determine and monitor a maximum allowable drive frequency for the controller at runtime, the maximum drive frequency limiting factors are determined in a respective operating state of the controller and directly into the determination of the maximum permissible drive frequency. It is conceivable that the control module is an integral part of the control device to be monitored. Furthermore, it is conceivable that the control module is designed specifically for a piezo valve injector. It is also conceivable that the control module is designed specifically for a solenoid valve injector.

The present invention also relates to a control device with a control module described above. Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination but also in other combinations or alone, without departing from the scope of the present invention.

Short description of the drawing

FIG. 1 shows a schematic representation of an embodiment of a function implemented in a control module according to the invention, which is particularly suitable for piezo valve injectors;

Figure 2 shows a schematic representation of a dependence of an output power of a DC-DC converter from a corresponding battery voltage;

FIG. 3 shows a schematic representation of a further embodiment of a function implemented in a control module according to the invention, which function can be used in particular for solenoid valve injectors;

Figure 4 shows a schematic representation of a current profile when driving a solenoid valve injector;

FIG. 5 shows a schematic representation of a profile of an integrator for limiting an overload operation in the case of a solenoid valve output stage.

Embodiments of the invention

The invention is schematically illustrated by means of embodiments in the drawings and will be described in detail below with reference to the drawings.

The figures are described in a coherent and comprehensive manner, like reference numerals designate like components. FIG. 1 shows in detail a possible embodiment of a function implemented in a control module according to the invention for a piezo valve output stage. The illustrated function first calculates a maximum permissible drive frequency, represented in stage 1 1, which the piezo valve output stage is capable of taking into account all limitations. Up to a rescaling with a speed-dependent factor S at the output of the function in the unit "number of actuators per cylinder and load cycle", shown as NMAX, the internal variables in the unit "number of actuators per time" are available, which meets the technical requirements the piezo valve output stage corresponds.

Essentially, two blocks are to be distinguished. In the upper part (above the dotted line) are limiting factors due to a maximum allowable effective current load of the controller shown. A maximum frequency is dependent on the so-called rail pressure P _RA i, since a respective on-control voltage for the control unit also depends on this rail pressure P _RA i. The rail pressure P _RA i thus represents an input variable for the function. All other influencing factors or limiting factors on the current required to achieve a desired voltage, such as ISA class and capacity of the corresponding piezo valve injector, voltage reserve for temperature and Life drift compensation of the voltage requirement, etc. are reflected in a Bedatung of the characteristic KL 1 shown here.

With the control module to be provided according to the invention, a temperature sensor can be coupled or also integrated in it, which can reduce the drive frequency as an additional security element. This means that, if the control unit internal temperature T _e cu is too high, which also flows as an input variable for the function, a maximum drive frequency can be reduced accordingly by a factor indicated in the characteristic curve KL 2, so that the control unit through the piezo valve Heating is not further heated.

A result of these restrictions resulting from these two paths or from KL 1 and KL 2 is limited to a minimum frequency f MIN. The purpose of such a lower limit is, for reasons of vehicle availability, to carry out a minimum number of actuations per cylinder and load cycle, even if this means that further heating of the respective control device can be tolerated. is taken. Accordingly, this minimum limit frequency f MIN must be calculated from the speed and the number of cylinders. Limiting only affects the RMS part of the function shown here, as a lower limit does not reflect the behavior of the piezo valve output stage when limited by a DC / DC converter power, since the DC / DC converter power is not temperature dependent.

From the characteristic curves KL 1 and KL 2 shown, a first maximum intermediate drive frequency now results, taking into account the minimum frequency f MIN mentioned, which is marked here in step 10 as MAX.

Below the dotted line, a function block is shown in which a respective limitation is calculated by the DC / DC converter power and an energy requirement per control. An output power of the DC / DC converter is dependent solely on the respective battery voltage U BATT both in a piezo and in a solenoid valve system. This dependency is shown in the characteristic curve KL 3. An example of a detailed dependency is shown in the following Figure 2.

The energy consumed per activation process depends on the control voltage for piezo valve injectors via the rail pressure P _RA i. A representation of this relationship is the characteristic KL 4.

Injector-specific data are taken into account in an application of the characteristic curve KL 4, similar to the characteristic KL 1. By dividing or dividing the power by the energy one obtains directly the maximum driving frequency of this path.

Since the result of this block indicates how many activations can be carried out to the maximum, limiting to a minimum value makes no sense, since, as already stated, the DC / DC converter performance in extreme cases only limits despite limitations to a minimum value in the function is sufficient for fewer activations and possibly omit injections arbitrarily.

However, it can also be limited to at least one control here, which is not shown in FIG. 1 in order to enable an engine start even in low battery voltage ranges. Finally, a minimum of both function blocks is formed, which is the correct value for the desired limit, which is indicated here by stage 11. The obtained maximum allowable drive frequency is then rescaled with a speed-dependent factor S, so that a maximum allowable number of drives per cylinder and load cycle N MAX is obtained.

As already mentioned, FIG. 2 shows a dependence of an output power of a DC / DC converter in units P [W] on a respective battery voltage

UBATT M.

FIG. 3 shows another embodiment of a function implemented in a control module according to the invention, as can be used, for example, for solenoid valve output stages. This function is structured structurally the same as the function shown in Figure 1 for piezo valve output stages, differs from this but in the following details. Again, the function is essentially given by two functional blocks, which are shown separated from each other by a dashed line.

In the upper part (above the dashed line) again limiting factors due to a maximum allowable effective current load of the controller are shown. Since in a calculation of the effective currents of the control unit, the current is received in square, especially the so-called booster phase, as shown in the following Figure 4, relevant. The duration and the current level of this booster phase are dependent on other control parameters, which is why an allowable maximum drive frequency f _NO R is approximately constant. However, it is allowed for a limited time to use a higher frequency fovrLd. This is necessary if, for example, a Blankshot- function that degrades the rail pressure P _RA i in systems without pressure valve DRV via control in which the respective injector does not open and only control amount is discharged into the return, requires more control for pressure regulation, as f _NO . An overload release takes place via a switch S1 only in case of need. The switch S1 is then monitored by an integrator. When switch position 1, the integrator is increased, lowered at switch position 0. If an upper limit is reached, a compulsory pause S1 = 0 takes place, so that the output stage can cool down if necessary. The course of the integrator is exemplary in shown in the following figure 5 and is also part of the function described here.

When balancing the DC / DC converter in the lower part of the illustration, the same applies. The energy consumption W _NO R per control is also characterized by a booster phase, since the current is driven through the DC / DC converter only in this booster phase. In a tightening and holding current phase, the power is fed directly from a corresponding onboard power supply battery. The exception here is the start at low temperatures (so-called TSC = temperature specific curent). If this function is active, a switch S2 to the energy W _H IGH, switched because in this operation, the pull-in current phase is also fed from the DC / DC converter or the associated buffer capacitor. The remaining part of the function is identical to the function already described in connection with FIG. 1 for the piezo valve output stage. In the upper part, taking into account a minimum frequency f MIN, a first maximum results

Intermediate drive frequency, which is referred to herein as "MAX" in step 100. Finally, similar to the case of FIG. 1, a minimum "MIN" of both function blocks is formed, which represents the correct value for the desired limitation, which is indicated here by stage 110. The obtained maximum allowable drive frequency is then rescaled with a speed-dependent factor S, so that a maximum allowable number of drives per cylinder and load cycle N MAX is obtained.

FIG. 4 shows a current profile when a solenoid valve injector is actuated, wherein the current in units of ampere [A] over time in unit [με] is shown here. You can distinguish three different phases here. Phase 1 is the so-called boat phase, which culminates in the booster current I_1 at the end, in phase 2 a pull-in phase with a slightly varying pull-in current I_2 and in phase 3 a hold phase with a slightly varying hold current I_3.

FIG. 5 shows a profile of an integrator or a corresponding integrator value (y-axis) over time (x-axis), which monitors the switch described in connection with FIG. In a switch position 1, the integrator is increased, at a switch position 0 is lowered. If an upper limit is reached (t1, t3), the integrator value is reduced until it reaches a certain level Threshold (+3, +4) has reached. As a result, a compulsory break takes place, in which the output stage can possibly cool down, because no overload operation is permitted.

Claims

claims

A method for monitoring a control unit for an injection system in a motor vehicle, is determined and monitored at run time of the controller, a maximum allowable drive frequency for the controller, the maximum drive frequency limiting factors are determined in a respective operating point of the controller and directly in the determination of the maximum permissible activation frequency.

Method according to Claim 1, in which at least one maximum permissible effective current for the control unit, a maximum permissible control unit internal temperature, a maximum output power for at least one DC-DC converter to be used and an energy requirement per control are determined as limiting factors and are included in the determination of the maximum permissible control frequency.

The method of claim 2, wherein a first maximum intermediate drive frequency taking into account the maximum allowable RMS for the controller and the maximum permissible controller temperature and a second maximum intermediate drive frequency, taking into account the maximum output power for the at least one DC-DC converter and the energy required per control is determined, and the maximum drive frequency is determined as the minimum of the first and the second maximum intermediate drive frequency.

The method of claim 1, 2 or 3, wherein first the maximum allowable driving frequency for the control unit is determined, which is then converted with a speed-dependent factor into a maximum number of actuators per cylinder and load cycle. 5. Control module, in particular for a method for monitoring a control unit for an injection system in a motor vehicle according to one of the Claims 1 to 4, which implements a function which is adapted to determine and monitor a maximum allowable drive frequency for the controller at runtime of the controller, wherein the maximum drive frequency limiting factors are determined in a respective operating point of the controller and directly into the Determine the maximum permissible drive frequency.

6. Control module according to claim 5, which is an integral part of the control unit.

7. Control module according to claim 5 or 6, which is designed specifically for a piezo valve injector.

8. Control module according to claim 5 or 6, which is designed specifically for a solenoid valve injector.

9. Control module according to one of claims 5 to 8, with the first the maximum allowable driving frequency for the control unit can be determined, which can then be converted with a speed-dependent factor in a maximum number of activations per cylinder and load cycle.

10. Control device with a control module according to one of claims 5 to 9.