EP1512868B1 - Method and device for controlling an actuator for a starter - Google Patents

Description

The invention relates to a control device and a method for controlling at least one actuator for a starter motor of a motor vehicle and a corresponding computer program and a data carrier with this computer program.

State of the art

Various such controllers and methods are known in the art. All these controllers is based on the problem that when starting a motor with the help of a starter usually the supply voltage of a respective control device breaks down very heavily at least once, because the operation of the starter motor loads the supply voltage very strong. Depending on the strength of the break in the supply voltage, it is at least for a short time to switch off these devices, in particular in the case of control devices designed as microcontrollers, that is, these devices then no longer provide their output signals properly. However, the operation of the starter or the starting process of a motor to be started should preferably not be adversely affected by these voltage dips.

Here is a first from the JP 02-119 674 known circuit for driving a starter. It provides that a start command given by the driver in the form of a short-term tip signal is first fed to a drive-holding device. This drive-holding device is the start command at its output for a direct and the other indirectly via an intermediate control device, in particular a microcontroller to the starter or its actuator on. It works in such a way that the start of the starter is first initiated via the direct connection between the holding member and the starter. In the case of a normal start-up course without serious voltage dips and functional failures of the microcontroller, the latter then assumes the longer-term control of the starter during the entire starting process. However, if immediately after the start of the starting process, a strong dip in the supply voltage of the microcontroller, so that it undergoes a reset, the holding member takes over for the time of switching off the microcontroller, the control of the starter; The prerequisite for this, however, is that the voltage dip still occurs during the predefined holding time of the drive-holding device and is completed. If its holding time is completed and the triggering signal triggering tip signal is no longer pending at the output, then this drive-holding device is no longer able to bridge a then occurring break in the supply voltage and a concomitant short-term shutdown of the microcontroller. The control of the starter and thus the starting process started would then inevitably and undesirably be canceled. In summary, it should be noted that the known circuit just described is indeed able to bridge a very shortly after the start of the starting process occurring suspension of the control device due to a voltage dip, but is not able to compensate for later occurring functional interruptions of this kind.

Another circuit and another method for maintaining the control of peripheral elements by microprocessors is for example from DE 198 55 143 C1 known. The control unit disclosed therein comprises a controller in the form of a microcontroller having an I / O port for outputting a control signal to an actuator or a controlled system in response to a start command. It further comprises a drive holding device which is arranged between the control device, that is to say the microcontroller and the controlled system, for buffering the control signal after it has been output by the microcontroller. In addition, the control device comprises a feedback device for feeding back a current state of the drive-holding device back to the output port of the microcontroller or to the input of the drive-holding device. The proposed drive circuit causes the drive-holding device and thus also the downstream actuator undergoes no state change by a voltage dip or reset of the microcontroller. By a reset, the drive-holding device is not turned off. If it was already switched off before the reset, it will not be switched on by the reset.

However, the known from the named document control unit adheres to the disadvantage that the current state of the drive-holding member, by the fed back Signal is represented by the microcontroller is not used in its decision on the further control of the actuator after its reset. Rather, decides in the disclosed circuit for the control unit, a superposition signal, which is formed from the fed-back signal and output from the microcontroller at its output port drive signal, via the control of the actuator or the starter after a reset. Characterized dominates during a reset and initialization phase of the microcontroller, the previous output state, while after the initialization of the microcontroller whose drive signal dominates.

Based on this prior art, it is therefore the object of the invention to develop a known control device, method and computer program for driving at least one actuator for a starter such that the control of the starter after a reset and thus a continuation of the starting process only takes place if that makes sense overall.

This object is solved by the claimed in claim 1 subject. Accordingly, the solution of this task for the above-mentioned control unit in such a way that its control device is formed, after a temporary collapse of their supply voltage and a consequent temporary shutdown of the controller due to a then regenerated supply voltage is activated again and is then to decide to resume the drive of the actuator via the drive-holding device when, as a first condition, the actuator at the time of the decision nor by the by the drive-holding device before breaking the Supply voltage is stored cached control signal and as a second condition of the cached also before the supply voltage start command after the onset of supply voltage is still stored.

Advantages of the invention

Such a design of the control device of the control unit has the advantage that an unintentional reconnection of the actuator is prevented after a reset of the control device, as long as not all conditions / criteria are met. A reset causes all outputs of the controller to be switched to ground. The control signal for the actuator originally output by the control device is only maintained after a reset by the drive holding device at the input of the actuator. However, for the drive-holding means, preferably, the discharge-related holding time is set so short that it is insignificant in view of the unwanted prolonged turn-on of the actuator. The proposed method thus causes an unintentional activation of the actuator or of the starter motor after a restart of the control device is prevented. At the same time, it is designed such that it maintains the control of the starter via the actuator not only during a first but also during a selectable number of subsequent voltage dips and associated resets of the control device.

According to a first advantageous embodiment of the claimed controller, this has at least one switch-off output for switching off the starter via the actuator, primarily and independently of the state of the switch-on output of the control device. An unintentional Switching on the starter according to the invention is also prevented by the fact that the control device resumes a control of the actuator after a reset not only when the actuator is still controlled via the drive-holding device, but if in addition further criteria are met. Thus, in particular, the ignition or the ignition must still be turned on, a predetermined target speed at the end of the starting process (start-end speed) may not yet be reached and the number of occurred so far during the boot reset did not exceed a predetermined reset threshold.

The above object is further achieved by a method for driving at least one actuator for a starter of a motor vehicle and a corresponding computer program and a data carrier on which this computer program is stored. The advantages of this method and of the computer program essentially correspond to the advantages mentioned above with regard to the control unit.

In addition, however, the method also includes other measures to prevent accidental activation of the starter. For example, redundant storage of a start signal given by the driver (terminal 50 signal) or a start command derived therefrom in different memory areas or in different microcontrollers, preferably in complementary form, in order to be able to ensure a later check of the presence of the start command , Another measure against unintentional activation of the starter is that, as part of the starting process, when a driving condition in the form that the ignition is turned on and the current speed of the is not met, the driver's original start request is discarded by deleting the start command or a stored terminal 50 information. Finally, another measure according to the invention for safeguarding against unintentional triggering in the provision of a reset counter for counting the number of resets occurring during a boot process, wherein the microcontroller re-activates the starter after a reset again, if so far during the boot process Resets that have occurred have not yet exceeded a preset reset threshold.

Further advantageous embodiments of the control device and the method are the subject of the dependent claims.

drawings

Figur 1

den Aufbau des erfindungsgemäßen Steuergerätes; und

Figur 2

das erfindungsgemäße Verfahren

veranschaulichen.The invention will now be described in detail in the form of various embodiments with reference to the figures accompanying the description, wherein

FIG. 1

the structure of the control device according to the invention; and

FIG. 2

the inventive method

illustrate.

Description of the embodiments

FIG. 1 shows the controller 100 according to the invention. It is used to control at least one actuator 200 for a starter 300 of a motor vehicle (not shown). The control device 100 includes a control device 110, which is preferably designed as a microcontroller. The microcontroller receives at its input a start request SW, he, if further conditions (see step S7 in FIG. 2 ) are satisfied, as a start command SB in a memory, preferably a persistent RAM 111, redundant and complementary stores. The microcontroller 110 has a switch-on output EA, which is connected to a drive-holding device 120. The output of this drive-holding device 120 leads to the input or the base of a first switching transistor 150 for direct driving of an actuator 200. The actuator 200 is preferably a relay, which the starter 300 directly on or off, according to the from the microcontroller to the power-on output EA output control signal. The control signal is forwarded without delay to the first switching transistor 150 by the drive-holding device 120. The drive-holding device comprises in detail an RC element comprising a capacitor 124 and a parallel connected discharge resistor 126. One end of this parallel circuit is connected via a diode 122 to the switch-on output EA of the controller 110, while the other end of this parallel circuit after Ground is connected. Furthermore, the drive-holding device 120 comprises a decoupling resistor 128 for coupling the non-grounded end of the RC element 124, 126 to the first switching transistor 150 and the actuator 200, respectively.

According to the invention, the current state of the drive-holding device 120, that is, their digital on or off state or their state of charge in a realization as an RC element to the microcontroller, preferably via an analog / digital converter (not shown), fed back. In FIG. 1 the tap of the feedback device 130 between the collector of the first switching transistor 150 and the actuator 200 is located.

However, it may also be attached to the output of the drive-holding device 120 or at a suitable location in its interior.

If, for example, due to a reset, the switch-on output EA of the microcontroller 110 is switched to ground, the starter 300 is switched off via the drive-holding device 120 and the actuator 200. However, this switch-off signal is only supplied to the actuator by the drive-holding device with a time delay passed to bridge the reset time of the computer.

In order to be able to avoid such a time delay and to be able to switch off the starter without delay and with priority and independently of the state of the drive hold circuit, the microcontroller 110 preferably has at least one switch-off output AA. A turn-off signal at this output then turns off the starter 300 immediately. To ensure that the starter is not actuated during malfunction of the microcomputer during a frictional connection in the transmission, it is advantageous if in addition a release signal F in automatic transmissions the parking / normal signal and manual transmissions the clutch signal for hardware shutdown of the starter is available. In order to implement such a circuit logic, the control device further comprises a switch-off logic module 160, which has an OR gate 162 and a second switching transistor 164 having. A first input E1 of the OR gate 162 receives the high-active turn-off signal of the microcontroller 110, and a second input E2 of the OR gate 162 receives the low-active enable signal F. These two input signals are logically combined by the OR gate 162 in such a way that a high level is present at its output when a switch-off request for the starter 300 output by the microcontroller 110 via its switch-off signal AA is present or when the enable signal F is not low-active. With the output signal A of the OR gate 162, a second switching transistor 164 is driven, which is connected between ground and the input of the first switching transistor 150. By means of this second switching transistor, the input of the first switching transistor 150 is switched to ground in response to the output signal A of the OR gate 162 when the starter 300 is to be turned off.

The method of the invention for driving at least one actuator 200 for a starter 300 of a motor vehicle via the control device 110 will be described in detail below with reference to FIGS FIG. 2 described in more detail.

To start the engine of a motor vehicle, the driver first activates the ignition lock of his motor vehicle by bringing it into a first possible position, represented by a terminal 15 signal (method step S1). Subsequently, the inventive method checks in the context of an initialization in a second method step S2, the presence of a plurality of conditions. Under these conditions, it is checked whether 1) a starter of the vehicle for starting the engine is possibly still active from a previous starting operation, whether 2) a so-called start command whose Generation is explained below, is still active and whether 3) the contents of a reset counter is less than a predetermined threshold. Conditions 1) and 2) are both mandatory; the 3) condition is optional. If the vehicle is restarted for the first time or the first time, the first conditions mentioned above are not met, which means that the other two have the first AND-linked condition. no longer need to be tested. In this case, the query is answered according to method step S2 with "no" and the method then checks in a method step S3, whether the driver, the ignition not only in the first position for switching on the ignition, but also in a third position for activating the starter has turned. Such a start request issued externally by the driver is indicated to the control unit 110 by an active so-called terminal-50 signal. If it is determined in method step S3 that the terminal 50 signal or the KL50 signal stored as a start request is no longer active, then the control unit 100 assumes that a starting operation has already been successfully carried out in the past, so that such a currently no longer necessary. The method then goes into normal operation of the internal combustion engine of the vehicle according to method step S4. If the terminal 50 signal is still active, the method proceeds from step S3 to step S5, in which it is checked whether the speed of the internal combustion engine falls below a predetermined minimum speed or not. If it is determined in method step S5 that the engine speed is greater than the predetermined threshold value Sn in the form of the minimum engine speed, then it is again assumed that the starting operation has occurred in the past successfully completed; the method then goes into normal operation according to method step S4.

However, if it has been determined in method step S5 that the engine speed has not yet reached the predetermined threshold value Sn in the form of the minimum engine speed, the control unit 100 and in particular the controller 110 interprets the present situation as the driver's start request and activates a corresponding internal signal; this takes place in method step S6. In a subsequent method step S7, a plurality of conditions are again checked, which are OR-linked with one another. Depending on whether at least one of these conditions is met, the starter is actuated according to method step S8 or a start-up procedure currently carried out according to method step S10 is aborted. The conditions which are checked in method step S7 involve the question as to whether the engine speed is greater than a predefined speed threshold Sn, whether the time during which the internal signal "starter active" activated in method step S6 has already been longer than a predetermined threshold time St is active or whether there is a frictional connection between the starter and a wheel of the vehicle, indicated for example by an engaged gear.

If, as already mentioned above, at least one of the conditions checked in method step S7 is not fulfilled, that is, for example, the engine speed is still lower than the predetermined threshold speed Sn, the starter is either driven for the first time or maintained in its function. Inside the control device 110, a so-called start command SB is then generated and stored or it remains stored if it has already been saved before. In any case, the start command is redundant, that is, for security reasons distributed to multiple memories stored. The start command SB generated or maintained according to method step S8a should not be confused with the signal "starter active" generated in method step S6. The difference is that the start command SB according to method step S8a is only satisfied if at least one of the conditions according to method step S7 is not fulfilled.

As part of the starter control or in the context of maintaining the startup process, the reset counter is incremented once in method step S8b. When the ignition is switched on for the first time, it can be assumed that the reset counter was previously set to zero. The state of the reset counter after incrementing according to method step S8b is subsequently compared in method step S9 with a predetermined reset counter threshold value Sz. This threshold for the reset counter represents the maximum number of allowed during a boot reset or voltage dips of the controller.

If it is determined in step S9 that this threshold Sz has not yet been reached, then the startup process is continued. More precisely, the method then branches into a so-called starter operating loop, which then branches to the beginning of method step S7 described above. The starter operating loop comprising the method steps S7, S8 and S9 is run through as long as the state of the reset counter is smaller than the predetermined one Counter threshold value Sz and none of the conditions according to method step S7 is satisfied.

If, however, it is determined in method step S9 that the status of the reset counter has reached the preset counter threshold value Sz, then the starting process in the form of the drive loop is discontinued; instead, the actuator 200 is shut down for the starter via the output A-A of the controller 110 and the method branches on the assumption that the previously dropped voltage across the actuator 200 has recovered to the beginning of the method step S2 described above. It is then checked again whether all conditions are met according to method step S2. If this is not the case, the method subsequently executes method step S3 and then proceeds as described above. If, however, all the conditions according to method step S2 are fulfilled, this means that a starting process already initiated in the past has not yet ended. The starting process is therefore continued, possibly even before the predetermined by the drive-holding device 120 hold time has expired. The control device 110 then generates the signal "starter active" according to method step S6. It then subsequently checks the conditions described above in accordance with method step S7 and re-activates the trigger holding device 120 via its E-A output if none of the discharge conditions according to method step S7 has been fulfilled. In contrast to the restart of the engine described above primarily now the starter is not first started according to step S8, but it remains activated.

However, at some point in method step S7, it is ascertained that at least one of them checked there Conditions is satisfied, the method branches from step S7 to step S10. There is a possibly still active startup process via the output AA of the controller 110 is stopped immediately. The starter is dropped and it is the redundant previously stored in step S8a stored start command now redundant (step S10a). In addition, according to method step S10b, the reset counter is reset to zero. In method step S10, it is fundamentally assumed that the starting process has been completed successfully and it is therefore subsequently branched off after method step S4, that is to say the normal mode.

Overall, it takes the process according to FIG. 2 only a few milliseconds. The gist of the invention is found in FIG. 2 in the branch of step S9 to the beginning of step S2 as long as the state of the reset counter is less than the predetermined threshold Sz. This branch indicates that after a break in the supply voltage, represented by an increment of the reset counter, the starting process is nevertheless continued. This is done in such a way that the control device 110 after a caused by the breaking of the supply voltage temporary shutdown, again initialized itself for the generation and output of the control signal, detects the current state of the drive-holding device by checking whether the control command is active, and in dependence thereon as well as in dependence of the further criteria according to the method steps S2 and S7 decides whether it resumes the actuation of the actuator or not.

The method just described is preferably realized in the form of a computer program for a control device for controlling an actuator for a starter. In the case of such a software implementation, it is possible that the computer program is optionally stored together with other computer programs on a computer-readable medium. The data medium may be a floppy disk, a compact disc, a flash memory or the like. The computer program stored on the data carrier can then be sold as a product to a customer.

In the case of such a software solution, it is also possible that the computer program is transmitted to a customer and sold even without the aid of the data carrier via an electronic communication network, in particular the Internet.

Claims (14)

1. Control unit (100) for controlling at least one actuator (200) for a starter (300) of a motor vehicle, comprising:

   - a control device (110) having a switch-on output (E-A) for outputting a control signal to the actuator (200) in response to a starting instruction (SB) for starting the starter (300);

   - an actuation-hold device (120) arranged between the control device (110) and the actuator (200) for buffering the control signal after it has been output by the control device (110); and

   - a feedback device (130) for feeding back a current state of the actuation-hold device (120) to the control device (110),

   characterized in that, after a temporary dip in the supply voltage of the control device (110) and temporary switching off of the control device (110) as a result of this, said control device (110) is reactivated on the basis of a supply voltage which is subsequently regenerated again, and said control device (110) is designed to decide, within the scope of an initialization, to resume the actuation of the actuator (200) via the actuation-hold device (120) if, as a first condition, the actuator (200) is still controlled at the time of the decision by the control signal which is buffered by the actuation-hold device (120) before the dip in the supply voltage, and, as a second condition, the starting instruction (SB) which is also buffered before the dip in the supply voltage is still stored after the dip in the supply voltage.
2. Control unit (100) according to Claim 1, characterized in that the control device (110) is designed as a microcontroller.
3. Control unit (100) according to Claim 1 or 2, characterized in that the actuation-hold device (120) has:

   - a timer element (124, 126) which is embodied as an RC element composed of a capacitor (124) and a discharge resistor (126) which is connected in parallel, wherein one end of the parallel circuit is connected via a diode (122) to the switch-on output (E-A) of the control device (110), and the other end of the parallel circuit is connected to earth; and

   - a decoupling resistor (128) for coupling the end of the timer element (124, 126) which has not been connected to earth to the actuator (200) via a first switching transistor (150).
4. Control unit (100) according to one of the preceding claims, characterized in that the control device (110) has at least one switch-off output (A-A) for switching off the starter (300) via the actuator (200) with priority and independently of the state of the switch-on output (E-A) of the control device (110).
5. Control unit (100) according to Claim 4, characterized by a switch-off logic module (160) comprising:

   - an OR gate (162), one input (E1) of which receives an output signal of the switch-off output (A-A) of the control device (110), and the other input (E2) of which receives an enable signal (F) for enabling the switch-off process, in order to generate an output signal (A) which represents the logic OR combination of the two input signals; and

   - a second switching transistor (164) which is connected between earth and the input of the first switching transistor (150) and has the purpose of switching off the starter via the actuator (200) in response to the output signal (A) of the OR gate (162).
6. Control unit (100) according to Claim 5, characterized in that the enable signal (F) is the park signal or normal signal in the case of motor vehicles with an automatic transmission.
7. Method for controlling at least one actuator (200) for a starter (300) of a motor vehicle via a control device (110), comprising the following steps:

   - generation of a control signal by the control device (110) for starting the starter (300) in response to a starting instruction (SB);

   - holding of the control signal after its generation at the input of the actuator (200); and

   - detection and recording of whether there has been a temporary dip in the supply voltage for the control device (110) during the operation of the starter (300), and as a result the generation and outputting of the control signal by the control device (110) have been stopped,

   characterized by

   - resumption of the actuation of the actuator (200) by the control device (110) if, after a temporary dip in the supply voltage of the control device (110), it is detected within the scope of an initialization that, as a first condition, the previously generated control signal is still present at the input of the actuator (200) on the basis of the hold function, and, as a second condition, the starting instruction (SB) which has also been previously stored is still stored after the dip (S2).
8. Method according to Claim 7, characterized in that a further condition for the resumption of the actuation is met if the current state of a reset counter which represents the number of dips in the supply voltage which have already occurred in the past does not exceed a predefined threshold value S₂ (S2).
9. Method according to Claim 7 or 8, characterized in that the resumption of the actuation of the actuator (200) comprises the following steps:

   - generation of a control-device-internal signal "starter active" which represents a still applicable starting wish by the driver (S6);

   - checking (S7), on the basis of abort conditions, whether a starting process which has been begun in the past and is currently still being carried out is to be continued further or aborted;

   - continuation of the starting process including maintenance of preferably redundant storage of the starting instruction and incrementation of a reset counter (S8, S8a, S8b), if none of the abort conditions is met;

   - checking whether the reading of the incremented reset counter has exceeded a predefined counter threshold value (SZ); and

   - jumping back to the start of the checking step (S7) if the reading of the reset counter has not yet passed the threshold value (SZ).
10. Method according to Claim 9, characterized by renewed checking of the conditions for the resumption of the actuation (S2), if the reading of the reset counter has passed the threshold value (SZ).
11. Method according to Claim 9 or 10, characterized in that the abort conditions are met (S7), if

    - the rotational speed of the internal combustion engine has exceeded a predefined threshold rotational speed (Sn);

    - the time during which the starter was already active, represented by the "starter active" signal, has exceeded a predefined time threshold value; or

    - frictional engagement is observed between the starter and the wheel.
12. Method according to Claim 11, characterized in that the starting process is terminated and the system goes into a normal operating mode, if at least one of the abort conditions is met (S10).
13. Computer program with program code for a control unit (100) for controlling at least one actuator (200) for a starter of a motor vehicle, characterized in that the program code is designed to carry out the method according to one of Claims 7-12.
14. Data carrier with program code according to Claim 13.

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