DE10313483B4 - Method for transmission or gear monitoring for an automatic transmission or an automated manual transmission - Google Patents

Abstract

Method for gear ratio or gear monitoring for an automatic transmission or an automated gearbox of a motor vehicle, the actual gear ratio being compared with the target gear ratio and the actual gear ratio being detected by measuring the input and output speeds and wherein the gear ratio or gear monitoring outside of gear shifts, during the gear changes and / or during gear engagement, characterized in that when the actual gear ratio deviates from the target gear ratio, a fault is detected and at least one fault counter of the switching elements involved is incremented, if the fault counter exceeds a predetermined maximum value, a symptom or error is recognized and replacement measures are initiated, and then if a fault is detected outside of circuits, the gear is shifted, which is still permitted on the basis of the speeds and in which the aktu The faulty gear in the clutches lying in the power flow are not involved.

Description

The present invention relates to a method for transmission or gear monitoring for an automatic transmission or an automated manual transmission of a motor vehicle according to the preamble of claim 1.

The ever increasing complexity of automatic transmissions used in motor vehicles (with and without converter) and automated manual transmissions places ever higher demands on the corresponding diagnostic and monitoring systems. Diagnostic and monitoring systems are primarily intended to ensure personal protection and driving safety; Another goal is to ensure vehicle availability and protection of the transmission and its components.

In today's automatic transmissions and automated manual transmissions (e.g. automated manual transmissions or dual clutch transmissions), the protective mechanisms are increasingly integrated into the software and hardware of the electronic transmission control according to the state of the art. Especially with the so-called shift by wire systems, in which the driver can no longer intervene directly in the system, very special requirements are placed on the protection and monitoring mechanisms.

Hydraulic interlocks, which were used in earlier transmissions, are no longer possible, since through multiple use of clutches in the different gears this represents a task that can hardly be solved on the mechanical side; in addition, the use of hydraulic locks is costly and space-intensive.

Safety systems for automatic transmissions are known from the prior art. For example, the DE 196 01 618 A1 proposed by the applicant to detect malfunctions outside the circuits by monitoring the measured transmission input and output speeds. Then the current gear is switched to a replacement gear, which is the next highest if possible; if the current gear is the highest, then the next lower gear is selected. As part of the DE 196 01 618 A1 a symptom counter is provided for each gear, which is incremented by one if a malfunction is present, an emergency driving program being activated when a predetermined limit value for the symptom counter is exceeded.

This procedure according to the prior art results in transmission systems in which a clutch or brake is shifted in several gears in succession, in the event of a malfunction in one of these shifting elements, in several shifts and a subsequent detection of malfunctions before a safe operating state is reached. The same also applies to transmission systems with recurrent activation of the same shift element in the next gear, in which case a safe state is reached for a short time; However, the next time the system upshifts or downshifts, the system tries again to bring a switching element with a function that no longer exists into the power flow.

Another method for gear monitoring outside of circuits is from the DE 38 43 101 A1 known. Here, for example, 5 seconds after actuation of the actuator system required for the desired gear, a comparison is made as to whether the actual gear ratio of the transmission measured by means of speed sensors corresponds to a theoretical gear ratio which should result from the actuators being actuated, taking into account the sensed selector plane position.

From the DE 695 11 058 T2 a method for gear monitoring during an overlap shift of the transmission is also known.

In the methods known from the prior art, monitoring is carried out outside the circuits or during the switching process; monitoring of gear engagement is not provided.

The present invention is based on the object, based on the cited prior art, of specifying a method for transmission or gear monitoring for an automatic transmission or an automated manual transmission of a motor vehicle which avoids the disadvantages of the prior art. The method according to the invention should also be usable for transmissions with multiple use of clutches and brakes and, after the detection of a fault, initiate replacement measures in order to keep the transmission system in a safe state or to transfer it to a safe state.

In addition, the method according to the invention is intended to ensure monitoring even during the shifting process or gear engagement.

This object is achieved by the features of patent claim 1. Further variants and advantages emerge from the subclaims.

Accordingly, a method for gear monitoring for an automatic transmission or an automated manual transmission of a motor vehicle is proposed, in which the actual translations which on the basis of which the measured input and output speeds are recorded and compared with the target gear ratios. If the actual translation - including permissible tolerances - deviates from the target translation, replacement measures are initiated.

If a fault is detected outside of gearshifts, the gearshift is then carried out in a gear that is still permitted on the basis of the rotational speeds and in which the clutches in the current faulty gear are not involved in a power flow.

In the context of a preferred variant of the method, an error is recognized after this deviation has occurred repeatedly in one gear or during a gearshift, so that only then can replacement measures be initiated. Therefore, a deviation is defined as a disturbance in the following; if a predetermined number of faults is exceeded, an error or a symptom is recognized, the predetermined number of faults also being able to assume the value zero, so that a one-time deviation or fault is treated as an error.

After an error has been detected, the system is brought into a safe state and the error is stored in the diagnosis management; In the diagnosis management, the further process is defined based on the error pattern.

Here, according to a particularly advantageous variant of the method according to the invention, the type of transfer to a safe state depends on the number of errors or symptoms. A fault counter is incremented if a fault or a fault occurs outside or within circuits. If the fault counter exceeds a predetermined maximum value, as already explained, then an error or symptom is recognized, a symptom counter is incremented and switched to an alternative gear, a symptom counter being provided for each switching element or circuit. If symptoms are recognized multiple times outside of circuits or during circuits, e.g. when the symptom counter reaches a maximum value, a replacement program is activated.

According to the invention, a gear that is detected as safe is “carried along” so that this gear is shifted when an error is determined.

• 1: Eine Darstellung der Soll-Übersetzungen und der Übersetzungstoleranzbänder für zwei Gänge x und y und der Ist-Übersetzung für den Gang x als Funktion der Abtriebsdrehzahl n_ab;
• 2: Eine Darstellung des Übersetzungstoleranzbandes für eine Hochschaltung vom Gang x in den Gang y und der Ist-Übersetzung als Funktion der Zeit;
• 3: Eine Darstellung der Verläufe der Kupplungsdrücke für die Gänge x und y während der in 2 gezeigten Hochschaltung als Funktion der Zeit;
• 4: Eine Darstellung des Übersetzungstoleranzbandes für das Einlegen des Ganges y und der Ist-Übersetzung als Funktion der Zeit; und
• 5: Eine Darstellung eines beispielhaften zeitlichen Verlaufs eines Kupplungsdruckes während des in 4 gezeigten Einlegens des Ganges y.

The invention is explained in more detail below with reference to the accompanying figures. They represent:

• 1 : A representation of the target translations and the translation tolerance bands for two gears x and y and the actual gear ratio x as a function of the output speed n_ab;
• 2 : A representation of the gear ratio tolerance band for an upshift from the gear x in the aisle y and the actual translation as a function of time;
• 3 : A representation of the curves of the clutch pressures for the gears x and y during the in 2 shown upshift as a function of time;
• 4 : A representation of the translation tolerance band for engaging the gear y and the actual translation as a function of time; and
• 5 : A representation of an exemplary time course of a clutch pressure during the in 4 shown gear engagement y ,

Within the scope of the method according to the invention, it is provided that the transmission or gear monitoring is carried out not only outside the gearshift but also during the gearshift operations and while the gear is engaged.

The actual translations are recorded on the basis of measurements of the input and output speeds and compared with the target translations. If the actual translation - including permissible tolerances - deviates from the target translation, replacement measures are initiated.

According to the invention, based on the tolerance specifications of the input and output speed for each gear, a permissible gear ratio tolerance band is calculated, which in 1 through the lines i_Gang_x_ob (upper limit) and i_Gang_x_un (lower limit) for the aisle x and the lines i_Gang_y_ob (upper limit) and i_Gang_y_un (lower limit) for gear y is shown. Again 1 can be seen, these lines envelop the actual fixed translation (target translation) i_Gang_x_fest respectively. i_Gang_y_fest , which is determined by the gears in the respective gear.

If you are driving in one gear and the calculated gear ratio, which is determined via the output speed and the turbine speed, is in the gear ratio tolerance band, then it is assumed that the transmission or the system is working correctly. This is the actual translation i-Gang_berechnet calculated from the quotient turbine speed divided by the output speed.

If the calculated actual translation is not within the specified tolerance range, then it is assumed that there is a fault. A fault could be, for example, that a clutch that is in the power flow cannot transmit the torque and slips because the clutch is defective, or because the necessary pressure is defective, or because the necessary pressure is not present in the clutch, or because a speed sensor is defective.

If a deviation occurs, a fault counter is incremented. If the fault counter exceeds a predetermined maximum value, a symptom or error is recognized. If there is no fault, the fault counter is decremented in a predetermined manner (until it has the value zero). When changing to a new actual gear, the fault counter is also set to zero.

If a symptom or error is detected, symptom counters are incremented according to the invention, a symptom counter being present for each switching element. The respective symptom counters of the clutches involved in this gear are increased by one.

If a symptom or error has been detected, an error code is entered in the error memory of the control or in the diagnosis management. At the same time, the diagnostic software is informed of the replacement gear to be inserted. The diagnostic management then determines the alternative gear and triggers the shift in the shift sequence control.

According to the invention, the predetermined maximum value of the fault counter can be zero, so that any deviation is classified as an error. If a symptom is not recognized in the actual gear and a subsequent switching, the symptom counter is reset to zero at the start of switching.

After the detection of an error, the situation changes to a corresponding safe state. This can e.g. be a gear that is still permitted based on the engine speed, but in which the clutches in the power flow in the current faulty gear are not involved.

The monitoring according to the invention can take place both in the forward gears and also in the reverse gear or in the reverse gears (if present).

The method presented here can also be used during a shift. In this case, the calculated actual translation, as in 2 shown using the example of an upshift, also compared with the corresponding permissible tolerance specifications. If the last predefined translation tolerance band is not left, then it is assumed that the shift or the shifting process is OK. If the tolerance band is left during the shift, for example because the clutch to be shifted cannot transmit the torque (the ratio increases when the engine is in train operation), a corresponding safety measure is initiated. The same applies, for example, even if the disengaging clutch cannot reduce the torque, which can result in the old gear ratio not being left, in which case the gear ratio would also increase and the tolerance band would be left.

If an incorrect clutch is engaged, then at the end of the shifting process - in individual cases even beforehand - the gear ratio is different than the permissible one. In this case, too, the calculated actual translation will leave the specified tolerance band, so that, according to the invention, the system changes to a safe state.

If there is a fault during a shift, a fault counter is incremented. If the fault counter exceeds a predetermined maximum value (which can also be zero), a symptom or error is recognized. If there is no fault, the fault counter is decremented (until it is zero). The fault counter is also set to zero each time the switching begins.

If a symptom is detected, symptom counters are incremented. A symptom counter is available for each circuit. The respective symptom counters of the associated circuit are increased by one.

If a symptom has been identified, an error code is entered in the error memory. At the same time, the diagnostic software is informed of the replacement gear to be inserted. The diagnosis management then determines the alternative gear and triggers the shifting with a signal in the shifting sequence control. According to the invention, all symptom counters are initialized to the value zero when restarting (ignition OFF / ON).

If a shift to a certain gear fails after a certain number of attempts, then a permanent safe state is entered; This circuit is advantageously no longer specified. For example, it is possible to continue driving in the current gear, or only certain circuits are permitted, which in turn are controlled analogously by means of the method.

The lower tolerance curve of the translation tolerance band is derived from the lower tolerance value of the old gear using a suitable algorithm or a calculation rule; the upper tolerance curve is used in the same way a further calculation rule derived from the upper tolerance value of the old gear, the timing of the calculation rules can be influenced on the basis of system events - for example on the basis of reaching discrete phases of the current shift.

In 3 the clutch pressure curve is shown during the upshift; the clutch pressure (curve A ) in the corridor x Switching element involved decreases and takes the value zero, while the clutch pressure in the switching element involved in gear y increases to take on a constant value (curve B ).

If several circuits, so-called nested circuits, are carried out in succession, the error must be clearly assigned to a circuit in the transition area from one circuit to the next upon detection of an impermissible translation, so that according to the invention, when an error occurs, this corresponds to the corresponding circuit or is assigned to the corresponding clutch system, so that the replacement functionality corresponding to this error can be called up.

During gear engagement, the gear ratio tolerance band of the target gear is specified as the target tolerance band according to the inventive method. This is in 4 illustrates which of the translation tolerance band as well as the actual translation for engaging the gear y shows. The corresponding clutch pressure curve is the subject of 5 (Curve C ). The permissible tolerance band during gear engagement is determined on the basis of the output speeds via corresponding specifications, which specifications can be based, for example, on the current speeds, load positions (engine torque / accelerator pedal, throttle valve ...). If the specified translation tolerance band is not left here, too, it is assumed that the gear engagement is OK. If the specified tolerance band is left, it is assumed that there is an error.

The response to the error can e.g. reloading the neutral position. According to a variant of the invention, renewed gear engagement can e.g. can only be allowed after a certain time if there is a driver request. If gear selection fails despite several attempts, it is assumed that the specific gear selection is permanently faulty, so that a safe state is permanently specified.

As an alternative to this, according to the invention, it is possible to shift into a gear other than the desired gear, in which case it is also checked here on the basis of the calculated actual gear ratio whether the newly selected gear can be engaged. The rest of the process is then the same as for the last gear tested.

According to an advantageous variant of the method according to the invention, switching to an alternative gear when a symptom is detected outside of gearshifts is carried out as follows: when the symptom is detected, the gear is shifted up by one gear. According to the invention, the replacement gear is the next higher gear with the exception of the replacement gear for the highest gear, which is the next lower gear. In the R-gear, Neutral is specified as a replacement gear if there is only one R-gear.

The gear specification by the replacement gear is a specification for the diagnosis management, where the priority of the gear specification is determined. This gives a signal to the switching sequence control. If it emerges from the signal that the translation monitoring requires an "alternative gear", this is treated with a higher priority than the torque protection, the gear holding or the reversal of a shift by the translation monitoring. Here, the downshift prevention is not switched off.

If a symptom or error is detected during a gearshift, the gearshift is terminated and the replacement gear is engaged without a shift sequence (changeover of the actuators to the replacement gear combination).

Outside of circuits, according to a particularly advantageous variant of the invention, it is provided to shift from the equivalent gear to the normal gear when the target gear is higher than or equal to the actual gear or when the output speed is less than a predetermined threshold and at the same time dki is less than a predetermined threshold. It is also possible to switch to normal function if the position is neither D yet R is. After a fault detection in R gear, normal function is returned if a driver request is not the same R is recognized.

During a shift it is provided to switch from the equivalent gear to the normal gear when the position N / R / P has been recognized or a predetermined delay time has expired.

Furthermore, within the scope of a further development of the invention it is provided that if symptoms are recognized multiple times outside of circuits, an error memory entry is made with an associated replacement program. If a predetermined maximum value for symptoms is reached by several symptom counters at the same time, an error memory entry is made for the couplings involved with an associated replacement program for the error entries.

If a symptom is detected during circuits, the associated symptom counter is incremented. This symptom counter is compared with the maximum permitted number (maximum value) of symptoms, depending on the circuit. If the number is less than the maximum value, the error is entered in the error memory via the diagnostic interface and the associated replacement gear to be engaged is transmitted, as already explained. If the value of the symptom counter is equal to the maximum value, a corresponding message is sent to the diagnostic software via the diagnostic interface, which then activates the associated replacement function of a replacement program. At the same time, a corresponding error entry is made in the error memory, which is dependent on the circuit type.

According to the invention, filtering back of the fault memory entries is provided, which is activated outside of circuits, preferably every 100 ms. A counter is provided for each checked actual gear, which records the number of all symptoms while driving. It also stores whether the respective gear has already been checked by the translation monitoring.

If all gears outside of gear shifts have been checked by the transmission monitoring and no symptom has been identified in any gear, then a fault memory entry is set to no longer by a symptom.

If the test conditions in the gear engaged are met once in a gear in which a certain clutch is involved, then this is stored temporarily, even if the test conditions are left again. If a gear change occurs without a symptom, the fault memory entry is withdrawn.

During a circuit, a symptom is filtered back with the return to normal function; the filtering back of an error memory entry is carried out at the end of the circuit, subject to the following conditions: an error code is set to nonexistent if the test in the associated circuit and the associated monitoring function has become active and no error has been detected.

LIST OF REFERENCE NUMBERS

i_Gang_x_ob

upper limit or curve of the gear ratio tolerance band for the gear x

i_Gang_x_un

lower limit or curve of the gear ratio tolerance band for the gear x

i_Gang_x_fest

fixed translation for the gear x , determined by the gears

i_Gang_berechnet

calculated actual translation

n_ab

Output speed

A

Coupling pressure curve of the switching element to be switched off

B

Coupling pressure curve of the switching element to be engaged

C

Clutch pressure curve during gear engagement

Claims (23)

Method for transmission or gear monitoring for an automatic transmission or an automated manual transmission of a motor vehicle, the actual transmission being compared with the target transmission and the actual transmission being detected by measuring the input and output speeds, and the transmission or transmission monitoring outside of gear shifts, during the gear changes and / or during gear engagement, characterized in that when the actual gear ratio deviates from the target gear ratio, a fault is detected and at least one fault counter of the switching elements involved is incremented, if the fault counter exceeds a predetermined maximum value, a symptom or error is recognized and replacement measures are initiated, and then if a fault is detected outside of circuits, the gear is shifted, which is still permitted on the basis of the speeds and in which the act not faulty gear in the power flow clutches are not involved. Procedure according to Claim 1 , characterized in that after the detection of a symptom the system is brought into a safe state and the error is stored in a diagnosis management system, the further process being defined in the diagnosis management system on the basis of the error pattern. Procedure according to Claim 1 or 2 , characterized in that after the detection of a symptom is switched to a replacement gear. Method according to one of the preceding claims, characterized in that after the detection of a symptom at least one corresponding symptom counter is incremented, a replacement program being activated when the symptom counter reaches a predetermined maximum value and a symptom counter being assigned to each switching element and each circuit. Method according to one of the preceding claims, characterized in that when a fault does not occur, the fault counter is decremented in a predetermined manner and that when a change is made to a new actual gear, the corresponding fault counter is set to zero. Method according to one of the preceding claims, characterized in that the predetermined maximum value of the fault counter has the value zero. Method according to one of the preceding claims, characterized in that a translation tolerance band is calculated for each gear, which envelops the curve of the target translation by means of a lower tolerance curve (i-Gang_x_un) and an upper tolerance curve (i-Gang_x_ob), so that if the values for the actual translation are within the translation tolerance band, the status is classified as error-free or trouble-free. Procedure according to Claim 7 , characterized in that the translation tolerance band is calculated based on tolerance specifications for input and output speed. Method according to one of the preceding claims, characterized in that when a shift operation in a specific gear fails after a specific predetermined number of attempts, a transition is made to a permanently safe state. Procedure according to Claim 9 , characterized in that if a shift in a certain gear fails after a certain predetermined number of attempts, this shift is no longer predetermined. Method according to one of the preceding claims, characterized in that, if a plurality of circuits are carried out in succession, upon detection of an impermissible translation in the transition area from one to the next circuit, the error is clearly assigned to a circuit on the basis of predefined decision criteria, so that the replacement functionality corresponding to this error can be called. Method according to one of the preceding claims, characterized in that the tolerance band of the target gear is specified as the target tolerance band during gear engagement. Procedure according to Claim 12 , characterized in that the permissible tolerance band is determined during gear engagement on the basis of the output speeds via corresponding specifications. Procedure according to Claim 13 , characterized in that the specifications depend on the current speeds and load positions. Procedure according to one of the Claims 12 to 14 , characterized in that when a fault is identified during gear engagement, the neutral position is reinserted, renewed gear engagement being permitted after a predetermined time. Procedure according to one of the Claims 12 to 14 , characterized in that when a fault is detected while shifting into gear, the gear is shifted to a gear other than the desired gear if this gear can be engaged based on the calculated actual gear ratio (i-gear calculated). Method according to one of the preceding claims, characterized in that during a shift operation the lower tolerance curve (i-Gang_x_un) of the translation tolerance band is derived from the lower tolerance curve of the old gear using an algorithm or a calculation rule and that the upper tolerance curve (i-Gang_x_ob) of the translation tolerance band is derived from the lower tolerance curve of the old gear on the basis of an algorithm or a calculation rule, the chronological sequence of the calculation rules being able to be influenced on the basis of system events. Method according to one of the preceding claims, characterized in that the monitoring takes place in the forward gears and / or in the reverse gear or in the reverse gears if a plurality of reverse gears are provided. Method according to one of the preceding claims, characterized in that for all gears with the exception of the highest gear, the replacement gear is the next higher gear, that for the highest gear the replacement gear is the next lower gear and that for the reverse gear, the replacement gear is neutral, whereby at Switch to the Spare gear outside of gearshifts This gearshift has a higher priority than torque protection, gear maintenance or the reversal of a gearshift by means of the transmission monitoring, and when shifting into the spare gear during a gearshift the spare gear is inserted without changing the actuators to the spare gear combination. Method according to one of the preceding claims, characterized in that a shift from the equivalent gear to the normal gear is carried out outside of gear shifts when the target gear is higher than or equal to the actual gear or when the output speed is less than a predetermined threshold and at the same time dki less than one is a predetermined threshold, or if the position is neither D nor R, whereby after a fault detection in R gear, normal function is returned if a driver's request other than R is recognized. Method according to one of the preceding claims, characterized in that a shift from the equivalent gear to the normal gear is carried out during a shift when the position N / R / P has been recognized or a predetermined delay time has expired. Method according to one of the preceding claims, characterized in that a counter is provided for each checked actual gear, which records the number of all symptoms during the journey and that it is stored whether the respective gear has already been checked by the translation monitoring, whereby if outside of Circuits all gears have been checked and no symptom has been recognized in any gear, an error memory entry for a symptom is set to no longer available and, if the test conditions are met once in a gear in which a certain shift element is involved, this is the case it is buffered even if the test conditions are left again and the fault memory entry is withdrawn without a symptom when the gear is changed. Method according to one of the preceding claims, characterized in that a back-filtering is carried out during a circuit, such that a symptom is deleted upon return to normal function and that an error code is not set to errors at the end of the circuit if the test in the associated circuit and the associated monitoring function became active and no error was detected.

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