DE102011006560B4 - Procedure for error detection when shifting an automated transmission - Google Patents

Abstract

Method for error detection when shifting an automated transmission of a vehicle, wherein an end position of a switched switching element is determined using a stop position, the criterion for error detection being the measured path (s_AnschIMess) to the stop position with a stored maximum path (s_AnschlMax) to the stop position, where an error reaction is triggered when an error is detected, and a path change (Δs_AnschlMess) between the measured path (s_AnschIMess) to the stop position and a stored, transmission-specific path (s_AnschIAdapt(i)) to the stop position is taken into account as a further criterion for error detection, characterized in that As an error reaction, no further switching of the manual transmission is permitted if the measured path (s_AnschIMess) to the stop position is greater than the stored, maximum path (s_AnschIMax) to the stop position and the path change (Δs_AnschlMess) between en the measured path (s_AnschIMess) to the stop position and the stored, gear-specific path (s_AnschIAdapt(i)) to the stop position are greater than a stored maximum path change (Δs_AnschlMax).

Description

The present invention relates to a method for error detection when shifting an automated transmission of a vehicle according to the type defined in more detail in the preamble of patent claim 1.

It is known that in automated transmissions a desired gear is engaged and disengaged by a transmission actuator that is driven, for example, electromechanically, hydraulically, or pneumatically. The form-fitting connection between the gear wheel and the associated shaft takes place by means of a sliding sleeve as a switching element, which is mounted on the shaft in an axially displaceable manner. To engage the gear, the shift sleeve is pushed axially on the shaft by the actuator with a switching mechanism until the shift sleeve and the gear wheel engage. The path covered by the switching element is recorded as the end position or stop position by a position sensor system and transmitted to control electronics, which activates the actuator accordingly.

For example from the publications DE 10 2005 036 895 A1 and DE 10 2006 044 538 A1 methods are known for detecting an error when shifting an automated manual transmission or for detecting damage to a gear selection unit of an automated transmission. To detect a break in the shifting mechanism, the path covered by the transmission actuator when a gear is engaged and thus the end position or stop position is measured and compared with stored values. If the transmission actuator has exceeded the stored or maximum path, it is assumed that there is a break in the shifting mechanism.

With this procedure, however, the problem arises that a maximum travel limit must be defined for all automated transmissions, which, if exceeded, can indicate a break in the shifting mechanism. Due to variances in series production, it can happen that the maximum achievable path in one gearbox is longer than the path in another gearbox where the switching mechanism is recognized as broken. In this case, the sole consideration of the comparison of the measured path to the stop position and the stored, maximum path leads to incorrect detection of an error.

A transmission device, in particular an automated manual transmission of a motor vehicle, with a switching device for actuating the transmission device is from DE 100 25 907 A1 known.

the DE 101 04 099 A1 discloses a method and a device for checking the gear change process of an automated manual transmission.

A method for starting a motor vehicle is through the DE 102 08 204 A1 disclosed.

The present invention is based on the object of proposing a method for error detection when shifting an automated transmission of a vehicle, with which error detection is improved.

According to the invention, this object is achieved by the features of patent claim 1 . Further advantageous configurations result in particular from the dependent claims and the drawing.

Accordingly, a method for detecting preferably mechanical faults during a shifting process in an automated transmission of a vehicle is proposed, with an end position of an actuated shift mechanism being determined using a stop position, with the measured path to the stop position or the stop position being used as a first criterion for error detection a stored maximum transmission-unspecific path to the stop position is compared, with a path change between the measured path to the stop position and a stored transmission-specific path to the stop position being determined and evaluated accordingly as the second criterion for error detection, and if the criteria for error detection are present, a corresponding error reaction is triggered .

The maximum possible path of the adjusting device or the gear actuator is limited by the end stop or by the end position of the sliding sleeve on the gear wheel. In the event of a mechanical interruption between the actuator and the sliding sleeve or the switching element, for example in the event of a mechanical fault, it will therefore be possible to travel through a larger travel range with the actuator. This effect is used in error detection. By expanding the erken according to the invention If a mechanical error is detected, the detection options are significantly improved. For this purpose, a relative displacement of the stop position is additionally taken into account within the scope of the method according to the invention. If the stored path to the end stop changes or is shifted by a defined amount, a mechanical error is assumed. The simultaneous consideration of the transmission-unspecific maximum travel and the transmission-specific travel change offers a sufficient degree of security against erroneous error detection.

If both criteria for error detection are met in the proposed method, it can be provided in a particularly advantageous embodiment that the stored transmission-specific path to the stop position or end position of the shifting element or the sliding sleeve is continuously taught in an intact transmission and not, for example, in one volatile memory of the control electronics is stored. For this purpose, the stored path to the stop position can be adapted at least as a function of the change in path of the stop position and/or as a function of the transmission temperature. To compensate for the influence of temperature, different paths to the stop position are taught for different temperature ranges.

With particular advantage, it can be provided in the method according to the invention that the measured change in path of the stop position is taken into account as a function of a suitable damping factor as part of the adaptation. In this way, the adaptation is implemented as a function of a selected characteristic. The damping factor can thus be used to determine how quickly the stored path to the stop position should approach the measured path to the stop position. For example, provision could be made for smaller changes to be taken into account to a greater extent than larger changes. An incorrect adaptation can thus be prevented by implausible measured values being given little or no consideration at all. Other adaptation options are also conceivable.

The proposed adaptation can also be used independently of the error detection criteria that are also proposed, so that the adaptation is also claimed separately.

The present invention is further described below with reference to the drawing. The only figure of the invention shows a flow chart, which is only indicated as an example, in which the method steps according to the invention are also contained.

The flow chart begins with the start of the shift in an automated transmission of a vehicle. When the ignition is switched on, an already stored or stored, transmission-specific path s_AnschIAdapt(i) to the stop position is known, which is stored in a non-volatile memory, for example. The path s to the stop position is understood to be the path covered by the sliding sleeve or the switching element of the switching mechanism from a starting position or neutral position to an end stop.

In the next method step in the flow chart, the transmission mechanism is actuated in order to engage the sliding sleeve or the new gear until the end position is reached. If the stop is not reached, the process is repeated. After reaching the end position, the distance s_AnschlMess covered up to the end position, i.e. the actual stop position, is measured.

If the measured path s_AnschlMess to the stop position is greater than a maximum transmission-unspecific path s_AnschlMax, the first criterion for error detection is met. In a next method step, the second criterion for error detection is checked by determining the change in path of the stop position Δs_AnschIMess. To do this, the stored transmission-specific path s_AnschIAdapt(i) to the stop position is subtracted from the actually measured path s_AnschlMess to the stop position. If this value of the path change exceeds a stored maximum, e.g. B exceeds the value Δs_AnschIMax that is not specific to a transmission, the second criterion for error detection is also met, so that it is assumed that there is a mechanical error. As a direct consequence of this, no further switching is permitted as an error response, for example, and the process is then terminated.

If the first criterion or the second criterion for error detection is not present, the path or the stop position is adapted. The change in path Δs_AnschIMess of the stop position determined as part of the second error detection criterion is used for the adaptation, so that this change in path Δs_AnschIMess must first be determined if the adaptation is already being carried out after the first error detection criterion has not been met.

As part of the adaptation, which is also claimed separately, a newly adapted path s_AnschlAdapt(i+1) to the stop position is determined from the sum of the old or previous, stored, transmission-specific path s_AnschIAdapt(i) to the stop position and the measured path s_AnschIMess to the stop position. A damping factor f is preferably taken into account for the corresponding weighting during the adaptation. The damping factor f is determined as a function of the measured change in path Δs_AnschIMess of the stop position.

In the flowchart shown in the figure, a characteristic curve of the damping factor f over the measured change in path Δs_AnschIMess of the stop position is shown as an example. In this curve, the damping factor f is about 0.3 for small measured changes in the stop position Δs_AnschIMess. However, other profiles can also be used, depending on the area of application.

ergibt sich durch den Dämpfungsfaktor f eine Adaption, die bei der Bestimmung der adaptierten Anschlagposition s_AnschlAdapt(i+1) etwa 30 % des gemessenen Weges der Anschlagpositon s_AnschlMess und etwa 70 % des alten bzw. hinterlegten Weges zur Anschlagposition s_AnschIAdapt(i) berücksichtigt.If the newly adapted path or stop value s_AnschlAdapt(i+1) is determined according to the following equation: $$\text{s\_AnschlAdapt}\left(\text{i}+1\right)=\text{s\_AnschlAdapt}\left(\text{i}\right)*\left(\text{f}-1\right)+\text{s\_AnschlMess*f}$$

the damping factor f results in an adaptation which, when determining the adapted stop position s_AnschlAdapt(i+1), takes into account about 30% of the measured path of the stop position s_AnschlMess and about 70% of the old or stored path to the stop position s_AnschIAdapt(i).

If the adaptation is also carried out as a function of the transmission temperature c_Getriebe, the following algorithm results for the adaptation: $$\begin{array}{l}\text{s\_AnschlAdapt}\left(\text{c\_gear}\text{, i}+1\right)=\text{s\_AnschlAdapt}\left(\text{c\_gear}\text{, i}\right)*\left(\text{f}-1\right)+\\ \text{s\_AnschlMess*f}\text{.}\end{array}$$

At the end of the adaptation, the value s_AnschIAdapt(i) stored in the memory is replaced by the newly determined value s_AnschlAdapt(i+1) and the method can then begin again. By carrying out the adaptation multiple times when using the damping factor f, the measured path s_AnschIMess can advantageously be adapted to the stored value s_AnschlAdapt(i).

Reference List

s_AnschlMess

measured path to stop position

s_AnschlMax

gear-unspecific max. travel e.g. stop position

Δs_AnschlMess

measured path change

s_AnschlAdapt(i)

Stored, transmission-specific path, e.g. stop position

Δs_AnschlMax

gear-unspecific maximum path change of the stop position

s_AnschlAdapt(i+1)

new adapted transmission-specific path to the stop position

f

damping factor

Claims (5)

Method for error detection when shifting an automated transmission of a vehicle, wherein an end position of a switched switching element is determined using a stop position, the criterion for error detection being the measured path (s_AnschIMess) to the stop position with a stored maximum path (s_AnschlMax) to the stop position, where an error reaction is triggered when an error is detected, and a change in path (Δs_AnschlMess) between the measured path (s_AnschIMess) to the stop position and a stored, transmission-specific path (s_AnschIAdapt(i)) to the stop position is taken into account as a further criterion for error detection, characterized in that As an error reaction, no further switching of the manual transmission is permitted if the measured path (s_AnschIMess) to the stop position is greater than the stored, maximum path (s_AnschIMax) to the stop position and the path change (Δs_AnschlMess) between hen the measured distance (s_AnschIMess) to the stop position and behind specified, transmission-specific path (s_AnschIAdapt(i)) to the stop position are greater than a stored maximum path change (Δs_AnschlMax). procedure after claim 1 , characterized in that the stored, transmission-specific path (s_AnschiAdapt(i)) to the stop position is adapted at least as a function of the change in path (Δs_AnschlMess) to the stop position and/or as a function of the transmission temperature if at least one of the criteria for error detection is not met. Method according to one of the preceding claims, characterized in that a new transmission-specific path (s_AnschiAdapt(i+1)) to the stop position is determined according to the following equation: $$\begin{array}{l}\text{s\_AnschlAdapt}\left(\text{i}+1\right)=\text{s\_AnschlAdapt}\left(\text{i}\right)*\left(\text{f}-1\right)+\text{s\_AnschlMess*f}\\ \end{array}$$

with s_AnschlAdapt(i+1) = new, adapted, transmission-specific path to the stop position; s_AnschIAdapt(i) = stored, transmission-specific path to the stop position; s_AnschlMess = measured path to the stop position; f = damping factor. procedure after claim 3 , characterized in that the damping factor (f) is determined depending on the measured path change (Δs_AnschlMess) to the stop position. procedure after claim 3 or 4 , characterized in that the transmission-specific path (s_AnschIAdapt(i)) stored in a memory to the stop position is replaced in each case by a newly determined transmission-specific path (s_AnschIAdapt(i+1)).

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