DE102011006560A1 - Method for error detection during switching automatic transmission of vehicle, involves considering displacement change between measured displacement to stop position and stored transmission-specific displacement to position as criterion - Google Patents

Abstract

The method involves determining an end position of a sliding sleeve using a stop position. A measured displacement of the sleeve to the stop position is compared with stored maximum displacement at the stop position as a criterion for error detection. An error reaction is triggered during the error detection. A displacement change between the measured displacement to the stop position and the stored transmission-specific displacement to the stop position is considered as another criterion. A damping factor is determined based on the measured displacement change at the stop position.

Description

The present invention relates to a method for error detection when switching an automated transmission of a vehicle according to the closer defined in the preamble of claim 1. Art.

It is known that in automated transmissions, a desired gear is engaged and disengaged by a transmission actuator which is driven electromechanically, hydraulically or pneumatically, for example. The positive connection between the gear and the associated shaft is effected by a sliding sleeve as a switching member which is mounted axially displaceably on the shaft. To engage the gear, the sliding sleeve is axially displaced by the actuator with a switching mechanism on the shaft until the sliding sleeve and the gear gear are engaged. The covered path of the switching element is detected as an end position or stop position by a position sensor and transmitted to an electronic control unit which controls the actuator accordingly.

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

With this procedure, however, the problem arises that for all automated transmissions, a maximum travel limit must be defined, which can be inferred that a breakage of the switching mechanism is exceeded. Due to variations in mass production, it may happen that the maximum achievable distance in one transmission is longer than the distance of another transmission, in which the switching mechanism is recognized as broken. The exclusive consideration of the comparison of the measured path to the stop position and of the stored maximum distance leads in this case to an erroneous detection of an error.

The present invention is based on the object to propose a method for detecting errors when switching an automated transmission of a vehicle, with which the error detection is improved.

This object is achieved by the features of claim 1. Further advantageous embodiments will become apparent in particular from the dependent claims and the drawing.

Accordingly, a method for detecting preferably mechanical errors during a switching operation in an automated transmission of a vehicle is proposed, wherein an end position of an actuated switching mechanism is determined by means of a stop position, wherein as a first criterion for error detection, the measured path to the stop position or the stop position with is compared with a stored maximum gearunspezifischen way to the stop position, as a second criterion for error detection a path change between the measured path to the stop position and a stored gear-specific path to the stop position is determined and evaluated accordingly, and if the criteria for error detection, a corresponding error response 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 gear. In a mechanical interruption between the actuator and the sliding sleeve or the switching element, for example, in a mechanical error, it will therefore be possible to go through with the actuator a larger path range. This effect is exploited in error detection. The inventive extension of the detection of a mechanical error, the detection possibilities are significantly improved. For this purpose, a relative displacement of the stop position is additionally taken into account in the context of the method according to the invention. If the stored path to the end stop is changed or shifted by a defined amount, a mechanical error is concluded. The simultaneous consideration of the transmission-unspecific maximum travel and the transmission-specific path change offers a sufficient degree of security against false fault detection.

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

With particular advantage, it may be provided in the method according to the invention that, in the context of the adaptation, the measured path change of the stop position is taken into account as a function of a suitable damping factor. In this way, the adaptation is realized, as it were, depending on a selected characteristic curve. Thus, the damping factor can be used to determine how fast the stored or stored path should approach the stop position on the measured path to the stop position. For example, it could be provided that smaller changes are considered more strongly than larger changes. Thus, an erroneous adaptation can be prevented by taking into account implausible measured values little or not at all. There are also other adaptation options conceivable.

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

Hereinafter, the present invention will be further described with reference to the drawings. The sole FIGURE of the invention shows a flowchart which is only indicated by way of example, in that the method steps according to the invention are also included.

The flowchart begins with the start of the shift in an automated transmission of a vehicle. In this case, when the ignition is switched on, an already stored or stored transmission-specific path s_AnschlAdapt (i) to the stop position is known, which is stored, for example, in a non-volatile memory. Under the way s to the stop position of the covered path of the sliding sleeve or the switching element of the switching mechanism is understood from an initial position or neutral position to an end stop.

At the next step in the flowchart, the transmission mechanism is actuated to engage the sliding collar or 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 covered s_AnschlMess to the final position, ie the actual stop position measured.

If the measured distance s_AnschlMess to the stop position is greater than a maximum gearing 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 path change of the stop position Δs_AnschlMess. For this purpose, the stored transmission-specific path s_AnschlAdapt (i) is subtracted to the stop position of the actually measured path s_AnschlMess to the stop position. If this value of the path change a stored maximum, z. B. gearunspezifischen value Δs_AnschlMax exceeds, the second criterion of error detection is met, so that it is assumed that there is a mechanical error. As a direct result, as an error reaction, for example, no further circuit is allowed and then the procedure is terminated.

If the first criterion or the second criterion for error detection is not present, the adaptation of the path or the stop position is carried out. For adaptation, the path change Δs_AnschlMess of the stop position determined within the framework of the second criterion of the error detection is used, so that this path change Δs_AnschlMess must first be determined if the adaptation is already carried out after the unfulfilled first criterion of error detection.

Within the context of the separately claimed adaptation, a newly adapted path s_AnschlAdapt (i + 1) to the stop position is determined from the sum of old or previous, stored, transmission-specific travel s_AnschlAdapt (i) to the stop position and the measured distance s_AnschlMess to the stop position. Preferably, an attenuation factor f is taken into account for the corresponding weighting in the adaptation. The damping factor f is determined as a function of the measured path change Δs_AnschlMess the stop position.

In the case of the flowchart shown in the figure, a characteristic curve of the damping factor f over the measured displacement Δs_AnschlMess the stop position is exemplified. In this course, the damping factor f is about 0.3 for small measured changes in the stop position Δs_AnschlMess. But there are also other gradients usable depending on the application.

If the newly adapted travel or stroke value s_AnschlAdapt (i + 1) is determined according to the following equation: s_AnschlAdapt (i + 1) = s_AnschlAdapt (i) · (f - 1) + s_AnschlMess · f results from the damping factor f an adaptation, which in determining the adapted stop position s_AnschlAdapt (i + 1) about 30% of measured distance of the stop position s_AnschlMess and about 70% of the old or stored path to the stop position s_AnschlAdapt (i) considered.

If the adaptation is also carried out as a function of the transmission temperature c_transmission, the following algorithm results for the adaptation: s_AnschlAdapt (c_Getriebe, i + 1) = s_AnschlAdapt (c_Getriebe, i) · (f - 1) + s_AnschlMess · f.

At the end of the adaptation, the value stored in the memory s_AnschlAdapt (i) is replaced by the newly determined value s_AnschlAdapt (i + 1) and then the process can begin again. By multiple execution of the adaptation when using the damping factor f, the measured path s_AnschlMess can be adapted to the stored value s_AnschlAdapt (i) in an advantageous manner.

reference numeral

• s_AnschlMess

  measured way to the stop position

  s_AnschlMax

  gearunspecific max. Way z. stop position

  Δs_AnschlMess

  measured path change

  s_AnschlAdapt (i)

  stored, gear-specific way z. stop position

  Δs_AnschlMax

  gearunspezifische maximum path change of the stop position

  s_AnschlAdapt (i + 1)

  new adapted transmission-specific way to the stop position

  f

  damping factor

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102005036895 A1 [0003]
• DE 102006044538 A1 [0003]

Claims (6)

A method for detecting errors when switching an automated transmission of a vehicle, wherein an end position of a switched switching element is determined by means of a stop position, wherein as a criterion for error detection of the measured path (s_AnschlMess) is compared to the stop position with a stored maximum distance (s_AnschlMax) to the stop position, and wherein in an error detection, an error response is triggered, characterized in that as a further criterion for error detection a Wegveränderung (Δs_AnschlMess) between the measured distance (s_AnschlMess) to the stop position and a stored, gear-specific way (s_AnschlAdapt (i)) is considered to the stop position. A method according to claim 1, characterized in that as an error reaction no further switching of the gearbox is allowed when the measured distance (s_AnschlMess) to the stop position greater than the stored, maximum distance (s_AnschlMax) to the stop position and the path change (Δs_AnschlMess) between the measured path (s_AnschlMess) to the stop position and the stored, gearbox-specific way (s_AnschlAdapt (i)) to the stop position are greater than a stored maximum path change (Δs_AnschlMax). Method according to one of the preceding claims, characterized in that the stored, gear-specific path (s_AnschlAdapt (i)) is adapted to the stop position at least in response to the path change (Δs_AnschlMess) to the stop position and / or depending on the transmission temperature, if at least one of the criteria for Error detection is not fulfilled. Method according to one of the preceding claims, characterized in that a new transmission-specific path (s_AnschlAdapt (i + 1)) to the stop position is determined according to the following equation: s_AnschlAdapt (i + 1) = s_AnschlAdapt (i) · (f - 1) + s_AnschlMess · f with s_AnschlAdapt (i + 1) = new adapted gear-specific travel to the stop position; s_AnschlAdapt (i) = stored, gear-specific path to the stop position; s_AnschlMess = measured way to the stop position; f = damping factor. A method according to claim 4, characterized in that the damping factor (f) is determined as a function of the measured path change (Δs_AnschlMess) to the stop position. A method according to claim 4 or 5, characterized in that the stored in a memory transmission-specific way (s_AnschlAdapt (i)) is replaced to the stop position in each case by a newly determined transmission-specific way (s_AnschlAdapt (i + 1)).

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