Method for operating a torque converter automatic transmission and control device

Abstract

Method for operating a torque converter automatic transmission (1) with at least one positive-locking switching element (A, F) and with several friction-locking switching elements (B, C, D, E), wherein in each engaged gear (1 to 9) a first number of switching elements are closed or engaged and a second number of switching elements are opened or disengaged, and wherein, when performing a gear change from an actual gear to a target gear, at least one switching element is opened or disengaged and at least one switching element is closed or engaged, wherein, for performing an upshift, at least one positive-locking switching element (A or F) is opened or disengaged and at least one friction-locking switching element (B or C) is closed or engaged, characterized in that the opening of the positive-locking switching element (A or F) is monitored on the basis of a current transmission ratio determined from rotational speeds (17, 17', 17"), in order to avoid over-regulation of the torque converter automatic transmission (1) if the positive-locking switching element (A or F) to be opened cannot be opened properly, and if, in the case of an overdetermination of the torque converter automatic transmission (1), one of the friction-locking switching elements (for example E) can no longer transmit the torque to be transmitted, so that, according to the signal curve (20"), a differential speed in the sense of slippage of the switching element (E) is formed at this friction-locking switching element (E).

Description

[0001] The invention relates to a method for operating a torque converter automatic transmission according to the preamble of claim 1. Furthermore, the invention relates to a control device, in particular a transmission control device.

[0002] In torque converter automatic transmissions, such as those known from DE 10 2008 000 429 A1, which have at least one positive shifting element in addition to frictional shifting elements, transmission over-determination can occur when executing a gear shift or a gear change from an actual gear to a target gear, particularly if at least one positive shifting element must be opened to execute the gear change. This can happen when the positive shifting element to be opened cannot be opened properly. For example, it may happen that a positive shifting element can no longer be opened due to excessively rapid or faulty torque reduction.

[0003] To ensure the functional reliability of a torque converter automatic transmission and avoid over-determination, it is necessary to monitor the opening of a positively engaging shifting element. To date, no methods are known by which this can be ensured simply and reliably. Based on this, the present invention is based on the object of creating a novel method for operating a torque converter automatic transmission and a novel control device. Only DE 103 13 483 A1 discloses how gear ratios can be calculated from speed signals and thus monitored for an automatic transmission with frictionally engaged shifting elements.

[0004] This object is achieved by a method for operating a torque converter automatic transmission according to claim 1. According to the invention, when at least one positive shifting element is opened or deactivated and at least one frictional shifting element is closed or engaged to execute a gear change, the opening of the positive shifting element is monitored based on a current transmission ratio determined from rotational speeds. This makes it possible to prevent over-determination of the torque converter automatic transmission if the positive shifting element to be opened cannot be opened properly, and if, due to over-determination of the torque converter automatic transmission, one of the frictional shifting elements can no longer transmit the torque to be transmitted, so that, according to the signal curve, a differential speed develops at this frictional shifting element, causing the shifting element to slip.

[0005] In the present invention, the proper opening of a positive-locking shift element that is to be opened during a gear change is monitored based on a current transmission ratio determined based on engine speeds. This allows for simple and reliable monitoring of whether a positive-locking shift element that is to be opened is properly opened during a gear change. This allows for over-determination of the transmission to be detected, and countermeasures to be initiated if such over-determination is detected.

[0006] These speeds, from which the current gear ratio is determined, are preferably verified speeds, which are verified both through measurement and through calculation. This can increase the reliability of the monitoring.

[0007] Preferably, the current transmission ratio is determined from the turbine speed of a converter and the speed of a transmission output shaft. These speeds are each measured and verified for plausibility through a calculation, thus ensuring that they are secured. This allows for particularly simple and reliable monitoring of whether a positive-locking shift element that is to be opened is opened properly when performing a gear change.

[0008] According to an advantageous development of the invention, if the current gear ratio changes toward a lower gear ratio during an upshift, it is concluded that the positive shifting element to be opened to execute the gear change has opened properly. Conversely, if the current gear ratio does not change or changes toward a higher gear ratio during an upshift, it is concluded that the positive shifting element to be opened to execute the upshift has not opened properly. The above monitoring of the proper opening of a positive shifting element to be opened to execute an upshift is particularly simple and reliable.

[0009] If it is determined that the positive-locking shift element required to execute the gear change has not opened properly, the torque converter automatic transmission is preferably actuated toward neutral or to restore the actual gear of the gear change being executed. Using one of these countermeasures, safety-critical conditions can be avoided.

[0010] Preferably, the opening of the positive-locking switching element is monitored based on the current gear ratio starting from a point in time at which the respective positive-locking switching element is triggered to open. The above starting point for monitoring the opening of the respective positive-locking switching element is preferably determined based on a secured trigger current signal of the respective positive-locking switching element. This can increase the reliability of the monitoring.

[0011] The control device according to the invention, which is preferably designed as a transmission control device, is defined in claim 10.

[0012] Preferred developments of the invention will become apparent from the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail, without being limited thereto, with reference to the drawings. Herein: Fig. 1 a diagram of a torque converter automatic transmission, and Fig. 2 diagrams to illustrate the method according to the invention for operating a torque converter automatic transmission.

[0013] The present invention relates to a method for operating a torque converter automatic transmission and a control device for carrying out the method.

[0014] Fig. Figure 1 shows a diagram of a torque converter automatic transmission, wherein the torque converter automatic transmission 1 comprises a transmission input shaft 2 and a transmission output shaft 3. A drive unit can be coupled to the transmission input shaft 2, and an output can be coupled to the transmission output shaft 3.

[0015] The torque converter automatic transmission 1 comprises a torque converter 4 with a torque converter lock-up clutch 5. A turbine wheel 6, a pump wheel 7, and a stator wheel 8 are shown on the torque converter 4, with the stator wheel 8 being connected to a so-called freewheel 9. When the torque converter lock-up clutch 5 is engaged, the turbine wheel 6 and the pump wheel 7 are coupled to one another.

[0016] The Fig. The torque converter automatic transmission 1 shown in Figure 1 comprises, in addition to the torque converter 4 and the torque converter lock-up clutch 5, a plurality of gear sets 10, 11, 12, and 13, as well as a plurality of shifting elements A, B, C, D, E, and F. In the exemplary embodiment shown, the torque converter automatic transmission 1 accordingly comprises six shifting elements A to F, with the shifting elements A and F being listed as positive-locking shifting elements and the shifting elements B, C, D, and E being listed as frictional-locking shifting elements. In the exemplary embodiment shown, the frictional-locking shifting elements B and E are clutches, and the frictional-locking shifting elements C and D are brakes.

[0017] In each gear engaged, the torque converter automatic transmission 1 of the Fig. 1 a first number of switching elements are closed or switched on and a second number of switching elements are opened or switched off, wherein in the embodiment of the Fig. 1 In each gear, three switching elements are switched on or closed and three switching elements are switched off or opened.

[0018] The following table lists the shift elements that are closed or engaged, as well as open or disengaged, for each of the nine available forward gears 1 to 9. In the following table, closed or engaged shift elements are marked with an x. A B C D E F 1 X X X 2 X X X 3 X X X 4 X X X 5 X X X 6 X X X 7 X X X 8 X X X 9 X X X

[0019] For example, if you want to Fig. 1 shown embodiment of a torque converter automatic transmission 1, a gear change from the actual gear 4 to the target gear 5 is to be carried out, then in the torque converter automatic transmission 1 the Fig. 1 the positive switching element F is opened or switched off and the frictional switching element B is closed or switched on.

[0020] The present invention relates to a method and a control device by means of which, when at least one positive switching element is opened or deactivated and at least one frictional switching element is closed or activated in order to carry out a gear change, the opening of the positive switching element can be monitored simply and reliably, wherein this monitoring in the sense of the present invention is carried out on the basis of a current transmission ratio determined from rotational speeds.

[0021] The speeds used to determine the current gear ratio and to check the proper opening of the positive switching element to be opened when a gear change is carried out are preferably secured speeds which are recorded by measurement on the one hand and calculated on the other hand for plausibility and thus security purposes.

[0022] Preferably, the current transmission ratio is determined on the basis of a turbine speed of the turbine 6 of the converter 4 and on the basis of a speed of the transmission output shaft 3, wherein both the turbine speed of the turbine 6 of the converter 4 and the speed of the transmission output shaft 3 are calculated on the one hand by measurement and on the other hand for plausibility and thus security purposes.

[0023] The calculation of the turbine speed of the turbine 6 of the converter 4 is preferably carried out on the basis of the gear ratio of the actual gear of the gearshift to be carried out and on the basis of the speed of the transmission output shaft 3. The calculation of the speed of the transmission output shaft 3 is preferably carried out as a function of measured wheel speeds of an output coupled to the output shaft 3.

[0024] The above monitoring of the opening of a positive-locking switching element to be opened during a gear shift preferably occurs from the time at which the positive-locking switching element to be opened is triggered by the control system, in particular by a corresponding change in the respective control current. The control current is also a protected signal, so that the entire monitoring of the positive-locking switching element to be opened is based on protected signals, including the start time of monitoring.

[0025] Further details of the invention are described below with reference to Fig. 2, where Fig. 2 Several temporal signal curves are plotted over time t.

[0026] A first signal curve 14 visualizes a shift request, whereby the shift request 14 is present at time t1. It is assumed below that this shift request 14 is the request for an upshift from forward gear 4 to forward gear 5 of the Fig. 1, in which the positive switching element F is to be opened and the frictional switching element B is to be closed.

[0027] A signal curve 15 shows the control of the positive-locking switching element F to be opened and a signal curve 16 shows the control of the friction-locking switching element B to be closed, whereby the signals 15 and 16 are each control currents. Fig. 2 it can be seen that between the times t1 and t2 a filling of the frictional switching element B to be closed takes place, wherein at the time t2 the control signal 15 for the positive switching element F to be opened is changed so that the positive switching element F to be opened is to be opened or switched off starting at the time t2.

[0028] At time t2, i.e. with the corresponding activation of the positive-locking switching element F to be opened by a corresponding change in the activation current 15, the monitoring according to the invention of the positive-locking switching element F to be opened with regard to a correct opening of the same begins, whereby for this purpose, starting at time t2, a current gear ratio is determined from speeds. With a signal curve 17, Fig. 2 visualizes the determined current gear ratio, which develops when the positive shift element F is properly opened when performing an upshift from forward gear 4 to forward gear 5. In this case, a change in the current gear ratio towards a lower ratio is detected in the sense of signal curve 17.

[0029] If, at the start of monitoring at time t2, it is determined that either the current transmission ratio does not change according to signal curve 17' or the current transmission ratio changes in the wrong direction, namely towards a higher ratio, according to signal curve 17", a counter reading of a fault counter is increased according to signal curve 18 depending on a calculation cycle or evaluation cycle of a control device executing the method according to the invention, in particular a transmission control device.

[0030] Then, if at time t3 the fault counter reading reaches or exceeds a limit value, an error flag is set according to the signal curve 19, so that at time t3 it is recognized that the positive switching element F to be opened when shifting from forward gear 4 to forward gear 5 was not opened properly, so that there is therefore an overdetermination in the torque converter automatic transmission 1.

[0031] Between times t2 and t3, the translation signal 17, 17', 17" is filtered by increasing the counter reading of the disturbance counter, which can increase the reliability of the method.

[0032] In the case of signal curve 17', in which there is no change in the transmission ratio, this means that the frictionally engaged shifting elements, which are closed in this case, can properly transmit the applied torque. Signal curve 17" with a change in the current transmission ratio in the wrong direction, i.e., towards a higher ratio, occurs when, due to an over-determination of the torque converter automatic transmission 1, one of the frictionally engaged shifting elements, for example, shifting element E in the illustrated embodiment, can no longer transmit the torque to be transmitted, so that according to signal curve 20" a differential speed develops at this frictionally engaged shifting element E, in the sense of shifting element E slipping.The signal curve 20' shows for the signal curve 17' that if the gear ratio remains unchanged, no differential speed in the sense of slipping develops at the switching element E.

[0033] If it is determined at time t3 that the positive switching element F, which is to be opened during the switching operation, has not been opened properly, then Fig. 2 according to the signal curve 16' or 16" from time t3 onwards, the control for the frictionally engaged switching element B to be closed is withdrawn, so that the torque converter automatic transmission is then transferred to a neutral position.

[0034] If, however, it is determined that the positive-locking switching element F to be opened has been opened correctly, the control of the friction-locking switching element B to be closed would follow the signal curve 16 starting at time t3.

[0035] In contrast to the embodiment described above, it is also possible that if it is determined that a positive-locking shift element to be opened has not been opened properly, the transmission is not transferred to neutral, but rather a control is selected so that the actual gear of the shift to be carried out is restored.

[0036] It is therefore within the meaning of the present invention, in a torque converter automatic transmission 1 with at least one positive shifting element and a plurality of frictional shifting elements, when at least one positive shifting element is opened or deactivated and at least one frictional shifting element is closed or activated to carry out a gear change, to monitor the opening of the positive shifting element on the basis of a current transmission ratio determined from rotational speeds, wherein the rotational speeds are preferably secured rotational speeds which are recorded by measurement on the one hand and calculated in parallel for plausibility and thus security on the other.

[0037] The method according to the invention is preferably carried out by a control device according to the invention, which is preferably a transmission control device. To carry out the method according to the invention, the transmission control device exchanges data with the torque converter automatic transmission 1, for example with the converter 4 to provide the turbine speed of the turbine 6 of the converter 4, and with the transmission output shaft 3 to provide its speed. The transmission control device can exchange data with the shift elements A to F via further interfaces in order to provide the shift elements with corresponding control signals for opening or closing them.

[0038] The control device according to the invention that carries out the method according to the invention has a processor for executing the method according to the invention and the necessary calculations of the gear ratio. Furthermore, the control device according to the invention has a memory for storing calculations performed during the method according to the invention, for example, a counter reading of the fault counter.

[0039] Details of the connection of the control device, in particular the transmission control device, to the torque converter automatic transmission 1, for example via a data bus, are familiar to the person skilled in the art addressed here and do not require any further explanation. Reference symbol 1 torque converter automatic transmission 2 transmission input shaft 3 Gearbox output shaft 4 converters 5 torque converter lock-up clutch 6 Turbine wheel 7 Pump wheel 8 Idler 9 Freewheel 10 wheel set 11 Wheel set 12 wheel set 13 wheelset 14 Signal flow / circuit requirement 15 Signal curve / control current switching element F 16, 16', 16" Signal curve / control current switching element B 17, 17', 17" Signal curve / current gear ratio 18 Signal curve / counter reading fault counter 19 Signal curve / error flag 20', 20" signal curve / speed difference

Claims

[1] Method for operating a torque converter automatic transmission (1) with at least one positive shifting element (A, F) and with a plurality of frictional shifting elements (B, C, D, E), wherein in each engaged gear (1 to 9) a first number of shifting elements is closed or engaged and a second number of shifting elements is opened or disengaged, and wherein when executing a gear change from an actual gear to a target gear, at least one shifting element is opened or disengaged and at least one shifting element is closed or engaged, wherein to execute an upshift at least one positive shifting element (A or F) is opened or disengaged and at least one frictional shifting element (B or C) is closed or engaged, characterized by , that the opening of the positive shift element (A or F) is monitored on the basis of a current transmission ratio determined from speeds (17, 17', 17") in order to avoid over-determination of the torque converter automatic transmission (1) if the positive shift element (A or F) to be opened cannot be opened properly, and if, in the event of an overdetermination of the torque converter automatic transmission (1), one of the frictionally engaged shifting elements (for example E) can no longer transmit the torque to be transmitted, so that a differential speed in the sense of slipping of the shifting element (E) is then formed at this frictionally engaged shifting element (E) according to the signal curve (20"). [2] Method according to claim 1, characterized by that the current gear ratio is determined from secured speeds. [3] Method according to claim 1 or 2, characterized bythat the current gear ratio is determined from a turbine speed of a converter (4) and from a speed of a transmission output shaft (3). [4] Method according to claim 3, characterized by that the turbine speed of the converter (4) and the speed of the transmission output shaft (3) are each measured on the one hand and checked for plausibility and thus secured by means of a calculation on the other. [5] Method according to one of claims 1 to 4, characterized by that when the current gear ratio changes towards a lower ratio (17) when an upshift is carried out, it is concluded that the positive switching element (F) to be opened to carry out the gear change has opened correctly. [6] Method according to one of claims 1 to 5, characterized bythat if, when an upshift is carried out, the current gear ratio does not change or changes towards a higher ratio (17', 17"), it is concluded that the positive switching element (F) which has to be opened to carry out the gear change has not been opened properly. [7] Method according to claim 6, characterized by that the torque converter automatic transmission (1) is then controlled towards neutral. [8] Method according to claim 6, characterized by that the torque converter automatic transmission (1) is then activated to restore the actual gear of the gearshift to be carried out [9] Method according to one of claims 1 to 8, characterized by that the opening of the positive switching element (F) is monitored on the basis of the current gear ratio from a time (t1) of the control to open the respective positive switching element (F). [10] Control device, in particular a transmission control device, characterized by Means for carrying out the method according to one or more of claims 1 to 9.

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