Method and control unit for operating a vehicle's powertrain

Abstract

A method for operating a vehicle's drivetrain, wherein the drivetrain comprises a drive unit (1), an output (3), and a transmission (2) arranged in the drivetrain between the drive unit (1) and the output (3), wherein the transmission (2) is associated with a transmission control unit (5) for controlling and / or regulating the operation of the transmission (2), and an acceleration sensor (6) for measuring the vehicle's acceleration, characterized in that, depending on a gear engaged in the transmission (2) or depending on the vehicle's direction of travel, a target acceleration appropriate to the gear or direction of travel is determined, which develops when the vehicle accelerates in that gear or direction of travel, the acceleration sensor (6) determines an actual acceleration when the vehicle accelerates, and it is determined whether the target acceleration and the actual acceleration correlate, wherein, if so,If the target acceleration and the actual acceleration correlate, the actual acceleration measured by the acceleration sensor (6) can be used by the transmission control unit (5) without adaptation; if the target acceleration and the actual acceleration do not correlate, the actual acceleration measured by the acceleration sensor (6) can be used by the transmission control unit (5) with adaptation.

Description

The invention relates to a method for operating a vehicle's powertrain. Furthermore, the invention relates to a control unit for operating a vehicle's powertrain. A vehicle's powertrain consists of a drive unit and a transmission located between the drive unit and an output shaft. The transmission converts speed and torque and makes the drive unit's tractive force available at the output shaft. The operation of a transmission is controlled and / or regulated by a transmission control unit. A transmission control unit is assigned to the transmission for this purpose. To control and / or regulate the operation of the transmission, the transmission control unit processes signals from sensors, such as a signal from an acceleration sensor. An acceleration sensor is assigned to the transmission for this purpose and may be an integral part of the transmission control unit. A transmission is installed in a defined position within the vehicle's drivetrain. It is possible that transmissions of the same type may be installed in different positions depending on the vehicle being manufactured. For example, it is common practice that in a truck, the transmission is installed with its input shaft pointing forward in the direction of forward travel, whereas in a bus, the transmission is typically installed with its input shaft pointing backward in the opposite direction of forward travel. Then, if the transmission control unit is permanently installed on the transmission and the acceleration sensor is also permanently installed in the transmission, for example integrated into the transmission control unit, the installation direction of the acceleration sensor also depends on the installation direction of the transmission in the drive train. For the proper operation of a transmission installed in a vehicle's drivetrain, it is therefore important to know the transmission's installation direction within the drivetrain, as otherwise the acceleration sensor may provide readings that do not correspond to the direction of travel. Therefore, during the production of a vehicle, such as a truck or bus, the transmission's installation position is determined, and the transmission control unit is parameterized accordingly to ensure that, during operation, the acceleration sensor provides readings that correspond to the vehicle's direction of travel. DE 43 35 756 A1 discloses a drive train of a vehicle comprising a drive unit and a transmission. Elements of the drive train can be pivotally mounted on an axle in a vertical plane. DE 10 2007 006 996 A1 discloses a shifting strategy of an automated transmission to be adapted using acceleration sensors present in the vehicle. Determining the installation position of a transmission during vehicle production and parameterizing the transmission control unit based on this position represent additional work steps. There is a need to eliminate these steps. The invention aims to provide a suitable method and control unit for operating a powertrain. This problem is solved by a method for operating a drive train of a vehicle according to claim 1. According to the invention, a target acceleration appropriate to the gear or direction of travel is determined depending on the gear selected in the transmission or the vehicle's direction of travel. This target acceleration develops when the vehicle accelerates in that gear or direction. The target acceleration, which develops when the vehicle accelerates in that gear or direction of travel, can be determined, for example, at the vehicle's output shaft or wheel. When the vehicle accelerates, the acceleration sensor determines the actual acceleration. The next step is to determine whether the target acceleration and the actual acceleration correlate. If the target acceleration and the actual acceleration correlate, the actual acceleration measured by the acceleration sensor can be used by the transmission control unit without adjustment. If the target acceleration and the actual acceleration do not correlate, the actual acceleration measured by the acceleration sensor can be used by the transmission control unit with adjustment. The present invention proposes a method by which the installation position of the transmission in the drivetrain can be automatically determined during operation of the drivetrain, namely by comparing a target acceleration suitable for the selected gear or the direction of travel of the vehicle and an actual acceleration measured by the acceleration sensor. If the actual acceleration correlates with the target acceleration, it can be concluded that the acceleration sensor is providing readings that correspond to the direction of travel. In this case, the actual acceleration measured by the acceleration sensor can be used by the transmission control unit without any adjustment, particularly without sign correction. However, if it is determined that the target acceleration and the actual acceleration do not correlate, it can be concluded that the transmission's installation position is such that the readings provided by the acceleration sensor do not correspond to the direction of travel. In this case, the transmission control unit can use the actual acceleration measured by the acceleration sensor with an adjustment, particularly a sign correction.The invention therefore evaluates a measured acceleration of a vehicle and compares it with a target acceleration expected depending on a selected gear or direction of travel. Depending on whether the target acceleration and the actual acceleration correlate or not, the measured actual acceleration is adjusted, specifically by changing the sign, or not. This ensures that the measured values ​​provided by the acceleration sensor can be used correctly for transmission operation, regardless of the transmission's specific installation position in the drivetrain. It is no longer necessary to determine the transmission's installation position in the drivetrain during vehicle production and to configure the transmission control unit accordingly. Preferably, when the target acceleration and the actual acceleration correlate with each other when the transmission is in forward gear or in the direction of forward travel, and when the transmission is in reverse gear or in the direction of reverse travel, the actual acceleration measured by the acceleration sensor is used by the transmission control unit without adjustment for the control and / or regulation of the transmission. Preferably, if the target acceleration and the actual acceleration do not correlate when the transmission is in forward gear or in the direction of forward travel, and when the transmission is in reverse gear or in the direction of reverse travel, the actual acceleration measured by the acceleration sensor is used by the transmission control unit with adjustment for the control and / or regulation of the transmission. Preferably, if, with the transmission in forward gear or in the direction of forward travel, the target acceleration and the actual acceleration correlate according to a first alternative or do not correlate according to a second alternative, and if, with the transmission in reverse gear or in the direction of reverse travel, the target acceleration and the actual acceleration do not correlate according to the first alternative or do correlate according to the second alternative, the actual acceleration measured by the acceleration sensor is not used by the transmission control unit. If the correlation check between target and actual acceleration is performed in this manner for both forward and reverse driving, an additional plausibility check can be carried out. If the plausibility check is unsuccessful—for example, if the acceleration sensor provides readings with the same sign for both forward and reverse driving—it can be concluded that the acceleration sensor is not functioning correctly, and the transmission control unit will then preferably not use the actual acceleration measured by the acceleration sensor. The control unit according to the invention is defined in claim 6. Preferred embodiments are described in the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawings, without being limited thereto. Figure 1 shows a schematic diagram of a vehicle's powertrain to illustrate the invention; Figure 2 shows a signal flow diagram to further illustrate the invention. Figure 1 shows a highly schematic representation of a vehicle's powertrain. The powertrain in Figure 1 comprises a drive unit 1 and a transmission 2, with the transmission 2 being connected between the drive unit 1 and an output shaft 3. The transmission 2 converts rotational speeds and torques and provides the tractive force from the drive unit 1 to the output shaft 3. The transmission 2 is preferably an automatic or automated manual transmission in which gear changes are performed automatically. The operation of the drive unit 1 is controlled and / or regulated by an engine control unit 4, and the operation of the transmission 2 by a transmission control unit 5. As shown in Figure 1, the engine control unit 4 exchanges data with the drive unit 1, and the transmission control unit 5 exchanges data with the transmission 2. Furthermore, engine control unit 4 and transmission control unit 5 exchange data with each other. In practice, the transmission control unit 5 is typically permanently installed on the transmission 2. Fig. 1 further shows an acceleration sensor 6. The acceleration sensor 6 is typically permanently installed in the transmission control unit 5. The acceleration sensor 6 can provide values ​​of a measured actual acceleration, which the transmission control unit 5 can then use to control and / or regulate the operation of the transmission 2. A transmission 2 is installed in the drivetrain with a defined mounting position. For example, in a truck, the transmission input shaft of transmission 2 points forward in the direction of forward travel, whereas in a bus, an identical transmission is installed in the drivetrain such that its input shaft points rearward in the opposite direction of forward travel. In this case, the mounting position of the transmission control unit 5 and the acceleration sensor 6 in the drivetrain also differs. Depending on the mounting position of the acceleration sensor 6, it then provides measured values ​​of the actual acceleration, which either correlate with the direction of travel or do not correlate with the direction of travel.Up to now, it has been necessary to determine the installation position of the transmission in the drivetrain during the production of the vehicle and to parameterize the transmission control unit 5 accordingly, in order to ensure that the acceleration sensor 6 always provides measured values ​​of an actual acceleration that correlate with the respective direction of travel. The invention proposes a method by which it is automatically determined whether an actual acceleration measured by a sensor correlates with a target acceleration of the vehicle expected depending on a gear engaged in the transmission 2 or a direction of travel of the vehicle, wherein, depending on this correlation, either an adjustment or no adjustment is made to the actual acceleration provided by the acceleration sensor, so that the transmission control unit 5 is always provided with an actual acceleration that correlates with the direction of travel. According to the invention, depending on a gear engaged in the transmission 2, which may be a gear for a forward direction of travel or a gear for a reverse direction of travel, or depending on a direction of travel of the vehicle determined, for example, depending on a wheel speed or output speed, in particular a target sign of a target acceleration suitable for the respective gear or direction of travel is determined, which develops when the vehicle accelerates in this gear or direction of travel. During actual acceleration of the vehicle, the acceleration sensor 6 additionally determines an actual acceleration with an actual sign. The target sign is compared with the actual sign to check whether the target acceleration correlates with the actual acceleration, i.e., whether the actual acceleration measured by acceleration sensor 6 corresponds to the gear or the direction of travel. If the actual acceleration correlates with the target acceleration, i.e., if the actual acceleration corresponds to the direction of travel, the transmission control unit 5 can use the actual acceleration measured by the acceleration sensor 6 for control and / or regulation without any adjustment, in particular without sign correction. However, if it is determined that the actual acceleration does not correlate with the target acceleration, i.e., if the actual acceleration does not correspond to the direction of travel, an adjustment, in particular a sign correction, is performed on the actual acceleration measured by the acceleration sensor 6, so that the transmission control unit 5 can then use the actual acceleration measured by the acceleration sensor 6 with sign correction for the control and / or regulation of the transmission 5. During operation of the vehicle, it can therefore be automatically checked whether a measured actual acceleration correlates with the gear or the direction of travel.Depending on this, a sign adjustment can then be performed. It is not necessary to determine the installation position of the transmission during vehicle production and to parameterize the transmission control unit accordingly. Further details of a possible embodiment of the invention are described below with reference to the signal flow diagram of Fig. 2. Fig. 2 visualizes in a block 7 the beginning of the method according to the invention, which is initiated by starting the vehicle or by switching on an ignition. In a subsequent block 8, it is checked whether a gear is engaged in the transmission. If block 8 determines that no gear is engaged in transmission 2, the process jumps back to block 8 (a back-branch occurs). Conversely, if block 8 determines that a gear is engaged in transmission 2, the process branches to block 9. In block 9, a target acceleration is determined depending on the gear selected in transmission 2; in particular, a target sign is determined that corresponds to the selected gear. Thus, if a forward gear is selected in transmission 2, a positive sign is used as the target sign. Conversely, if a reverse gear is selected in transmission 2, a negative sign is typically used as the target sign. Starting from block 9, the process branches to block 10, where it is checked whether the vehicle is moving. If block 10 detects that the vehicle is not moving, the process branches back to block 10. Conversely, if block 10 detects that the vehicle is moving, the process branches to block 11. In block 11, the acceleration sensor then determines the actual acceleration with a corresponding sign. In a subsequent block 12, the actual sign of the actual acceleration recorded by the acceleration sensor 6 is compared with the target sign determined in block 9 of the target acceleration determined depending on the gear engaged in transmission 2, in order to determine a correlation factor depending on this comparison. If the target sign is found to correlate with the actual sign, a correlation factor greater than zero is set in Block 12. Conversely, if the target sign is found to not correlate with the actual sign, a correlation factor less than zero is determined in Block 12. In a subsequent step 13, it is then checked whether the correlation factor is greater or less than zero. If block 13 determines that the correlation factor is greater than zero, the process branches to block 14. If the correlation factor is greater than zero, meaning that the target sign of the target acceleration correlates with the actual sign of the actual acceleration, then in block 14, the transmission control unit 5 can use the actual acceleration measured by the acceleration sensor 6 without sign correction to control and / or regulate the transmission 2. If, however, block 13 detects that the correlation factor is less than zero, the process branches from block 13 to block 15, in which case the target sign does not correlate with the actual sign. Therefore, the actual acceleration measured by acceleration sensor 6 does not correlate with the direction of travel. In this case, a sign adjustment is then performed in block 15 for the actual acceleration from acceleration sensor 6, so that the transmission control unit 5 can use the value measured by the acceleration sensor with the sign adjustment for controlling and / or regulating the transmission. It may be possible to perform the above check both with a forward gear engaged or in the forward direction of travel, and with a reverse gear engaged or in the reverse direction of travel. In this case, it is specifically intended that if, with a forward gear engaged or in the forward direction of travel, and with a reverse gear engaged or in the reverse direction of travel, the target sign correlates with the actual sign, the actual acceleration measured by the acceleration sensor 6 is used by the transmission control unit 5 for the control and / or regulation of the transmission 2 without any sign adjustment. Then, if the target sign does not correlate with the actual sign when the transmission 2 is in forward gear or in the direction of forward travel, and when the transmission 2 is in reverse gear or in the direction of reverse travel, the actual acceleration measured by the acceleration sensor 6 is used by the transmission control unit 5 with sign adjustment to control and / or regulate the operation of the transmission 2. If, however, it is found that when the transmission is in forward gear or in the direction of forward travel, the target sign correlates with the actual sign, and when the transmission is in reverse gear or in the direction of reverse travel, the target sign does not correlate with the actual sign, i.e., that the acceleration sensor 6 provides actual accelerations with an identical actual sign in both forward and reverse travel, then it can be concluded that the acceleration sensor 6 is defective, and the actual acceleration measured by the acceleration sensor 6 is then not used by the control unit 5. Even if, when the transmission is in forward gear or in the direction of forward travel, the target sign does not correlate with the actual sign, and when the transmission is in reverse gear or in the direction of reverse travel, the target sign correlates with the actual sign, the measurement signal provided by the acceleration sensor 6 is not plausible, so that it is preferably not used by the transmission control unit 5. The invention therefore proposes to check whether the actual acceleration detected by an acceleration sensor correlates with the direction of travel of the vehicle, i.e., whether a measured actual acceleration corresponds to the direction of travel. If this is the case, i.e., if the actual acceleration matches the direction of travel, then no correction of the measured value provided by the acceleration sensor is necessary. If, however, it is determined that a measured actual acceleration does not match the direction of travel, the measured value provided by the acceleration sensor is corrected with a sign adjustment in order to then use it for the operation of the transmission. It should be noted again at this point that the actual acceleration is an acceleration measured by acceleration sensor 6. The target acceleration is an acceleration determined independently of acceleration sensor 6. The target acceleration is determined depending on the gear engaged in transmission 2 or on the vehicle's direction of travel. For this purpose, the signal from a drive switch or selector lever of the transmission, whose position specifies a gear and thus a direction of travel, can be evaluated. Alternatively, the output speed or wheel speed of the vehicle can be evaluated to determine the target acceleration. In this case, the target acceleration is the actual acceleration that develops. The term target acceleration refers to the target state.Target value of the acceleration, which is measured by the acceleration sensor 6 as actual acceleration. The invention further relates to a control unit 5 for operating a transmission 2 of a vehicle, wherein an acceleration sensor 6 is assigned to the transmission 2 in order to measure the acceleration of the vehicle. Depending on the gear engaged in the transmission 2 or the vehicle's direction of travel, the control unit determines a target acceleration appropriate to the gear or direction of travel, which develops when the vehicle accelerates in that gear or direction. The acceleration sensor 6 measures the actual acceleration. The control unit 5 determines whether the target acceleration and the actual acceleration correlate. If the target acceleration and the actual acceleration correlate, the actual acceleration measured by the acceleration sensor 6 can be used by the control unit 5 without adjustment.Then, if the target acceleration and the actual acceleration do not correlate, the actual acceleration measured by the acceleration sensor 6 can be used by the control unit 5 with adaptation. The control unit 5 according to the invention is configured to execute the method according to the invention. The control unit 5 according to the invention is preferably a transmission control unit. Reference sign 1 Drive unit 2 Transmission 3 Output 4 Engine control unit 5 Transmission control unit 6 Acceleration sensor 7 Block 8 Block 9 Block 10 Block 11 Block 12 Block 13 Block 14 Block

Claims

A method for operating a vehicle's drivetrain, wherein the drivetrain comprises a drive unit (1), an output (3), and a transmission (2) arranged in the drivetrain between the drive unit (1) and the output (3), wherein the transmission (2) is associated with a transmission control unit (5) for controlling and / or regulating the operation of the transmission (2), and an acceleration sensor (6) for measuring the vehicle's acceleration, characterized in that, depending on a gear engaged in the transmission (2) or depending on the vehicle's direction of travel, a target acceleration appropriate to the gear or direction of travel is determined, which develops when the vehicle accelerates in that gear or direction of travel, the acceleration sensor (6) determines an actual acceleration when the vehicle accelerates, and it is determined whether the target acceleration and the actual acceleration correlate, wherein, if so,If the target acceleration and the actual acceleration correlate, the actual acceleration measured by the acceleration sensor (6) can be used by the transmission control unit (5) without adaptation; if the target acceleration and the actual acceleration do not correlate, the actual acceleration measured by the acceleration sensor (6) can be used by the transmission control unit (5) with adaptation. The method according to claim 1, characterized in that, depending on the gear engaged in the transmission (2) or depending on the direction of travel of the vehicle, a target sign is determined for a target acceleration corresponding to the gear or direction of travel, which develops during acceleration of the vehicle; during acceleration of the vehicle, the acceleration sensor (6) determines an actual acceleration with an actual sign; the target sign is compared with the actual sign; if the target sign correlates with the actual sign, the actual acceleration measured by the acceleration sensor (6) can be used by the transmission control unit (5) without sign adjustment for controlling and / or regulating the transmission (2); if the target sign does not correlate with the actual sign, the actual acceleration measured by the acceleration sensor (6) can be used by the transmission control unit (5) with sign adjustment for controlling and / or regulating the transmission (2). Method according to claim 1 or 2, characterized in that when the forward gear is engaged or in the forward direction of travel and when the reverse gear is engaged or in the reverse direction of travel, the target acceleration and the actual acceleration correlate, the actual acceleration measured by the acceleration sensor is used by the transmission control unit without adjustment for the control and / or regulation of the transmission. Method according to one of claims 1 to 3, characterized in that when the forward gear is engaged or in the forward direction of travel and when the reverse gear is engaged or in the reverse direction of travel, the target acceleration and the actual acceleration do not correlate, the actual acceleration measured by the acceleration sensor is used by the transmission control unit with adaptation for the control and / or regulation of the transmission. Method according to one of claims 1 to 4, characterized in that, when the transmission is in forward gear or in the direction of forward travel, the target acceleration and the actual acceleration correlate according to a first alternative or do not correlate according to a second alternative, and when the transmission is in reverse gear or in the direction of reverse travel, the target acceleration and the actual acceleration do not correlate according to the first alternative or correlate according to the second alternative, the actual acceleration measured by the acceleration sensor is not used by the transmission control unit. Control unit (5) for operating a transmission (2) of a vehicle, wherein an acceleration sensor (6) is assigned to the transmission (2) in order to measure the acceleration of the vehicle, characterized in that the control unit determines a target acceleration appropriate to the gear or direction of travel, depending on a gear engaged in the transmission (2) or depending on a direction of travel of the vehicle, which develops when the vehicle accelerates in that gear or direction of travel, the acceleration sensor (6) determines an actual acceleration, the control unit determines whether the target acceleration and the actual acceleration correlate, wherein, if the target acceleration and the actual acceleration correlate, the actual acceleration measured by the acceleration sensor (6) can be used by the control unit (5) without adjustment, if the target acceleration and the actual acceleration do not correlate,The actual acceleration measured by the acceleration sensor (6) can be used by the control unit (5) with adjustment. Control unit according to claim 6, characterized in that the control unit determines a target sign of a target acceleration corresponding to the gear or direction of travel, which develops during acceleration of the vehicle, depending on the gear engaged in the transmission (2) or depending on the direction of travel of the vehicle; the control unit evaluates an actual acceleration measured by the acceleration sensor (5) with an actual sign during acceleration of the vehicle in such a way that it compares the target sign with the actual sign; if the target sign correlates with the actual sign, the actual acceleration measured by the acceleration sensor (6) can be used by the control unit (5) for the control and / or regulation of the transmission (2) without sign adjustment; if the target sign does not correlate with the actual sign,The actual acceleration measured by the acceleration sensor (6) can be used by the control unit (5) with sign adjustment for the control and / or regulation of the transmission (2). Control unit according to claim 6 or 7, characterized in that when the forward gear is engaged or in the forward direction of travel and when the reverse gear is engaged or in the reverse direction of travel, the target acceleration and the actual acceleration correlate, the control unit uses the actual acceleration measured by the acceleration sensor from the transmission control unit without adaptation for the control and / or regulation of the transmission. Control unit according to one of claims 6 to 8, characterized in that when the forward gear is engaged or in the forward direction of travel and when the reverse gear is engaged or in the reverse direction of travel, the target acceleration and the actual acceleration do not correlate, the control unit uses the actual acceleration measured by the acceleration sensor from the transmission control unit with adaptation for the control and / or regulation of the transmission. Control unit according to one of claims 6 to 9, characterized in that, when the transmission is in forward gear or in the direction of forward travel, the target acceleration and the actual acceleration correlate according to a first alternative or do not correlate according to a second alternative, and when the transmission is in reverse gear or in the direction of reverse travel, the target acceleration and the actual acceleration do not correlate according to the first alternative or correlate according to the second alternative, the control unit does not use the actual acceleration measured by the acceleration sensor for controlling and / or regulating the transmission.

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