Method for controlling gear shifting in a transmission of a motor vehicle drive train

Abstract

The invention relates to a method for controlling gear shifting in a transmission of a motor vehicle drive train, wherein the presence of a permanent brake device of the motor vehicle drive train is taken into account in the design of the gear shift strategy of the gear shifting. In order to design the gear shifting optimally in consideration of the permanent brake device, with the start of the permanent brake device, it is checked with which activation criterion the permanent brake device is introduced. Depending on the detected activation criterion, either the current load (x Ausl_Ret ) of the permanent brake device is checked and compared with the associated threshold value (x Grenz1 , x Grenz2 ), or the gear shifting of the motor vehicle transmission is directly prompted into the possible smallest gear. In the case of a comparison of the current load (x Ausl_Ret ) of the permanent brake device with the associated threshold value (x Grenz1 , x Grenz2 ), the gear shift strategy is adjusted when the threshold value (x Grenz1 , x Grenz2 ) is exceeded.

Description

Technical Field

[0001] This invention relates to a method for controlling gear shifting in a transmission of a motor vehicle drive system, wherein the operation of a continuous braking device in the motor vehicle drive system is taken into account in the design of the gear shifting strategy. Furthermore, this invention also relates to a controller, a computer program product, and a data carrier. Background Technology

[0002] In automated shifting transmissions and automatic transmissions, gear shifting is performed automatically, and the control of the corresponding gear shift occurs according to the selected shifting strategy. In part, the design of the corresponding shifting strategy also takes into account the operation of the vehicle's continuous braking system, so as to shift to an appropriate gear in the transmission during the continuous braking operation of the system.

[0003] DE 102 42 567A1 discloses a method for controlling gear shifting in a transmission of a motor vehicle drive system, wherein the shifting process should be designed to be appropriate and optimal for driving conditions, taking into account various parameters. Furthermore, the operation of the continuous braking device of the motor vehicle drive system is taken into consideration. Summary of the Invention

[0004] Based on the prior art described above, the objective of this invention is now to control the gear shifting in the transmission of a motor vehicle drive system during the operation of a continuous braking device, thereby achieving optimal participation of the continuous braking device for braking operation.

[0005] From a methodological perspective, this task is solved by starting with the preamble of claim 1 and combining it with its characteristic portion. The following dependent claims provide advantageous improvements to the invention. Furthermore, a controller capable of performing the method according to the invention is the subject of claims 8 and 9. Additionally, claim 10 relates to a computer program product, and claim 11 relates to a data carrier having the aforementioned computer program product.

[0006] According to the present invention, in a method for controlling gear shifting in a transmission of a motor vehicle drive system, the presence of continuous braking of the motor vehicle drive system is taken into account in the design of the gear shifting strategy. Therefore, the method according to the present invention is used to take into account the operation of the continuous braking device just in time in the design of the gear shifting strategy (according to which gear shifting in the motor vehicle transmission is performed).

[0007] In the context of this invention, a "continuous braking device" is a wear-free continuous brake located on the drive side of the transmission, such that the gear selection in the transmission, and consequently its gear ratio, affects the effective braking effect of the continuous braking device on the drive wheels of the vehicle. In the case of a continuous braking device located on the drive side of the transmission, the braking torque generated by the braking device is transmitted to the output side of the transmission and then to the driven wheels according to the currently selected gear shift. Within the scope of this invention, the continuous braking device can be a retarder located between the drive engine and the transmission, specifically a hydraulic retarder or an electric retarder. Therefore, this retarder is configured as the main retarder in the vehicle's drivetrain. Alternatively, the continuous braking device can also exist as a motor brake, implemented in the area before the internal combustion engine and located in the transmission. Specifically, this motor brake can be configured as an exhaust valve brake and / or a pressure relief brake.

[0008] This invention now includes the following technical teaching: upon initiation of continuous braking operation, the starting criterion for initiating continuous braking operation is first determined. Depending on the detected starting criterion, either the current load of the continuous braking system is checked and compared with a corresponding threshold, or the vehicle transmission is directly prompted to shift to the lowest possible gear. If the current load of the continuous braking system is compared with the corresponding threshold, the shifting strategy is adjusted if the threshold is exceeded. In other words, in the method according to the invention, upon detection of braking operation via the continuous braking system, the starting criterion for initiating braking operation is first determined, i.e., by what is the continuous braking system's operation initiated. A first or second measure is executed based on the presence of the starting criterion. In the first measure, the current load of the continuous braking system is queried and compared with a corresponding threshold, wherein, if the current load is detected to exceed the threshold, the shifting strategy designed for gear shifting in the transmission is adjusted. In the second measure, the transmission is prompted to shift to the gear that achieves the highest gear ratio of the transmission.

[0009] This control of gear shifting in the transmission has the advantage that the shifting strategy in the transmission can be matched to different operating conditions of the continuous braking system. On the one hand, during the operation of the continuous braking system, it can be checked whether the shifting strategy in the transmission needs to be adjusted considering the appropriate participation of the continuous braking system in the drive system by comparing the current load of the continuous braking system with its corresponding threshold. Here, this adjustment is made when it is identified that the current load of the continuous braking system exceeds the threshold. On the other hand, if the corresponding initiation criteria for the operation of the continuous braking system have been identified, it is also possible to directly switch to the smallest possible gear in the transmission to achieve the maximum gear ratio of the braking torque of the continuous braking system. Therefore, the shifting strategy in the transmission can be adjusted depending on the way the continuous braking system is introduced.

[0010] When controlling gear shifting according to DE 102 42 567A1, although the operation of the continuous braking device is also taken into account in the design of the shift strategy, i.e., the current stage and / or the output torque of the continuous braking device are considered, it is unclear how to specifically match the shift strategy to the operation of the continuous braking device.

[0011] In the context of this invention, the threshold is specifically defined as a fixed, preset value, and the current load of the continuous braking device is compared with this threshold based on the detected initiation criterion. Different thresholds can also be stored for different, possible initiation criteria. Which of the stored thresholds the current load of the continuous braking device is compared with depends on the separately detected initiation criteria for the start of operation of the continuous braking device.

[0012] According to one embodiment of the present invention, in order to perform an adjustment shifting strategy when a threshold is exceeded, a reference parameter is determined from a stored comprehensive characteristic curve based on the current load of the continuous braking device and the currently selected operating level of the continuous braking device, wherein the reference parameter is further used to adjust the shifting strategy. Therefore, within the scope of this embodiment, when it has been detected that the current load of the continuous braking device exceeds its respective threshold, a reference parameter is obtained for adjusting the shifting strategy, and for this purpose, the stored comprehensive characteristic curve is used. By adjusting the shifting strategy according to the reference parameter, which depends on the current load of the continuous braking device and the currently selected operating level, supported by the comprehensive characteristic curve, a simple and simultaneously reliable adjustment of the shifting strategy can be achieved.

[0013] In the improved embodiment described above, adjustment parameters are obtained using reference parameters and the current operating degree of the vehicle's service brakes, based on a stored additional comprehensive characteristic curve. The shift characteristic curve for gear switching is then designed based on these adjustment parameters. Additionally, considering the current operating degree of the vehicle's service brakes, it is possible to detect states where the shifting strategy in the transmission is altered due to the involvement of the continuous braking device and the current load on the service brakes. Here, for example, if the current load on the continuous braking device is detected to be low (reflected by the reference parameters), but simultaneously there is a high current operating degree of the service brakes, then the load on the service brakes can be reduced by specifically altering the shifting strategy and the resulting higher gear ratio of the continuous braking device's braking torque.

[0014] Specifically, the shifting strategy can be adjusted by selecting a shifting characteristic curve from a stored collection of different characteristic curves based on adjustment parameters. Alternatively or supplemented here, the shifting characteristic curve is shifted according to the adjustment parameters. Particularly preferably, both measures can be implemented together, thereby first selecting a shifting characteristic curve from the stored collection of different characteristic curves and then shifting the shifting characteristic curve when necessary. Advantageously, this allows the shifting strategy to be easily matched to the operation of the continuous braking device. Here, the adjustment is particularly made such that, with the increase of the adjustment parameters, a higher downshift speed for gear shifting is exhibited.

[0015] According to one design possibility of the invention, as a starting criterion, it is checked whether the operation of the continuous braking device is initiated due to a request from the vehicle driver. Here, in the affirmative case, i.e., if the reason for operating the continuous braking device is a corresponding request from the vehicle driver, then the operating level of the continuous braking device selected by the vehicle driver is further queried. If the highest operating level is detected, the transmission is prompted to shift to the lowest possible gear; otherwise, a comparison of the current load of the continuous braking device with its corresponding threshold is performed. This has the advantage that the shifting strategy is thus adjusted based on the braking power desired by the vehicle driver and achieved through the continuous braking device. If the vehicle driver selects the highest operating level of the continuous braking device and thereby signals that he wants to achieve maximum possible braking through the continuous braking device, then the transmission is directly shifted to the lowest possible gear without comparing the current load with its corresponding threshold, so as to achieve the highest possible gear ratio for the braking torque of the continuous braking device based on the selected maximum possible gear ratio of the transmission. If the vehicle driver selects a lower operating level than the highest operating level, then the previously described adjustment of the shifting strategy for exceeding the threshold is performed by comparing the load of the continuous braking device with its corresponding threshold. This allows us to consider the different requirements and desires of vehicle drivers.

[0016] Another advantageous embodiment of the invention involves checking, as a triggering criterion, whether the operation of the continuous braking device is initiated due to a request from a driver assistance system, wherein, if yes, a comparison is performed between the current load of the continuous braking device and its corresponding threshold. Therefore, if the operation of the continuous braking device is initiated not by the vehicle driver but by the driver assistance system, then adjustments to the shifting strategy can also be made within the scope of the method according to the invention. The driver assistance system may here be adaptive cruise control (ACC), adaptive speed-limited cruise (ASL), or a speed limiter. Particularly preferably, the triggering criterion for operating the continuous braking device via the driver assistance system is checked together with the previously described triggering criterion for operation by the vehicle driver, in order to appropriately address different possible triggering criteria for the operation of the continuous braking device. Particularly preferably, upon detecting a triggering of the operation of the continuous braking device via the driver assistance system, a comparison with a threshold, which differs from the threshold in the case of triggering by the vehicle driver, is then performed. Furthermore, when the threshold is exceeded and during further adjustment of the shifting strategy, the currently selected operating level of the continuous braking device is set to zero and thus determined in the corresponding comprehensive characteristic curve.

[0017] In an improved embodiment of the invention, when comparing the current load of the continuous braking device with a threshold value, the shift strategy is not adjusted if the load is below the threshold. Accordingly, gear shifting in the transmission is subsequently performed according to the adopted shift strategy.

[0018] The subject of this invention is also a controller, preferably a transmission controller for a gearbox. Here, the controller is configured to consider the operation of the continuous braking device when designing the shifting strategy for gear shifting in the transmission, and to check, upon the commencement of continuous braking operation, what initiation criterion led to its initiation. The controller relies on the detected initiation criterion to check the current load of the continuous braking device and compare it with a corresponding threshold, wherein, alternatively, the controller initiates a gear shift to the lowest possible gear based on the detected initiation criterion. Furthermore, the controller is configured to adjust the shifting strategy if the current load of the continuous braking device exceeds the corresponding threshold when the comparison shows a match. Advantageously, the method according to the invention can thus be implemented in the drivetrain region by having the controller perform the necessary steps. Particularly preferably, the controller is also configured to perform other previously described variations of the method.

[0019] The method according to the invention can also be embodied as a computer program product, which, when run on a processor (e.g., the processor of the aforementioned controller), instructs the processor in a software manner to perform the method steps to which the subject matter of the invention pertains. In this case, a computer-readable medium also falls under the subject matter of the invention, on which the aforementioned computer program product is retrievably stored.

[0020] This invention is not limited to the combinations of features described in the parallel or dependent claims. Furthermore, there is the possibility of combining various features with each other, provided they are derived from the claims, the following description of preferred embodiments of the invention, or directly from the drawings. References to the drawings by the use of reference numerals in the claims should not limit the scope of the claims. Attached Figure Description

[0021] Advantageous embodiments of the invention, which will be described subsequently, are illustrated in the accompanying drawings. Wherein:

[0022] Figure 1 A schematic diagram of a motor vehicle drive system is shown; and

[0023] Figure 2 The invention illustrates a method for... Figure 1 A flowchart of a method for controlling gear shifting in the transmission of a motor vehicle drive system. Detailed Implementation

[0024] from Figure 1 A schematic diagram of a motor vehicle drive system 1 is provided, wherein the motor vehicle drive system is particularly a drive system for commercial vehicles, such as trucks. The motor vehicle drive system 1 includes a drive motor 2, which is implemented as an internal combustion engine, and is connected to the input end of a subsequent transmission 4 via an intermediate torsional damper 3 on the output side. The torsional damper 3 and a starting element, which may be located on the input side of the transmission 4, are integrated together into the housing of the transmission 4.

[0025] In the current configuration, transmission 4 is implemented as an automated shift transmission or automatic transmission, in which gear shifting is performed automatically. For this purpose, a controller for controlling gear shifting in transmission 4 is assigned to transmission 4. On the output side, transmission 4 is connected to axle differential 6, through which the drive power of drive motor 2, converted and transmitted via transmission 4, is distributed to the drive wheels 7 and 8 of the drive axle 9 of the vehicle.

[0026] Between the drive unit 2 and the transmission 4, the vehicle drive system 1 also includes a continuous braking device 10 in the form of a retarder 11, preferably constructed as a hydraulic retarder, and connected to the output side of the drive unit 2 in a rotationally resistant manner. Here, the retarder 11 is used to feed braking torque during braking operation within the vehicle drive system 1 to support the service brake 12, which brakes the drive wheels 7 and 8 of the vehicle, as well as other wheels (not shown further). Different handling levels can be generated in the retarder 11, resulting in different braking torques, which are transmitted to the drive wheels 7 and 8 of the drive axle 9 via the subsequent transmission 4. The corresponding handling level is set by the controller 13 of the retarder 11, either based on the selection made by the driver on the input element 14 or based on a preset by a driver assistance system. Here, the driver assistance system can be adaptive cruise control (ACC), adaptive speed-limited cruise control (ASL), or a speed limiter.

[0027] During the braking operation of retarder 11, the controller 5 of transmission 4 checks whether the shifting strategy in the gear shifting design of transmission 4 should be adjusted to achieve optimal engagement of retarder 11. This check is performed according to the method according to the invention, the flowchart of which is shown in... Figure 2 As shown in the image.

[0028] At the start of the method according to the invention, in the first step S1, it is first checked whether the braking operation of the retarder 11 has been initiated and is still effective. If this is not the case, the method is terminated; otherwise, step S2 is executed, in which it is checked whether there is a request from the vehicle driver as a starting criterion for the operation of the retarder 11. If this is not the case, the process switches to step S3, in which the preset of the driver assistance system is identified as the starting criterion for the operation of the retarder 11.

[0029] Conversely, if the operation of retarder 11 is detected in step S2 based on a preset setting by the vehicle driver, then in step S4, after a preset time, it is queried which control level of retarder 11 the vehicle driver selected on input element 14. In the subsequent step S5, it is checked whether the control level is the highest control level, wherein if yes, step S6 is executed; otherwise, step S7 is executed after step S5.

[0030] In step S6, controller 5 introduces a downshift to the lowest gear in transmission 4, i.e., the gear with the highest gear ratio. Then it jumps back to step S1 and thus rechecks whether retarder 11 is still operating and subsequently checks whether the vehicle driver may have changed their selection regarding the steering level.

[0031] In step S7, the current load x of the retarder 11 is queried. Ausl_Ret In particular, the load percentage of the retarder 11 relative to the maximum achievable braking power is detected. Using this detected current load, in step S8, an action is performed with respect to the threshold x. Grenz1 The threshold is fixed and stored after comparison. If in step S8, the current load x of the retarder 11... Ausl_Ret Exceeding the threshold x Grenz1 If the current shift strategy in the transmission 4 is maintained in step S10, then the process switches to step S9; otherwise, the current shift strategy in the transmission 4 is maintained in step S10 and the process returns to step S1.

[0032] In step S9, based on the current load x of the retarder 11 Ausl_Ret and the selected control level a Bet Determine the reference parameter z from the comprehensive characteristic curve. ref Then proceed to step S11, in which the reference parameter z from step S9 is used... ref The current operating degree a of the service brake 12 Betrbrems Determine the adjustment parameter z from another comprehensive characteristic curve. Stell For this purpose, the current operating degree a of the service brake 12 is known in advance. Betrbrems Then, in step S12, according to the adjustment parameter z StellThe shifting strategy in the transmission 4 is adjusted by the controller 5 in the following way: the controller 5 adjusts the shifting strategy according to the adjustment parameter z. Stell The shift characteristic curve is selected from different stored characteristic curves, and its shifting is performed as necessary. Here, the shift characteristic curve is selected and its shifting is designed as needed, so that it adjusts according to the parameter z. Stell The increase in speed results in a higher downshift speed in transmission 4. After step S12, the process jumps back to step S1 and thus begins to recheck whether the retarder 11 is still operating and whether this may have changed.

[0033] Instead, step S3 is performed after step S2, in which the operation of retarder 11 requested by the driver assistance system has been identified as the starting criterion, and therefore the process then switches to step S13, in which the current load x of retarder 11 is detected. Ausl_Ret The same applies in step S7. In step S14, the current load x of the retarder 11 is used. Ausl_Ret To perform with threshold x Grenz2 The comparison shows that this threshold is different from the threshold x in step S8. Grenz1 In step S14, if the current load x of the retarder 11... Ausl_Ret Below the threshold x Grenz2 Then proceed to step S10, where the current load x of the retarder 11 is... Ausl_Ret Exceeding the threshold x Grenz2 Then, switch to step S9. However, here, in order to determine the reference parameter z from the comprehensive characteristic curve... ref The currently selected control level a of retarder 11 Bet It is set to zero. After step S9 or S10, the process continues in the manner previously described.

[0034] By means of the measures according to the invention, the design of gear shifting in the transmission can be optimally matched with the operation of the continuous braking device.

[0035] List of reference numerals

[0036] 1. Motor vehicle drive system

[0037] 2. Drive unit

[0038] 3 Torsional vibration damper

[0039] 4. Transmission

[0040] 5 Controllers

[0041] 6. Axle differential

[0042] 7 drive wheels

[0043] 8 drive wheels

[0044] 9 drive axles

[0045] 10. Continuous braking device

[0046] 11. Retarder

[0047] 12 Service brakes

[0048] 13 Control transpose

[0049] 14 Input Elements

[0050] x Ausl_Ret load

[0051] x Grenz1 threshold

[0052] x Grenz2 threshold

[0053] a Bet control level

[0054] z ref Reference parameters

[0055] z Stell Adjust parameters

[0056] a Betrbrems Operating degree of service brake

[0057] Steps S1 to S14

Claims

1. Method for controlling the switching of gears in a transmission (4) of a motor vehicle drive train (1), wherein In the design of a gear shift strategy for gear shifting, the presence of the operation of a continuous brake device (10) of the motor vehicle drive train is taken into account, characterized in that, with the start of the operation of the continuous brake device (10), it is checked with which starting criterion the operation of the continuous brake device (10) was introduced, depending on the detected starting criterion, either the current load (x Ausl_Ret ) of the continuous brake device (10) is checked and compared with the associated threshold value (x Grenz1 , x Grenz2 ), or the gear shift of the motor vehicle transmission (4) is directly prompted into the possible smallest gear, and in the case of a comparison of the current load (x Ausl_Ret ) of the continuous brake device (10) with the associated threshold value (x Grenz1 , x Grenz2 ), the gear shift strategy is adjusted when the threshold value (x Grenz1 , x Grenz2 ) is exceeded.

2. The method of claim 1, wherein, For adjusting the shift strategy, a reference parameter (z ref ) is determined from a stored overall characteristic curve depending on a current load (x Ausl_Ret ) of the continuous braking device (10) and a current selected actuation level (a Bet ) of the continuous braking device (10), wherein the reference parameter (z ref ) is further used for adjusting the shift strategy.

3. The method of claim 2, wherein, using the reference parameter (z ref ) and a current degree of actuation (a Betrbrems ) of a service brake (12) of the motor vehicle, a regulation parameter (z Stell ) is ascertained from a stored further overall characteristic map, from which a shift characteristic map for the gear shift is designed.

4. The method of claim 3, wherein, The shift characteristic curve is selected from the stored different characteristic curves in dependence on the regulation parameter (z Stell ) 5. The method of claim 3, wherein, According to the adjustment parameter (z Stell ) shift characteristic curve.

6. The method according to any one of claims 1 to 5, characterized in that, As a starting criterion, it is checked whether the actuation of the continuous brake device (10) is initiated as a result of a request by the vehicle driver, wherein, in the positive case, it is also queried whether the actuation level of the continuous brake device (10) is selected here by the vehicle driver (a Bet ), and wherein, in the case of detection of the selection of the highest actuation level by the vehicle driver, the gear of the transmission (4) is prompted to switch to the possible smallest gear, otherwise a comparison of the current load (x Ausl_Ret ) of the continuous brake device (10) with the associated threshold value (x Grenz1 , x Grenz2 ) is carried out.

7. The method according to any one of claims 1 to 5, characterized in that, As a starting criterion, it is checked whether the actuation of the hold brake device (10) is initiated as a result of a request by a driver assistance system, wherein, in the positive case, a comparison of the current load (x Ausl_Ret ) of the hold brake device (10) with the associated threshold value (x Grenz1 , x Grenz2 ) is carried out.

8. Controller (5), which is set up to take into account the operation of a permanent brake device (10) when designing a shift strategy for gear shifting in a transmission (4) and, in conjunction with the start of the operation of the permanent brake device (10), checks which start criterion the operation of the permanent brake device (10) was introduced with, wherein Depending on the detected starting criterion, the controller (5) either checks the current load (x Ausl_Ret ) of the continuous brake device (10) and compares it to the associated threshold value (x Grenz1 , x Grenz2 ), or introduces a gear shift of the transmission (4) to the possible smallest gear, and wherein the controller (5) is configured to adjust the shift strategy in the event of an exceeding of the threshold value (x Grenz1 , x Grenz2 ) in the case of a comparison of the current load (x Ausl_Ret ) of the continuous brake device (10) with the associated threshold value (x Grenz1 , x Grenz2 ).

9. The controller (5) according to claim 8, which is further set up for carrying out the method according to any one of claims 2 to 7.

10. A controller (5) according to claim 8 or 9, characterized in that The controller (5) is a transmission controller.

11. Computer program product for a controller (5) according to any one of claims 8 to 10, by which the method according to any one of claims 1 to 7 is executable, wherein, The routines for controlling the gear shift in the transmission (4) are implemented by corresponding control commands stored in the software.

12. Data carrier having a computer program product according to claim 11.

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