Method for operating a motor vehicle and transmission control device

Abstract

Method for operating a motor vehicle with a drive unit (1), a transmission (2) connected between the drive unit (1) and an output (14), the transmission having several switching elements (9, 10, 11, 12, 13) and a parking lock (15), wherein in each traction-transmitting gear of the transmission (2) a first number of switching elements are closed and a second number of switching elements are open, and wherein in a parking position of the transmission (2) the parking lock (15) is engaged, where the gearbox is in the park position with the drive unit running a first switching element, which is closed in a starting gear for forward travel and in a starting gear for reverse travel and is hydraulically coupled to the parking lock (15), is controlled to close in such a way that a torque less than a maximum torque can be transmitted from it and the parking lock (15) remains engaged, a second switching element, which is closed in the starting gear for forward travel and in the starting gear for reverse travel, is controlled to close in such a way that the maximum torque can be transmitted from it, Then, if the inclination in which the motor vehicle is currently positioned is greater than or equal to a limit value, at least two further switching elements are activated for closing, wherein a third switching element is used to form a starting gear specified by a driving strategy and a fourth switching element is not used to form the starting gear specified by the driving strategy. where, when the transmission (2) is to leave the park position in accordance with a driver request, the first switching element is controlled to close in such a way that the maximum torque can be transmitted from it and the parking lock (15) is engaged, whereupon, when the parking lock (15) is engaged, the previously closed switching elements are controlled in such a way that a transmission switching state corresponds to the driver's request.

Description

[0001] The invention relates to a method for operating a motor vehicle. Furthermore, the invention relates to a transmission control device for carrying out the method.

[0002] Motor vehicles with a drive unit and a transmission interposed between the drive unit and an output shaft, comprising several shift elements and a parking lock, are familiar to those skilled in the art. EP 2 104 794 B1 discloses such a motor vehicle with a drive unit, an output shaft, and a transmission, wherein the transmission comprises shift elements for providing six forward gears and one reverse gear, as well as a parking lock. In each engaged, power-transmitting gear, a first number of shift elements are closed and a second number of shift elements are open. When a park position is selected for the transmission, the transmission's parking lock is engaged.

[0003] From EP 2 104 794 B1, a method for operating such a motor vehicle is known, namely for engaging the parking lock while reducing or preventing a so-called relief shock acting on the output shaft when the parking lock is engaged. For this purpose, when the inclination exceeds a threshold value, switching elements are brought into a defined slip, depending on the sign of the inclination, so that the output shaft rotates in the opposite direction to its tension direction when the parking lock is active. In a second process step, at least one switching element that can be engaged for frictionally locking the output shaft is additionally closed. In a third process step, the parking lock is engaged. In a fourth process step, at least one switching element that was closed for frictionally locking the output shaft is reopened, so that the output shaft can be driven according to the driver's command.

[0004] Another method for operating a motor vehicle, which can reduce or avoid a relief shock when the parking lock is deployed, is known from DE 102 55 714 B4.

[0005] Although existing methods already allow for the deployment of a parking lock while reducing the so-called relief shock, there is a need to make the deployment of the parking lock even more convenient. Based on this, the invention aims to provide a novel method for operating a motor vehicle with a transmission featuring a parking lock and a transmission control device for carrying out this method.

[0006] This problem is solved by a method according to claim 1 and a transmission control device according to claim 8. According to this method, in a park position of the transmission with the drive unit running, a first switching element, which is closed in a starting gear for forward travel and in a starting gear for reverse travel and is hydraulically coupled to the parking lock, is actuated to close such that a torque less than a maximum torque can be transmitted from it and the parking lock remains engaged, wherein a second switching element, which is closed in the starting gear for forward travel and in the starting gear for reverse travel, is actuated to close such that the maximum torque can be transmitted from it.When the vehicle's current incline exceeds or equals a certain threshold, at least two additional shift elements are activated to close. A third shift element engages a starting gear specified by a driving strategy, while a fourth shift element does not engage the starting gear specified by the driving strategy. When the transmission is to leave the park position at the driver's request, the first shift element is activated to close, enabling it to transmit maximum torque and disengaging the parking lock. Once the parking lock is engaged, the previously closed shift elements are activated to select a transmission shift state corresponding to the driver's request. This allows for a particularly smooth parking lock operation, reducing or eliminating the need for a sudden release shock.

[0007] According to an advantageous embodiment of the invention, the at least two additional switching elements, which are closed when the inclination of the vehicle is greater than or equal to a limit value, are selected depending on the vehicle's inclination direction, i.e., whether the vehicle is inclined downhill or uphill. Preferably, the closing sequence of these at least two additional switching elements is also selected depending on the vehicle's inclination direction. This allows for a particularly convenient design of the parking lock.

[0008] According to an advantageous embodiment of the invention, when the driver requests a neutral position for the transmission, the first and second shift elements are held closed after the parking lock is disengaged, and the other previously closed shift elements are opened. Then, when the driver requests a reverse or, alternatively, a forward position for the transmission, the first and second shift elements are held closed after the parking lock is disengaged, and of the other previously closed shift elements, the shift element(s) that are not involved in the starting gear for reverse or, alternatively, for forward travel are opened. Thus, the driver's request can be quickly accommodated after the parking lock is disengaged.

[0009] 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 drawing, without being limited thereto. The drawing shows: Fig. 1 a schematic representation of a motor vehicle drive train with an automatic transmission; Fig. 2 a shift matrix of the automatic transmission; Fig. 3 a block diagram of the method according to the invention; Fig. 4 a time diagram to illustrate a first variant of the method according to the invention; Fig. 5 a time diagram to illustrate a second variant of the method according to the invention; Fig. 6 a time diagram to illustrate a third variant of the method according to the invention; Fig. 7 a time diagram to illustrate a fourth variant of the method according to the invention; Fig. 8 a time diagram to illustrate a fifth variant of the method according to the invention; Fig. 9 a time diagram to illustrate a sixth variant of the method according to the invention; Fig. 10 a time diagram to illustrate a seventh variant of the method according to the invention; Fig. 11 a time diagram to illustrate an eighth variant of the method according to the invention; Fig. 12 a time diagram to illustrate a ninth variant of the method according to the invention; Fig. 13 a time diagram to illustrate a tenth variant of the method according to the invention; Fig. 14 a time diagram to illustrate an eleventh variant of the method according to the invention; Fig. 15 a time diagram to illustrate a twelfth variant of the method according to the invention; Fig. 16 a time diagram to illustrate a thirteenth variant of the method according to the invention; Fig. 17 a time diagram to illustrate a fourteenth variant of the method according to the invention; Fig. 18 a time diagram to illustrate a fifteenth variant of the method according to the invention; and Fig. 19 a time diagram to illustrate a sixteenth variant of the method according to the invention.

[0010] The invention relates to a method for operating a motor vehicle and a control device for carrying out the method.

[0011] Fig. Figure 1 shows a highly schematic representation of a powertrain diagram of a motor vehicle in which the method according to the invention is preferably used. The powertrain of the Fig. 1 comprises a drive unit 1, a transmission 2 and an output 14, wherein the transmission 2 is designed as an automatic transmission and is connected between the drive unit 1 and the output 14.

[0012] The transmission 2 has several gear sets 3, 4, 5, and 6, as well as several switching elements 9, 10, 11, 12, and 13 that interact with these gear sets. Switching elements 9 and 10 are also referred to as switching elements A and B, while switching elements 11, 12, and 13 are also referred to as switching elements C, D, and E. Switching elements A and B, as well as switching elements C, D, and E, are friction-based switching elements; specifically, switching elements A and B are brakes, and switching elements C, D, and E are clutches.

[0013] Fig. Figure 2 shows a shift matrix of gearbox 2 of the Fig. 1. Fig. 2 can be seen that with the gearbox 2 the Fig. 1. A total of eight forward gears and one reverse gear can be provided. In each of these traction-transmitting gears, a first number of switching elements, namely three switching elements, are closed, whereas a second number of switching elements, namely two switching elements, are open in each traction-transmitting gear. The switching elements that are closed in the respective traction-transmitting gear are in Fig. 2 is marked by a dot. Thus, in forward gear 1, switching elements A, B, and C are closed, and in forward gear 2, switching elements A, B, and E are closed. In reverse gear, switching elements A, B, and D are closed. The switching elements closed in forward gears 3, 4, 5, 6, 7, and 8 also follow from the switching matrix of the Fig. 2. Forward gears 1 and 2 are possible starting gears for forward travel. The reverse gear is a starting gear for reversing. The shift matrix of the Fig. 2 can be seen that in these starting gears, i.e. in forward gears 1 and 2 as well as in reverse gear R, the switching elements A and B are closed.

[0014] Fig. Figure 1 shows that the drive unit 1 is coupled to a transmission input shaft 7 and the output 14 to a transmission output shaft 8. Depending on the gear selected in the transmission 2, the transmission 2 converts speeds and torques, thus providing the tractive force of the drive unit 1 at the output 14.

[0015] Fig. Figure 1 further shows a parking lock 15, which is part of the gearbox 2. The parking lock 15 can be engaged via a hydraulic cylinder 17 and a solenoid valve 16. In the parking position P of the gearbox 2, the parking lock 15 is engaged. The parking lock 15 is preferably engaged mechanically.

[0016] The invention presented here relates to details for operating a motor vehicle which, when transferring the transmission 2 from the parking position P, allows the parking lock 15 of the transmission 2 to be set comfortably, namely by reducing or avoiding a so-called relief shock.

[0017] According to the present invention, in a park position of the transmission 2 with the drive unit 1 running, several switching elements are actuated to close, namely such that a first switching element, which is closed in the two starting gears for forward travel and in the starting gear for reverse travel, and which is hydraulically operatively connected or hydraulically coupled to the parking lock 15, is actuated to close such that a torque less than a maximum torque can be transmitted from it, with the parking lock 15 remaining engaged. A second switching element of the transmission 2, which is also closed in the starting gears for forward travel and in the starting gear for reverse travel, is actuated to close such that the maximum torque can be transmitted from it.

[0018] Then, if the inclination in which the motor vehicle is currently positioned is greater than or corresponds to a limit value, at least two further switching elements in the park position P of the transmission 2 are activated to close while the drive unit 1 is running.

[0019] In this case, a third switching element controlled for closing serves to form a starting gear specified by a driving strategy, and a fourth switching element does not serve to form the starting gear specified by the driving strategy.

[0020] Then, when the transmission 2 is to leave the parking position P according to a driver request, the first switching element of the transmission 2 is controlled to close in such a way that the maximum torque can be transmitted by it and the parking lock 15 is engaged.

[0021] Then, when the parking lock 15 is engaged, the previously closed switching elements of the transmission 2 are controlled in such a way that a transmission shift state corresponds to the driver's request.

[0022] Further details of the invention are described below with reference to the signal flow diagram of the Fig. 3 and the exemplary time diagrams of the Fig. 4 to 19 described. In Fig. Figures 4 to 19 show time-dependent curve progressions 18, 19, 20, 21, 22, 23, 24, 25, 26 and 27.

[0023] The temporal curve profile 18 corresponds to a driver request specified on a gear selector lever, whereby the driver request on the gear selector lever can be, for example, a park position P, a position D for forward travel, a position R for reverse travel and a position N for a neutral position of the transmission 2.

[0024] The time-dependent curve 19 corresponds to a rotational speed of the drive unit 1.

[0025] A time-dependent curve 20 corresponds to a rotational speed of a transmission input shaft, where in Fig. 4 to 19 assumes that a converter is connected between the drive unit 1 and the transmission input shaft 7, whereby the curve 20 corresponds to the turbine speed of the converter.

[0026] The time-based curves 21, 22, 23, 24, and 27 illustrate pressure control for switching elements of transmission 2. Curve 21 illustrates the pressure control of switching element A. Curve 22 visualizes the pressure control of switching element B. Curve 23 visualizes the pressure control of switching element D. Curve 24 visualizes a pressure control of switching element E. Curve 27 visualizes a pressure control of switching element C. Curve 25 visualizes the control of the solenoid valve 16 of the parking lock 15. Curve 26 shows the state of the parking lock, where state I corresponds to an engaged parking lock 15 and state II to a disengaged parking lock 15.

[0027] Fig. Figures 4 to 19 each show different scenarios of the invention, namely scenarios in which the motor vehicle, with respect to forward travel, is either uphill or downhill on a slope, namely situations in which the driver's wish changes from the parking position P of the transmission, either to a transmission position D for forward travel or a transmission position R for reverse travel or to a transmission position N for a neutral position, wherein in the case of a transmission position D for forward travel a further distinction is made as to whether the first forward gear or the second forward gear is desired as the starting gear for the subsequent start in forward travel.

[0028] First, with reference to Fig. 3 and Fig. 11 describes the scenario of the invention in which a motor vehicle is parked on a slope with an incline relative to forward travel uphill, i.e. with the front part of the motor vehicle pointing upwards, and in which, starting from the parking position P, the transmission position D is changed for forward travel, and a start-up in forward gear 1 is to take place.

[0029] In Fig. 11, before time t0 according to signal sequence 18, a gear selector position P is selected for a parking position of the transmission; according to signal sequence 26, the parking lock 15 assumes state I for an engaged parking lock.

[0030] Before time t0, the drive unit 1 is started according to signal waveform 19. According to signal waveforms 19 and 20, the rotational speeds of the drive unit 1 and the transmission input shaft 7 increase, the rotational speed of the transmission input shaft 7 preferably corresponding to the turbine speed of a converter (not shown).

[0031] Starting at time t0, i.e. with parking lock 15 engaged and in the parking position P of the transmission 2, several switching elements of the transmission 2 are activated to close.

[0032] In this process, a first switching element is activated according to the signal sequence 21, specifically in the transmission of the Fig. 1 and Fig. 2 the switching element A, controlled to close, which is closed in both the two starting gears 1 and 2 for forward travel as well as in starting gear R for reverse travel, and which is hydraulically coupled to the parking lock 15 and is therefore hydraulically in operative connection.

[0033] In this process, the first switching element, i.e., for the transmission of the Fig. 1 and Fig. 2 the switching element A, is actuated with such pressure to close that a torque can be transmitted from the first switching element which is less than a maximum transmissible torque, which is referred to as the maximum torque, and at which the parking lock 15 remains engaged.

[0034] Likewise, when the parking lock 15 is engaged and the transmission 2 is in parking position P, a second switching element of the transmission 2, which is also closed in the two starting gears 1 and 2 for forward travel and in starting gear R for reverse travel, is activated to close, in accordance with Fig. 11 for the gearbox of the Fig. 1 and Fig. 2 according to the signal waveform 22 the switching element B.

[0035] In this process, the second switching element, i.e., for the transmission of the Fig. 1 and Fig. 2, the switching element B is actuated with a pressure such that the maximum torque can be transmitted from it.

[0036] The above process steps, namely the activation of the first switching element and the second switching element in park position P of the transmission 2 with the drive unit 1 running, are shown in the block diagram of the Fig. 3 is visualized by blocks 28, 29, and 30. Block 28 shows the park position P engaged in transmission 2 after starting the drive unit 1, while block 29 visualizes the pressure control of the first shift element, i.e., in transmission 2, the Fig. 1 and Fig. 2 the control of switching element A, and block 30 the control of the second switching element, i.e., in the case of transmission 2 the Fig. 1 and Fig. 2 the actuation of the switching element B, as described above, with the pressures such that a torque less than the maximum torque can be transmitted from the first switching element and the parking lock 15 remains engaged, whereas the second switching element is actuated with a pressure such that a maximum torque can be transmitted from it.

[0037] In block 31, it is checked whether the inclination, i.e., the magnitude of the inclination at which the vehicle is currently positioned, is greater than or equal to a limit value. If this is not the case, i.e., if the magnitude of the inclination at which the vehicle is positioned is less than a predefined limit value, the process branches from block 31 to block 32, and in block 32 the parking lock 15 is then deployed conventionally.

[0038] If, however, it is determined in block 31 that the magnitude of the inclination in which the motor vehicle is standing is greater than or equal to the limit value, then starting from block 31, the system branches to block 33 and the parking position of the transmission 2 and the parking lock 15 are set as described below.

[0039] In a subsequent block 34, it is checked whether, if the magnitude of the incline in which the vehicle is currently positioned is greater than or equal to a limit value, the vehicle is inclined uphill or downhill. If inclined uphill, the vehicle is positioned with its front end pointing upwards. If inclined downhill, the vehicle is positioned with its front end pointing downwards.

[0040] If it is determined in block 34 that the vehicle is tilted uphill, the system branches off from block 34 to block 35. Conversely, if it is determined in block 34 that the vehicle is tilted downhill, the system branches off from block 34 to block 36. As already explained, this concerns Fig. 11. The case where the vehicle is parked uphill on a slope where the slope exceeds the limit, the system branches from block 28 to block 35. Block 35 checks whether a driving strategy stored in a transmission control unit specifies starting in forward gear 1 or forward gear 2 for a forward start. If the driving strategy specifies starting in first forward gear, the system branches from block 35 to block 37. Conversely, if the driving strategy in block 35 determines that starting in second forward gear is specified for a forward start, the system branches from block 35 to block 38. Fig. 11. It is assumed that the driving strategy for forward travel involves starting in the first forward gear 1, so that therefore in Fig. 11 branches off to block 37.

[0041] In block 37, a third switching element is then activated for closing, which serves to form the starting gear specified by the driving strategy, whereby this third switching element is, in the case of transmission 2, the Fig. 1 and Fig. 2 around the switching element C (see curve 27 of the Fig. 11). After rapid filling of this third switching element in block 37, a fourth switching element is activated for closing in a subsequent block 39, which is not involved in the gear formation of the starting gear specified by the driving strategy, namely in the transmission of the Fig. 1 and Fig. 2 the switching element D (see signal waveform 23 of the Fig. 11), which according to the switching matrix of the Fig. 2 in combination with the first and second switching elements would provide reverse gear R, which, in comparison to the third switching element, which in combination with the first and second switching elements acts in the direction of forward travel, tensions the drive train or the transmission in a direction opposite to forward travel.

[0042] According to Fig. 11. Accordingly, with the drive unit 1 running (see signal flow 19), four switching elements are actuated to close when the transmission 2 is in park position P and the parking lock 15 is engaged. These elements are the first and second switching elements, which are closed in both forward and reverse starting gears, as well as the third and fourth switching elements. The third switching element participates in the gear selection of the starting gear specified by the driving strategy, while the fourth switching element does not participate in the gear selection of the starting gear specified by the driving strategy, but rather acts in the opposite direction of travel. The first switching element is initially actuated to close with such pressure that a torque can be transmitted from the first switching element that is less than the maximum torque and at which the parking lock 15 remains engaged.The second switching element is actuated with a pressure sufficient to transmit the maximum torque. The third switching element is first rapidly filled and then actuated only to the point of closing, allowing it to transmit the idle torque of the drive unit. The fourth switching element is first rapidly filled and then actuated only to the point of closing, preventing the transmission of any torque.

[0043] In block 40, it is checked whether the speed 20 of the transmission input shaft decreases to a predetermined limit. This is in Fig. 11 at time t2. It is determined that the rotational speed of turbine 20 has decreased accordingly, i.e., in Fig. If signal 11 is detected at time t2, the system branches from block 40 to block 41 and the third and fourth switching elements are further closed according to signal waveforms 23 and 27, starting at time t2. In this context, block 42 monitors whether the pressures at the third and fourth switching elements exceed a limit value. If this is the case, the system branches from block 42 to block 43, where the parking lock 15 can be deployed. This is shown in Fig. This is the case at time t3. At time t3, the gearbox 2 is under tension. The second and third shifting elements can transmit the maximum torque at time t3. The first and fourth shifting elements can transmit a torque that is less than the maximum torque at time t3. Actuating the fourth shifting element with a pressure capable of transmitting the maximum torque is also possible. Crucially, the third and fourth shifting elements must be actuated with a pressure and torque transmission capability that allows the drivetrain to be tensioned according to the incline.

[0044] At time t4, in Fig. 11 a transfer of the gear selector lever from position P to position D (see signal flow 18) and therefore a change in the driver's request.

[0045] In block 44 of the Fig. Step 3 then checks the actual driver request. While the blocks before block 44, especially blocks 35 to 43, depend on the driving strategy, block 44 subsequently checks the actual driver request. If block 44 detects that the driver has requested to drive forward, i.e., position D has been selected on the gear selector lever, the system branches from block 44 to block 45. Conversely, if block 44 detects that the gear selector lever has been moved to position R for reverse, i.e., the driver has requested to drive in reverse, the system branches from block 44 to block 46. If, however, the gear selector lever has been moved from the Park position P to the Neutral position N, the system branches from block 44 to block 47.

[0046] In Block 45 of the Fig. 3. It is checked whether the actual driver request for the starting gear is first forward gear or second forward gear. If block 45 determines that the actual driver request is first forward gear, the system branches from block 45 to block 48. Conversely, if block 45 determines that second forward gear is requested, the system branches from block 45 to block 49. Fig. Figure 11 visualizes the case in which the driver's actual wish to travel forward corresponds to using the first forward gear as the starting gear, so that therefore in Fig. 11 branches off to block 48.

[0047] According to block 48, at time t4 the first switching element, i.e. in the case of the transmission, is engaged. Fig. 1 and Fig. 2 the switching element A, according to the signal waveform 21 of the Fig. 11 is fully closed, meaning it can transmit the maximum torque. As a result of the coupled control of the switching element A with the parking lock 15 and the control of the solenoid valve 16, which is visualized in signal 25, the parking lock is activated for deployment.

[0048] In a subsequent step 50, it is monitored whether the parking lock 15 is actually deployed. This can be done with the help of a parking lock sensor, which is installed in the parking lock 15 and monitors whether the parking lock 15 has actually been deployed. Fig. At time t5, it is determined that, according to the change from state I to state II of signal waveform 26, the parking lock 15 is deployed. At time t5, the system then branches from block 50 to block 51, whereby in block 51 the pressure control for the third switching element C subsequently remains at the pressure level of time t4 according to signal waveform 27, whereas, according to signal waveform 23, the fourth switching element is fully opened starting at time t5.

[0049] If, therefore, block 50 detects that the parking lock 15 is engaged, block 51 then provides a control signal for the shift elements of the transmission 2 so that the resulting transmission shift state corresponds to the driver's request, i.e., in Fig. 11 Starting off in the forward direction in the first forward gear is possible as a starting gear, in particular following time t6, at which only the switching elements A, B and C, i.e. the first switching element, the second switching element and the third switching element, remain closed, whereas the fourth switching element, namely the switching element D, which was previously controlled to close, is open again, so that at time t6 starting off in the first forward gear with the parking lock 15 engaged is possible according to block 52 of the Fig. 3 can be done.

[0050] Fig. 11 therefore concerns the scenario in which the motor vehicle is stationary on an uphill slope whose magnitude is greater than or equal to the limit value, and when the driver requests forward travel, the actual driver request corresponds to the starting gear specified by the driving strategy, whereby this in Fig. 11 is the first forward gear. This occurs in Fig. 11 the transfer of the gear selector lever from the park position P to the position D at time t4, i.e. with the gearbox already under tension.

[0051] In contrast, it shows Fig. 12 a variation of the Fig. 11, who separated from Fig. 11 differs only in that the transfer of the gear selector lever from the park position P to the position D takes place at time t1, i.e. when the gearbox 2 is not yet preloaded.

[0052] Then, if at time t1 the Fig. 12. If the driver's request changes from the park position P, i.e., the transmission 2 is to leave the park position P according to the driver's request, the first shift element, namely in the transmission of the Fig. 1 and Fig. 2. The switching element A, which is hydraulically coupled to the parking lock 15, is actuated with pressure so that it can subsequently transmit a maximum torque and the parking lock 15 is engaged. This actuation of the first switching element, i.e., in the transmission of the Fig. 1, Fig. 2 of switching element A, in Fig. 12 cannot occur immediately at time t1, but only at time t4', i.e. a time offset Δt later, whereby this time offset Δt can be specified either time-controlled or event-controlled.

[0053] This time offset Δt is used in blocks 40, 41 and 42 of the Fig. 3. Event-driven. In block 40, it is first checked whether the speed 20 of the transmission input shaft has decreased to a predetermined limit. This is in Fig. 12 at time t2. If it is determined that the rotational speed of turbine 20 has decreased accordingly, i.e., in Fig. If signal 12 is reached at time t2, the process branches from block 40 to block 41 and the third and fourth switching elements are further closed according to signal waveforms 23 and 27. In this context, block 42 monitors whether the pressures at the third and fourth switching elements exceed a limit value. If this is the case, the process then branches from block 42 to block 43, where the parking lock 15 can generally be deployed. This is in Fig. 12 at time t4'. At time t4', gearbox 2 is under load. The first, second, and third shifting elements can transmit the maximum torque at time t4'. In this example, the fourth shifting element can transmit a torque that is less than the maximum torque at time t4'. Analogously to Fig. 11. The fourth switching element could also be controlled with a pressure that can transmit the maximum torque.

[0054] In the following block 44, the actual driver request is checked. Therefore, if the blocks before block 44, especially blocks 35 to 43, depend on the driving strategy, block 44 subsequently checks which driver request is actually present.

[0055] If block 44 detects that the driver has requested forward travel, i.e., that position D has been selected on the gear selector lever, the system branches from block 44 to block 45. Conversely, if block 44 detects that the gear selector lever has been moved to position R for reverse travel, i.e., that the driver has requested reverse travel, the system branches from block 44 to block 46. If, however, the gear selector lever has been moved from the Park position P to the Neutral position N, the system branches from block 44 to block 47. Block 45 checks whether the actual driver request is for first or second forward gear to start in.If block 45 determines that the driver's actual request is for first forward gear as the starting gear, the system branches from block 45 to block 48. Conversely, if block 45 determines that second forward gear is requested as the starting gear, the system branches from block 45 to block 49. Fig. Figure 12 visualizes the case in which the driver's actual wish to travel forwards corresponds to using the first forward gear as the starting gear, so that therefore in Fig. 12 branches off to block 48.

[0056] According to block 48, at time t4' the Fig. 12 the first switching element, i.e., in the transmission the Fig. 1 and Fig. 2 the switching element A, according to the signal waveform 21 of the Fig. 12 is completely closed, meaning it can transmit the maximum torque. As a result of the coupled control of the switching element A with the parking lock 15 and the control of the solenoid valve 16, the parking lock 15 is activated for disengagement. In a subsequent step 50, it is monitored whether the parking lock 15 is actually disengaged. This can be done with the help of a parking lock sensor, which is installed in the parking lock 15 and monitors whether the parking lock 15 has actually been disengaged. Fig. At time t5, it is determined that, according to the change from state I to state II of signal waveform 26, the parking lock 15 is deployed. At time t5, the system then branches from block 50 to block 51, whereby in block 51 the pressure control for the third switching element C subsequently remains at the pressure level of time t4' according to signal waveform 27, whereas, according to signal waveform 23, the fourth switching element is fully opened starting at time t5.

[0057] If, therefore, block 50 detects that the parking lock 15 is engaged, block 51 then provides a control signal for the shift elements of the transmission 2 so that the resulting transmission shift state corresponds to the driver's request, i.e., in Fig. 12 Starting off in the forward direction in the first forward gear is possible as a starting gear, in particular following time t6, at which only the switching elements A, B and C, i.e. the first switching element, the second switching element and the third switching element, remain closed, whereas the fourth switching element, namely the switching element D, which was previously controlled to close, is open again, so that at time t6 starting off in the first forward gear with the parking lock 15 engaged according to block 52 of the Fig. 3 can be done.

[0058] Fig. 5, Fig. Figures 13, 18, 19, 20, 21, 22, 23, 24, 25 and 26 visualize temporal signal progressions for the case in which, with an uphill slope greater than or equal to the limit value, the gear selector lever is moved from the park position P to the forward position D, and in contrast to Fig. 11, Fig. 12. The second forward gear is specified by the driving strategy as the starting gear for forward travel, and this forward gear specified by the driving strategy also corresponds to the actual driver request in transmission position D.

[0059] Fig. 5 concerns the case in which the gear selector lever is moved from the park position P to the position D with the gearbox already under tension. Fig. 13 concerns the modification of the Fig. 5, which differ from Fig. 5 differs only in that the transfer of the gear selector lever from the park position P to the position D takes place earlier, namely when the gearbox is not yet pre-tensioned 2.

[0060] The signal patterns of the Fig. 5, Fig. 13 largely agree with the signal patterns of the Fig. 11, Fig. 12 are identical, but with the difference that the third switching element, which is already activated to close in the park position P of the transmission 2 with the drive unit 1 running, is the switching element E, which is involved in gear formation in the second forward gear.

[0061] In the cases of Fig. 5, Fig. According to this, block 13 branches off from block 35 to block 38, in which the driving strategy initially specifies the second forward gear as the starting gear for forward travel, regardless of the driver's request. Therefore, in block 38, after the first and second shift elements have been activated to close (see curves 21 and 22 of the Fig. 5, Fig. 13) Subsequently, the third switching element E and then the fourth switching element D in block 53 are activated for closing, each in the sense of rapid filling. Subsequently, as already mentioned with reference to Fig. 11, Fig. 12 is discussed, and in a subsequent block 54 it is monitored whether a defined speed reduction can be observed with respect to the transmission input speed (curve 20), i.e., whether the speed 20 of the transmission input shaft has decreased to a defined limit value. This is in Fig. 5, Fig. 13 is the case at time t2. Subsequently, the process branches from block 54 to block 55, whereby in block 55, in accordance with block 41, the third and fourth switching elements are further closed until, in block 56, which corresponds to block 42, it is determined that the pressure on the third and fourth switching elements reaches or exceeds a limit value. If this is the case, the process branches to block 57, which corresponds to block 43, so that in block 57, the parking lock 15 can then be deployed. This is in Fig. 5 at time t3 and in Fig. 13 at time t4'. As already explained, block 44 checks the driver's request, i.e., whether the gear selector lever has been moved from the Park position P to position D, position R, or position N. In the case of Fig. 5, Fig. In block 45, the gear selector lever is moved from the park position P to the drive position D. Block 45 then determines that starting in second forward gear is desired, so the process branches from block 45 to block 49. In block 49, which corresponds to block 48, the pressure control for the first shift element 21 is increased so that it can subsequently transmit maximum torque. At time t4 or t4', the control of the solenoid valve also changes (see curve 25), such that this change in control at time t4 or t4' causes the solenoid valve 16 to engage the parking lock 15 via the hydraulic cylinder 17.

[0062] In block 58, which corresponds to block 50, it is monitored whether parking barrier 15 is actually deployed, whereby this is in Fig. 5, Fig. 13 again at time t5, in which the state of the parking lock 15 changes from state I for an engaged parking lock to state II for a disengaged parking lock. In a subsequent block 59, the shifting elements of the transmission 2 are then controlled in such a way that a transmission shift state corresponding to the driver's request is established, whereby in block 59 at time t5 the third shifting element E, which is involved in gear formation in the second forward gear, is held closed, in particular at a pressure level which prevails at time t4 or t4', whereas at time t5 the shifting element D, i.e. the fourth shifting element, which is not involved in gear formation, is fully opened, so that then at the latest at time t6 in accordance with block 60, starting uphill in the second forward gear can take place.

[0063] In Fig. 5, Fig. 13 and Fig. 11, Fig. 12. The starting gear actually requested by the driver corresponded to the starting gear specified by the driving strategy. It should be noted here that the starting gear actually requested by the driver, as determined in block 45, may also differ from the starting gear specified in block 35 of the driving strategy. In this case, the third shift element, which is closed depending on the driving strategy, must be opened in block 51 or block 59, and the fifth shift element, which was not previously activated to close, must be closed so that a transmission shift state corresponding to the driver's request is established in the transmission.

[0064] Fig. 9, Fig. Figures 14 show time-dependent signal progressions 18, 19, 20, 21, 22, 23, 27, 25 and 26 for the case in which the motor vehicle is on an incline uphill, i.e. with the front of the vehicle pointing upwards, at an incline whose magnitude is greater than or equal to the limit value, in which the driving strategy specifies the first forward gear as the starting gear for forward travel, and in which the driver's request changes from the park position P to a position R for reverse travel.

[0065] Fig. 9 concerns the case in which the gear selector lever is moved from the park position P to the position R when the gearbox is already under tension. Fig. 14 concerns the modification of the Fig. 9, which differ from Fig. 9 differs only in that the transfer of the gear selector lever from the park position P to the position R takes place earlier, namely when the gearbox is not yet pre-tensioned 2.

[0066] In Fig. 9, Fig. Block 14 therefore branches from block 35 to block 37 and from block 44 to block 46. This is correct up to time t2. Fig. 9 with Fig. 11 and Fig. 14 with Fig. 12 agree. In Fig. 9, Fig. However, at time 14 the driver requests a transmission position R for reverse travel, so that after time t4 or t4', in which, according to the signal sequence 21, the first switching element A is pressurized to maximum pressure and the solenoid valve 16 is activated to engage the parking lock 15, at time t5 the switching element C is opened and the switching element D is completely closed, so that at time t6, with switching elements A, B and D closed, according to the switching matrix of the Fig. 2 in the gearbox, the reverse gear R is formed.

[0067] At Fig. 9, Fig. 14. The third switching element is switching element D and the fourth switching element is switching element C. In Fig. 9, Fig. Block 14 traverses blocks 46, 61, 62, and 63, with block 46 corresponding to blocks 48 and 49, in which the first switching element A is fully closed. In block 61, which corresponds to blocks 50 and 58, it is monitored whether the parking lock 15 is actually engaged. In block 62, starting at time t5, the fourth switching element C is activated to open, so that in block 63, at time t6, a reverse gear start can be initiated.

[0068] Fig. 7, Fig. Figure 15 shows time-dependent signal profiles 18, 19, 20, 21, 22, 23, 27, 25 and 26 for the case in which, on an uphill slope whose magnitude is greater than or equal to the limit value, the driver's request changes from a park position of transmission 2 to a neutral position N of transmission 2, and in which, in accordance with the Fig. 11, Fig. 12 and Fig. 9, Fig. 14 in the driving strategy in block 35 of the Fig. 3, in turn, was specified as the starting gear for forward travel, the first forward gear.

[0069] Fig. 7 concerns the case in which the gear selector lever is moved from the park position P to the position N with the gearbox already under tension. Fig. 15 concerns the modification of the Fig. 7, which differ from Fig. 7 differs only in that the transfer of the gear selector lever from the park position P to the position N takes place earlier, namely when the gearbox is not yet pre-tensioned 2.

[0070] In Fig. 7, Fig. According to this, line 15 branches from block 35 to block 37 and from block 44 to block 47. In Fig. 7, Fig. Accordingly, with the transmission in position P engaged and the drive unit running, four switching elements A, B, C, and D are activated to close. If the pressures at the third switching element C and the fourth switching element D exceed a corresponding limit value, switching element A in block 47 (corresponding to blocks 48, 49, and 46) is fully closed, and the control signal to the solenoid valve 16 of the parking lock 15 is also changed. Subsequently, in block 64 (corresponding to blocks 50, 58, and 61), it is monitored whether the parking lock 15 is disengaged. If this occurs, at time t5, the third and fourth switching elements (C and D) are fully opened, so that at time t6 in block 66... Fig. 3. In the gearbox, the neutral position N is present, in which only the first shift element and the second shift element are closed, i.e., in the gearbox of the Fig. 1 and Fig. 2 the switching elements A and B.

[0071] Fig. 5, Fig. 7, Fig. 9 and Fig. 11 or Fig. 12, Fig. 13, Fig. 14 and Fig. 15 all concerned cases of the method according to the present invention in which the motor vehicle was parked on a slope facing uphill, i.e., with the front of the vehicle pointing upwards. In contrast, they show Fig. 4, Fig. 6, Fig. 8 and Fig. 10 or Fig. 16, Fig. 17, Fig. 18 and Fig. 19. Scenarios of the method according to the invention in which the vehicle is positioned on a slope with a downward incline, i.e., with the front of the vehicle pointing downwards, specifically when the magnitude of the slope is greater than or equal to the limit value, such that in the signal flow diagram of the Fig. 3 the case scenarios of Fig. 4, Fig. 6, Fig. 8 and Fig. 10 or Fig. 16, Fig. 17, Fig. 18 and Fig. 19 branches off from block 34 to block 36.

[0072] Fig. 4, Fig. 6, Fig. 8 and Fig. 10 all concern cases in which the gear selector lever is moved out of the park position P while the gearbox is already under tension. Fig. 16, Fig. 17, Fig. 18 and Fig. 19 concerns the modifications in which the transfer of the gear selector lever from the park position P takes place earlier, namely when the gearbox is not yet preloaded 2.

[0073] In block 36, in accordance with block 35, the starting gear specified by a driving strategy for forward travel is checked, whereby if in block 36 the driving strategy for forward travel specifies the first forward gear as the starting gear, a branch is made to block 67, whereas if in block 36 it is determined that the driving strategy for forward travel specifies the second forward gear as the starting gear, a branch is made to block 68.

[0074] For the signal profiles of the Fig. 10, Fig. 16 was assumed to branch off in block 36 to block 67, that is, the driving strategy on downhill slopes, which is greater than or equal to the limit, specifies the first forward gear as the starting gear, whereby blocks 69, 70, 71, 72 and 73 are then subsequently traversed.

[0075] In blocks 67 and 69, after the first and second switching elements have been activated for closing in blocks 29 and 30, the third and fourth switching elements are activated for closing in a rapid filling process. Specifically, when driving downhill, first the fourth switching element D, which is not involved in the gear selection of the starting gear specified by the driving strategy, is activated, followed by switching element C in block 69, which is involved in the gear selection of the starting gear specified by the driving strategy. This is evident from signal waveforms 23 and 27 of the Fig. 10, Fig. 16.

[0076] After the four switching elements A, B, C and D are activated, the system branches to block 70, which essentially corresponds to blocks 40 and 54, and checks whether the speed of the transmission input shaft (see curve 20) has decreased in a defined manner, whereby this is Fig. 10, Fig. 16 is the case at time t2.

[0077] In Fig. 10, Fig. At time t2, block 70 branches to block 71, and subsequently the fourth and third switching elements, i.e., switching elements D and C, are further closed, whereby, according to block 72, which basically corresponds to blocks 42 and 56, it is monitored whether the pressure at the third and fourth switching elements is subsequently greater than a limit value.

[0078] This is in Fig. 10 at time t3 and in Fig. 16 at time t4', so that then in Fig. 10 at time t3 and in Fig. 16 at time t4' from block 72 to block 73, which corresponds to the state in which the gearbox 2 is pre-tensioned and the parking lock 15 can basically be deployed.

[0079] Then, in block 74, which corresponds to block 44, the system checks which driver request has actually been made, i.e., whether the gear selector lever has been moved from the Park (P) position to position D for forward travel, position R for reverse travel, or position N for neutral. If block 74 determines that position D has been selected on the gear selector lever, the system branches off from block 74 to block 75.

[0080] If, however, block 74 detects that the gear selector lever position R has been selected, then the process branches from block 74 to block 76. If the gear selector lever has been moved from position P to position N, meaning the driver has requested a neutral position for transmission 2, then the process branches from block 74 to block 77.

[0081] In Fig. 10 and Fig. Block 16, in which it is determined that the selector lever is in position D, branches from block 74 to block 75. In block 75, in accordance with block 45, it is checked whether the driver has selected first or second forward gear as the starting gear. If the driver has selected first forward gear as the starting gear, the process branches from block 75 to block 78. If, however, second forward gear is selected as the starting gear in block 75, the process branches from block 75 to block 82.

[0082] In Fig. 10 and Fig. 16, in which, at time t2, it was determined in accordance with block 70 that, with respect to the transmission input speed (curve 20), a defined speed reduction is present, and in which, in accordance with block 72, it was determined that the pressures at the third and fourth switching elements have reached a limit value or threshold, the system branches to block 78 at time t4 or t4', so that in block 78 the pressure control for the first switching element, i.e., in the illustrated embodiment for switching element A, is increased such that the first switching element A is completely closed, so that it can subsequently transmit a maximum torque, and that, as a result of the change in the control of the solenoid valve 16, the parking lock 15 is also activated for disengagement at time t4 or t4'.

[0083] In the subsequent block 79, it is monitored, in particular with the aid of a parking lock sensor assigned to the parking lock 15, whether the parking lock 15 is actually engaged. If it is determined in block 79, which corresponds to blocks 50, 58, 61 and 64, that this is the case, then at time t5, the system branches from block 79 to block 80. In block 80, switching element D is then opened, which is not required to provide the first forward gear corresponding to the driver's request. Consequently, in block 81 at time t6, switching elements A, B and C for the first forward gear are closed and switching element D is fully open, so that starting on a downhill slope in first forward gear is then possible in block 81.

[0084] The case scenarios of Fig. 4 and Fig. 17 generally correspond to the case scenarios of Fig. 5 and Fig. 13, however, in the event that, with a downward slope, i.e. with the front of the motor vehicle pointing downwards, a subsequent start in forward motion from parking position P is to take place, namely in the second forward gear as the starting gear, and again when branching from block 36 to block 68, i.e. in accordance with Fig. 5 and Fig. 13 each in the case in which the driving strategy specifies the second forward gear as the starting gear for forward travel.

[0085] In Fig. 4. The gear selector lever is moved from the park position P at time t4 with the transmission already pre-tensioned. Fig. 17. The transfer of the gear selector lever from the park position P takes place earlier at time t1, namely when the gearbox 2 is not yet preloaded.

[0086] The blocks 83, 84, 85, 86 and 87, which follow block 68, therefore correspond in principle to blocks 53, 54, 55, 56 and 57, however, unlike blocks 53 to 57 and unlike Fig. 5, Fig. 13 such that, according to block 68, first the switching element D and then, in block 83, the switching element E according to the signal waveform 24 of the Fig. 4, Fig. 17 undergoes rapid filling. This is done in block 84 in Fig. 4, Fig. If, at time t2, it is determined that a defined speed reduction exists for the input speed of transmission 2 (see curve 20), then in block 85 the switching elements D and E are subsequently closed further until in block 86 it is determined that the pressure at the switching elements D and E is greater than a limit value. Subsequently, in block 87, with transmission 2 under tension, the disengagement of the parking lock is generally possible. This is in Fig. 4 at time t3 and in Fig. 17 at time t4' the case.

[0087] In Fig. 4, Fig. Block 17 branches from block 75 to block 82, indicating a driver request to start in a forward gear, with the following then occurring in block 82: Fig. 4, Fig. 17 the control for the switching element A is increased and at the same time the parking lock 15 is controlled via the solenoid valve 16 according to the signal curve 25 starting at time t4 or t4' for deployment.

[0088] In block 88, it is subsequently checked, particularly via a parking lock sensor, whether the parking lock is actually engaged. If this is the case, in block 89, the switching element D is reopened and the control of the switching element E is maintained, so that at time t6 the second forward gear is engaged and the switching element D for reverse gear is fully open. Following time t6, starting off in the second forward gear can therefore occur as a starting gear, as described in block 90.

[0089] The case scenarios of Fig. 8, Fig. 18 generally correspond to the case scenarios of Fig. 9, Fig. 14 and the case design of the Fig. 6, Fig. 19 basically the case scenarios of Fig. 7, Fig. 15, however, with the difference that in Fig. 8, Fig. 18 and in Fig. 6, Fig. 19 the motor vehicle is parked downhill on the slope, whereas in Fig. 9, Fig. 14 and in Fig. 7, Fig. 15 the motor vehicle is parked uphill on a slope, each with an incline greater than the respective limit value or corresponding to it.

[0090] Fig. 8, Fig. Figures 18 each show an embodiment in which the driver's request changes from the park position P of the transmission 2 to a position for reverse travel R, specifically in the case where the first forward gear is specified as the starting gear for forward travel by the driving strategy. Accordingly, in Fig. 8, Fig. 18 branches from block 34 to block 36 and from block 36 to block 67, furthermore in Fig. 8, Fig. 18 in block 74 branches to block 76, in which the actual driver request is specified by the gear selector position R for a reverse drive.

[0091] In this case, in Fig. 8, Fig. 18 in accordance with Fig. 9, Fig. 14 when the parking lock 15 is deployed at time t5 the switching element C is reopened according to the signal sequence 27, whereas according to the signal sequence 23 the control of the switching element D is maintained, so that at time t6 with the switching elements A, B and D closed the reverse gear R of the transmission 2 is positively engaged, so that a start in reverse gear R can then take place on a slope downhill with the front of the vehicle pointing downwards.

[0092] In Fig. 8, Fig. 18 is therefore recognized at time t5 in accordance with block 91 that after the clutch A is actuated to close completely according to block 76, the parking lock 15 is deployed, so that then from block 91 to block 92 the switching elements C and D are actuated in block 92 as described, i.e. switching element C to open and switching element D to close completely, so that at time t6 according to block 93 the reverse gear is positively engaged, the parking lock 15 is deployed and starting in reverse gear is possible.

[0093] Fig. 6, Fig. 19 concerns the cases in which the vehicle is on a slope with its front end pointing downwards, where the degree of inclination is again greater than or equal to the corresponding limit value, where the driving strategy in block 36 specifies the first forward gear as the starting gear for forward travel, so that from block 36 a branch is made to block 67, and where the actual driver request corresponds to a neutral position N of the transmission, so that in block 74 a branch is made to block 77.

[0094] In Fig. 6, Fig. At time t4 or t4', in accordance with block 77, which corresponds to blocks 78, 82, and 76, the control signal for the first switching element A is increased, so that, via this and the solenoid valve 16 according to curve 25, the parking lock 15 is activated for disengagement. Subsequently, block 77 in block 94, which corresponds to blocks 79, 88, and 91, monitors, particularly with the aid of a parking lock sensor, whether the parking lock 15 is actually disengaged. If, at time t5, the Fig. 6, Fig.19 if it is recognized that the parking lock 15 is actually deployed, the process then branches to block 95, in which, to provide the neutral position N for the transmission, the third and fourth switching elements, namely in the illustrated embodiment the switching elements C and D, are both controlled to fully open, so that at time t6 only the switching elements A and B are closed, so that at time t6 according to block 96 the transmission assumes the neutral position.

[0095] The embodiments of the invention all have in common that, with the drive unit 1 running, and in particular after it has been started, at least four switching elements are activated for closing even when the transmission 2 is still in park position P. These elements are a first switching element and a second switching element, each of which is gear-forming in the starting gear for forward travel and in the starting gear for reverse travel. The first switching element is hydraulically coupled to the parking lock 15 and is only activated to the extent that the parking lock 15 is not yet activated to disengage. The second switching element is fully closed so that it can transmit the maximum torque.

[0096] In addition, two further switching elements are activated in the park position P of the transmission for closing, namely the third switching element and the fourth switching element, whereby the third switching element is involved in the gear formation for the starting gear specified by the driving strategy, while the other switching element is not involved in this starting gear specified by the driving strategy, but rather preferably acts in the opposite direction.

[0097] Then, when the driver's request changes such that the transmission 2 is required to leave its park position, the first shift element, which is hydraulically coupled to the parking lock 15, is fully closed. This, along with the actuation of the solenoid valve 16, disengages the parking lock 15. Once the parking lock 15 is disengaged, the previously closed shift elements are actuated to establish a shift state in the transmission that corresponds to the driver's request.

[0098] When the driver requests neutral, the first and second shift elements remain closed, while the third and fourth shift elements, which were previously closed, open. Similarly, when the driver requests reverse, the first and second shift elements remain closed, and one of the third and fourth shift elements, which were previously closed, opens while the other remains closed to engage reverse.Should the driver request forward travel for the transmission, the first and second shift elements remain closed. Of the other previously closed shift elements, namely the third and fourth, the one not involved in the starting gear for forward travel is opened. If the actual starting gear requested by the driver differs from the starting gear specified by the driving strategy, both the third and fourth shift elements are opened, and a fifth shift element, which was not previously activated to close, is closed instead.

[0099] The invention further relates to a transmission control unit that serves to carry out the methods described above according to the invention. The transmission control unit executes these methods on the control side and, for this purpose, exchanges data with the assemblies involved in carrying out the method according to the invention. These include, in particular, the switching elements A, B, C, D, and E of the transmission 2, which are controlled by the transmission control unit to close or open as described above. Furthermore, the transmission control unit exchanges data with a parking lock sensor to monitor whether the parking lock is actually engaged. The transmission control unit can also exchange data with an inclination sensor that determines the magnitude and direction of the inclination, although the magnitude and direction of the inclination can also be calculated.

[0100] For its control-side implementation, each transmission control unit comprises both hardware and software components. The hardware components include data interfaces for exchanging data with the assemblies involved in carrying out the method according to the invention. Furthermore, the hardware components include a processor for data processing and a memory for data storage. The software components include program modules for carrying out the method, which are stored in the data memory and executed by the processor. Reference sign 1 drive unit 2 gearboxes 3 wheelset 4 wheelset 5 wheelset 6 wheelset 7 Gearbox input shaft 8 Gearbox output shaft 9 Switching element A 10 Switching element B 11 Switching element C 12 Switching element D 13 Switching element E 14 Drive 15 Parking restrictions 16 Solenoid valve 17 hydraulic cylinders 18 Signal waveform 19 Signal waveform 20 Signal waveform 21 Signal waveform 22 Signal waveform 23 Signal waveform 24 Signal waveform 25 Signal waveform 26 Signal waveform 27 Signal waveform Block 28 Block 29 30 blocks Block 31 32 blocks Block 33 Block 34 35 Block 36 Block Block 37 38 Block Block 39 40 blocks Block 41 42 Block Block 43 44 Block 45 Block 46 Block Block 47 48 blocks Block 49 50 blocks Block 51 52 Block Block 53 Block 54 55 Block 56 Block 57 Block 58 Block 59 Block 60 Block 61 Block 62 Block 63 Block 64 Block 65 Block 66 Block 67 Block 68 Block 69 Block 70 Block 71 Block 72 Block 73 Block 74 Block 75 Block 76 Block 77 Block 78 Block 79 Block 80 Block 81 Block 82 Block 83 Block 84 Block 85 Block 86 Block 87 Block 88 Block 89 Block 91 Block 92 Block 93 Block 94 Block 95 Block 96 Block

Claims

[1] Method for operating a motor vehicle with a drive unit (1), a transmission (2) connected between the drive unit (1) and an output (14), having a plurality of shifting elements (9, 10, 11, 12, 13) and a parking lock (15), wherein in each traction-transmitting gear of the transmission (2) a first number of shifting elements is closed and a second number of shifting elements is open, and wherein in a park position of the transmission (2) the parking lock (15) is engaged, where in the park position of the gearbox with the drive unit running a first switching element, which is closed in a starting gear for forward travel and in a starting gear for reverse travel and is hydraulically coupled to the parking lock (15), is controlled to close in such a way that a torque less than a maximum torque can be transmitted by it and the parking lock (15) remains engaged, a second switching element, which is closed in the starting gear for forward travel and in the starting gear for reverse travel, is controlled to close in such a way that the maximum torque can be transmitted from it, when an inclination at which the motor vehicle is currently positioned is greater than or equal to a limit value, at least two further switching elements are activated to close, with a third switching element serving to form a starting gear specified by a driving strategy and a fourth switching element not serving to form the starting gear specified by the driving strategy, When the transmission (2) is to leave the parking position according to a driver request, the first switching element is controlled to close in such a way that the maximum torque can be transmitted by it and the parking lock (15) is disengaged, wherein, when the parking lock (15) is disengaged, the previously closed switching elements are controlled in such a way that a transmission switching state corresponds to the driver's request. [2] Method according to claim 1, characterized by that the at least two further switching elements, which are closed when the inclination at which the motor vehicle is currently positioned is greater than or equal to a limit value, are selected depending on a direction of inclination of the motor vehicle, i.e. depending on whether the motor vehicle is positioned downhill or uphill in relation to a forward journey. [3] Method according to claim 1 or 2, characterized by that the third switching element and the fourth switching element, together with the first switching element and the second switching element, each provide starting gears in opposite directions. [4] Method according to one of claims 1 to 3, characterized bythat the closing sequence of the at least two further switching elements, which are closed when the inclination at which the motor vehicle is currently positioned is greater than or equal to a limit value, is selected depending on the direction of inclination of the motor vehicle, i.e. depending on whether the motor vehicle is positioned downhill or uphill in relation to a forward journey. [5] Method according to one of claims 1 to 4, characterized by that when the driver requests a neutral position of the transmission, after the parking lock is disengaged, the first switching element and the second switching element are kept closed and the other previously closed switching elements are opened. [6] Method according to one of claims 1 to 5, characterized bythat when the driver requests a reverse gear position of the transmission, after the parking lock has been disengaged, the first switching element and the second switching element are kept closed and of the other previously closed switching elements, the switching element or each switching element which is not involved in the starting gear for reverse driving is opened. [7] Method according to one of claims 1 to 6, characterized by that when the driver requests a forward drive position of the transmission, after the parking lock has been disengaged, the first switching element and the second switching element are kept closed and of the other previously closed switching elements, the switching element or each switching element which is not involved in the starting gear for forward drive is opened. [8] Transmission control device for a transmission (2) of a motor vehicle, wherein the transmission has a plurality of shift elements (9, 10, 11, 12, 13) and a parking lock (15), wherein in each traction-transmitting gear of the transmission (2) a first number of shift elements is closed and a second number of shift elements is open, wherein in a park position of the transmission (2) the parking lock (15) is engaged, and wherein the same in a parking position of the gearbox (2) a first switching element, which is closed in a starting gear for forward travel and in a starting gear for reverse travel and is hydraulically coupled to the parking lock (15), is actuated to close in such a way that a torque less than a maximum torque can be transmitted by the first switching element and the parking lock (15) remains engaged, a second switching element, which is closed in the starting gear for forward travel and in the starting gear for reverse travel, is activated to close in such a way that the maximum torque can be transmitted by it, when an inclination at which the motor vehicle is currently positioned is greater than or equal to a limit value, triggers at least two further switching elements to close, whereby a third switching element serves to form a starting gear specified by a driving strategy and a fourth switching element does not serve to form the starting gear specified by the driving strategy, the same when the gearbox (2) is to leave the parking position according to a driver request the first switching element is activated to close in such a way that the maximum torque can be transmitted by it and the parking lock (15) is disengaged, When the parking lock (15) is designed, it controls the previously closed switching elements in such a way that a gear shift state corresponds to the driver's request. [9] Transmission control device according to claim 8, characterized by that it comprises means for carrying out the method according to one of claims 1 to 7.

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