Motor vehicles having at least two drive motors and an automatic transmission with fixed gear ratio stages and power split gear ratio stages.

Abstract

This invention relates to a motor vehicle having at least two drive motors, at least one of which is an electric motor, the motor vehicle having a high-voltage accumulator, an automatic transmission, and an electronic control unit, the automatic transmission having at least one fixed gear ratio stage and at least one power-split gear ratio stage and / or at least one series gear ratio stage for gear ratio adjustment toward at least one fixed gear ratio stage, the electronic control unit having functional modules such that within the range of gear ratio adjustment between engagement and load of a switching element, a torque curve of the following type can be predetermined to control the internal combustion engine and the electric motor: - at a first time point, the switching element to be engaged is loadn with a predetermined torque gradient until a second time point, at which at least a tooth-to-tooth position can be assumed; - during a predetermined waiting period, from the second time point to a third time point, the predetermined torque is limited to the maximum permissible torque; and - after the end of the waiting period or when the engagement state is identified, the switching element to be engaged continues to be loadn with the previously predetermined torque gradient, preferably until the torque in a fully loaded fixed gear is reached.

Description

Technical Field

[0001] The present invention relates to a motor vehicle having at least two drive motors, wherein at least one drive motor is an electric motor, the motor vehicle having a high-voltage accumulator, an automatic transmission and an electronic control unit, the automatic transmission having at least one fixed gear ratio stage and at least one power split gear ratio stage or a series gear ratio stage derived from the at least one fixed gear ratio stage. Background Technology

[0002] Automatic transmissions for motor vehicles are known. Furthermore, automatic transmissions for hybrid electric vehicles are known, which, in addition to an internal combustion engine, have at least one electric motor for drive. Current automatic transmissions for hybrid electric vehicles (hybrid transmissions) are typically based on existing automatic transmissions. The electric motor for electrification is usually positioned between the internal combustion engine and the transmission (so-called P2 hybrid). However, this hybridization does not bring any advantages to the transmission itself.

[0003] Transmissions suitable for hybrid powertrains are, for example, power-switching automatic transmissions that provide different fixed gear ratio levels via friction-locked switching elements. In such transmissions, at least one switching element operates in a slip (Schlupf) state during gear shifts. The frictional work during slip operation is converted into heat, which must be removed from the friction-locked switching element by a sufficient flow of cooling oil. Furthermore, the friction-locked switching element generates corresponding drag losses in the open state. The switching element is typically hydraulically controlled. To enable the switching element to transmit force in the closed state, the friction plates of the switching element must be continuously pressed together at a correspondingly high hydraulic pressure. The hydraulic pump required for this purpose is used not only for cooling but also for operating the switching element. However, the hydraulic pump requires a certain amount of power to operate, thus reducing overall efficiency.

[0004] According to the technical solution DE102017217133A1, an automatic transmission is provided together with an internal combustion engine. The automatic transmission has at least two fixed gear ratio stages, three transmission shafts, a rotary transmission mechanism or rotary gear train, two switching elements, and a variator. Here, the first side of the variator is coupled to the first transmission shaft to transmit torque, and the second side of the variator is connected to the rotary transmission mechanism via the second transmission shaft to adjust the gear ratio. This means that the second side of the variator operates in a three-shaft configuration along with the internal combustion engine and the driven components of the automatic transmission, thereby enabling the second side of the variator to adjust the gear ratio of the internal combustion engine via the rotary transmission mechanism. The variator can achieve continuous gear ratio adjustment. Therefore, other gear ratios, especially any intermediate states between the fixed gear ratio stages, can be adjusted independently of the fixed gear ratio stages. Preferably, the variator is formed by two motors. Here, one of the motors operates as a generator, and the other operates as a motor. By temporarily converting mechanical energy into electrical energy, the speeds of the two motors can be decoupled, thus providing a speed-changing mechanism through these two motors. The rotary transmission mechanism can be a planetary gear transmission mechanism.

[0005] In the case of a series transmission ratio stage, the internal combustion engine is not mechanically coupled to the vehicle's drive shaft. The engine's drive power is converted into 100% electrical power by the first motor and then converted back to mechanical drive power on the drive shaft by the second motor. In contrast to a power-split transmission ratio stage, the transmission mechanism therefore transmits all the drive power in a series transmission ratio stage. Since the conversion from a series transmission ratio stage and a power-split transmission ratio stage to a fixed transmission ratio stage is similar within the scope of this invention, the invention will be described below with respect to power-split transmission ratio stages, but the same applies to series transmission ratio stages. Summary of the Invention

[0006] The objective of this invention is to improve the type of hybrid electric vehicle with an automatic transmission described at the beginning in terms of the gear ratio adjustment of the automatic transmission.

[0007] This task is solved by the features of the present invention.

[0008] This invention relates to a motor vehicle having at least two drive motors, wherein at least one drive motor is an electric motor, the motor vehicle having a high-voltage accumulator, an automatic transmission, and an electronic control unit, the automatic transmission having at least one fixed gear ratio stage (fixed gear) and at least one power-split gear ratio stage (E-CVT) and / or a series gear ratio stage for gear ratio adjustment toward at least one fixed gear ratio stage, the electronic control unit having functional modules such that a torque curve of the following type can be predetermined within the range of gear ratio adjustment between the engagement and disengagement of the switching element of the (new) fixed gear ratio stage, in order to control the internal combustion engine and the electric motor.

[0009] - At a first time point, the switching element to be engaged / connected is borne with a predetermined torque gradient until a second time point. At the first time point, at least a tooth-to-tooth position can be assumed, or in other words, at least a tooth-to-tooth position can be started from at the first time point.

[0010] - During the predetermined waiting period, from the second time point to the third time point, the predetermined torque is limited to the maximum permissible torque, and

[0011] - After the waiting period ends or when the engagement / engagement state is detected, the switching element to be engaged continues to be carried at a previously predetermined torque gradient, preferably until the torque in the fixed gear is fully carried is reached.

[0012] For example, it is also meaningful to start from the power split transmission ratio stage (E-CVT) and engage the only fixed gear.

[0013] This invention relates particularly to a motor vehicle having an internal combustion engine, at least one electric motor, and an automatic transmission having at least two fixed gear ratio stages and a transmission mechanism for adjusting the gear ratio between the two fixed gear ratio stages, the transmission mechanism comprising, for example, two electric motors. One electric motor may also be sufficient. In this case, the transmission mechanism includes the electric motor and a high-voltage accumulator.

[0014] Furthermore, the motor vehicle according to the invention includes an electronic control unit designed such that a method for reliably engaging a switching element can be executed within the shift range of the DHT transmission.

[0015] This application is based on the following considerations:

[0016] The use of form-locking switching elements in DHT transmissions is to minimize drag and actuation losses in the transmission.

[0017] However, the switching elements of form-locking have the following drawback: they can only establish form-locking within a very small angular range through the rotation of their two connecting elements. This means that there is a so-called tooth-to-tooth position in the remaining rotational angular range.

[0018] This drawback is typically minimized through the design of the geometry of the connecting elements. For example, a geometry in the form of a dogtooth or roof slope is used. The rotation of the two connecting elements relative to each other is ensured here by the force of an actuator.

[0019] However, the geometric solution still has some issues with tooth-to-tooth positioning and also has the disadvantage of a large actuation path.

[0020] However, reliable engagement is required to avoid excessive speed differences caused by delayed engagement based on the shifting element. This is because the torque pulse generated during engagement increases proportionally to the speed difference to be reduced and can lead to comfort issues or material damage if it exceeds the limits associated with the gear and shifting element.

[0021] Therefore, according to the present invention, a functional solution is proposed that allows the engagement or locking of a form-locking switching element, preferably in the case of using a blunt, but also in the case of using any type of form-locking switching element.

[0022] The actuating force, friction, and therefore frictional torque of the actuator based on the switching element act in the tooth-to-tooth position, resisting the rotation of the two connecting elements. This frictional torque can be specifically overcome in a DHT compared to a conventional transmission.

[0023] By controlling the internal combustion engine and the electric motor in this way, the torque to be transmitted, which is just slightly more than the frictional torque, is applied to the switching element to be engaged, so that the connecting element rotates and the switching element can be engaged or locked.

[0024] For comfort reasons, but also for material damage reasons, the difference between the torque to be transmitted and the frictional torque applied must not exceed the value associated with the gear to be engaged.

[0025] To enable a controlled engagement process from the tooth-to-tooth position, it is recommended that the switching element to be engaged is already borne in the tooth-to-tooth position. This establishes a torque to overcome frictional torque.

[0026] To limit the difference between the torque to be transmitted and the applied frictional torque, starting from a value to be parameterized or applied, the torque build-up on the switching element is stopped or at least slowed down, so that the rotation and final engagement of the switching element are carried out below the torque level and speed difference level to be applied on the switching element.

[0027] After the application period has ended or when the engagement state is detected, the initial torque build-up continues on the now fully engaged switching element.

[0028] In order to minimize the frictional torque generated by the actuator or reduce it from the static friction coefficient to the sliding friction coefficient, it is preferable to perform pulsed operation of the switching element-actuator.

[0029] Here, it is preferable to apply or parameterize the frequency of the pulse in such a way that the average actuator force still reaches the required value, but drops to 70%, 50%, 30%, or possibly 0% of the required value in terms of the minimum value of its curve. Attached Figure Description

[0030] The invention will now be described with reference to the accompanying drawings. The drawings are as follows:

[0031] Figure 1 State 1 is shown as the entire shifting process when switching from a first fixed gear to a second fixed gear using an automatic transmission according to the invention;

[0032] Figure 2 This schematically illustrates the important components of a motor vehicle or transmission according to the present invention and their states during state 1 of the entire gear shifting process;

[0033] Figure 3 State 2 shows the entire shifting process when switching from a first fixed gear to a second fixed gear using an automatic transmission according to the invention;

[0034] Figure 4 The illustration shows important components of a motor vehicle or transmission according to the present invention and their states during state 2 of the entire gear shifting process;

[0035] Figure 5 State 3 shows the entire shifting process when switching from a first fixed gear to a second fixed gear using an automatic transmission according to the invention;

[0036] Figure 6 The illustration shows important components of a motor vehicle or transmission according to the present invention and their states during state 3 of the entire gear shifting process;

[0037] Figure 7 State 4 shows the entire shifting process when switching from a first fixed gear to a second fixed gear using an automatic transmission according to the invention;

[0038] Figure 8 The illustration shows important components of a motor vehicle or transmission according to the present invention and their states during state 4 of the entire gear shifting process;

[0039] Figure 9State 5 shows the entire shifting process when switching from a first fixed gear to a second fixed gear using an automatic transmission according to the invention;

[0040] Figure 10 The illustration shows important components of a motor vehicle or transmission according to the present invention and their states during state 5 of the entire gear shifting process;

[0041] Figure 11 The states 6 and 7 are shown during the entire shifting process when switching from a first fixed gear to a second fixed gear using an automatic transmission according to the invention;

[0042] Figure 12 The illustration shows important components of a motor vehicle or transmission according to the invention and their states at states 6 and 7 throughout the shifting process;

[0043] Figure 13 This illustrates an important intermediate step according to the invention, between states 5 and 6 of the entire shifting process when shifting from a first fixed gear to a second fixed gear using an automatic transmission according to the invention; and

[0044] Figure 14 The diagram illustrates the torque variation curves generated on the relevant switching elements by the present invention. Detailed Implementation

[0045] Figure 1 This shows the initial state, i.e., state 1, when the first gear (fixed gear G1) is engaged before the shift command. Subsequently, the shift command is issued in the electronic control unit SG via the corresponding input signal.

[0046] Figure 2 This illustrates some of the most important components of the invention, which are also applicable to... Figure 4 , 6 , 8, 10 and 12: in Figure 2 The diagram schematically illustrates a hybrid vehicle having a DHT automatic transmission, an internal combustion engine VM, a first electric motor EMA, a second electric motor EMB, a high-voltage accumulator HVS, and an electronic control unit SG.

[0047] The automatic transmission includes a rotary transmission mechanism UG in the form of a power-split planetary gear transmission mechanism, a transmission mechanism including two motors EMA and EMB, a first switching element K1 for engaging the first fixed gear ratio stage G1 (hereinafter also referred to as fixed gear G1), and a second switching element B2 for engaging the second fixed gear ratio stage G2.

[0048] The number of two gear ratio stages is used here only for better illustration; in practice, a greater number of gear ratio stages may also be used.

[0049] An automatic transmission also includes two transmission shafts: an input shaft in the form of a drive shaft and an output shaft in the form of a driven shaft. The automatic transmission is coupled to the internal combustion engine VM via the drive shaft to transmit torque, and to the vehicle wheels R via the driven shaft to transmit torque.

[0050] Automatic transmissions can also have three or more fixed gear ratio stages, in which case they may also have a correspondingly larger number of switching elements configured to engage other gear ratio stages. Individual switching elements can also be configured for multiple gear ratio stages, and / or combinations of multiple switching elements can be configured for a single gear ratio stage.

[0051] The planetary gear transmission mechanism UG has a planet carrier 1, a ring gear 2, and a sun gear 3. The rotary transmission mechanism UG is coupled to transmit torque not only to the input shaft but also to the output shaft. Furthermore, the rotary transmission mechanism UG includes a shaft through which the rotary transmission mechanism can be coupled to the input shaft to transmit torque via a first switching element K1 forming a coupling thereon, and can be coupled to a second switching element B2 forming a brake thereon. This shaft here serves to regulate the speed of the internal combustion engine VM. In an alternative embodiment, the switching elements K1 and B2 can be configured for any torque transmission function.

[0052] Switching elements K1 and B2 are each constructed as claw-shaped connectors. That is, the switching elements are form-locking switching elements and require only small pressure to remain in the closed position. In an alternative embodiment, switching elements K1 and B2 can be any other suitable switching elements, such as force-locking switching elements.

[0053] By operating the first motor EMA as a generator and the second motor EMB as a motor, a speed-changing mechanism for adjusting the transmission ratio is provided. Thus, kinetic and electrical energy can be converted into each other, and therefore the speeds of the two motors EMA and EMB can be decoupled.

[0054] The automatic transmission switches from the first fixed gear ratio stage (fixed gear) G1 to the second fixed gear ratio stage (fixed gear) G2 according to the method of transmission. Figure 3 , 5 The shifting process is shown in 7, 9, 11 and 13.

[0055] according to Figure 1 and 2 The first fixed transmission ratio G1 is engaged, meaning the first switching element K1 is closed and the second switching element B2 is open. Furthermore, the transmission mechanism is decoupled, meaning the motor is not coupled to either the input or output shaft to transmit torque. All speeds nG1 are the same. The first motor EMA can operate as a generator to charge the high-voltage accumulator HVS.

[0056] In order to switch to the second fixed gear ratio G2, now according to Figure 3 Reduce the load on the switching element K1 of the current (old) fixed gear G1.

[0057] like Figure 4 As can be seen, the transmission mechanism is coupled to the output shaft to transmit torque, and also coupled to the rotary transmission mechanism UG via the shaft to transmit torque. In other words, the second motor EMB operates as an electric motor with the driven element or gear ring 2 or wheel R and is powered by the high-voltage accumulator HVS. The internal combustion engine VM can be off or can be turned off.

[0058] The load on the first switching element K1 (K1 is shown in dashed line) is now reduced by means of a speed change mechanism via torque superposition through the output shaft.

[0059] At this point, the core of the invention begins, which will again be referred to Figure 13 and 14 To explain.

[0060] According to Figure 5 The state 3 shown in the active position will then switch element K1 to be disconnected / unconnected, as shown in the image. Figure 6 As shown in K1, which is now open.

[0061] Then it is based on Figure 7 State 4 refers to optimized electrical and continuous transmission ratio adjustment in the power split transmission ratio stage (E-CVT). This is in Figure 8 The rotational speed movement on the sun gear 3 is shown in the diagram. Therefore, after the first switching element K1 is opened, the transmission ratio of the second transmission ratio stage (fixed gear) G2 is set by continuous transmission ratio adjustment of the transmission mechanism or the motor EMA. The brake B2 remains open here.

[0062] This means that three-axis operation occurs, thereby reducing the speed difference on the second switching element B2.

[0063] Figure 9 State 5 is shown, in which switching element B2 is closed for the new fixed gear G2.

[0064] Here, in Figure 10 As can be seen, once the speed difference decreases to zero or below a certain limit, the second switching element B2 closes. Thus, the second switching element B2 takes over the load from the transmission mechanism, and the transmission mechanism can be decoupled (see...). Figure 10 (The dashed line indicates the motor EMB). Brake B2 is not yet mounted (B2 is shown by the dashed line).

[0065] exist Figure 11 In the process of reaching state 6 and directly connected state 7, or reaching state 1 again, in which state the new switching element B2 can be carried (in Figure 12 (B2 is completely closed in the middle). Figure 12 The gear shifting process is complete.

[0066] exist Figure 13 The diagram shows an intermediate state according to the invention between states 5 and 6, which is achieved by the functional module ZVV (tooth clamping prevention) in the control unit SG or by a method implemented by the control unit SG, the effect of which functional module or method on the torque M on the switching element SE (B2 in this case) as a function of time t. Figure 14 The text shows:

[0067] The following is based on the generated evidence. Figure 14 Example of torque curve M:

[0068] In the tooth-to-tooth position, an actuating force of, for example, 200 N is applied to the form-locking switching element SE (e.g., B2), which has an effective radius of, for example, 100 mm. The assumed coefficient of friction is, for example, 0.15. This results in an estimated frictional torque M1 to be overcome, amounting to 3 Nm. The ratio of the speed difference gradient to the effective torque (M-M1) is generated based on the effective moment of inertia (J), here 10 rad / Nm². 2 In the worst-case scenario, the switching element SE must be rotated 28° to be engaged, but engagement with a speed difference greater than 10 rad / s is not permitted.

[0069] Accordingly, it is concluded Figure 14 The time interval T2-T1 (0.1s (waiting duration) in the middle) ) and 100 rad / s 2The angular acceleration. Based on the ratio of the speed difference gradient to the effective torque (M-M1), the maximum permissible additional torque dM of 10 Nm is calculated. Therefore, it is not allowed to exceed 3 Nm + 10 Nm = 13 Nm (M1 + dM = M2) on the switching element SE. Therefore, the torque plateau M2 of M1 + dM is predetermined to decrease during the waiting period of 0.1 s in T2-T1, which is 13 Nm in this case. Before reaching the waiting period T2-T1 and after the end of the waiting period, the initially required torque gradient dM / dt is achieved on the switching element SE: the predetermined torque gradient dM / dt from T0 to T1 and from T2 to T3. T0 is the time point from which it is assumed that the actuator of the switching element SE has moved the switching element SE to at least the tooth-to-tooth position, and ideally, to the engagement region. Starting from T0, a new form-locking switching element SE (B2 in this case) is allowed to carry torque M according to the proposed functional process to avoid damage or discomfort. The torque gradient dM / dt is predetermined from T2 to T3 until the torque M3 in the fully loaded fixed gear (G2 in this case) is reached.

[0070] If the torque does not remain constant over the time range T1 to T2, but increases slightly—still not allowed to exceed 13 Nm—the duration for reliable engagement will increase because the required torsional angle must still be achieved (see [reference]). Figure 14 (The dashed line in the middle).

[0071] therefore, Figure 14 An example is shown of the engagement process of the switching element SE in conjunction with the control of the internal combustion engine VM and / or the electric motor generator EMA in the DHT, so that the switching element SE can also be reliably engaged from possible tooth-to-tooth positions.

[0072] The entire gear shifting process, starting from the current fixed gear and having intermediate states according to the present invention, is summarized as follows:

[0073] - The old switching element K1 is unloaded by the motor, or the load on the old switching element K1 is reduced by the motor (state 2).

[0074] - Activate the function module DZA for speed adjustment (which generates a load change on the switching element K1 to be opened and simultaneously controls the actuator for opening the switching element K1).

[0075] - Turn on the old switching element K1 (state 3) (switch to E-CVT mode).

[0076] - Speed ​​adjustment for gear ratio adjustment (nG1 => nG2) is performed in the transmission via E-CVT mode (state 4).

[0077] - Connect a new switching element (B2) (state 5).

[0078] - Activate the functional module ZVV according to the invention in the control unit SG to perform the switching element SE (B2 in this case) for reliable engagement of the form-locking device.

[0079] - Make the new switching element (B2) carry (state 6).

[0080] - Separate the motor EMA and EMB (state 7 = state 1) => new fixed position G2.

[0081] The method implemented using the functional module ZVV according to the present invention is summarized as follows:

[0082] - Starting from time point (T0), the switching element (SE; B2) to be engaged carries torque (M) with a predetermined torque gradient (dM / dt), at which time point it can at least start from the tooth-to-tooth position (the gear may also have been engaged by chance).

[0083] - In particular, the frictional torque (M1) to be overcome is estimated based on the effective radius, the assumed friction value, and the available actuation force of the switching element (SE) actuator.

[0084] - In particular, the predetermined waiting duration period (T2-T1) is determined based on the effective moment of inertia, the maximum torsional angle, and the maximum predetermined speed difference gradient.

[0085] - A maximum permissible torque (M1) is predetermined during the waiting period (T2-T1), which is determined by the estimated frictional torque (M1) to be overcome and the additional torque (dM);

[0086] - The additional torque (dM) is determined in particular by the ratio of the resulting speed difference gradient to the effective torque (M-M1) or based on the effective moment of inertia (J) of the switching element to be engaged;

[0087] - After the waiting period (T2-T1) ends (or when the gear has been engaged but not in the tooth-to-tooth position), the torque control is re-preset with a predetermined torque gradient (dM / dt) until the torque (M2) is fully loaded in the new fixed gear (G2 in this case) is reached (at time T3).

Claims

1. A motor vehicle having at least two drive motors, wherein, At least one drive motor is an electric motor (EMA), the motor vehicle has a high-voltage accumulator (HVS), an automatic transmission, and an electronic control unit (SG), the automatic transmission having at least one fixed gear ratio stage (G1; G2) and at least one power-split gear ratio stage (E-CVT) and / or at least one series gear ratio stage for gear ratio adjustment toward at least one fixed gear ratio stage (G1; G2), the electronic control unit having a functional module (ZVV) that allows for the predetermined torque curve of the following type within the range of gear ratio adjustment between the engagement and load of the switching element (SE; B2) to control the internal combustion engine (VM) and the electric motor (EMA): - At a first time point (T0), the switching element (SE; B2) to be engaged is borne with a predetermined torque gradient (dM / dt) until a second time point (T1), at which time point at least a tooth-to-tooth position can be assumed. - During the predetermined waiting period, from the second time point (T1) to the third time point (T2), the predetermined torque (M) is limited to the maximum permissible torque (M2), and - After the waiting period ends or when the engagement state is detected, the switching element (SE; B2) to be engaged continues to be carried with a previously predetermined torque gradient (dM / dt).

2. The motor vehicle according to claim 1, characterized in that, Torque (M) control is performed in a pulse manner during the predetermined waiting period.

3. The motor vehicle according to claim 1 or 2, characterized in that, The maximum permissible torque (M2) is determined by the estimated frictional torque (M1) to be overcome and the additional torque (dM).

4. The motor vehicle according to claim 3, characterized in that, The frictional torque (M1) to be overcome is estimated based on the effective radius, the assumed coefficient of friction, and the available actuation force of the switching element actuator.

5. The motor vehicle according to claim 3, characterized in that, The additional torque (dM) is determined based on the maximum permissible difference in switching element speeds and the effective moment of inertia (J).

6. The motor vehicle according to claim 1 or 2, characterized in that, The predetermined waiting period is determined based on the effective moment of inertia (J), the maximum torsional angle, and the maximum predetermined speed difference gradient.

7. An automatic transmission for a motor vehicle according to any one of claims 1 to 6, the automatic transmission comprising a rotary transmission mechanism (UG), at least one switching element, at least one motor (EMA) as a drive motor, and an actuator controllable by means of a functional module (ZVV) by an electronic control unit (SG), said motor being part of the transmission mechanism, wherein, Within the range of transmission ratio adjustment between the engagement and disengagement of the switching element, the following types of torque curves can be predetermined for controlling the internal combustion engine (VM) and the electric motor (EMA): - At a first time point (T0), the switching element to be engaged is borne with a predetermined torque gradient (dM / dt) until a second time point (T1), at least a tooth-to-tooth position can be assumed at the first time point. - During the predetermined waiting period, from the second time point (T1) to the third time point (T2), the predetermined torque (M) is limited to the maximum permissible torque (M2), and - After the waiting period ends or when the engagement state is detected, the switching element to be engaged continues to be carried with a previously predetermined torque gradient (dM / dt).

8. An electronic control unit (SG) for a motor vehicle according to any one of claims 1 to 6 or an automatic transmission according to claim 7, the electronic control unit having a functional module (ZVV).

9. A method for switching an automatic transmission in a motor vehicle according to any one of claims 1 to 6, wherein, By means of an electronic control unit (SG), a torque curve of the following type is predetermined within the range of gear ratio adjustment between the engagement and bearing of the switching element (SE; B2) to control the internal combustion engine (VM) and the electric motor (EMA): - At a first time point (T0), the switching element (SE; B2) to be engaged is borne with a predetermined torque gradient (dM / dt) until a second time point (T1), at which point it can at least start at a tooth-to-tooth position. - During the predetermined waiting period, from the second time point (T1) to the third time point (T2), the predetermined torque (M) is limited to the maximum permissible torque (M2), and - After the waiting period ends or when the engagement state is identified, the switching element (SE; B2) to be engaged continues to be carried with a previously predetermined torque gradient (dM / dt).

Images