DE102019219959B4 - Method for shift control of an automated group transmission - Google Patents

Abstract

Method for shift control of an automated group transmission (1), which is arranged in a drive train of a motor vehicle between a drive motor and an axle drive and comprises at least two sub-transmissions (HG, GP), which can each be shifted via positive shifting elements, with a shifting process of the group transmission (1st ) includes a change of gear ratios in the at least two sub-transmissions (HG, GP) and synchronization of the second sub-transmission (GP) takes place after the change to a target gear ratio (G3) in the first sub-transmission (HG) has been carried out, with the synchronization of the second sub-transmission (GP) takes into account whether a tooth-on-tooth position has occurred when the target gear ratio (G3) of the first sub-transmission (HG) is engaged, with the presence of a tooth-on-tooth position in the first sub-transmission (HG), the synchronization of the second sub-transmission (GP) with a reduced synchronous torque required lgt, where the synchronous torque to be applied to synchronize the second sub-transmission is dimensioned such that a maximum torque that can be transmitted via the tooth-on-tooth position is not exceeded and a maximum torque that can be transmitted via the tooth-on-tooth position is a maximum permissible speed gradient for synchronizing the second sub-transmission (GP) is calculated.

Description

The invention relates to a method for shift control of an automated group transmission. Furthermore, the invention relates to a control unit which is designed to carry out the method and a corresponding computer program for running the method on the control unit. Furthermore, the invention relates to an automated group transmission and a motor vehicle with an automated group transmission.

When shifting gears in an automated group transmission involving a positive-locking shifting element, a so-called tooth-on-tooth position can occur on the positive-locking shifting element, which prevents the positive-locking shifting element from closing. In order to implement fast and comfortable shifts, tooth-on-tooth positions must be recognized and resolved when executing a shift.

A method for switching control of an automated group transmission is already from DE 10 2007 043 694 A1 known.

the DE 10 2017 222 436 A1 discloses a method for operating a drive train of a motor vehicle with a hybrid drive having an internal combustion engine and an electric machine.

A method for operating a motor vehicle drive train comprising a motor, a multi-group transmission and a clutch connected between the motor and the multi-group transmission is known from EP 2 215 385 B1 known. The multi-group transmission includes a dog-shifted main transmission and at least one synchronized group, namely a synchronized front-mounted group and/or a synchronized rear-mounted group.

the DE 10 2009 002 921 A1 discloses a method for operating a drive train which has at least one drive unit, a transmission and an output.

The object of the present invention is to provide a novel method for shift control of an automated group transmission with positively shiftable shifting elements. In addition, a control unit that is designed to carry out the method and a computer program for executing the method on the control unit are to be specified.

From a procedural point of view, this object is achieved by the features of patent claim 1. A control device designed to carry out the method according to the invention is also the subject of patent claim 5. With regard to a computer program, reference is made to patent claim 6. Advantageous developments are the subject matter of the subclaims and the following description and drawings. Features that are described in connection with the method should also apply in connection with the control unit according to the invention and the computer program according to the invention and vice versa, so that the disclosure of the individual aspects of the invention can always be referred to reciprocally.

According to the present invention, a method for shift control of an automated group transmission is provided. The automated group transmission is preferably arranged in a drive train of a motor vehicle between a drive motor and an axle drive. The group transmission comprises at least two sub-transmissions, each of which can be shifted via positively designed shifting elements. During a shifting operation of the group transmission, in which the gear ratios in the at least two partial transmissions are changed, the second partial transmission is synchronized after the change to a target gear ratio in the first partial transmission has been carried out. The method for shift control of the group transmission provides that when synchronizing the second sub-transmission, it is taken into account whether a tooth-on-tooth position has occurred when the target gear ratio of the first sub-transmission is engaged.

If there is no tooth-on-tooth position in the first sub-transmission, then a standard sequence is used to synchronize the second sub-transmission. For example, a defined synchronous torque can be provided by partially engaging a separating clutch arranged between the drive motor and the group transmission. In this case, the synchronous torque is dimensioned in such a way that a synchronous rotational speed for shifting the second sub-transmission is quickly reached, as a result of which the shifting process can be carried out with a short shifting time. The torque introduced into the group transmission via the separating clutch to synchronize the second sub-transmission can be in a range of 600 to 800 Newton meters, for example.

If, on the other hand, there is a tooth-on-tooth position in the first sub-transmission, then it is provided that the second sub-transmission is synchronized with a reduced synchronous torque. For this, the to synchronize the second Partial transmission to be applied synchronous torque dimensioned in such a way that a maximum transmissible torque via the tooth-on-tooth position of the first partial transmission is not exceeded. This can prevent the shifting claws of the interlocking shifting element of the first partial transmission, which are on top of one another, from twisting while the second partial transmission is being synchronized. It is thus possible to avoid rattling of the positive-locking shifting element in the first sub-transmission, which would lead to the typical development of noise. This increases shifting comfort. The torque introduced via the separating clutch into the group transmission for synchronizing the second sub-transmission can be, for example, in a range of 100 to 200 Newton meters when a tooth-on-tooth position prevails in the first sub-transmission.

Within the framework of the maximum torque that can be transmitted, the synchronous torque can be adjusted depending on an expected switching time. In this way, a higher synchronous torque can be provided if a short shifting time is to be achieved. The higher synchronous torque shortens the synchronous time required to synchronize the second sub-transmission.

The maximum torque that can be transmitted via the tooth-on-tooth position can be determined, for example, from a contact pressure force acting on the tooth-on-tooth position. For example, if a pneumatic shift actuator is used to adjust the interlocking shift element, then the contact pressure at the tooth-on-tooth position can be derived via the pressure in the shift cylinder. The pressure in the shift cylinder can either be detected via a pressure sensor or can be determined via a valve function of the shift valves for actuating the shift cylinder with knowledge of the valve mass flows. The contact pressure force acting at the tooth-on-tooth position, the pressure in the shift cylinder and the valve mass flows via the shift valves can be both calculated and determined empirically and stored on a control unit.

Finally, a maximum permissible speed gradient for synchronizing the second sub-transmission is calculated from the maximum torque that can be transmitted via the tooth-on-tooth position. The maximum permissible speed gradient ensures that the dynamically effective torques for the inertial masses of the transmission parts to be synchronized do not exceed the maximum torque that can be transmitted via the tooth-on-tooth position. An actuator for synchronizing the second partial transmission is controlled in such a way that the maximum permissible speed gradient for synchronizing the second partial transmission is not exceeded. An internal combustion engine, for example, which can be connected to the transmission input shaft of the group transmission via a separating clutch, or an electric machine can be used as an actuator for synchronizing the second partial transmission.

The positive-locking shifting elements of the range-change transmission can be claw shifting elements, for example. The form-fitting shifting elements or the claw shifting elements can be unsynchronized or synchronized. The form-fitting shifting element can be designed in particular as a shifting clutch.

A shifting process is preferably to be understood as a process in which a positive-locking shifting element is brought into operative connection with another shifting element, in particular a gear wheel. As part of the shifting process, the group transmission changes from a first shifting state to a second shifting state. A shifting process can therefore be understood as shifting from one gear to another gear, shifting from one gear to a neutral position, and shifting from a neutral position to a gear.

The switching element can be adjusted by means of an adjustment device, which can be designed as a switching actuator. The shift actuator can be designed as a hydraulically or pneumatically actuated actuating cylinder or as an electric actuator, by means of which a shifting mechanism of the transmission is actuated to adjust the shifting element during a shifting operation.

A tooth-on-tooth position can be recognized by the fact that the detected shifting path of the shifting element for engaging a gear ratio of the transmission does not reach the end position but remains in an intermediate position. This persistence in the intermediate position forms an area in the recorded shifting path which is characteristic of a tooth-on-tooth position. This persistence can also be detected on a time basis, with a tooth-on-tooth position being recognized if the switching element has not reached its end position after a predefinable period of time.

A shifting path course can be detected, for example, by detecting the position of the shifting element using a path sensor system during the adjustment of the shifting element. The displacement sensor system can be designed as a displacement sensor, which can be arranged on the shift mechanism of the transmission, such as the shift actuator, a shift rail or a shift fork.

The invention also relates to a control device which is designed to carry out the method according to the invention. The control unit includes means that are used to carry out the method according to the invention. These means are hardware-side means and software-side means. The hardware means of the control device are data interfaces in order to exchange data with the assemblies involved in carrying out the method according to the invention. For this purpose, the control unit is also connected to the necessary sensors and, if necessary, also to other control units in order to record the data relevant to the decision or to forward control commands. The control unit can be designed as a transmission control unit, for example. The hardware means of the control unit are also a processor for data processing and possibly a memory for data storage. The software-side means are program modules for carrying out the method according to the invention.

A computer program according to the invention is designed to cause a control unit to execute the method according to the invention or a preferred development when the computer program is executed on the control unit. In this context, the subject matter of the invention also includes a computer-readable medium on which a computer program described above is stored in a retrievable manner.

• 1 einen schematischen Aufbau eines automatisierten Gruppengetriebes;
• 2 einen als Bereichsrückschaltung ausgeführten Schaltablauf, bei welchem beim Einlegen des Hauptgetriebes keine Zahn-auf-Zahn-Stellung auftritt; und
• 3 einen als Bereichsrückschaltung ausgeführten Schaltablauf, bei welchem beim Einlegen des Hauptgetriebes eine Zahn-auf-Zahn-Stellung auftritt.

The invention is explained in more detail below with reference to figures from which further preferred embodiments and features of the invention can be inferred. Show it

• 1 a schematic structure of an automated group transmission;
• 2 a shift sequence designed as a range downshift, in which no tooth-on-tooth position occurs when the main transmission is engaged; and
• 3 a shift sequence designed as a range downshift, in which a tooth-on-tooth position occurs when the main transmission is engaged.

This in 1 illustrated automated group transmission 1 is designed as a manual transmission of a motor vehicle. The motor vehicle can be a commercial vehicle, for example. Group transmission 1 includes a three-stage main transmission HG, an upstream group or splitter group GV that is upstream of the main transmission HG in terms of drive technology, and a range group GP that is downstream of the main transmission HG. The main transmission HG of group transmission 1 is designed here as a direct drive transmission with countershaft construction and has a main shaft W _H and two countershafts W _VG1 and W _VG2 , the first countershaft W _{VG1 being provided} with a controllable transmission brake Br.

The main transmission HG is designed in three stages with three transmission stages G1, G2, G3 for forward travel and one transmission stage R for reverse travel. Loose gears of the gear ratios G1, G2 and R are each rotatably mounted on the main shaft W _H and can be shifted via assigned clutches. The assigned fixed gears are arranged in a torque-proof manner on the countershafts W _VG1 and W _VG2 .

The shifting clutches of the transmission stages G3 and G2 and the shifting clutches of the transmission stages G1 and R are each combined in a common shifting package S1 or S2. The main transmission HG is designed to be switched in an unsynchronized manner.

The front-mounted group GV of group transmission 1 has two stages and is also designed in countershaft design, with the two transmission stages K1, K2 of front-mounted group GV forming two switchable input constants of main transmission HG. Due to a lower translation difference between the two translation stages K1, K2, the upstream group GV is designed as a splitter group. The idler wheel of the first transmission stage K1 is rotatably mounted on the input shaft W _GE , which is connected via a controllable separating clutch TK to a drive motor designed, for example, as an internal combustion engine or an electric motor.

The idler gear of the second transmission stage K2 is rotatably mounted on the main shaft W _H . The fixed gears of both transmission stages K1, K2 of the front-mounted group GV are each connected in a torque-proof manner to the countershafts W _VG1 and W _VG2 of the main transmission HG. The synchronized shifting clutches of the upstream group GV are combined in a common shifting package SV.

The range group GP of the group transmission 1, which is arranged downstream of the main transmission HG, is also designed in two stages, but in a planetary design with a simple planetary gear set. The sun gear PS is non-rotatably connected to the main shaft W _H of the main transmission HG, which is extended on the output side. The planetary carrier PT is coupled to the output shaft W _GA of the group transmission 1 in a torque-proof manner. The ring gear PH is connected to a switching package SP with two unsynchronized shifting clutches, through which the range group GP alternately connects the ring gear PH to a stationary one Housing part in a low speed stage L and through the connection of the ring gear PH with the planet carrier PT in a high speed stage S can be switched. The area group GP is designed so that it can be switched in an unsynchronized manner.

Activation of the clutches present in the range-change transmission for setting a desired gear ratio (K1, K2, G3, G2, G1, R, L, S) is controlled or regulated via a control unit. The control unit can preferably be designed as a transmission control unit. The shifting clutches are adjusted via a shifting mechanism, not shown here, with the shifting mechanism being actuated by means of a shift actuator.

The method according to the invention for shift control of group transmission 1 can be used both for a range upshift and for a range downshift. The gear ratio steps in the range group GP and in the main transmission HG are changed both during the range upshift and during the range downshift.

In the case of a range upshift, the transmission stage in the range group GP is first changed and then the transmission stage in the main transmission HG is changed. Thus, when changing the gear ratio of the range group GP, a tooth-on-tooth position can occur, which is taken into account in the subsequent synchronization of the target gear ratio of the main transmission HG.

In the case of a range downshift, on the other hand, the transmission stage in the main transmission HG is first changed and then the transmission stage of the range group GP is changed. When changing the gear ratio of the main transmission HG, this can lead to a tooth-on-tooth position, which is taken into account in the subsequent synchronization of the target gear ratio of the range group GP.

The method according to the invention is explained below using the diagrams in FIG 2 and 3 explained in more detail, considering a shift sequence executed as a range downshift. In the upper part of 2 and 3 the time curves of different speeds are shown, with nEng_act representing the actual speed of the drive motor, nInShaft_act the actual speed of the input shaft, nInShaft_tgt the target speed of the input shaft and nOutShaft_act the actual speed of the output shaft.

In the underlying part of 2 and 3 the gear stages are displayed, where Gear_act is the actual gear stage and Gear_tgt is the target gear stage.

In the part of 2 and 3 the actuation processes of the transmission elements are shown schematically, under the designation sGGrShf a shifting process within the range group GP, i.e. a shifting path when changing the actual transmission stage to the target transmission stage of the range group GP, under the designation sMGrShf a switching process within the main transmission HG, i.e. on Switching path when changing the actual gear ratio to the target gear ratio of the main transmission HG and under the designation sMGrSel a selection process within the main transmission HG, i.e. a selection path when changing the shift gate of the main transmission HG.

In the lower part of 2 and 3 time curves of different torques are shown, with trqCl_act representing the actual clutch torque, trqCl_req the target clutch torque and trqEng_act the actual torque of the drive engine.

the 2 shows a shift sequence designed as a range downshift, in which no tooth-on-tooth position occurs when the main transmission HG is engaged. A new target gear Gear_tgt is requested at time t1. It begins the load reduction on the drive motor, which is completed at the latest at time t2. At the same time, the separating clutch TK is pre-opened, ie disengaged to above the slip limit. At time t2, the actual gear ratio stage G1 of the main transmission HG is initially disengaged, ie the main transmission HG is switched to its neutral position (HG=N). At about the same time, the separating clutch TK is fully disengaged.

After that, by actuating the transmission brake Br between times t2 and t4, the countershaft W _VG1 and the input shaft W _GE connected to it via the input constant of the upstream group GV are braked and the target transmission ratio G3 of the main transmission HG is thus synchronized. At about the same time, the control of the drive motor to the target speed of the input shaft W _GE for the overall transmission ratio of the target gear begins. After reaching the synchronous speed at the relevant shifting clutch S1 of the main transmission HG, at time t3 there is first a gate change within the main transmission HG, ie switching from the shifting packet S2 to the shifting packet S1. At this point in time, a synchronized switchover of the upstream group GV can also be carried out via the Switching package SV take place from the input constant K1 to the input constant K2.

Then, at time t4, the target gear ratio G3 of the main transmission HG is engaged and at about the same time the actual gear ratio S of the range group GP is designed, ie the range group GP is switched to neutral (GP=N). Then, at time t5, the target transmission ratio L of the range group GP is synchronized by partially engaging the separating clutch TK by accelerating the input shaft W _GE and the main shaft W _H connected to it via the engaged target transmission ratio G3 of the main transmission HG. When the synchronous speed is reached at the corresponding shifting clutch SP at time t6, the target gear ratio L of the range group GP is engaged. After a short tooth-on-tooth position of the shifting clutch SP, the shifting claws of the shifting clutch SP engage at time t7 and the target gear ratio L of the range group GP is engaged. At time t7, the separating clutch TK is fully engaged. The load of the drive motor then builds up.

Since there was no tooth-on-tooth position when engaging the target transmission stage G3 of the main transmission HG in the described shifting sequence, a correspondingly high synchronous torque for synchronizing the target transmission stage L be provided to the area group GP. The synchronization of the area group GP can thus take place correspondingly quickly. This causes the actual speed of the input shaft nInShaft_act to rise rapidly, as a result of which the synchronous speed for engaging the target gear ratio L of the range group GP can be reached quickly and yet precisely. In the main transmission HG, the target transmission stage G3 is already engaged during the synchronization of the range group GP.

In contrast to the one in the 2 shown switching sequence, shows the 3 a shift sequence designed as a range downshift, in which a tooth-on-tooth position occurs when changing the gear ratio of the main transmission HG. The tooth-on-tooth position when engaging the target gear ratio G3 of the main transmission HG is determined between times t4 and t5.

Since when synchronizing the range group GP it should be avoided that the shifting dogs in the main transmission HG, which are on top of one another, slip over one another, the synchronization of the range group GP is adjusted if a tooth-on-tooth position has been determined in the main transmission HG. A shifting claw of a positive-locking shifting element that slides over one another at different speeds is also referred to as ratcheting.

It is provided that the partial engagement of the separating clutch TK at time t5, i.e. after a tooth-on-tooth position has been detected in the main transmission HG, takes place in such a way that, compared to the partial engagement of the separating clutch TK, when no tooth-on -tooth position prevails, a lower synchronous torque prevails. The partial engagement of the separating clutch TK also takes place more slowly, as a result of which the speed gradient is correspondingly lower until the synchronous speed is reached.

The synchronous torque generated via the separating clutch TK and the drive motor is dimensioned in such a way that a maximum torque that can be transmitted via the tooth-on-tooth position in the main transmission HG is not exceeded. Although this increases the time for synchronizing the range group GP, ratcheting in the main transmission HG, which would lead to the typical development of noise, can be avoided.

When the synchronous speed is reached at the corresponding shifting clutch SP at time t6, the target gear ratio L of the range group GP is finally engaged. The target transmission stage G3 of the main transmission HG also engages after the tooth-on-tooth position has resolved. At time t6, the separating clutch TK is fully engaged and the load of the drive motor is built up.

Reference List

1

group transmission

HG

first partial transmission, main transmission

G1

First translation stage of HG

G2

Second translation stage of HG

G3

Third translation stage of HG

R

Backward translation level of HG

S1

First switching package from HG

S2

Second switching package from HG'

gp

second partial transmission, range group

S

Fast driving stage of GP

L

Slow speed level from GP

SP

Switch pack from GP

PH

ring gear from GP

hp

Sun gear from GP

pt

Planet carrier from GP

GM

Split group, upstream group

K1

First translation stage of GV

K2

Second translation stage of GV

SV

Switch pack from GV

WGA

output shaft

WGE

input shaft

WH

main shaft

WVG1

First countershaft from HG

WVG2

Second countershaft from HG

TC

disconnect clutch

brother

transmission brake

t

time

t0 - t7

Points in time for area switchback

nEng_act

Actual speed of the drive motor

nlnShaft_act

Actual input shaft speed

nlnShaft_tgt

Target speed of the input shaft

nOutShaft_act

Actual speed of the output shaft

Gear_act

actual gear

Gear_tgt

target gear

sGGrShf

Shifting path range group

sMGrShf

Main gear shift path

sMGrSel

Main transmission selector path

trqCI_act

Actual clutch torque

trqCI_req

target clutch torque

trqEng_act

Actual engine torque

Claims (8)

Method for shift control of an automated group transmission (1), which is arranged in a drive train of a motor vehicle between a drive motor and an axle drive and comprises at least two sub-transmissions (HG, GP), which can each be shifted via positive shifting elements, with a shifting process of the group transmission (1st ) includes a change of gear ratios in the at least two sub-transmissions (HG, GP) and synchronization of the second sub-transmission (GP) takes place after the change to a target gear ratio (G3) in the first sub-transmission (HG) has been carried out, with the synchronization of the second sub-transmission (GP) takes into account whether a tooth-on-tooth position has occurred when the target gear ratio (G3) of the first sub-transmission (HG) is engaged, with the presence of a tooth-on-tooth position in the first sub-transmission (HG), the synchronization of the second sub-transmission (GP) with a reduced synchronous torque required lgt, where the synchronous torque to be applied to synchronize the second sub-transmission is dimensioned such that a maximum torque that can be transmitted via the tooth-on-tooth position is not exceeded and a maximum torque that can be transmitted via the tooth-on-tooth position is a maximum permissible speed gradient for synchronizing the second sub-transmission (GP) is calculated. procedure after claim 1 , characterized in that a contact pressure force is determined at the tooth-on-tooth position and the maximum torque that can be transmitted via the tooth-on-tooth position is determined from the determined contact pressure force. procedure after claim 1 , characterized in that at least one actuator for synchronizing the second partial transmission is controlled in such a way that the maximum speed gradient for synchronizing the second partial transmission (GP) is not exceeded. Method according to one of the preceding claims, characterized in that a downshift of the group transmission (1) is carried out with the following steps if the first partial transmission (HG) is of countershaft design with at least one countershaft (W _VG1 , W _VG2 ) is executed and an input shaft (W _GE ) of the group transmission (1) via a tax bare separating clutch (TK) is connected to the drive motor: - load reduction of the drive motor, - interpretation of the actual gear ratio of the main gearbox (HG = N) and - complete disengagement of the separating clutch, - synchronizing the target gear ratio of the main gearbox (HG) by actuation the transmission brake and - start of the control of the drive motor to the target speed of the input shaft (WGE), - engaging the target gear ratio of the main gear (HG) and - interpreting the actual gear ratio of the range group (GP = N), - detecting a tooth open -Tooth position when engaging the target gear ratio of the first sub-transmission (HG), - synchronizing the target gear ratio of the range group (GP) by partially engaging the separating clutch, the partial engagement of the separating clutch taking place in such a way that a tooth on-tooth position of the first sub-transmission transmitted synchronous torque is smaller than the maximum over the tooth-on-tooth position tolerable torque, - engagement of the target gear ratio of the range group (GP), - complete engagement of the separating clutch and - load build-up of the drive motor. Control unit designed to carry out a method according to one of the preceding claims. Computer program designed to cause a control unit to execute a method according to one of the preceding method claims when the computer program is executed on the control unit. Automated group transmission (1), which according to a control unit claim 5 comprises and according to a method according to any one of Claims 1 until 4 is operable. Motor vehicle with an automated group transmission (1). claim 7 .

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