DE102004035534B4 - Method for controlling a transmission - Google Patents

Abstract

Method for controlling a transmission, in particular a double clutch transmission (1), with at least a first partial transmission (5) and a second partial transmission (6), the first partial transmission (5) being connectable to a transmission input element (2) by means of a first shift element (3) and the second sub-transmission (6) can be connected to the transmission input element (2) by means of a second shift element (4), the first and second sub-transmissions (5, 6) having wheel sets (20, 21, 22, 23) for setting the gear ratio, so that when there is a change of gear ratio by one gear ratio, the drive torque from one sub-transmission (5, 6) to the other sub-transmission (6, 5) takes place by controlled, essentially simultaneous connection and disconnection of the first and second shifting elements (3, 4) A control and evaluation unit (40) activates such an emergency program strategy when a fault or a failure of the transmission or a switching element is detected, so that in the event that one of the partial transmissions (5, 6) or the related shift element (3, 4) is affected by the error, the control and evaluation unit (40) for a gear change essentially only the at least one other partial transmission (6, 5) with the assigned shift element (4, 3), characterized in that as part of an emergency program strategy and in the event that one of the partial transmissions (5, 6) which comprises a reverse gear or the related shift element (3, 4) by the If the error is affected, the control and evaluation unit (40) controls only the remaining at least one other sub-transmission (6, 5) with the associated shift element (4, 3) for a change of gear ratio, in the event that the shift element (3 , 4) of the defective partial transmission can at least partially be engaged, when the reverse gear is engaged, the latter is engaged and the associated shift element (3, 4) is at least partially engaged.

Description

The invention relates to a method for controlling a transmission, in particular a double clutch transmission for a motor vehicle, according to the kind defined in the preamble of claim 1.

So-called double clutch transmissions are known for motor vehicles, the mode of operation of which, for example, in the DE 199 44 879 A1 is described. These transmissions have at least two sub-transmissions which can be connected to the transmission input shaft on the input side by means of a coupling in each case and have a common output. Depending on the gear ratio selection, the transmission input can be connected to the downstream respective partial transmission by means of one or the other clutch. Such gears have at least two switchable gear ratios with respective gear sets within the sub-gears, so that the gear ratio between the gear input and gear output can be determined by selecting the gear ratio of the respective sub-gear, the gear ratio being switched depending on the synchronized and engaged gear set.

In practice, the arrangement of the gear ratios with respect to the respective sub-transmission is selected so that a translation change to the next higher or lower transmission ratio of the sub-transmission takes place by opening and closing the shift elements provided for this purpose, so that the translation change takes place under load without or without substantial interruption in tractive power can. The successive gear ratios are typically assigned to different sub-transmissions.

Double clutch transmissions are controlled electronically, the actuation of the gear change, that is to say the actuation of the clutches or the switching of the wheel sets, being controlled by means of an actuator system, such as, for example, a pressure medium actuatable actuator system or control hydraulics.

In the case of such transmissions, the sub-transmissions, the shifting elements or the respective actuator system may have errors or a failure under certain operating conditions. This means that the motor vehicle may no longer be able to continue driving with such a transmission in such a fault situation.

From the DE 101 49 528 A1 is known to continue driving the vehicle with the other clutch in the event of failure of a clutch of a dual clutch transmission.

The object of the invention is to provide a method for controlling a transmission of the type mentioned in the introduction, by means of which the transmission can be controlled or switched in the event of a fault or failure in such a way that the motor vehicle can still be driven, even if with restrictions.

According to the invention, this object is achieved by a method having the features of patent claim 1.

In a method according to the invention for controlling a transmission, in particular a double clutch transmission, with a first partial transmission and a second partial transmission, the first partial transmission being connectable to a transmission input element by means of a first shift element and the second partial transmission being connectable to the transmission input element by means of a second shift element, the first and second sub-transmissions having gear sets for gear ratio setting, so that when a gear ratio is changed by one gear ratio, the drive torque from one sub-transmission to the other sub-transmission takes place through controlled, essentially simultaneous engagement and disengagement of the first and second shifting elements According to the invention, it is advantageous if a control and evaluation device activates such an emergency program strategy when a fault or a failure of the transmission or a switching element is detected, so that in the event that one of the Sub-transmission or the relevant shift element is affected by the error, the control and evaluation unit for a gear change essentially only controls the at least one other sub-transmission with the associated shift element.

Such a dual clutch transmission is appropriately shifted in the alternating arrangement of the successive gear ratios or gears on the existing partial transmissions by overlapping disengagement and engagement of the assigned shifting elements or clutches, so that no or no significant interruption of traction occurs in normal operation, which the driver considers uncomfortable or possibly feels unsafe if the vehicle engine reaches a speed limit during an overtaking maneuver and an upshift is necessary.

If, however, a failure or a fault in a subsystem of the transmission, such as one of the shift elements designed as a clutch or a controlling hydraulic system, a synchronization device or its actuation, by sensors or other important components, or an entire sub-transmission, is detected, an emergency program strategy is activated to continue driving under partially restricted conditions reach and avoid the vehicle stopping. In the event that one of the sub-transmissions or the related shift element is affected by the error, the control and evaluation unit advantageously only controls the other, non-defective sub-transmission with the associated shift element for a change of gear ratio.

Since in a dual clutch transmission there is in principle a transmission with two spur gears, such control is in the event of failure of a clutch system or a synchronization system, which, for. B. is monitored via a distance sensor system, possible with continuing on a transmission side.

The control according to the invention permits limited functionality with respect to the gear ratios that are still to be switched, although not all gears or gear ratios can be shifted anymore, but these without significant speed or torque restrictions in the respective gears. However, in order to use the remaining gears, an engine control intervention is necessary in order to carry out the gear changes with traction interruption.

A first control strategy is thus used in normal operation, which allows gear changes without interruption in tractive power and engine control intervention, and a second control strategy is implemented for the emergency strategy, which - like in an automated manual transmission - allows the gear control to perform the gear changes during the shift by means of engine control intervention by the transmission control.

According to the invention, it is advantageous if in the context of an emergency program strategy and in the event that one of the preferably two partial transmissions, which includes the reverse gear, or the shifting element in question is affected by the error, the control and evaluation unit for a change of translation essentially only the remaining one controls other sub-transmissions with the shift element assigned to them, and in the event that the shift element of the defective sub-transmission can at least partially be engaged, when the reverse gear is engaged, the latter is engaged and the associated clutch is at least partially engaged.

The reverse gear is typically engaged from standstill or close to standstill, so that an engine control intervention may not be necessary. However, engine control intervention can also be made in other operating situations. This is also useful for switching the forward gears while the vehicle is in operation. In the event that the shift element of the partial transmission with reverse gear can only be partially engaged, it is advantageous if the vehicle engine is limited by the engine control in such a way that the engine torque is limited to the value of the torque that can be transmitted by the shift element.

According to a preferred embodiment of the invention, it is advantageous if, as part of the emergency program strategy for a translation change within a sub-transmission to change the translation, the associated shift element is first disengaged, then the respective wheel set is decoupled to disengage the gear ratio, then the gear set is synchronized with the gear ratio to be inserted and is coupled and then the associated switching element is engaged again.

Furthermore, it is expedient if an engine control intervention continues to take place by means of the engine control in order to lower the engine speed and / or the engine torque before the gear change and / or before the shifting element is disengaged and after the gear change and / or after the shifting element is engaged, the engine speed and / or set the engine torque back to a predeterminable value.

According to the invention, a sensed error or failure of a shift element or the actuator system of the shift element or also of the partial transmission is assessed as an error or failure. This can be determined, for example, by monitoring the actuation and the expected sensor signals of the transmission in relation to the actually occurring sensor signals. A fault or failure of the actuator system of the switching element can also be a fault or failure of the hydraulic system, the pressure regulator, a valve, a pump or a sensor. A failure of the shift element or of the clutch itself, for example due to unauthorized lowering of the coefficient of friction due to contamination of the shift element, can also be taken into account.

Further advantages and advantageous developments of the invention result from the patent claims and the embodiment described in principle with reference to the drawing.

• 1 ein vereinfachtes Räderschema eines Getriebes eines Kraftfahrzeuges,
• 2 eine schematische Darstellung eines Verfahrensablaufs zur Ansteuerung des Getriebes der 1 als Blockschaltbild.

It shows:

• 1 a simplified wheel diagram of a transmission of a motor vehicle,
• 2nd a schematic representation of a process sequence for controlling the transmission of the 1 as a block diagram.

The 1 shows schematically simplified as a dual clutch transmission 1 trained transmission of a motor vehicle. The gear 1 has two clutches 3rd , 4th as switching elements, which with a transmission input shaft 2nd are connected and via which the transmission input torque M_in on a first partial transmission 5 and a second sub-transmission 6 which on a countershaft 8th are arranged, is feasible.

The first clutch 3rd connects in the engaged state via a hollow shaft 9 the transmission input shaft 2nd with the first sub-transmission 5 , and the second clutch 4th connects the transmission input shaft when engaged 2nd with the second sub-transmission 6 . The first and the second sub-transmission 5 , 6 are each on the output side with a gearbox output shaft 7 connected.

Using actuators 10th , 11 can present two sets of wheels 20 , 21 of the first sub-transmission 5 and two sets of wheels 22 , 23 of the second sub-transmission 6 with the countershaft 8th synchronized and blocked or coupled so that the respective gear can be engaged.

The actuators 10th , 11 represent known synchronizations in the embodiment shown, such as hydraulic actuators that synchronize the wheel sets 20 , 21 , 22 , 23 Taxes. The hydraulic actuators preferably comprise a hydraulic pump, which can also be used together, valves, pressure regulators, actuators and sensors. For example, speed sensors can also be used 30th , 31 , 32 and 33 be used which is a transmission input shaft speed N_in , a transmission output shaft speed N_ab , as well as a speed N_K1 the first clutch 3rd and a speed N_K2 the second clutch 4th capture.

In the event of a gear change or gear change, the respective wheel sets are synchronized and blocked, wherein a gear of one of the partial transmissions is engaged when the clutch is closed and the gear to be engaged is characterized by the clutch that is still disengaged.

If a gear change is now made, the two clutches 3rd , 4th overlapping and disengaged so that a gear change can take place without or without substantial interruption of the tractive force. There is thus a change from one sub-transmission to the other sub-transmission.

The control of the actuators 10th , 11 an in takes over to change gear 1 symbolically represented electronic evaluation and control unit 40 . This controls the actuators 10th , 11 for actuating the partial gears 5 , 6 how to synchronize and lock the wheel sets 20 to 23 , and the clutches 3rd and 4th on.

The 2nd shows a schematic representation of a control method according to the invention.

This is done first in a test module 100 queried whether an error or a failure of a partial transmission 5 , 6 or a clutch 3rd , 4th is present.

If this is not the case, a subsequent control block is used 101 a gear change without interruption of tractive power by overlapping engagement or disengagement of the two clutches 3rd , 4th and a gear change by changing the partial transmission according to the control block 108 performed. A motor intervention by the engine control to reduce the engine torque is preferably not carried out, but if necessary, an engine intervention with a small torque reduction can also be carried out.

If in the test module 100 an error or failure is detected becomes a control block 102 branches, in which a gear change with interruption of traction is initiated.

In a subsequent distinction module 103 is queried whether the defect of the clutch or the partial transmission with respect to the clutch 4th or the partial transmission 6 is present, which also includes the reverse gear in the present embodiment.

If this is not the case, the sub-transmission that is still functioning is the sub-transmission 6 with the reverse gear. Thus, with only this sub-transmission, if necessary, with loss of comfort and with failure of a part of the gear ratio stages of the transmission, it is possible to continue driving according to a control block 107 be guaranteed. In the present case, the gear ratio changes are carried out with an interruption in tractive force under engine control intervention by means of speed and / or engine torque control. The corresponding motor intervention generates a comparatively high torque reduction.

Is the error regarding the partial transmission? 6 with reverse gear or the related clutch 4th before, so in a differentiation module 104 asked whether the relevant clutch 4th is at least partially indentable.

If this is the case and the reverse gear can still be synchronized and engaged, then according to a subsequent control block 106 a gear change with the non-defective partial transmission 5 be carried out, for engaging the reverse gear on the other partially defective sub-transmission 6 is changed. The relevant coupling 4th can, if necessary, be engaged completely or only partially up to a specifiable transferable torque for engaging the reverse gear.

However, this is according to the query from the distinction module 104 not the case, so in a subsequent control block 105 only a forward gear of the unaffected sub-transmission 5 be inserted. The gear ratio changes are carried out with traction interruption under engine control intervention by speed and / or engine torque control.

Reference list

1

Double clutch

2nd

Transmission input shaft

3rd

first clutch

4th

second clutch

5

first partial transmission

6

second sub-transmission

7

Transmission output shaft

8th

Countershaft

9

Hollow shaft

10th

Actuator, synchronization

11

Actuator, synchronization

20

Wheelset

21st

Wheelset

22

Wheelset

23

Wheelset

30th

Speed sensor

31

Speed sensor

32

Speed sensor

33

Speed sensor

40

Control and evaluation unit

100

Test module

101

Control block

102

Control block

103

Distinctive module

104

Distinctive module

105

Control block

106

Control block

107

Control block

108

Control block

M_in

Transmission input torque

N_ab

Transmission output shaft speed

N_in

Transmission input shaft speed

N_K1

Speed of the first clutch

N_K2

Second clutch speed

Claims (5)

Method for controlling a transmission, in particular a double clutch transmission (1), with at least a first partial transmission (5) and a second partial transmission (6), the first partial transmission (5) being connectable to a transmission input element (2) by means of a first shift element (3) and the second sub-transmission (6) can be connected to the transmission input element (2) by means of a second shift element (4), the first and second sub-transmissions (5, 6) having wheel sets (20, 21, 22, 23) for setting the gear ratio, so that when there is a change of gear ratio by one gear ratio, the drive torque from one gearbox (5, 6) to the other gearbox (6, 5) is achieved by controlled, essentially simultaneous engagement or disengagement of the first and second shifting elements (3, 4) A control and evaluation unit (40) activates such an emergency program strategy when a fault or a failure of the transmission or a switching element is detected, so that in the event that one of the partial transmissions (5, 6) or the related shift element (3, 4) is affected by the error, the control and evaluation unit (40) for a gear change essentially only the at least one other partial transmission (6, 5) with the associated shift element (4, 3), characterized in that as part of an emergency program strategy and in the event that one of the partial transmissions (5, 6) which comprises a reverse gear or the related shift element (3, 4) by the If the error is affected, the control and evaluation unit (40) essentially only controls the remaining at least one other sub-transmission (6, 5) with the associated shift element (4, 3) for a gear change, in the event that the shift element (3 , 4) of the defective partial transmission can at least partially be engaged, when the reverse gear is engaged, the latter is engaged and the associated shift element (3, 4) is at least partially engaged. Procedure according to Claim 1 characterized in that within the framework of the emergency program strategy for a gear change within a sub-transmission (5, 6) for shifting the associated shift element (3, 4) only disengaged is then decoupled the respective gear set to disengage the gear ratio, then the gear set of the gear ratio to be engaged is coupled and then the associated shift element is engaged again. Procedure according to Claim 2 , characterized in that a motor intervention continues to take place by means of motor control in order to lower the motor speed and / or the motor torque before the gear ratio change and / or before the shift element (3, 4) is disengaged and after the gear ratio change and / or after the shift element () is switched on. 3, 4) to set the engine speed and / or the engine torque back to a predeterminable value. Procedure according to one of the Claims 1 to 3rd , characterized in that a detected error or failure is a failure of a switching element (3, 4) or the actuator system of the switching element (3, 4). Procedure according to Claim 4 , characterized in that a fault or failure of the actuator system (10, 11) of the switching element (3, 4) is a sensed fault or failure of the hydraulic system, the pressure regulator, a valve, a pump or a sensor.

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