DE102015215753A1 - Method and electronic control unit for controlling a multi-speed automatic transmission for a motor vehicle - Google Patents

Abstract

In the context of a method for controlling a multi-speed automatic transmission (30) for a motor vehicle (10), comprising a hydrodynamic torque converter (34) with converter lockup clutch (35), which in the power flow between a crankshaft (21) of a drive motor (20) of the motor vehicle (10 ) and a transmission input shaft (31) of the automatic transmission (30), and an electronic control unit (37) in which a shift strategy (SST) for specifying desired gears (G30) in the automatic transmission (30) and for setting desired Slip (N35) of the lockup clutch (35) is implemented, it is proposed that only if and only as long as the automatic transmission (30) within a predefined transmission output speed range with at least approximately constant transmission output speed (N32) or at least approximately constant driving speed is operated, the switching strategy (SST) deka activated and at the same time in the electronic control unit (37) implemented operating strategy (BST) is activated, in which a crankshaft speed (N21) of the crankshaft (21) is adjusted by control interventions in the automatic transmission (30) to an at least approximately constant value.

Description

The invention relates to a method for controlling a multi-speed automatic transmission for a motor vehicle, according to the preamble of claim 1. Furthermore, the invention relates to an electronic control unit, in which this method is implemented, as well as controlled by this method multi-speed automatic transmission.

In a modern motor vehicle with automatic or automated multi-speed transmission usually a control system is used, in which an appropriate for the respective driving situation gear is determined in an electronic control unit and transmitted as a shift command to a gear change device of the transmission. Methods for determining driving situations suitable transmissions are widely known from the prior art. From the DE 39 22 051 C2 For example, a method for controlling an automatic transmission is known in which by evaluating current data for engine throttle position, engine speed, vehicle lateral acceleration, vehicle speed, vehicle longitudinal acceleration and vehicle longitudinal deceleration discrete parameters for the current driving activity or for the current sportiness the driving style of the driver are determined. Each of these parameters are associated with upshift and downshift characteristics for gear selection in the transmission. To determine the current target gear, the parameters are mathematically weighted, so that the result of this weighting maps the appropriate to the current driving style of the driver gear and thus the current driver's request regarding the transmission gear. The current operating point of such a motor vehicle with automatic or automated multi-speed transmission is thus obtained primarily via the switching point control of the transmission.

Modern automatic transmissions have as a starting element usually a hydrodynamic torque converter with integrated lockup clutch, which is arranged in the power flow between the drive motor of the motor vehicle and an input shaft of the transmission. To avoid unnecessary losses in the drive train of the motor vehicle, this converter lockup clutch of the torque converter is usually kept largely closed during driving, which minimizes the slip losses in the torque converter.

The problem with such a shift point control is that the crankshaft speed of the drive motor moves at low vehicle speeds in the range between the idle speed of the drive motor - typically 800rpm - and the next higher gear associated shift point - typically up to 2000rpm. This can be perceived as unpleasant or uncomfortable by the driver of the motor vehicle as acoustic and also from the driving behavior, in particular in the so-called stop-and-go mode and in the low-speed range up to approximately 50 km / h.

Then is from the DE 44 11 940 A1 a control method for a continuously variable transmission (CVT) of a motor vehicle, in which when the motor vehicle is traveling at a constant vehicle speed, the engine speed of the gearbox driving internal combustion engine of the motor vehicle is kept constant, if this can be realized with small interventions in the continuously variable transmission of the transmission is. However, this control method is not applicable to a stepped transmission.

The present invention is based on the object to provide a novel method for controlling an electronic control unit and a hydrodynamic torque converter with lockup clutch comprehensive multi-stage automatic transmission for a motor vehicle, through which the motor vehicle can be operated with the automatic transmission in a more comfortable manner. Furthermore, an electronic control unit is to be created, in which this novel method is implemented. Furthermore, a multi-speed automatic transmission is to be created, which is controlled by this novel method.

This object is achieved by a method having the features of independent patent claim 1 and by a method having the features of independent claim 5. Advantageous embodiments and further developments of this method will become apparent from the dependent claims. An electronic control unit, in which this method is implemented, is the subject of independent claim 17. A controlled by this method multi-speed automatic transmission is the subject of independent claim 18.

Accordingly, in a first aspect of the invention, a method for controlling a multi-speed automatic transmission for a motor vehicle is proposed in which the automatic transmission comprises a hydrodynamic torque converter with lockup clutch arranged in the force flow between a crankshaft of a drive motor of the motor vehicle and an input shaft of the automatic transmission and an electronic control unit, in which a shift strategy for the specification of gears in the multi-stage transmission and for the specification of switching states of the lockup clutch is implemented, according to the invention only if and only as long as the automatic transmission is operated within a predefined transmission output speed range with at least approximately constant transmission output speed, deactivates the switching strategy and at the same time an operating strategy implemented in the electronic control unit independent of the shift strategy is activated, in which a crankshaft speed of the crankshaft of the drive motor by at least one approximately constant value is adjusted.

In this case, the predefined transmission output rotational speed range preferably forms a driving speed range between 10 km / h and 50 km / h.

In a second aspect of the invention, a method for controlling a multi-speed automatic transmission for a motor vehicle is proposed in which the automatic transmission is a hydrodynamic torque converter with lockup clutch arranged in the power flow between a crankshaft of a drive motor of the motor vehicle and an input shaft of the automatic transmission and an electronic control unit, in a switching strategy for the specification of gears in the multi-stage transmission and for setting switching states of the lockup clutch is implemented, according to the invention only if and only as long as the automatic transmission is operated within a predefined driving speed range with at least approximately constant driving speed, disables the switching strategy and at the same time a in electronic control unit regardless of the switching strategy implemented operating strategy we activated d, in which a crankshaft speed of the crankshaft of the drive motor is adjusted to an at least approximately constant value by control interventions in the multi-speed transmission.

Preferably, the driving speed range is predefined as a range between 10 km / h and 50 km / h.

Both inventive method allow over the prior art, a significant for the driver of the motor vehicle driving comfort in the driving range with constantly low vehicle speed, as a result of the now even engine noise and now no longer constantly fluctuating engine speed in the driver's field of view.

As an example of an operation of the automatic transmission with at least approximately constant transmission output speed or with at least approximately constant vehicle speed, a driving operation is mentioned in which the driver has set a constant target vehicle speed via a device suitable for this purpose. Such devices are also known by the name "cruise control".

Too frequent changes between shift strategy and operating strategy may be perceived by the driver of the motor vehicle under certain circumstances as a "nervous driving". To avoid this loss of comfort can be provided in one embodiment of the invention that the operating strategy is only activated instead of the shift strategy after the automatic transmission within the predefined transmission output speed range or driving speed range over a predefined period of time - for example, 10 seconds - with at least approximately constant transmission output speed or driving speed was operated.

In a preferred embodiment of both aspects of the invention, it is proposed that the engine speed of the drive motor be adjusted by specifying a combination of setpoint gear for the automatic transmission and setpoint slip for the lockup clutch. Accordingly, the target gear can be transmitted as a control intervention to a gear change device of the automatic transmission, while the target slip can be transmitted as a control intervention to a slip control device of the torque converter.

In another embodiment of the invention can be provided that when adjusting the engine speed of the drive motor and a current operating state of an existing addition to the drive motor electric motor with which the automatic transmission is driven, is taken into account.

In a further embodiment of the invention, it may be provided that the operating strategy replaces the switching strategy only if predefined criteria are met. Thus, to ensure a desired rapid heating of the drive motor and thus to improve the exhaust quality of the drive motor may be provided, for example, that the operating strategy is only activated instead of the shift strategy, when the drive motor and / or stepped automatic transmission are not in a defined warm-up mode or if a predefined lower temperature threshold for drive motor and / or stepped automatic transmission and / or ambient air is exceeded. As overheating protection of the automatic transmission, for example, be provided that the operating strategy is only activated instead of the switching strategy when a predefined upper temperature threshold for drive motor and / or automatic transmission and / or ambient air is not exceeded. For an express driver's request not to be dubbed, can be provided, for example, that the operating strategy is only activated instead of the switching strategy, if no driver request "sport" and / or "manual gear default" is present. To prevent malfunction, for example, be provided that the operating strategy is only activated instead of the switching strategy when the automatic transmission is not in emergency mode.

In a third aspect of the invention, an electronic control unit is proposed in which the inventive method for controlling a multi-speed automatic transmission for a motor vehicle is implemented in the electronic control unit.

In a fourth aspect of the invention, a stepped automatic transmission with an electronic control unit and a hydrodynamic torque converter with lockup clutch is proposed, wherein the method according to the invention for controlling the automatic transmission is implemented in the electronic control unit.

The invention will be explained in more detail with reference to the drawings. Showing:

1 a schematic of a powertrain in a motor vehicle; and

2 a flow diagram to illustrate the method according to the invention.

The invention relates to a method and an electronic control unit for controlling a multi - speed automatic transmission in a in 1 exemplified drive train of a motor vehicle, as well as controlled by this method stage automatic transmission. The motor vehicle is included herein 10 referred to, the automatic transmission with 30 , The automatic transmission 30 includes a torque converter 34 with integrated torque converter lockup clutch 35 , as the starting element of the automatic transmission 30 on the one hand with a transmission input shaft 31 connected or operatively connected and on the other hand with a crankshaft 21 a drive motor designed as an internal combustion engine 20 of the motor vehicle 10 connected or operatively connected. As an optional additional drive for the automatic transmission 30 is a dashed line an electric motor 22 drawn here, the example here with the transmission input shaft 31 connected or operatively connected. One me 32 designated transmission output shaft of the automatic transmission 30 is with an output of the motor vehicle 10 - here by example with wheels 40 of the motor vehicle 10 - connected or actively connected. During operation, the crankshaft rotates 21 with crankshaft speed N21, the transmission input shaft 31 with transmission input speed N31 and the transmission output shaft 32 with transmission output speed N32, so that the motor vehicle 10 moved at driving speed V10.

Furthermore, the stepped automatic transmission comprises 30 an electronic control unit 37 , on the one hand for controlling a gear change device 33 the stepped automatic transmission 30 is provided, on the other hand, for controlling a on the lockup clutch 35 acting slip control device 36 of the torque converter 34 , In this case, such a control can include both control tasks and control tasks.

In the electronic control unit 37 is a situational addressable switching strategy SST and - independent of this switching strategy SST - additionally implemented a situational addressable operating strategy BST. Depending on which of these two strategies is currently active, either shift strategy SST or the operating strategy BST transmits a target gear G30 to the gear change device 33 and a target slip S35 to the slip control device 36 , situational and the driver's request adapted to the current operating condition of motor vehicle 10 and stepped automatic transmission 30 , The specification of the setpoint slip S35 also includes the operating states "converter lockup clutch 35 opened "and" torque converter lockup clutch 35 closed".

Then is in the electronic control unit 37 implements an algorithm which maps the method according to the invention, which is described below with reference to FIG 2 in which a flow chart is shown for clarification of the method according to the invention, will be explained.

The in 2 illustrated flowchart is based on an embodiment of the method according to the invention, in which only if and only as long as the stepped automatic transmission 30 is operated within a predefined transmission output speed range DN32 with at least approximately constant transmission output speed N32, the switching strategy SST deactivated and at the same time in the electronic control unit 37 regardless of the switching strategy SST implemented operating strategy BST is activated, in which the crankshaft speed N21 of the crankshaft 21 of the drive motor 20 by controlling interventions in the automatic transmission 30 - Specifically, by control commands for both the gear change device 33 as well as for the slip control device 36 - Is adjusted to an at least approximately constant value. The process steps required for this purpose are indicated by X1 to X8.

The method starts with method step X1, in which a timer is started, which maps a predefined period of time. In the subsequent method step X2 it is checked whether the transmission output rotational speed N32 is currently within the predefined transmission output rotational speed range DN32 and is thereby at least approximately constant. If the test result is positive, the method is continued with method step X3, otherwise with method step X6.

In step X3, it is checked whether the timer has expired. If the test result is positive, the method is continued with method step X4, otherwise a return to method step X2 takes place. The timer thus ensures that the input conditions defined in method step X2 over the predefined period of time-for example, 5 or 10 seconds-are fulfilled.

• • Antriebsmotor 20 und/oder Stufenautomatgetriebe 30 befinden sich nicht in einem definierten Warmlaufmodus;
• • eine vordefinierte untere Temperaturschwelle für Antriebsmotor 20 und/oder Stufenautomatgetriebe 30 und/oder Umgebungsluft ist überschritten;
• • eine vordefinierte obere Temperaturschwelle für Antriebsmotor 20 und/oder Stufenautomatgetriebe 30 und/oder Umgebungsluft ist nicht überschritten;
• • kein Fahrerwunsch „Sport“ erkannt;
• • kein Fahrerwunsch „manuelle Gangvorgabe“ erkannt;
• • Stufenautomatgetriebe 30 befindet sich nicht im Notlaufmodus.

In method step X4, it is checked whether further predefined criteria are fulfilled. Such criteria may be, for example:

• • Drive motor 20 and / or stepped automatic transmission 30 are not in a defined warm-up mode;
• • a predefined lower temperature threshold for the drive motor 20 and / or stepped automatic transmission 30 and / or ambient air is exceeded;
• • a predefined upper temperature threshold for the drive motor 20 and / or stepped automatic transmission 30 and / or ambient air is not exceeded;
• • no driver request "Sport"detected;
• • no driver request "manual gear selection"detected;
• • Automatic gearbox 30 is not in runflat mode.

If the test result is positive, the method is continued with method step X5, otherwise a return to method step X2 takes place.

In method step X5, the previously activated switching strategy SST is switched over to the operating strategy BST. If the operating strategy BST is activated in method step X5, the method is continued with a return to method step X2.

While the operating strategy BST is active, controls the electronic control unit 37 the stepped automatic transmission 30 the crankshaft speed N21 of the drive motor 20 to an at least approximately constant value by a currently suitable for solving this control task combination of target gear G30 for the automatic transmission 30 and target slip S35 for the lockup clutch 35 is determined and thus determined target gear G30 as a control intervention to the gear change device 33 is transmitted while the thus determined target slip S35 as a control intervention to a slip control device 36 is transmitted. Is in the drive train of the motor vehicle 10 an electric machine 22 present, with which the automatic transmission is independent of or in addition to the drive motor 20 can be driven, when adjusting the crankshaft speed N21 by the operating strategy BST and the current operating state of this electric motor 22 be taken into account.

In step X6, which is addressed by the algorithm when the test result of method step X2 is negative, that is, when the transmission output speed N32 is no longer approximately constant or is no longer within the transmission output speed range DN32, the timer is reset. Subsequently, the method is continued with the method step X7.

In this method step X7 it is checked whether the operating strategy BST is active. If this is the case, then in a subsequent method step X8 the operating strategy BST is deactivated and at the same time the switching strategy SST is reactivated in place of the operating strategy BST before the method starts again with method step X1. If the test result in method step X7 is negative, the switching strategy SST is still active so that a jump to method step X1 takes place immediately and the method starts again.

As is known, the transmission output speed N32 and the vehicle speed V10 are equivalent, so that in the algorithm as an alternative to the predefined transmission output speed range DN32, a vehicle speed range DV10 may be predefined, within which the vehicle speed V10 must be at least approximately constant in order for the operating strategy BST to be activated instead of the shift strategy SST.

LIST OF REFERENCE NUMBERS

10

motor vehicle

20

drive motor

21

Crankshaft of the drive motor

22

E-machine

30

Mare automatic transmission

31

Transmission input shaft

32

Gearbox output shaft

33

Gear shifter

34

torque converter

35

Converter lockup clutch

36

A slip control system

37

electronic control unit

40

wheel

BST

operating strategy

DN32

Transmission output speed range

DV10

Driving speed range

G30

Target speed

N21

Crankshaft speed

N31

Transmission input speed

N32

Transmission output speed

S35

Target slip

SST

shifting strategy

V10

driving speed

X1 to X8

steps

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 3922051 C2 [0002]
• DE 4411940 A1 [0005]

Claims (18)

Method for controlling a multi-speed automatic transmission ( 30 ) for a motor vehicle ( 10 ), with one in the power flow between a crankshaft ( 21 ) of a drive motor ( 20 ) of the motor vehicle ( 10 ) and an input shaft ( 31 ) of the automatic transmission ( 30 ) arranged hydrodynamic torque converter ( 34 ) with torque converter lockup clutch ( 35 ), as well as with an electronic control unit ( 37 ), in which a shift strategy (SST) for setting desired gears (G30) in the automatic transmission ( 30 ) and for specifying setpoint slip (S35) of the lockup clutch ( 35 ) is implemented, characterized in that only if and only as long as the automatic transmission ( 30 ) is operated within a predefined transmission output rotational speed range (DN32) with at least approximately constant transmission output rotational speed (N32), the shift strategy (SST) is deactivated and at the same time an electronic control unit ( 37 ) is activated independently of the shift strategy (SST) implemented operating strategy (BST), in which a crankshaft speed (N21) of the crankshaft ( 21 ) of the drive motor ( 20 ) by control interventions in the automatic transmission ( 30 ) is adjusted to an at least approximately constant value. A method according to claim 1, characterized in that the predefined transmission output speed range (DN32) maps a driving speed range (DV10) between 10 km / h and 50 km / h. Method according to Claim 1 or 2, characterized in that the operating strategy (BST) is activated in place of the shift strategy (SST) only after the automatic transmission ( 30 ) was operated within the predefined transmission output speed range (DN32) for a predefined period of time with at least approximately constant transmission output speed (N32). A method according to claim 3, characterized in that is predefined as a period of 10 seconds. Method for controlling a multi-speed automatic transmission ( 30 ) for a motor vehicle ( 10 ), with one in the power flow between a crankshaft ( 21 ) of a drive motor ( 20 ) of the motor vehicle ( 10 ) and a transmission input shaft ( 31 ) of the automatic transmission ( 30 ) arranged hydrodynamic torque converter ( 34 ) with torque converter lockup clutch ( 35 ), as well as with an electronic control unit ( 37 ), in which a shift strategy (SST) for setting desired gears (G30) in the automatic transmission ( 30 ) and for specifying setpoint slip (S35) of the lockup clutch ( 35 ) is implemented, characterized in that only if and only as long as the automatic transmission ( 30 ) is operated within a predefined driving speed range (DV10) with at least approximately constant driving speed (V10), the switching strategy (SST) is deactivated and at the same time one in the electronic control unit ( 37 ) is activated independently of the shift strategy (SST) implemented operating strategy (BST), in which a crankshaft speed (N21) of the crankshaft ( 21 ) of the drive motor ( 20 ) by control interventions in the automatic transmission ( 30 ) is adjusted to an at least approximately constant value. A method according to claim 5, characterized in that the driving speed range (DV10) is predefined as a range between 10 km / h and 50 km / h. Method according to claim 5 or 6, characterized in that the operating strategy (BST) is activated in place of the shift strategy (SST) only after the automatic transmission ( 30 ) within the predefined driving speed range (DV10) over a predefined period of time with at least approximately constant driving speed (V10) was operated. A method according to claim 7, characterized in that is predefined as a period of 10 seconds. Method according to one of claims 1 to 8, characterized in that when adjusting the crankshaft speed (N21) and a current operating state of an electric motor ( 22 ), with which the automatic transmission ( 30 ) is drivable is taken into account. Method according to one of claims 1 to 9, characterized in that the crankshaft speed (N21) by specifying a combination of target gear (G30) for the automatic transmission ( 30 ) and target slip (S35) for the lockup clutch ( 35 ) is adjusted. A method according to claim 10, characterized in that the desired gear (G30) as a control intervention to a gear change device ( 33 ) of the automatic transmission ( 30 ), and that the target slip (S35) is applied as a control intervention to a slip control device (S35). 36 ) of the torque converter ( 34 ) is transmitted. Method according to one of claims 1 to 11, characterized in that the operating strategy (BST) is only activated instead of the switching strategy (SST) when the drive motor ( 20 ) and / or the automatic transmission ( 30 ) are not in a defined warm - up mode, or if a predefined lower temperature threshold for the drive motor ( 20 ) and / or the automatic transmission ( 30 ) and / or an ambient air is exceeded. Method according to one of claims 1 to 11, characterized in that the operating strategy (BST) is only activated instead of the switching strategy (SST) when a predefined upper temperature threshold for the drive motor ( 20 ) and / or the automatic transmission ( 30 ) and / or an ambient air is not exceeded. Method according to one of claims 1 to 13, characterized in that the operating strategy (BST) is activated only in place of the shift strategy (SST), if no driver request "Sport" is present. Method according to one of claims 1 to 14, characterized in that the operating strategy (BST) is only activated instead of the shift strategy (SST), if no driver request "manual gear default" is present. Method according to one of claims 1 to 15, characterized in that the operating strategy (BST) is only activated instead of the shift strategy (SST) when the automatic transmission ( 30 ) is not in runflat mode. Electronic control unit ( 37 ), with one in the electronic control unit ( 37 ) implemented method according to one or more of claims 1 to 16, for controlling a multi-speed automatic transmission ( 30 ) for a motor vehicle ( 10 ). Automatic transmission ( 30 ) with an electronic control unit ( 37 ) and a hydrodynamic torque converter ( 34 ) with torque converter lockup clutch ( 35 ), wherein in the electronic control unit ( 37 ) a method according to one or more of claims 1 to 16 is implemented.

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