DE102017214838A1 - Method for operating a drive train of a motor vehicle - Google Patents

Abstract

The invention relates to a method for operating a drive train (1) of a motor vehicle, in particular an agricultural or municipal utility vehicle, wherein the drive train (1) comprises a drive unit (2) and a gear arrangement (4) comprising a creeper gear group (8) and a PTO transmission module (11) for driving at least one power take-off shaft (13), wherein the insertion of a creeper in the Kriechganggruppe (8) is detected. In order to protect the gear assembly (4) in case of recognized creep ratio from overloading, due to a detected engagement of a crawl, one of the drive unit (2) output drive torque is automatically reduced to an operating torque, wherein upon detection of commissioning of the PTO (11) the presence of a to be driven load on the at least one power take-off shaft (13) is determined, wherein an adjustment of the output from the drive unit (2) drive torque is performed in dependence on the specific load.

Description

The invention relates to a method for operating a drive train of a motor vehicle, in particular an agricultural or municipal utility vehicle, which comprises a drive unit, a transmission arrangement which has a creeper gear group and a power take-off module for driving at least one PTO shaft, and an output, wherein the insertion a crawlspace is detected. Furthermore, the invention relates to a control device for a drive train of a motor vehicle, a computer program product and a data carrier having this computer program product.

Motor vehicles, especially agricultural or municipal work or commercial vehicles, often have a drive train with a gear assembly in a group construction, which is composed of several sub-transmissions. In order to cover a wide range of tasks of such vehicles, such a gear assembly must meet a variety of requirements, from a working or field operation to a road driving operation. This requires a large spread between the slowest gear and the fastest gear. For this purpose, in particular a crawler gear provides a series of gear stages, which each allow a very strong reduction of the speed and thus allow extreme slow driving. The driving of an attachment arranged on the motor vehicle takes place by means of a PTO transmission module for driving a PTO shaft, the so-called PTO shaft. In some cases, work with the attachment is also carried out in crawlspace. In particular, heavy pulling work can lead to an overload of the gear assembly, the transmission damage result.

A method for operating a drive train of a motor vehicle according to the preamble of claim 1 is known from DE 10 2009 028 567 A1 known.

From the DE 1 016 572 A For example, a motor vehicle is known which is used to carry implements or to drive attached equipment or vehicles and for this purpose has a transmission gear stage for a particularly low driving speed, a creeper. In order to exclude a risk of engine parts with normal design when using the motor vehicle in conjunction with attachment or trailer devices in which under certain circumstances unusually large driving resistances occur, the switching device is provided with a device by which with the involvement of the creeper the means for limiting the amount of fuel that can be supplied to the drive motor is adjusted in the direction of a reduction of the maximum amount. By limiting the maximum engine torque, the risk of overloading the drive parts is avoided.

Starting from the above-described prior art, it is now the object of the present invention to realize a method for operating a drive train of a motor vehicle, which provides protection against overloading of a gear assembly when Kriechgangübersetzung recognized and at the same time a flexible adaptation to changing load situations, in particular of Nebenantriebsstranges allows.

This object is achieved from the procedural point of view, starting from the preamble of claim 1 in conjunction with its characterizing features. From a device technical point of view, a solution of the problem by the technical features of the independent claim 8. The subsequent thereto, each dependent claims give each advantageous developments of the invention. Furthermore, a computer program product, as well as a data carrier having this, is the subject matter of claims 10 and 11.

According to the invention, in a method for operating a drive train of a motor vehicle, in particular an agricultural or municipal utility vehicle, wherein the drive train comprises a drive unit and a gear arrangement having a creeper gear group and a PTO module for driving at least one PTO shaft, the insertion of a Creeper in the crawler gear group recorded. The motor vehicle is preferably an agricultural or municipal utility vehicle, in particular a tractor or farm tractor.

By inserting a crawlspace vehicle speeds of about 1 km / h or less can be realized. In crawl traction is often performed by a connected to the power take-off implement, which may be attached implements, for example, for tillage, as well as towed vehicles, such as forage wagons with a recording device. The operation of such implements is due to the different operating and operating conditions associated with a different torque requirement that lead to overloaded gearshift when switched creep.

The invention now includes the technical teaching that due to a detected insertion of a creeper one of the drive unit output torque is automatically reduced to an operating torque and that upon detection of the commissioning of the PTO module, the presence of a driven load on the at least one PTO shaft is determined, wherein an adjustment of the output from the drive unit driving torque is performed depending on the specific load. The term load is understood to mean a working device connected to the power take-off shaft, which may be an attachment or a towed vehicle. To protect the gear assembly, the drive torque is automatically reduced to a, in particular adjustable, operating torque when engaged crawl. Depending on the presence and type of a driven by the Nebenwellenabtrieb load adjustment of the output from the drive unit drive torque is performed, whereby a high flexibility of the drive train is achieved, at the same time a protection against overloading of the gear assembly is ensured.

Such an embodiment of a method for operating a drive train has the advantage that due to the automatic reduction of the torque to an operating torque overloading of the gear assembly is prevented in creeper engaged. Preferably, an absolute or relative value for the operating torque can be specified, which is automatically reduced when the creep speed ratio is detected in order to protect the transmission arrangement.

The method according to carried out detection of the commissioning of the PTO transmission module in conjunction with the determination of a load makes it possible to adjust the drive torque to the operating situation, if necessary, in particular to increase. Such adaptation may become necessary when the load is set up to almost completely accommodate the drive torque provided by the power plant due to its operating parameters.

In contrast, found in the from the DE 1 016 572 B known method by the device for limiting the maximum amount of fuel supplied to the drive motor with creeper engaged a corresponding limitation of the torque provided by the drive motor instead, which is not changeable beyond this limited value of the torque.

Preferably, the detection of the insertion of a creeper by means of a speed monitoring can be performed. For this purpose, a speed sensor may be arranged in the part of the drive train downstream of the crawler gear group whose signals are evaluated in order to determine the respective rotational speed.

The presence of a load on the PTO shaft can be determined by monitoring a power shift element upstream of the PTO transmission module. For switching on the PTO transmission module, the load switching element is controlled by a control device which receives a corresponding control signal by the actuation of an actuating element by an operator of the motor vehicle.

To determine what kind the load is, i. which torque can absorb the load to be driven, a switching pressure of the designed as a hydraulic or electro-hydraulic clutch power switch element can be monitored. In this way, a distinction can be made between a light and a heavy implement or attachment. This distinction is used to decide on an adjustment of the output from the drive unit drive torque.

According to a preferred embodiment, the presence of a load on the PTO shaft may be determined by providing operating parameters of the load transmitted from the load via a bus system. A corresponding communication between the load and the motor vehicle can preferably take place via an ISO bus system. Among other things, the operating parameters transmitted by the load include information about the type of load and the maximum torque requirement that is to be provided by the motor vehicle.

In a further development of the invention it is provided that the presence of a load on the power take-off shaft is determined by the wireless transmission or readout of data stored in a data supply device arranged at the load. For this purpose, the data providing device can be embodied as a so-called "tag" or "beacon", an active transmitting device with data memory, which sends data to a receiver device by means of Bluetooth low-energy radio technology, if this is within range. It is also conceivable to use a QR code on the load designed as a working device which is read in by means of a reading device and transmitted to a control device of the motor vehicle for evaluation.

Once the load coupled to the PTO shaft has been determined, exceeding the reduced operating torque by a torque that can be absorbed by the load the reduced operating torque can be increased to the output from the working unit drive torque. It can be carried out an increase to the entire output torque of the drive unit or a gradual increase carried out, depending on the specific torque requirement of the load. If, on the other hand, no load on the PTO shaft has been determined or if the load falls below the torque limit, the reduced operating torque is maintained. The torque limit can be specified as a function of operating parameters of the drive unit.

Within a motor vehicle drive train, the method according to the invention is preferably controlled by a control unit, which is in particular the control unit of a transmission arrangement arranged in the drive train, which has a creeper gear group and a PTO transmission module for driving at least one power take-off shaft. The control unit is in the installed state control technology with a motor control device for controlling or regulating a drive torque connectable, and includes means for detecting an insertion of a crawler gear in the crawler gear group. The control unit is set up to control the engine control unit in response to a detected engagement of a creeper gear in such a way that an automatic reduction of the drive torque to a reduced operating torque takes place. A value for the reduced operating torque can be specified. Furthermore, the control unit comprises a device which determines the presence of a load to be driven on the at least one power take-off shaft when starting the PTO module, wherein an adaptation of the output from the drive unit drive torque takes place in dependence on the specific load. Thus, in order to protect, in particular, the transmission arrangement, the control device controls the engine control device independently of the presence of a load on the power take-off shaft in order to reduce the torque output by the drive assembly to an operating torque when a creeper gear is engaged. In addition, the presence of a load to be driven on the at least one power take-off shaft is determined by the device of the control unit when commissioning the PTO.

According to one embodiment of the invention, the control unit in the installed by a CAN bus with the engine control device signal technically in conjunction to control this. In addition to the control of the engine control device for reducing the torque in a detected engagement of a crawl, the engine control device is driven in a corresponding manner when a change from a crawl is detected in a suitable example for road travel switching gear.

Thus, the control unit for detecting the insertion of a creeper may be connected to at least one arranged in the drive train behind the creeper speed sensor, by means of which a speed detection is performed.

In order to detect the presence of a load on the power take-off shaft, the control unit can be set up to determine the switching pressure of a power-shift element arranged upstream of the power take-off gearbox module. The power shift element is designed as a hydraulic or electro-hydraulic clutch. From a pressure sensor associated with the load switching element signals are sent to the control unit, which evaluates them in order to be able to conclude the presence of a load on the PTO shaft.

The solution according to the invention can also be embodied as a computer program product which, when running on a processor of a control unit, instructs the processor by software to carry out the associated process steps according to the invention. In this context, a computer-readable medium is the subject of the invention, on which a computer program product described above is stored retrievably.

The invention is not limited to the specified combination of the features of the independent or the dependent claims. It also results in ways to combine individual features, even if they emerge from the claims, the following description of preferred embodiments of the invention or directly from the drawings. The reference of the claims to the drawings by use of reference numerals is not intended to limit the scope of the claims.

• 1 eine schematisierte Darstellung eines Kraftfahrzeugs;
• 2 eine schematisierte Darstellung eines Antriebsstranges des Kraftfahrzeugs; und
• 3 ein Ablaufdiagramm eines Verfahrens zum Betreiben des Antriebsstranges aus 2, entsprechend einer bevorzugten Ausführungsform der Erfindung.

Advantageous embodiments of the invention, which are explained below, are shown in the drawings. It shows:

• 1 a schematic representation of a motor vehicle;
• 2 a schematic representation of a drive train of the motor vehicle; and
• 3 a flowchart of a method for operating the drive train from 2 , according to a preferred embodiment of the invention.

1 shows a schematic representation of a motor vehicle 30 , in particular a tractor or tractor. A powertrain 1 includes a drive unit 2 of the motor vehicle 30 and one between the drive unit 2 and a downforce 3 switched gear arrangement 4 , which is executed in group construction. The drive unit 2 is designed as an internal combustion engine. The downforce 3 includes an axle drive 6 and a drive axle 7 , where by the axle drive 6 one from the gearbox 4 translated drive movement of the prime mover 2 on two wheels 32 the drive axle 7 is distributed. Furthermore, a steerable front axle with wheels 31 intended.

The gear arrangement 4 includes in the embodiment shown a load switching group 7 , a creeper gear group 8th and a sync group 9 , being between the crawler gear group 8th and the sync group 9 a startup clutch 10 is switched, which is also referred to as the main clutch. The starting clutch 10 is operable by a driver preferably via a clutch pedal. At the starting clutch 10 However, it may also be an automatic or automatically operated clutch. The starting clutch 10 is in the creeper gear group 8th downstream part of the drive train 1 at least one speed sensor 15 assigned. Furthermore, the powertrain includes 1 a PTO transmission module 11 , which by a hydraulically or electrohydraulically switchable load switching element 12 driving with the drive unit 2 is connectable. The power shift element 12 , which is designed as a wet-running multi-plate clutch, is a pressure sensor 14 assigned. Output side of the PTO transmission module 11 is a PTO shaft 13 , which drove with a load 22 respectively coupled to a working device.

2 shows a schematic representation of the drive train 1 of the motor vehicle 30 , The prime mover 2 , the gear arrangement 4 , the starting clutch 10 the axle drive 6 , as well as the PTO transmission module 11 is ever a control unit 17 respectively. 18 respectively. 19 respectively. 20 respectively. 21 associated with other - not shown here - control devices and sensors in a CAN bus system designed as a data bus system 16 of the motor vehicle 30 are involved and communicate with each other. It controls the designed as a motor control device controller 17 the prime mover 2 , In particular, one of these deliverable drive torque M _Ant , while by the control unit 19 an automated opening and closing of the starting clutch 10 is controllable. In addition to this automated operation of the starting clutch 10 However, it is also possible to make a manual opening and closing of the starting element according to the specifications of the driver, for which purpose the control unit 19 with a - not shown here - clutch pedal is in communication. The starting clutch 10 in the creeper group 8th downstream part of the drive train 1 arranged speed sensor 15 is with the controller 19 connected by signal technology. Alternatively or additionally, the speed sensor between the sync group 9 and the axle drive 5 be arranged. By means of the speed sensor 15 the insertion of a creeper can be determined.

The control unit 18 is the gear arrangement 4 assigned and can regulate them in the manner of an automated manual transmission, which also here is the possibility to perform in a manual mode switching operations according to the specifications of the driver. Finally, the controller 20 the axle drive 6 and the controller 21 the PTO transmission module 11 assigned. The the load switching element 12 assigned pressure sensor 14 is signaling with the control unit 21 of the PTO transmission module 11 connected. Through the pressure sensor 14 becomes the switching of the load switching element 12 detected, ie the connection or disconnection of the PTO transmission module 11 , In addition, it can be determined on the basis of the clutch pressure, which type of load or the implement 22 is, ie which torque to be driven implement 22 can record.

Furthermore, a reading and receiving device 24 on the motor vehicle 30 arranged, which is adapted to operating-specific data of the implement 22 in one on the work tool 22 arranged data supply device 23 read out or receive. This is the data delivery device 23 designed as a so-called "day" or "Beacon", ie an active transmitting device with a data storage, which by means of Bluetooth low energy radio technology data to the reading and receiving device 24 if this is within range of the data delivery facility 23 is. Alternatively, the controller 18 respectively. 21 via ISO bus directly or indirectly with the connected implement 22 communicate.

Against the background that carrying out heavy pulling work by a to the PTO shaft 13 coupled implement 22 , such as a tillage implement, with inserted creeper to overload the gear assembly 4 can lead, the engine control unit 17 from the controller 18 triggered due to a detected creeper ratio. In this case, the engine control device 17 from the controller 18 controlled in such a way that that of the drive unit 2 output torque M _{Ant is} reduced to an operating torque (M _Red ) when the creep speed ratio is detected transmission assembly 4 to protect against damage due to overloading. In the further course is by the control unit 18 Check if a work tool 22 to the PTO shaft 13 is coupled and what torque demand the implement 22 because of its specification. Depending on the specific load is an adaptation of the of the drive unit 2 output drive torque M _Ant performed. The control unit controls this 18 the engine control device 17 in accordance with that in the flowchart in 3 represented methods:

At the beginning of the procedure is in one step S1 first asked if a creeper was engaged. The detection of the Kriechgangübersetzung by means of speed monitoring by the at least one speed sensor 15 , which sends its signals to the control unit 19 the starting clutch transmitted for evaluation. The result of the evaluation is via the data bus 16 to the control unit 18 transfer. If this is to be answered in the negative, it is reduced to the beginning and nothing further is undertaken until a crawl gear ratio is recorded.

Is the result in step S1 On the other hand, it is positive, because of the recorded crawl gear ratio becomes a step S2 in which a reduction of the drive speed M _Ant to a reduced operating speed M _Red is automatically performed. This is done by the control of the engine control device 17 through the control unit 18 the gear arrangement 4 , In particular, the relative value of the operating speed M _{Red is} about 50%. Deviating values of the operating speed M _Red can be specified as a function of the specification of the drive unit.

In one step S3 is checked if the PTO transmission module 11 was switched on. For this purpose, a switching position of a running in a cabin of the tractor as a motor vehicle 30 arranged actuating element are detected by the actuation of the switching of the load switching element 10 is controlled. Is the condition in step S3 fulfilled, so becomes a step S4 passed over, while in the case to be negated before step S3 is jumped back.

In step S4 is the presence of one to the PTO shaft 13 coupled implement 22 checked. Furthermore, in this step S4 Check if it is a light or heavy attachment 22 is. The distinction between a light and an attachment 22 Based on the determination of a necessary for operation torque M _{work of} the attachment 22 , Is the required torque M _{work of} the attachment 22 Less than or equal to the reduced operating torque M _Red , this is a lightweight attachment 22 , On the other hand, exceeds the required torque M _{work of} the attachment 22 that for the protection of the transmission arrangement 4 Reduced operating torque M _Red , this is a heavy working tool 22 , Has the step S4 to the result, that a light work tool 22 to the PTO shaft 13 has been connected, so becomes a step S6 passed. If yes, that is, when recognizing a heavy implement 22 becomes a step S5 passed.

In the step S5 An adaptation of the of the drive unit 2 output drive torque M _Ant . This is done by the drive unit 2 provided torque from the reduced operating torque M _Red to the total drive torque M _Ant by driving the engine control unit 17 through the control unit 18 raised. It can in step S5 an immediate release of the total drive torque M _Ant done or a gradual increase. By recognizing that a heavy work tool 22 is coupled, it is ensured that the almost total drive torque M _{Ant is} absorbed by this, so that overloading the gear assembly 4 is avoided when crawl is engaged.

Following the step S5 is in the step S6 continuously checks whether through the PTO shaft 13 a torque is delivered. This can, as has already been stated above, by monitoring the switching position of the actuating element or the clutch pressure of the load switching element 10 respectively. Is a shutdown of the PTO shaft 13 to deny that will be in step S2 or step S5 by controlling the engine control device from the drive unit 2 provided reduced operating torque M _Red or the total drive torque M _Ant continues to be provided.

If a shutdown of the PTO shaft 13 so be on step S7 passed. In step S7 is that of the drive unit 2 If necessary, provided torque is reduced to the reduced operating torque M _Red . Following the step S7 gets on step S1 jumps back.

By means of the inventive design of a method for operating a drive train of a motor vehicle damage can be avoided by overloading a gear assembly during the implementation of traction while creeper engaged simultaneously with a flexible adaptation to operation with heavy equipment is possible.

LIST OF REFERENCE NUMBERS

1

powertrain

2

power unit

3

output

4

transmission assembly

5

transaxles

6

drive axle

7

Powershift Group

8th

creeper

9

synchronous group

10

clutch

11

PTO module

12

Load switching element

13

PTO shaft

14

pressure sensor

15

Speed sensor

16

bus

17

Motor controller

18

control unit

19

control unit

20

control unit

21

control unit

22

implement

23

Data providing device

24

Reading and receiving device

30

motor vehicle

31.32

bikes

S1 to S7

individual steps

M _ant

drive torque

M _red

operating torque

M _work

torque

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 102009028567 A1 [0003]
• DE 1016572 A [0004]
• DE 1016572 B [0012]

Claims (11)

Method for operating a drive train (1) of a motor vehicle, in particular an agricultural or municipal utility vehicle, wherein the drive train (1) comprises a drive unit (2) and a gear arrangement (4) comprising a creeper gear group (8) and a PTO transmission module (11) Driving at least one power take-off shaft (13), wherein the insertion of a creeper in the Kriechganggruppe (8) is detected, characterized in that due to a detected engagement of a creeper issued by the drive unit (2) drive torque (M _Ant ) automatically to an operating torque (M _Red ) is reduced and that upon detection of the commissioning of the PTO module (11) the presence of a driven load on the at least one PTO shaft (13) is determined, wherein depending on the particular load, an adjustment of the output from the drive unit (2) drive torque (M _Ant) carried is leads. Method according to Claim 1 , characterized in that the detection of the insertion of a creeper by means of a speed detection is performed. Method according to Claim 1 or 2 , characterized in that the presence of a load on the PTO shaft (13) by the monitoring of the PTO transmission module (11) upstream of the load switching element (12) is determined. Method according to Claim 3 , characterized in that a switching pressure of the designed as a hydraulic clutch load switching element (12) is monitored. Method according to Claim 1 or 2 characterized in that the presence of a load on the PTO shaft (13) is determined by the provision of operating parameters of the load transmitted by a bus system. Method according to Claim 1 or 2 characterized in that the presence of a load on the PTO shaft (13) is determined by the wireless transmission or reading of data stored in a data provider (23) located at the load. Method according to one of Claims 1 to 6 , characterized in that when the reduced operating torque (M _Red ) is exceeded by a recordable by the load torque (M _work ), the reduced operating torque (M _Red ) is raised to the drive torque (M _Ant ). Control unit (18) for a transmission arrangement (3) arranged in the drive train (1) of a motor vehicle (30), which has a creeper gear group (8) and a PTO transmission module (12) for driving at least one auxiliary output shaft (13), wherein the control unit (18) with a motor control device (17) for controlling or regulating a drive torque (M _Ant ) is controllably connectable, and means (15) for detecting a creeper in the Kriechganggruppe (8), wherein the control device (18) is arranged in that the motor control device (17) is actuated due to a detected engagement of a creeper in such a way that an automatic reduction of the drive torque (M _Ant ) to an operating torque (M _Red ) takes place, and in that the control device (18) comprises a device which at a Commissioning of the PTO transmission module (11) the presence of a driven load on the at least one power take-off determined (13), wherein depending on the specific load, an adjustment of the output from the drive unit (2) drive torque (M _Ant ) is carried out. Control unit after Claim 8 , by which a method according to one or more of Claims 2 to 7 is feasible. Computer program product for a control unit (18) according to Claim 8 or 9 , by which a method according to one or more of Claims 1 to 7 is feasible, wherein a routine for performing the method is implemented by appropriate stored in a software control commands. Disk with a computer program product after Claim 10 ,

Images