WO2005065982A1

WO2005065982A1 - Gear shifting method for use in the case of a sensor failure of an automated shift-dog transmission

Info

Publication number: WO2005065982A1
Application number: PCT/EP2004/014079
Authority: WO
Inventors: Manfred Guggolz; Werner Hillenbrand; Markus Veit
Original assignee: Daimlerchrysler Ag
Priority date: 2003-12-24
Filing date: 2004-12-10
Publication date: 2005-07-21
Also published as: DE10361299A1

Abstract

The invention relates to a gear shifting method for use in an automated manual transmission having a dog clutch. According to the inventive gear shifting method, the gears are shifted with closed main clutch in order to reduce wear and allow for rapid gear shifts. When a signal of a speed sensor of the transmission input shaft required for this shifting process supplies a defective signal, a speed sensor for the crankshaft speed alternatively takes over this function while the main clutch remains closed.

Description

SWITCHING METHOD IN THE EVENT OF A SENSOR FAILURE FOR AN AUTOMATED SWITCHING CLAW GEAR

According to claim 1, the invention relates to a drive train and, according to claim 4, to a control method for such a drive.

Such a drive train or such a control method is already known from WO 02/060715 AI, which describes a method for operating a drive train of a motor vehicle, in which a decision is made with each gear change depending on measured operating variables of the motor vehicle whether a clutch during the Gear change is opened or remains closed. When changing gear with a closed clutch, the synchronization of a speed of a transmission input shaft to a target speed in the target gear also takes place by influencing the drive motor. The gear change takes place depending on a signal from a speed sensor for the transmission input shaft. A drive motor speed sensor is also provided in this drive train.

EP 0 695 665 AI describes a method for operating a drive train of a motor vehicle with an automated transmission in the form of an automatic transmission. The gearbox can be connected to a drive motor by means of an automated clutch. Each time the gearbox is changed, the clutch is opened and closed again when the gear change is complete. This leads to heavy wear on the clutch, especially if the drive train is used in a commercial vehicle with a large vehicle mass and high mileage.

EP 0 676 566 AI describes a method for operating a drive train of a motor vehicle with an automated transmission. The gearbox can be connected to a drive motor by means of a foot-operated or an automated clutch. In the described method, gear changes of the transmission are carried out from an original gear into a target gear with the clutch closed. The synchronization of a speed of a transmission input shaft to a target speed in the target gear takes place by influencing the drive motor. When an upshift is requested, for example by the vehicle driver, it is determined on the basis of currently recorded vehicle operating conditions whether the requested upshift can be carried out. Only feasible gear changes are triggered, requests for impracticable gear changes are modified or deleted. This means that a large number of gear changes, which would be possible with the clutch disengaged, are not carried out.

Non-generic JP 01-129892 and JP 01-136349 relate to the evaluation of an abnormal value of a transmission input shaft sensor of a planetary automatic transmission with a hydrodynamic torque converter.

EP 0 241 216 B1 relates to a method for controlling an automatic mechanical transmission in which one program ignores an identified, faulty input signal and processes the rest Input signals is modified according to defined logic rules.

DE 42 37 983 C2 relates to a method for automatically controlling a friction clutch. An emergency operating mode is provided for the failure of the engine sensor.

The object of the invention is to provide a reliable or fail-safe drive train.

According to one advantage, the drive train has a shift dog gear. Such a shift dog gear is not subject to frictional wear due to the absence of synchronizer rings, so that the shift elements designed as shift dogs are long-lasting for engaging and disengaging the gears.

According to the invention, the engagement of the two shift claw halves, in contrast to completely unsynchronized shift claw transmissions, takes place almost jerk-free and thus is also non-destructive, since the drive motor control and possibly an additional central synchronization when changing gears align the speeds of the transmission shafts with one another.

This central synchronization can be carried out in a particularly advantageous manner in such a way that the drive motor carries out the speed adjustment. This means that the drive shaft speed of the drive motor is reduced when shifting up and the drive shaft speed of the drive motor is increased when shifting down. For this purpose, the drive motor has actuators which are controlled by a control device. For example, the control device can an injection quantity of a fuel, an ignition timing or specify the use of so-called engine brakes, for example in the form of an exhaust flap or a constant throttle. The actuators of the shift dog gear and the clutch can also be controlled by the control device mentioned or by a further control device. The control devices are in signal connection.

Depending on the selection rules and vehicle parameters and / or operating parameters of the motor vehicle, the control device of the shift dog gear can make a selection as to whether the clutch is opened or remains closed when changing gear.

If gear changes are made from an original gear to a target gear of the shift dog gear with a closed clutch, after disengaging the original gear, i.e. when there is no longer a connection between an input and an output shaft of the shift dog gear, the speed of the transmission input shaft is adjusted to a target speed in the target gear so-called synchronous speed, by influencing the drive motor. At synchronous speed, shift elements of the target gear, which are connected on the one hand to the transmission input shaft and on the other hand to the transmission output shaft and thus to driven vehicle wheels, have the same speed. For downshifts, a torque is requested from the control device of the drive motor, by means of which the speed of the drive motor and thus also the speed of the transmission input shaft is increased. With upshifts, a very low or a negative, a so-called thrust torque, is requested in order to reduce the speed of the transmission input shaft. To support this, the motor brakes mentioned or other ones that do not belong to the drive motor can also be used Delay means, for example a transmission brake, can be controlled.

Knowledge of the transmission input shaft speed is therefore necessary for the speed adjustment. For this purpose, a speed sensor is provided according to the invention, which determines a value representing the transmission input shaft speed. In a particularly advantageous manner, this is a speed sensor that directly decreases the speed from the transmission input shaft. This speed sensor is also referred to as a transmission input shaft speed sensor. Likewise, the speed sensor for determining the transmission input shaft speed can remove the latter from a coupling half of the clutch, which is directly connected to the transmission input shaft in a rotationally fixed manner or with the interposition of a torsion damper. In the case of a countershaft transmission with one or more constants, the speed sensor can advantageously also be arranged on the countershaft, since then there is a fixed speed ratio between the countershaft and the transmission input shaft. In the case of a countershaft transmission with several — in particular two — constants, the transmission input shaft speed can be determined by knowing the constants in the power flow in each case via a speed sensor that decreases the countershaft speed. Depending on the geometric or thermal installation conditions, the speed sensor can also be arranged on a main shaft, the gear of which meshes with a gear of the main shaft.

In the event of a fault, ie if this transmission-side speed sensor fails or provides a nonsensical signal, the control unit that controls the gear change when the clutch is closed provides a replacement signal according to the invention used or generated. This replacement signal comes from another speed sensor located on the drive motor side of the clutch. This takes into account the fact that when the clutch is closed, the drive motor speed is at least approximately the same as the transmission input shaft speed. A possible clutch slip can be compensated for by a compensation factor. This compensation factor can be parameter-dependent. For example, the compensation factor can be dependent on the engine torque that the engine control unit supplies and / or the compensation factor is dependent on the contact pressure or the disengagement path that is stored in the control unit of the automated clutch.

The further speed sensor for the substitute signal can in particular be the speed sensor of the drive motor, which preferably decreases the drive motor speed from an incremental wheel on the flywheel of the crankshaft. However, it is also possible to take the TDC sensor as a further speed sensor, whose signal transmitter rotates at half the crankshaft speed and, by doubling this sensor signal over time

To determine transmission input shaft speed. The TDC sensor is not a speed sensor in the actual sense, but the sensor that determines top dead center directly or indirectly on the camshaft for the control of the drive motor ignition. Due to the halved speed and the smaller number of increments or signal generators, the TDC sensor delivers an imprecise value than the speed sensor of the drive motor. However, this inaccurate value is acceptable in the event of a fault in the failure of the actual transmission-side speed sensor, since the failure is displayed or stored in the fault memory and the gearbox-side speed sensor is changed during the next routine workshop visit.

In a further embodiment of the invention, it is also possible for the transmission-side speed sensor to take over its function in the event of a fault in the drive-motor-side speed sensor. For example, in the event of a fault in the crankshaft speed sensor while driving with the clutch closed or during a gear change with the clutch closed

Transmission input shaft speed sensor take over the function of the crankshaft speed sensor. Thus, the control of the drive motor, which is basically an α-n control depending on the input variables, receives the load request signal, i.e. α and crankshaft speed, i.e. n works as an input variable instead of

Crankshaft Speed The gearbox input shaft speed. Such an emergency running program for the drive motor advantageously controls the drive motor relatively precisely.

In a particularly advantageous embodiment of the invention, controls or a control of the drive train can be provided, in each of which one speed sensor provides a replacement signal and / or comparison signal for the other speed sensor for error evaluation. That is, - if the transmission-side speed sensor fails, the drive-side speed sensor supplies the replacement signal for the transmission-side speed sensor and if the drive-side speed sensor fails, the transmission-side speed sensor supplies the replacement signal for the drive-side speed sensor.

The faultiness of a signal of the transmission-side speed sensor and / or of the drive-side speed sensor can be compared in a particularly advantageous manner two speed sensor signals take place with each other. In this way, both an error in the crankshaft speed sensor for controlling the drive motor and an error in the transmission input shaft speed sensor for controlling the switching processes can be determined. Which of the two speed sensors or which signal of the two speed sensors is defective can be determined, for example, by comparing the signals with the signal from the aforementioned TDC sensor. To determine the crankshaft speed by means of the TDC signal, the latter must be observed over time by the control device, for example the drive motor or the shift dog gear.

Gear changes or shift processes can be requested by a vehicle driver using a suitable actuating device in a manual mode, for example with a shift lever, or in an automatic mode by the control device of the shift dog gear.

Gear changes or gear changes with an open clutch can also be carried out. With the clutch open, no torque can be transmitted from the transmission input shaft to the transmission output shaft. It is not necessary that the clutch actuation path has been completely covered.

This means that every gear change or shift operation can be carried out with a clutch state that is suitable with regard to the operating conditions of the motor vehicle. This ensures reliable operation of the drive train, in which requested gear changes of the shift dog gear are carried out safely. At the same time, low wear on the clutch and thus cost-effective operation of the motor vehicle is made possible. In addition, when the clutch is open, gear changes are possible in which the speed of the drive motor in the target gear is lower than the so-called idle speed, i.e. the speed that occurs when the driver is idling without intervention from the driver. This can be advantageous, for example, before entering a steep uphill or downhill gradient.

In a particularly advantageous embodiment of the invention, gear changes are performed with the clutch disengaged with the exception of the transmission-side and / or drive-side speed sensor in a period of time after the drive train has been started up for the first time and / or after the drive motor has started and / or after a malfunction has been detected. After an initial start-up of the drive train and / or a start of the drive engine, upshifts are carried out in particular with the clutch open.

Initial commissioning is understood to mean the commissioning of the drive train after the manufacture of the motor vehicle or the commissioning after the replacement of an element, for example the drive motor, of the drive train. The time period can be fixed or can be ended after some conditions have been met.

When starting up for the first time or after starting the drive engine, not all vehicle parameters which are taken into account in the selection and the test mentioned are known. For example, the course parameters of the speed of the drive motor may be unknown during initial commissioning. These can then be measured and stored in a control device become. After starting the engine, for example, the vehicle weight may have changed significantly due to a changed payload. This is particularly the case with commercial vehicles in which the payload can far exceed an empty weight of the vehicle.

A condition for ending the specified time period can be, for example, that all vehicle parameters relevant for the selection are determined.

As long as the vehicle parameters are not determined, no reliable selection can be made. This ensures safe operation of the motor vehicle in this phase by changing gear with the clutch open.

In a particularly advantageous embodiment of the invention, when a malfunction of a component of the drive train is detected, with the exception of the failure of the transmission-side and / or the drive-side speed sensor, the switching operations can also be carried out with the clutch open. For example, the control device of the drive motor may have recognized a defect and then only guarantee emergency operation of the drive motor. Furthermore, for example, an engine brake can be so stiff that the operation of the engine brake is no longer possible or only to a very limited extent.

The behavior of the faulty component when changing gears is therefore no longer predictable. This means that no reliable check and selection can be carried out. When a component malfunctions is detected, safe operation of the motor vehicle is ensured by changing gear with the clutch open.

In one embodiment of the invention, the control device carries out a test as a function of test rules, whether a requested gear change can be carried out with the clutch closed. The selection of whether the clutch is opened or remains closed when changing gear depends on the result of the test. In particular, all possible gear changes with the clutch closed are also carried out in this way. This enables the largest possible number of gear changes to be carried out with the clutch closed, which leads to particularly low wear on the clutch.

In an embodiment of the invention, the test can be carried out as a function of vehicle parameters and / or operating parameters of the motor vehicle. Vehicle parameters of the motor vehicle describe the general condition of the motor vehicle, for example:

- a vehicle weight,

- a drag coefficient and a face,

- rolling resistance coefficients of vehicle tires,

- Course parameters of the speed of the drive motor when synchronizing during a gear change, for example a maximum positive and negative gradient or

- a general condition of the engine brakes, for example smooth or stiff.

Operating variables describe the state of the motor vehicle at a specific point in time, for example when a gear change is requested. Company sizes are for example:

- the speed of the drive motor,

- the torque of the drive motor,

a position of a power request element, for example an accelerator pedal,

a state of the engine brakes, for example active or inactive,

- the origin gear. The vehicle parameters and the operating variables can in some cases be recorded directly by means of further sensors, measured in special operating situations or determined from measured variables using suitable calculation methods.

The behavior of the motor vehicle, for example the course of the vehicle speed or the rotational speed of the drive motor, can thus be predetermined during a gear change, in particular for the period in which the drive motor is not connected to the vehicle wheels. Taking these variables into account, it can be checked precisely whether a gear change can be carried out with the clutch engaged. The risk that the test will give an incorrect result is therefore low.

When selecting whether a gear change is carried out with the clutch open or closed, this can ensure that the requested gear changes can be carried out.

In an embodiment of the invention, the selection and / or the check are carried out at least in partial operating areas depending on the target gear of the shift dog gear.

This minimizes the risk that the test of whether a gear change can be carried out with the clutch closed will give incorrect results.

For example, in the case of an upshift, the speed of the drive motor and thus the speed of the transmission input shaft are decelerated in the direction of the synchronous speed by means of the braking torque which the drive motor applies. The braking torque is built up by injecting little or no fuel. In addition, it can Braking torque can be increased by the use of engine brakes. The synchronous speed results from the speed of the motor vehicle and the target gear, taking into account further gear ratios, for example a rear axle, in the drive train. This changes the synchronous speed as the vehicle speed changes. In order to achieve the synchronous speed, the gradient of the speed of the drive motor must therefore be significantly larger than the gradient of the synchronous speed. The danger that this is not the case arises, in particular, when the vehicle weight is high and the motor vehicle decelerates sharply when the gear is disengaged, ie without drive torque. When checking whether the gear change can be carried out with the clutch engaged, depending on the vehicle parameters and / or operating variables mentioned, a deceleration of the motor vehicle determined from the vehicle mass can be compared with a maximum negative gradient of the rotational speed of the drive motor. This makes it possible to precisely predict whether the synchronous speed, which is dependent on the target gear, will be reached and whether the gearshift can be carried out with the clutch engaged.

In an embodiment of the invention, the selection and / or the testing will be carried out at least in partial operating areas depending on quantities that describe the environment of the motor vehicle. These sizes are for example:

- slope of the road,

- condition of the road, for example paved road, gravel or mud,

- ambient temperature,

- geodetic height or

- ambient pressure. Some of these variables can be recorded directly using additional sensors, measured in special operating situations or determined using suitable calculation methods. Some sizes, such as the inclination of the roadway, can also be made available by a navigation system known per se with a digital road map.

In this way, the prediction of the behavior of the motor vehicle when changing gears and thus also the aforementioned test can be carried out particularly precisely.

In an embodiment of the invention, the vehicle parameters can be changed. The vehicle parameters can be determined in selected operating areas of the motor vehicle and compared with stored parameters. In the event of deviations, new parameter values can be calculated and saved, i.e. a so-called adaptation can be carried out. The newly saved parameter values are then taken into account in the selection and testing.

Parameters that can change very quickly, such as the vehicle weight, can be adapted.

Furthermore, parameters can be adapted that cannot be precisely defined before or during initial commissioning, such as the course parameters of the speed of the drive motor. The course parameters, for example the maximum gradients of the speed, differ from drive motor to drive motor and can also change over a longer period of time. For safety reasons, unfavorable values must therefore be assumed as starting values for the adaptation, for example only small possible gradients of the speed of the drive motor. The test can incorrectly do so The result is that a requested gear change cannot be carried out with the clutch closed, although this would be possible with the actual vehicle parameters. The adaptation brings the stored values closer and closer to the actual values so that more and more gear changes can be carried out with the clutch closed.

This enables particularly low-wear operation of the motor vehicle.

In an embodiment of the invention, the shift dog gear has a central synchronizing device which can be controlled by the control device and by means of which a transmission input shaft can be braked. In contrast to conventional synchronizer rings, the central synchronization device is assigned to several gears. In the case of upshifts with the clutch disengaged, the control device selects whether the central synchronizing device is activated and thus the transmission input shaft is braked or whether activation is omitted. The central one

The synchronization device can be designed, for example, as a transmission brake known per se, which acts directly on the transmission input shaft or on a countershaft.

This ensures that the transmission input shaft reaches the synchronous speed of the target gear safely and quickly during upshifts with the clutch open, even when the vehicle speed changes significantly. This enables fast upshifts and ensures safe operation of the motor vehicle.

In an embodiment of the invention, the clutch remains closed at the start of downshifts and the control device controls an actuator for disengaging the Source gear. The control device then determines a time since the control of the actuator and monitors whether the original gear is disengaged. If this is the case, the gear change is carried out with the clutch closed. If the determined time since actuation of the actuator exceeds a threshold without the original gear having been disengaged, the control device opens the clutch and the gear change is carried out with the clutch open.

In order to be able to design a gear, no or only a very low torque may be transmitted from associated shift elements, for example a sliding sleeve. This can be achieved, on the one hand, by opening the clutch or, when the clutch is closed, by deliberately changing the output torque of the drive motor. If the motor vehicle is in train operation, the torque must be reduced; A torque increase is necessary in overrun mode. If the vehicle speed changes at the time of the desired design, the drive motor must set the stated state on the shift element of the original gear against the forced speed change of the transmission output and input shaft. This is only possible if the dynamics of the drive motor are greater than the dynamics of the motor vehicle. For example, a strong vehicle deceleration with a downshift requested at the same time is particularly critical in this regard.

With the method described above, even in critical situations, requested circuits can be carried out safely. In addition, it is not necessary to have precise knowledge of the vehicle parameters, the operating parameters or the environmental parameters for the largest possible proportion of gear changes with the clutch engaged. Thus, low-wear and safe operation of the motor vehicle can can be guaranteed if the quantities mentioned cannot be determined or have not yet been determined.

The motor vehicle can be designed as a commercial vehicle in a particularly advantageous manner. The shift dog gear can advantageously have a primary gear, for example a split group, and a secondary gear, for example a range group.

In a particularly advantageous manner, it can be provided that in the event that the faulty signal of the transmission input shaft speed sensor is determined, shifting will then only take place with the clutch closed. This ensures that gear changes are made with knowledge of the transmission input shaft speed. The clutch control unit is only reset when the gearbox input shaft speed sensor is operational again.

Sub-claim 5 is particularly advantageous in combination with claim 4.

Further advantages of the invention emerge from the description and the drawing. Embodiments of the invention are shown in simplified form in the drawing and explained in more detail in the following description. The drawing shows:

1 shows a drive train of a motor vehicle with an automated shift dog gear in a schematic representation,

2 is a flow chart of a gear change,

3a, 3b each show a diagram for the temporal representation of operating variables of the Motor vehicle with an upshift of the shift dog gear and

Fig. 4 is a flowchart of a downshift in a second embodiment.

1, a drive train 10 of a motor vehicle (not shown) has a drive motor 14 which is controlled by a control device 16. The control device 16 is in signal connection with actuators (not shown), for example for an exhaust flap (not shown) of the drive motor 14. The control device 16 can thus send manipulated variables to the actuators of the drive motor 14. In addition, the control device 16 is in signal connection with only partially shown sensors. These sensors include, among other things, a crankshaft speed sensor 100 of a crankshaft 13, a temperature sensor 101, by means of which the oil / water temperature of the drive motor 14 can be detected, and an TDC sensor 102, by means of which the top dead center of the respective piston for the ignition point can be determined.

The crankshaft speed sensor 100 is a Hall sensor or alternatively a magnetoresistive sensor which senses the speed of the crankshaft 13 very precisely on an increment wheel 103. The speed at this crankshaft speed sensor 100 is detected in the program by the variable S ₂ . The OT sensor 102 is a Hall sensor or alternatively a magnetoresistive sensor which senses the position of a camshaft 105 rather imprecisely on an increment wheel 104. The difference in the accuracy of the measurement is due to the fact that the crankshaft 13 or its incremental wheel 103 rotates at twice the speed in a four-stroke engine, like the camshaft 105 or its incremental wheel 104. If the control device determines the position of the If camshaft 105 is determined over time, control cam 16 results in a camshaft speed or, by doubling this camshaft speed, the speed of crankshaft 13.

The crankshaft 13 is connected in a rotationally fixed manner to a primary half 106 of a friction clutch 12, which also forms the flywheel mass of the drive motor 14, via a crankshaft flange (not shown). This primary half 106 can be frictionally coupled to a secondary half 107 of the friction clutch 12.

The friction clutch 12 is arranged axially between the crankshaft 13 and a transmission input shaft 11 of an automated synchronizer-free shift dog gear 19. The clutch 12 and the shift dog gear 19 are controlled by a control device 49. The control device 49 is in signal connection with an actuator 110 of the clutch 12, a transmission input shaft speed sensor 108, with which the speed of the transmission input shaft 11 can be detected, and sensors (not shown) of the clutch 12 and the shift dog gearbox 19. This allows the control device 49 to open or close the clutch 12 and change gear in the shift dog gear 19. One from

Transmission input shaft speed sensor 108, the continuously determined value for the transmission input shaft speed is stored in the control unit 49 under the variable Si, which is constantly updated. Operating variables such as the temperature of the clutch 12 and the transmission oil of the shift dog gear 19 can be detected by means of further sensors, not shown in any more detail. In addition, the control device 49 is in signal connection with the control device 16, as a result of which an exchange of data, for example of operating variables of the drive motor 14 or the shift dog gear 19, as well as a request for speed changes of the drive motor 14, which are then implemented by the control device 16. In particular, the control device 16 can forward the speed of the crankshaft 13 to the control device 49. This speed of the crankshaft 13 is detected by means of the speed sensor 103. If its signal is implausible or even not available, the crankshaft speed is specified in an emergency operation program by the transmission input shaft speed sensor 108. The control device 49 is also connected to an operating unit 51, by means of which a vehicle driver can request gear changes of the shift dog gear 19. Alternatively, gear changes from an origin gear into a target gear can also be triggered in a fully automated manner by the control device 49. The determination of the target gear depends, among other things, on the speed of the motor vehicle and the degree of actuation of an accelerator pedal by the vehicle driver.

The shift dog gear 19 is designed as a so-called two-group gear. A primary transmission in the form of a split group 17 is arranged in a rotationally fixed manner with the transmission input shaft 11. A main transmission 18 is arranged downstream of the split group 17. The transmission input shaft 11, a central main shaft 400 and the second main shaft 29 are thus arranged axially in succession in the shift dog gear 19. The central main shaft 400 is supported at its one front axial end in the transmission input shaft 11 and at its rear axial end in the second main shaft 29.

By means of the split group 17, the transmission input shaft 11 can be connected to one via two different gear pairs 20a, 21a arranged parallel to the transmission input shaft 11

Layshaft 22 are brought into operative connection. For this purpose, the front gear stage 20a comprises a fixed gear 20b, which is arranged non-rotatably and coaxially at the front end of the countershaft 22, and an idler gear 20c, which is arranged rotatably and coaxially with the transmission input shaft 11 in the plane of the fixed gear 20b with the latter in toothed engagement.

The rear gear stage 21a, on the other hand, comprises a fixed gear 21b, which is arranged in a rotationally fixed and coaxial manner on the countershaft 22 behind the fixed gear 20b, and a fixed gear 21c, which is arranged in a gear-locked engagement with the latter in the plane of the fixed gear 21b in the plane of the fixed gear 21b ,

The two gear pairs 20a, 21a have a different ratio. The translation of the respective gear pair 20a, 21a is selected by pushing a sliding sleeve 41 axially forward from a neutral position, by a rotationally fixed connection between the transmission input shaft 11 and the idler gear 20c of the front gear pair 20a or by axially sliding the sliding sleeve 41 out of the neutral position is pushed behind to establish a rotationally fixed connection between the transmission input shaft 11 and the central main shaft 400 or the idler gear 21c.

Fixed wheels 23, 24, 25 for the 3rd, 2nd and 1st gear of the main transmission 18 are also arranged on the countershaft 22 in a rotationally fixed manner. The fixed gears 23, 24, 25 each mesh with associated idler gears 26, 27, 28, which are rotatably arranged on the second main shaft 29 arranged coaxially to the transmission input shaft 11. The idler gear 26 can by means of a sliding sleeve 30, the idler gears 27 and 28 by means of a Sliding sleeve 31 are connected to the second main shaft 29 in a rotationally fixed and positive manner.

A synchronization device in the form of a gear brake 52 is arranged on the countershaft 22 and can be controlled by the control device 49. The speed of the countershaft 22 and thus also the speed of the transmission input shaft 11 can be selectively reduced by means of the gear brake 52.

The sliding sleeve 41 of the split group 17 and the sliding sleeves 30, 31, 39 of the main transmission 18 can each be actuated with shift rods 42, 43, 44, 45. A positive connection between the associated switching elements with switching claws and the second main shaft 29 can thus be established or interrupted. The shift rods 42, 43, 44, 45 can be actuated with an actuator in the form of an xy actuator 48a, 48b, which is controlled by the control device 49. If no gear is engaged in the shift dog gear 19, that is to say no idler gear is positively connected to the second main shaft 29, the shift dog gear 19 is in a so-called neutral position.

From the second main shaft 29, the converted torque and the speed of the drive motor 14 are transmitted by means of a flanged drive shaft 32 to an axle drive 33 which, with balanced torque, the speed via a differential in the same or different proportions via two output shafts 34, 35 to drive wheels 36, 37 transmits.

When changing gear from an original gear to a target gear, the original gear must be designed first. Since the shift dog gear 19 is designed as a transmission without synchronizer rings, at least in downshifts, around the To be able to engage the target gear, the countershaft 22 and thus also the input shaft 11 are adjusted approximately to the synchronous speed of the target gear by means of the drive motor 14 with the clutch 12 closed. The synchronous speed is reached when the idler gear of the target gear and the second main shaft 29 have at least approximately the same speed. In upshifts with the clutch 12 open, the countershaft 22 can be braked by means of the gear brake 52 and the input shaft 11 can thus be synchronized.

The original gear can be disengaged either with the clutch closed or open. Frequent opening and closing of the clutch 12 leads to heavy wear and thus to high costs for replacing the clutch and failure of the motor vehicle during the exchange. It is therefore the goal to carry out the highest possible number of gear changes with the clutch closed.

For this purpose, the control device 49, as shown in the flowchart in FIG. 2 _, sets a variable S active to the Si after _a shift request according to block 60 in the subsequent block 200, so that from this point in time the constantly updated transmission input shaft speed is determined by means of the

Transmission input shaft speed sensor 108 is detected. In the following branch 61 it is checked whether the drive train 10 has not been started up for the first time and whether a period of time has elapsed after the drive motor 14 started. If the test is positive, a check is made in block 62 as to whether, under the constantly updated variable S active _, an incorrect, implausible or none at all Value is stored. If this check of the signal from the transmission shaft speed sensor 108 is positive, there is an error, so that from next block 201 the signal for the variable S _act i _{v is} taken from the crankshaft speed sensor 100, S _{2 being} stored under the variable S _act iv.

If, on the other hand, the check in the branch 62 turns out to be negative, so that the variable S _act iv has a plausible value, the block 201 is skipped and it is checked in the branch 202 whether a malfunction or an on a further component of the drive train 10 Another sensor has detected a faulty signal. For this purpose, information from other control devices, for example control device 16, or from other program parts of a control program of control device 49, which monitor functions of components, is evaluated. If the test is negative - there is therefore no fault - it is checked in branch 63 whether the shift can be carried out with the clutch 12 closed. For this purpose, the course of the rotational speed of the transmission input shaft 11 during the requested shift is calculated in advance on the basis of the known vehicle parameters, the operating variables of the motor vehicle and the environmental variables by means of motion equations known per se. The previously calculated course is then compared with the stored maximum gradients of the rotational speed of the drive motor 14 and it is determined whether it is possible, on the one hand, to disengage the original gear and, on the other hand, to synchronize the rotational speed of the transmission input shaft 11 to the synchronous rotational speed of the target gear. If the test is positive, the shift or gear change is carried out with the clutch 12 closed in block 64. This is done by changing the torque delivered Drive motor 14 by the control device 16 reduces the transmitted torque on the shifting elements of the original gear so far that the original gear can be designed. The synchronization then takes place by means of the drive motor 14. As soon as the speed of the transmission input shaft 11 or the crankshaft 14, which is constantly updated under S _act iv, has at least somewhat reached the synchronous speed of the target gear, the target gear is engaged. The torque that the vehicle driver specifies by means of an accelerator pedal, not shown, is then set again on the drive motor 14. This completes the circuit in block 65.

If the test in branch 202 is positive or negative in branch 61 or 63, i.e. there is an initial start-up or a time threshold after the start of the drive motor 14 has not yet expired, or it has occurred for a component of the drive train 10 or a sensor If a malfunction is found or if the shift cannot be carried out with the clutch 12 closed, the clutch 12 is opened in block 66 by activation by the control device 49. It is then checked in branch 67 whether an upshift should be carried out. If this is the case, it is checked in branch 68 on the basis of the prognoses calculated in branch 63 whether the transmission brake 52 is activated, the countershaft 22 and thus also the transmission input shaft 11 are to be actively braked. If the test is positive, the shift is carried out in block 69 in a manner known per se with activation of the transmission brake 52. For this purpose, the original gear is designed, the synchronization is carried out with the support of the gear brake 52 and the target gear is then engaged. If the test in branch 67 or 68 is negative, that is to say a downshift or an upshift is to be carried out without activating the transmission brake 52, block 70 the shift is carried out in a manner known per se without activating the transmission brake 52.

Subsequent to blocks 69 or 70, that is, when the target gear is engaged, the clutch 12 is closed again in block 71 and the torque specified by the driver of the drive motor 14 is set again. The circuit is thus also completed in block 65.

The method can also be carried out without branches 61 and / or 202.

3a and 3b show the time profile of operating variables of the motor vehicle when the shift dog gear 19 is shifted up from an origin gear into a target gear. The feasibility of upshifts with the clutch closed is explained in more detail by means of these curves.

3a and 3b, the time is plotted on the abscissa 80a, 80b, and a speed or a clutch status is plotted on the ordinate 81a, 81b.

The phase of origin is still engaged in a phase A1 in FIG. 3a. The drive motor 14 outputs a constant torque and the motor vehicle accelerates, so that the speed of the drive motor 14 represented by line 82a increases. At time 83a, the vehicle driver requests an upshift using the control unit 51. In phase bl, the drive motor 14 reduces the output torque (not shown) so that the original gear can be disengaged. This causes the speed of the drive motor to fluctuate 14 in phase bl. At the end of phase b 1, at time 84 a, the original gear is disengaged, so that the shift dog gear 19 is in a neutral position. In phase cl, the speed of the drive motor 14 drops due to the engine braking effect.

As described, the synchronous speed of the target gear is proportional to the speed of the motor vehicle. Lines 85a and 86a show the course of the synchronous speed in two different cases. In the first case, represented by line 85a, the synchronous speed drops only slowly. This can be due, for example, to the fact that the road is slightly sloping. At time 87a, the speed of the drive motor 14 reaches the synchronous speed, which is shown by the fact that the lines 82a and 85a meet. This enables the target gear to be engaged and the torque requested by the driver to be set. The circuit is thus completed and the motor vehicle accelerates again, the speed of the drive motor 14 increases again in phase d1. The clutch 12 remains closed during the entire switching process, as can be seen in the state 1 on the basis of line 88a.

The second case is shown using line 86a. In this second case, the synchronous speed drops very sharply. This can be due, for example, to the fact that the roadway rises and / or the vehicle is heavily loaded and / or the roadway surface is very soft. The synchronous speed drops faster than the speed of the drive motor 14. As a result, the speed of the drive motor 14 cannot reach the synchronous speed, and the target gear cannot be engaged. This means that the shift cannot be carried out with the clutch 12 closed. When checking whether the shifting can be carried out with the clutch 12 closed - branch 63 in FIG. 2 - these profiles of the rotational speeds are calculated in advance and it is checked whether the rotational speed of the drive motor 14 reaches the synchronous rotational speed or not. If this is not the case, the shift cannot be carried out with the clutch 12 closed.

3b shows the second case again, with the difference that the clutch 12 is opened in the illustrated gear change. In phase a2, clutch 12 is closed, which is shown by line 88b in state 1. With the shift request at time 83b, the course of the speeds is calculated in advance and it is established that the shift can only be carried out with clutch 12 open. As a result, clutch 12 is opened immediately so that it is in state 0. In phase b2, the original gear is disengaged and in phase c2, the speed of the drive motor 14 shown by line 82b is braked by means of the gear brake 52. Thus, at time 87b, the speed of the drive motor 14 reaches the synchronous speed, the target gear can be engaged and the clutch 12 can be closed. The circuit is thus completed and the motor vehicle accelerates again in phase d2. The shift can thus be carried out with the clutch open.

4 shows a flow chart of a downshift according to a second embodiment. After a downshift request according to block 90, the output torque of the drive motor 14 is changed in block 91 as in a shift with a closed clutch 12, so that the original gear would have to be able to be selected. In the following block 92, the xy actuator 48a, 48b is activated to disengage the original gear. It is then checked in block 93 whether the original gear has been disengaged. Is this the If so, it is queried in the branch 94 whether the signal coming from the transmission input shaft speed sensor 108, which is stored under the variable Si in an updated manner, is correct or plausible or is present at all.

If this is the case, then according to block 300, the variable S _act iv assumes the value of the variable Si in a constantly updated manner, the value of which is formed by means of the signal from the transmission input shaft speed sensor 108.

If this is not the case - that is, there is an error - according to block 301, the variable S _act i _v assumes the value of the variable S ₂ in a constantly updated manner, the value of which is formed by means of the signal from the crankshaft speed sensor 100.

Following the processing performed in block 300 and 301, selection of the speed sensor, the circuit is performed _ak tiv with the clutch in dependence on the variables in the block S 302nd After downshifting has been carried out, the process in block 95 is ended. If the test in block 93 is negative, that is to say the original gear has not been disassembled, it is checked in block 96 whether the time since actuation of the xy actuator 48a, 48b has exceeded a threshold. If this is not the case, block 93 is repeated. If the threshold is exceeded in block 96, the clutch is opened in block 97, the shift is performed with the clutch open in block 98 and the clutch is closed again in block 99. The circuit is thus also completed in block 95.

The time threshold mentioned in block 96 can be determined from vehicle parameters of the motor vehicle, for example the vehicle weight, and / or from operating variables of the motor vehicle, for example the rotational speed of the drive motor 14, and / or from variables which affect the environment of the vehicle Describe motor vehicle, for example, the inclination of the roadway, depending.

The method shown in FIG. 4 is carried out when the gear change is to be carried out with the clutch closed.

The previously described occurrence of an error in the signal of the transmission input shaft speed sensor 108 can be determined, for example, by comparing the signal of the crankshaft speed sensor 100 with the signal of the transmission input shaft speed sensor 108 when the clutch 12 is closed. If the two signals deviate from one another by a tolerance value, then there is an error either on the crankshaft speed sensor 100 or on the transmission input shaft speed sensor 108. A comparison of the respective signal, for example with the signal of the TDC sensor over time, makes it possible to determine whether the transmission input shaft speed sensor 108 or the crank shaft speed sensor 100 is delivering a faulty signal.

In the event of a complete failure of one sensor, the occurrence of an error can also be determined without comparison with another sensor.

The threshold mentioned can be dependent on vehicle parameters of the motor vehicle and / or on operating variables of the motor vehicle and / or on variables which describe the environment of the motor vehicle.

Instead of the two control devices 16, 49 for the drive motor and the switching operations, a common control device can be provided. Instead of a common control device, which replaces the latter two control devices, a higher-level one can also be used Control device can be provided, which coordinates the control devices of the drive motor and the shift dog gear. Such a control unit can be designed as a drivetrain manager, which converts the driver's performance requirement into an optimization based on drive motor torque - drive motor speed, gear ratio, ie gear ratio in the transmission.

In Fig. 1, an alternative embodiment of the invention is additionally shown. Instead of the gearbox input shaft speed sensor 108, a hatched gearbox input shaft speed sensor 108b is provided, which does not decrease the speed of the gearbox input shaft 11 directly on the gearbox input shaft 11. Instead, the speed of the middle main shaft 400 is sensed by the transmission input shaft speed sensor 108b. This speed is transmitted to the control unit 49 via a data transmission line (not shown). The control unit 49 knows the current positions of the xy actuator 48a, 48b, so that the current positions of the sliding sleeves 41, 30, 31, 39 are also known to the control unit 49. If the sliding sleeve 41 establishes a rotationally fixed connection between the transmission input shaft 11 and the central intermediate shaft 400, the speed sensed at the transmission input shaft speed sensor 108b is equal to the transmission input shaft speed. If, on the other hand, the sliding sleeve 41 establishes a non-rotatable connection between the transmission input shaft 11 and the idler gear 20c of the gear pair 20a, the control device 49 determines the speed sensed at the transmission input shaft speed sensor 108b and the known gear ratios of the two gear pairs 20a, 21a the transmission input shaft speed.

In a further alternative embodiment of the method for controlling a gearshift operation, each gear change is carried out with the clutch engaged from the point at which an incorrect, implausible or no value is supplied by the transmission input shaft speed sensor 108 or 108b. Various alternatives are possible when this suppression of gear changes with open clutch 12 is ended or reset. In an alternative, this suppression of gear changes with the clutch 12 disengaged can be reset when the drive motor 14 has been switched off and then started again. In a further alternative, this suppression of gear changes with the clutch 12 disengaged can only be reset manually via a bidirectional diagnostic and / or application device. A specialist from the workshop connects this diagnostic and / or application device to a diagnostic connector of the control device 49 and is shown in the display of the diagnostic device that the diagnostic device

Transmission input shaft speed sensor 108 or 108b delivered value is incorrect. The fault can then be repaired, for example, by cleaning a plug contact or changing the transmission input shaft speed sensor 108 or 108b. The fault memory is then opened by means of the bidirectional diagnostic and / or Application device emptied so that the suppression of gear changes with clutch 12 disengaged is ended or reset.

Instead of indenting the two switching claw halves of the switching claw transmission when the speed is the same, a shifting method can also be used in the invention in which the switching claw halves are engaged at a speed difference. Such a shifting method can be carried out particularly well with a certain shifting claw geometry and is described, for example, in DE 197 17 042 C2. The content of the latter patent is hereby to be considered as included in this application.

Instead of a transmission brake for braking the countershaft, other devices or control methods are also conceivable. In particular, measures on the drive motor side, such as a constant throttle or an exhaust gas throttle, can be used in a drive train according to the invention.

The described embodiments are only exemplary configurations. A combination of the features described for different embodiments is also possible. Further, in particular not described features of the device parts belonging to the invention can be found in the geometries of the device parts shown in the drawings.

Claims

claims

Drivetrain with a drive shaft (13) which can be coupled by means of an automated clutch (12) to a transmission input shaft (11) of an automated shift dog gear (19), shifting operations with the clutch closed depending on a value (Si) representing a transmission input shaft speed, which can be carried out can be determined by a transmission-side sensor (108), a drive-side sensor (100 or 102) is also provided, which determines a value (S ₂ ) representing a drive shaft speed, characterized in that in the event of an error in the signal of one sensor (108 or . 100/102) the other sensor (100/102 or 108) forms an equivalent signal.

Drive train according to claim 1, characterized in that in the event of a fault in the transmission-side sensor (108), the value of the drive-side sensor (100 or 102) provides a substitute signal for the value (S ₂ ) representing the transmission input shaft speed, so that switching operations as a function of the substitute signal of the drive-side sensor (100 or 102) can be carried out.

3. The drive train according to claim 1, characterized in that the drive-side sensor is a crankshaft speed sensor (100) and in the event of a fault the value of the transmission-side sensor (108) provides a replacement signal for the value (S ₂ ) representing the crankshaft speed, so that a drive motor control (16) controls the speed and / or the torque of the drive shaft (13) as a function of the replacement signal from the transmission-side sensor (108).

4.Method for controlling a switching process of an automated shift dog gear (19), into which a drive torque of a drive shaft (13) is introduced via an automated clutch (12), switching operations with the clutch closed (12) as a function of a value representing the transmission input shaft speed ( Sx), characterized in that, if the value (Si) is incorrect, a further value (S ₂ ) is provided as an alternative, which represents a drive shaft speed.

5. The method according to claim 4, characterized in that an error of the value is determined by comparing the two values (Si and S ₂ ).

6. The method according to any one of claims 4 or 5, characterized in that switching operations when the value (Si) is incorrect only be carried out with the clutch (12) closed until an error set in the error memory of a control unit (49 or 16) is reset.