DE10230773A1 - Automatic clutch control system for road vehicle to optimize pulling away from rest has speed sensors on engine and output drive to regulate clutch and keep engine speed within given limits - Google Patents

Abstract

The control system automatically regulates engine speed and clutch slip while the vehicle starts to move forward. At time (t1) the driver wishes to move forward and opens the throttle valve (dki,1). The engine speed (3) rises toward a curve for the maximum allowed speed (5) and clutch engagement starts at time (t2). The engine speed rises slowly, crossing from above to below the ideal engine speed line (2), until it reaches the curve for minimum allowed engine speed (4) at time (t3). The vehicle starts to move forward at time (t4) and accelerates (6) with clutch slip gradually ceasing at time (t5). Other curves are given for abnormal operating conditions.

Description

The invention relates to a method for controlling a starting process of a motor vehicle with a automated gearbox driven by a drive motor or Automatic transmission, the automated transmission or automatic transmission at least one as electro-hydraulic or electro-pneumatic actuated Start-up switching element formed starting element. The drive motor is over an electronic engine control unit that can be controlled or regulated automated transmissions or automatic transmissions, in particular its Start-up switching element, via an electronic transmission control unit.

From the DE 100 23 053 A1 A control system for a motor vehicle transmission with a torque converter or a hydroddynamic clutch and with at least one switching element carrying torque during the starting process of the motor vehicle is known, in which an electronic transmission control unit controls the starting power of the motor vehicle via a slipping switching element which is arranged in the transmission and is electro-hydraulic can be actuated, regulates as a function of a driver's request, including parameters of the torque converter or the hydrodynamic clutch. The slip in the torque-carrying switching element can be used to specifically influence a speed ramp-up of a drive motor of the transmission via the electronic transmission control unit. In this way, in particular a torque build-up of an exhaust-gas-charged internal combustion engine can be improved during the starting process of the motor vehicle. The slip control of the torque-guiding switching element always requires full functionality of the electro-hydraulic control of the switching element, i.e. both a fully functional electronic transmission control unit and a fully functional hydraulic actuating device of the switching element.

It is an object of the invention Method for controlling a starting process of a motor vehicle with an automated one powered by a drive motor Represent transmission or automatic transmission, in which the starting power of the motor vehicle over a slipping gear shift element, which is electro-hydraulic or can be operated electro-pneumatically is and controlled by an electronic transmission control unit or is regulated, even if the electro-hydraulic is not fully functional or electro-pneumatic control of the switching element as a function a driver's request is adjustable.

The task is solved with one the features of the main claim method. advantageous Refinements and developments result from the subclaims.

The invention is based on one known drive train of a motor vehicle with a drive motor, the over an electronic engine control unit is controllable, as well as with an automated transmission driven by the drive motor or Automatic transmission. The automated transmission or automatic transmission has at least one as electro-hydraulic or electro-pneumatic actuated Switching element formed starting element, which at a Starting process of the motor vehicle is torque leading. Thereby are corresponding trained actuators of electro-hydraulic or electro-pneumatic actuator of the start-up switching element via an electronic transmission control unit controllable or regulatable. The electronic transmission control unit can communicate with the engine control unit to exchange data, for example about a data bus system or over fixed electrical wiring.

In "normal operation" of the gearbox, i.e. with full functionality the electro-hydraulic or electro-pneumatic actuator of the Start-up switching element (including the electronic transmission control unit) controls or the electronic transmission control unit regulates the starting power of the motor vehicle via a Slip of the start-up switching element, in the usual way as a function a driver request.

In the following, "restricted normal operation" of the transmission is understood to mean an operating state in which the start-up switching element can in principle still be controlled via the electronic transmission control unit, but the actual functionality of the electro-hydraulic or electro-pneumatic actuation device of the start-up switching element is impaired. Such impairments can be caused, for example, by a delayed pressure build-up on an actuating device of the start-up switching element due to a high viscosity of the pressure medium at low temperature, by a temporary or permanent undersupply of pressure in the actuating device of the start-up switching element due to leakage or a general lack of pressure medium, by a temporary or permanent malfunction within the hydraulic or pneumatic transmission control unit, through a non-optimized application of individual control or regulating parameters within the electronic transmission control unit, or through changes in the coefficient of friction on the friction lining of the start-up switching element due to aging or temporary overheating. It is clearly recognizable that all of these impairments mentioned by way of example are conveniently closed in normal operation of the transmission at least complicate the start-up switching element. In extreme cases, damage to the start-up switching element is even possible, for example due to excessive slip in the start-up switching element over a long period of time.

Furthermore, below an "emergency operation" of the transmission Understand the operating state in which the electronic transmission control unit is not more functional is, however, the starting switching element by the hydraulic or pneumatic transmission control unit in a kind of emergency function can be switched purely hydraulically or pneumatically.

According to the invention, the electronic engine control unit has a starting function with which the starting performance of the motor vehicle over the start-up shift element of the transmission slipping during the starting process not fully functional electro-hydraulic or electro-pneumatic control of the Start-up switching element and / or when not fully functional or Completely failed electronic transmission control unit as a function of a driver request is adjustable. The start function of the electronic works Engine control unit as a control loop subordinate to the electronic transmission control unit for the Slip control of the starting switching element.

An existence of "restricted normal operation" of the transmission or an "emergency operation" of the transmission from the start-up function of the electronic engine control unit via a Communication with the electronic gearbox control unit recognized. For this purpose, the electronic transmission control unit preferably sends a special message to the electronic engine control unit. For example the electronic gearbox control unit sets a control bit "GEARBOX", which depends on the starting function of the electronic engine control unit is evaluated on a Value "NORMAL" as long as that Gearbox in normal operation with full functionality of the electro-hydraulic or electro-pneumatic control of the start-up switching element. The electronic transmission control unit recognizes, for example, control deviations while closing the start-up switching element impaired the functionality of the electro-hydraulic or electropneumatic control of the start-up switching element, the electronic gearbox control unit sets the "GEARBOX" control bit accordingly a value "RESTRICTED". Is that Gearbox in an emergency program in which the electronic gearbox control unit is no longer directly to the electro-hydraulic or electro-pneumatic Activation of the start-up switching element can act, but still Can send messages, the electronic transmission control unit sets the control bit "TRANSMISSION" accordingly on one Value "EMERGENCY RUN". Is it electronic Transmission Control Module Completely failed, the start-up function of the electronic engine control unit recognizes it Operating state of the transmission in the absence of the transmission message "TRANSMISSION".

If there is "restricted normal operation" or "emergency operation" of the gearbox, the start function of the electronic engine control unit regulates the Speed ramp-up of the drive motor by changing the motor speed gradient or a time course of the engine speed gradient to one Value limited within a defined tolerance band. In the event of an operating state "restricted normal operation" is the Regulation of the electronic transmission control unit when the Start-up switching element effectively supported. In the event of an "emergency operation" operating state, the start-up function takes over of the electronic engine control unit regulates the starting power of the motor vehicle over the slipping start switching element completely. Since the limitation of Motor speed gradient is only temporary, is the mobility of the motor vehicle not restricted when the start-up switching element is closed.

In a first embodiment of the Invention is proposed that the starting function of the electronic Engine control unit an upper and a lower permissible engine speed gradient or an upper and a lower permissible temporal engine speed gradient curve for the Starting process of the motor vehicle determined, preferably depending the driver's request and / or a driving speed or transmission output speed and / or a current engine speed and / or a current Motor torque and / or a transmission temperature and / or a current Gear ratio. The driver's request can be made, for example, from an accelerator pedal angle or Throttle valve angle and / or a gradient of the accelerator pedal angle or throttle valve angle formed and as the target engine torque or Output target torque are shown.

exceeds the current engine speed gradient is now the permissible upper limit or the current engine speed gradient now falls below the permissible lower one Limit value, the start-up function of the electronic engine control unit takes effect suitable engine-side measures in the speed ramp-up of the drive motor in that the actual Motor speed gradient to a value within that of the start function of the electronic. Engine control unit determined currently permissible tolerance band is settled. Known engine-side measures are, for example ignition angle or a fueling intervention or a throttle intervention.

In an advantageous manner, with this first embodiment, closing of the start-up switching element can also be controlled or regulated via the start-up function of the electronic engine control unit even if the electronic transmission control unit has failed. The starting performance of the motor vehicle is unchanged via the slipping on Driving switching element regulated, in the usual way as a function of the driver's request. The synchronization point calculation of the closing process of the start-up switching element required for this regulation, which is implemented in the usual way in the electronic transmission control unit, is also functionally implemented in the start-up function of the electronic engine control unit. In this case, a synchronous speed, which is to be present at the output of the starting switching element when the start-up switching element is closed, can be calculated in a known manner via the engine speed and the transmission output speed or driving speed, taking into account the known transmission ratio. If the emergency program of the transmission has, for example, several different (known) gear stages, these must be taken into account accordingly, the actually effective emergency program translation being able to be recognized, for example, when changing from normal operation to emergency operation depending on the current driving speed. Predefined tolerances can also be taken into account in the calculation of the synchronous speed, for example to take into account inaccuracies when determining the actual current speeds in the force flow direction in front of and behind the starting switching element, or also as a safety margin for the status "starting switching element closed". Of course, the synchronous speed is constantly tracked via the changing transmission output speed or driving speed.

In a second embodiment of the Invention is proposed that the electronic transmission control unit for the closing process of the starting switching element a target engine speed gradient or temporal engine speed target gradient curve determined, as before already described for example as a function of accelerator pedal angle or throttle valve angle, accelerator pedal angle gradient or throttle valve angle gradient, Engine speed, driving speed or gearbox output speed, Engine torque, gear temperature, gear ratio. The one from the electronic Transmission Control Module determined engine speed target gradient or temporal engine speed target gradient curve is sent to the electronic Engine control unit transmitted and evaluated by its start function. The start-up function determines of the electronic engine control unit the current intervention limits for the Limitation of the engine speed gradient, i.e. a current upper one and a current lower allowable tolerance value to the specified engine speed target gradient or temporal engine speed target gradient curve. Can advantageously here engine-specific parameters, for example a current one Engine temperature and / or an actual engine torque and / or current ignition angle intervention limits considered become. exceeds or falls below the actual Motor speed gradient that from the start function of the electronic Engine control unit determined tolerance limits, so the start-up function of the electronic Engine control unit suitable engine-side measures to increase the speed of the drive motor to a value within of the determined limits.

The proposed second embodiment sets ahead of that electronic transmission control unit not completely has failed and carry out the corresponding calculations without restrictions and can send the corresponding broadcast messages. A synchronization point calculation by the starting function of the electronic engine control unit for the closing process the start-up switching element is not necessary, correspond to low is the programming effort.

In a third embodiment of the Invention is proposed that the electronic transmission control unit for the closing process the start-up switching element has a tolerance band for a permissible engine speed gradient or an allowable temporal engine speed gradient curve determined and sent to the electronic Engine control unit transmitted. The upper and lower currently allowed The engine speed gradient or its time profile can - as before already described - for example one Function be from accelerator pedal angle or throttle valve angle, accelerator pedal angle gradient or throttle angle gradient, engine speed, driving speed or gearbox output speed, engine torque, gearbox temperature, Gear ratio. If exceeded of the upper allowable Engine speed gradient and if the value falls below the lower one permissible Engine speed gradients engage the start-up function of the electronic Engine control unit through suitable engine-side measures - as well previously described - in the speed ramp-up of the drive motor.

Also the proposed third embodiment assumes that electronic transmission control unit not completely has failed and carry out the corresponding calculations without restrictions and can send the corresponding broadcast messages. A sync point calculation due to the start-up function of the electronic engine control unit for the closing process the start-up switching element is not necessary, correspond to low is the programming effort.

In principle, the start-up process of the motor vehicle instead of the defined tolerance band for the engine speed gradient but also a tolerance band for the engine speed itself or a tolerance band for a temporal engine speed curve be specified, its limits during the closing process of the start-up switching element neither exceeded should still be undercut and if necessary by the engine activities be respected.

To further clarify the invention based on the single figure, a time course of an example Starting course of the motor vehicle described.

In the upper part of the is a time course of an accelerator pedal angle or throttle valve angle dki shown and with 1 designated. At a time t1, the driver of the motor vehicle actuates the accelerator pedal or the throttle valve and thus signals his desire to start.

In the middle part of the figure, several temporal engine speed profiles are shown, in the lower part of the figure, the temporal profiles of an output speed of the transmission corresponding to these different engine speed profiles. In the case of a fully functional electrohydraulic or electro-pneumatic actuation device of the start-up shift element located in the power flow, that is to say in "normal operation" of the transmission, the ideal engine speed curve is now shown on the basis of the accelerator pedal value specification or throttle valve value specification and the slip control of the start-up shift element by the electronic transmission control unit 2 , From time t1, the engine speed runs up to an optimal engine operating point in order to achieve the highest possible starting performance and is then brought to synchronous speed via the closing start-up switching element. At a time t4, the torque transmission of the starting switching element exceeds the current driving resistance of the motor vehicle and the motor vehicle rolls on. The corresponding output speed curve is designated by 6. A time t5 denotes the synchronization point of the closing process of the start-up switching element, the start-up switching element is now completely closed.

With 7 is a dash-dot line denotes an exemplary engine speed curve which occurs in a "restricted normal operation" or "emergency operation" of the transmission without the measures acting on the engine side according to the invention, if the starting switching element at a time t2 is too low a switching pressure. First, the engine runs up with an excessively high engine speed gradient (more or less freely), with the consequence of a significantly too high relative speed at the starting switching element. Given the setting of a comparable grinding time for the switching process, i.e. a comparable time between a reduction in the input speed at the start-up switching element to the synchronization point, the subsequent closing process runs accordingly uncomfortably under high thermal load on the start-up switching element. The synchronization point t51 of this shifting process lies behind the synchronization point t5 of the ideal engine speed curve 2 , wherein the vehicle at a time t41 (corresponding output speed curve 8th ), which is later than the starting point t4 of the ideal starting process, starts rolling.

According to the invention, a tolerance band is now provided within which the engine speed is to move in the course of the starting process. As already described in detail above, this tolerance band can, for example, be continuously calculated by the electronic engine control unit or the electronic transmission control unit, for example as a function of one or more of the current values of engine speed, engine torque, accelerator pedal or throttle valve angle, accelerator pedal or throttle valve angle speed, Target engine torque, gearbox output speed or driving speed, gear ratio and gearbox temperature. A lower limit of this tolerance band is in the figure 4 designated and shown in dashed lines, an upper limit with 5 , As already explained above, instead of the tolerance band for a permissible engine speed, a tolerance band can also be specified for an engine speed gradient or a temporal engine speed gradient or a temporal engine speed curve during the starting process of the motor vehicle.

An exemplary engine speed curve is now shown in a thick, solid line 3 , which occurs in "limited normal operation" or "emergency operation" of the transmission due to the measures acting on the motor side according to the invention. The engine speed curves are up to time t2 3 and 7 identical. At time t2, the engine speed reaches the upper limit 5 , with the result that the start-up function of the electronic engine control unit initiates suitable measures on the engine side, which limit the engine start-up, for example by a temporary ignition angle intervention, and bring the actual engine speed back to a value within the tolerance band. The now visibly flattened engine speed curve 3 reaches the lower limit at time t3 4 of the tolerance band. So that the start-up process of the motor vehicle does not take too long, the start-up function of the electronic engine control unit intervenes in the engine speed ramp-up, this time using measures on the engine side to increase the engine speed gradient, for example by temporarily increasing the fuel quantity. All in all, the support functions acting on the motor side result in the ideal engine speed curve 2 approximate engine speed curve 3 , ie an at least approximately simultaneous rolling of the motor vehicle (time t4) and an at least approximately simultaneously synchronized point of the closing operation of the starting switching element (time t5).

In order to clarify the effectiveness of the described function, there is also an engine speed curve in the figure for comparison 9 in dotted Line drawn in, which would occur in a starting process with the same starting request if the starting power of the motor vehicle cannot be influenced by a shift element slipping in the starting process, such as in a classic automatic transmission with a torque converter as starting element. The torque of the torque converter results in a relatively sluggish reaction of the motor vehicle to the driver's desire to start, and the motor vehicle only starts to roll at a late point in time t42 (corresponding output speed curve) 10 ).

1

Accelerator pedal angle curve, Throttle angle curve

2

ideal Engine speed curve with start-up support by slipping start-up switching element

3

Engine speed course with start support by

slippage of Start-up switching element, with motor-side support

4

lower Tolerance value of the engine speed curve

5

upper Tolerance value of the engine speed curve

6

Output speed curve, corresponding to the engine speed curve

2 and 3

7

Engine speed course with start support due to slipping start-up switching element, without motor-side support

8th

Output speed curve, corresponding to the engine speed curve 7

9

Engine speed course without start support due to slipping start switching element

10

Output speed curve, corresponding to the engine speed curve 9

ki

Accelerator pedal angle, Throttle angle cap

n

rotational speed

t

timeline

t1

time the start request

t2

Times of exceedance the upper tolerance value of the engine speed curve

t3

time falling below the lower tolerance value of the engine speed curve

t4

Time of the rolling of the motor vehicle, corresponding to the engine speed curve 2 and 3

t5

Synchronization point, corresponding to the engine speed curve 2 and 3

t41

Time of the rolling of the motor vehicle, corresponding to the engine speed curve 7

t42

Time of the rolling of the motor vehicle, corresponding to the engine speed curve 9

t51

Synchronization point, corresponding to the engine speed curve 7

Claims (15)

Method for controlling a starting process of a motor vehicle with an automated transmission or automatic transmission driven by a drive motor, in which the starting performance of the motor vehicle in an "normal operation" of the transmission is controlled by at least one electrohydraulically or electro-pneumatically actuated starting switching element of the transmission that slips in the starting process from an electronic one Transmission control unit is controlled or regulated as a function of a driver's request, the electronic transmission control unit being able to communicate with an electronic engine control unit of the drive motor for the exchange of data, characterized in that the starting power of the motor vehicle is in a "restricted normal operation" of the transmission and / or in an "emergency operation""of the transmission can be controlled by the starting function of the electronic engine control unit as a function of a driver request via the starting switching element of the transmission slipping during the starting process is, in the "restricted normal operation" or "emergency operation" of the transmission, the electro-hydraulic or electro-pneumatic control of the starting switching element is not fully functional and / or the electronic transmission control unit is not fully functional or has failed completely. Method according to claim 1, characterized in that the starting function of the electronic engine control unit as one of the electronic Transmission Control Module subordinate control loop for the slip control of the start-up switching element works. Method according to claim 1 or 2, characterized in that the starting function of the electronic engine control unit with "limited normal operation" of the transmission and / or "emergency operation" of the transmission Motor speed gradient of the drive motor or a temporal Course of the engine speed gradient to a value within a tolerance band limited by measures acting on the drive motor side. A method according to claim 3, characterized in that a target value of the engine speed gradient or a temporal setpoint course of the engine speed gradient through the start function of the electronic Engine control unit is determined. A method according to claim 3, characterized in that a target value of the engine speed gradient or a temporal setpoint course of the engine speed gradient determined by the electronic transmission control unit and the start-up function of the electronic engine control unit becomes. A method according to claim 4 or 5, characterized in that the target value of the engine speed gradient or the temporal setpoint curve of the engine speed gradient is determined as a function of the driver's request, in particular under consideration one or more of the parameters accelerator pedal angle, throttle valve angle, Accelerator pedal angular velocity, throttle valve angular velocity, Engine torque, target engine torque, engine speed, driving speed, Transmission output speed, transmission ratio and transmission temperature. Method according to claim 1 or 2, characterized in that the starting function of the electronic engine control unit with "limited normal operation" of the transmission and / or "emergency operation" of the transmission Engine speed of the drive motor or a time course of the Motor speed to a value within a tolerance band by the drive motor side effective measures limited. A method according to claim 6, characterized in that a target value the engine speed or a temporal setpoint course of the engine speed determined by the start-up function of the electronic engine control unit becomes. A method according to claim 6, characterized in that a setpoint the engine speed or a temporal setpoint course of the engine speed determined by the electronic transmission control unit and the starting function of the electronic engine control unit is transmitted. A method according to claim 7 or 8, characterized in that that the Setpoint of the engine speed or the temporal setpoint curve of the Engine speed is determined as a function of the driver's request, in particular considering one or more of the parameters accelerator pedal angle, throttle valve angle, Accelerator pedal angular velocity, throttle valve angular velocity, Engine torque, target engine torque, engine speed, driving speed, Transmission output speed, transmission ratio and transmission temperature. Method according to one of claims 3 to 10, characterized in that the existence permissible lower and a permissible upper value of the tolerance band is determined by the start-up function of the electronic engine control unit becomes. Method according to one of claims 3 to 10, characterized in that the existence permissible lower and a permissible upper value of the tolerance band determined by the electronic transmission control unit and the start-up function of the electronic engine control unit becomes. A method according to claim 11 or 12, characterized in that the permissible lower and the allowable upper value of the tolerance band determined as a function of the driver's request will, especially taking into account one or more of the parameters accelerator pedal angle, throttle valve angle, Accelerator pedal angular velocity, throttle valve angular velocity, Engine torque, target engine torque, engine speed, driving speed, Transmission output speed, transmission ratio and transmission temperature. Method according to one of claims 1 to 13, characterized in that that the Start-up function of the electronic engine control unit the "restricted normal operation" of the transmission and / or the "emergency operation" of the transmission via transmission messages of the electronic transmission control unit recognizes. Method according to one of claims 1 to 13, characterized in that that the Start-up function of the electronic engine control unit the "emergency operation" of the transmission via an unsent transmission message of the electronic transmission control unit recognizes.