DE19827585C1 - Automobile drive train operating condition detection method for feedback control of engine - Google Patents

Abstract

The operating condition detection device calculates the operating condition of the drive train provided by the clutch and the drive transmission using the ratio (NV) between the engine revs (N) and the vehicle velocity (V) and the rate of variation in this ratio. An Independent claim for a device for detecting the operating condition of an automobile drive train is also included.

Description

State of the art

A method and a device for recognizing the Operating state of the drive train of a motor vehicle described.

In the control of motor vehicles, especially in the Control of the engine of motor vehicles is often the Operating state of the drive train of the motor vehicle from Interest in whether there is a positive connection or not. this applies especially in vehicles with manual transmissions. From the Solutions are known in the prior art, in which Er Version of the operating state of a clutch and / or the Gear position mechanical switching elements are used (See e.g. DE 34 26 697 C3, U.S. Patent 4,120,373). A Clutch switch should have its switching edge on an actuator have the clutch pedal on which the clutch non-slip closes. However, this switching point is due of tolerances and clutch wear not exactly put. It has been shown that it can happen that the The clutch is still powerful when the clutch pedal is slightly pressed is closed, although the switch is already one open clutch signals. Conversely, the  Clutch still open or dragging, although the scarf ter already indicates a closed clutch. Because of who the control functions of the motor vehicle, which depend on frequency of the clutch switch signal or one of the abge headed adhesion signal work, negatively affected.

Such functions are, for example, idle control, Vehicle speed control or load change functions. Load change functions are functions which are used during the transition from pushing to pulling an internal combustion engine Prevent vibrations in the drive train. This will in a special embodiment, the driver request si gnal filtered (compare e.g. DE-A 43 21 333). At a such function is the information about the clutch condition or the frictional connection in the drive train especially important to avoid when the drive train is closed limited by vibrations torque requests be filtered to jerk the vehicle prevent. In contrast, when the dome is open lung, d. H. open powertrain, torque change wishes can be realized very quickly, for example with Start increasing the engine speed quickly enough or to prevent gear upshifts from full load the engine over revs when opening the clutch.

It is therefore an object of the invention to implement measures for detection of the operating state of the drive train specify. This is due to the distinctive features of the independent claims achieved.

Advantages of the invention

It is of particular distribution that the information about the Operating state of the drive rod, whether there is a positive connection or not, from the ratio of the speed of the drive  unit of the vehicle (engine speed) to the driving speed (Gearbox output speed) is derived. This informat on is independent of the tolerance level of mechanical scarf ter, in particular a clutch switch.

In addition, the Lö described below In contrast to the clutch switch, not only the solution drive state of the clutch, but the adhesion in ge entire drive train is determined, especially for the Load change function is crucial.

It is also advantageous to use the to recognize the Operating state of the drive train described Prege for diagnostic purposes of a mechanical clutch switch to provide a second piece of information regarding the operating status. By comparison with that The switch signal becomes the respective tole when a gear is engaged The mechanical clutch switch is detected. In be is particularly advantageous in the case of unsatisfactory Tolerance positions on the procedure described below se switched.

The procedure described is particularly advantageous in addition to a mechanical clutch switch put. As part of a logical link, the linked the two operating status information, advantageously the information "closed Coupling or frictional connection "is present when one of the two operating status signals on a closed coupling Let the lung close while the information "open Coupling or no frictional connection "is present if both Infor have an open clutch indicated. This leads to special advantages in connection with the outlined load change function, since then a filtering on in any case takes place when one of the operating conditions  information a closed coupling or a ge closed drive train shows. This procedure is then advantageous when the clutch switch to a very changes its state early after pressing the pedal. Än If the condition changes very late, it is advisable to reverse approach to choose, d. H. the information "Closed clutch or frictional connection" is then present if both operating status signals are closed Have the clutch closed while the information "Open clutch or no frictional connection" is present if one or both of the information on an open Let the clutch close.

drawing

The invention is explained below with reference to the embodiments shown in the drawing. Here, FIG. 1 shows an overview block diagram of a control unit for controlling a vehicle, in which the procedure described below is implemented for detecting the Betriebszu article. FIG. 2 shows a preferred exemplary embodiment of this procedure as a flow chart, which outlines the implementation of the procedure as a program of a computing element comprising the control unit. A flow chart of an example of the evaluation Fig. 3 shows the operating condition signal for motor control.

Description of exemplary embodiments

In Fig. 1, an electronic control unit 10 for controlling the drive unit 12 , in particular an internal combustion engine, is shown. In addition to the drive unit 12 to the drive train 14 includes a crankshaft 16 , a driver-operated clutch 18 , a transmission input shaft 20 , a switchable transmission 22 and a transmission output shaft 24th The torque generated by the drive unit 12 is brought by these shafts, the clutch and the transmission to the drive wheels of the vehicle, not shown. The speed of the crankshaft 16 and thus the speed of the drive unit 12 is detected by a measuring device 26 which leads a corresponding signal N via a line 28 to the control unit 10 . Accordingly, in a preferred embodiment, the speed of the transmission drive shaft 24 is supplied to the control unit 10 via a line 32 from a speed sensor 30 . The speed of the transmission output shaft represents the driving speed of the vehicle. In another embodiment, the driving speed from signals from other sensors, the z. B. detect the wheel speeds, derived. The clutch 18 can be opened or closed by the driver by actuating the clutch pedal 36 via a mechanical connection 34 . In one embodiment, a clutch switch 38 is also provided, which can be brought to the clutch itself or to the pedal and which, when the clutch is closed, transmits a corresponding switching signal via line 40 to the control unit 10 . In another game Ausführungsbei this clutch switch 38 is missing and the detection of the clutch state takes place exclusively by the procedure shown below. In addition to the Darge presented input variables, the control unit 10 via the input line 42 is a measure of the deflection of an accelerator pedal 44 which can be actuated by the driver and via lines 46 to 50 of measuring devices 52 to 56 further operating variables of the vehicle or the drive unit, such as those mentioned above Wheel speeds, the engine temperature, etc. transmitted over. The control unit 10 controls the power, the torque of the drive unit 12 z. B. by influencing the air supply 58 , the fuel injection 60 and / or the ignition angle 62nd

The driver's request, preferably a desired torque, is derived in the control unit 10 from the extent of the deflection of the accelerator pedal. For this target torque of the current operating state is determined in consideration of the drive unit 12 to a control signal for setting 12 determines the torque of the drive unit, wherein the torque delivered by the engine to approach the pre-added target torque. The operating variables read in by the control unit 10 are used in the calculation of the control signals. The control unit 10 also includes a load change function, the driver request derived from the driving pedal position being filtered. This filtering takes place when a transition from pushing to pulling the internal combustion engine when the drive train is closed, that is to say when the clutch is engaged and a gear engaged, or when z. B. there is a quick withdrawal of the accelerator pedal. In operating conditions with the drive train open, e.g. B. with the clutch open, the load change function is not active. In the following, the terms "closed and opened clutch" are used as synonyms for the terms "adhesion or no adhesion" ver.

The information about the operating state of the drive train is to be generated from the ratio NV of the engine speed N to the vehicle speed V. The information is independent of the tolerance position of a clutch switch 38 that may be present. In a preferred embodiment, the detection of a stepped or let go clutch is made with the gear engaged in that the ratio of the engine speed to the vehicle speed and the change in time of this ratio is used. The transition from a closed to an open clutch is recognized when the ratio is outside the tolerance band for the current gear or the amount of the change over time is much larger than a predetermined threshold value. Correspondingly, the transition from an open to a closed clutch is recognized when the amount of the change over time is smaller than the threshold and the ratio is within a predetermined tolerance band of a gear.

This algorithm is used to improve the functionality debounced. A change of state is only recognized as taken when the calculation is repeated several times gives the same information about the clutch condition.

The gradient of the relationship (change over time) is made Measured values of the ratio at different times calculates and filtered with a time constant.

When a clutch is closed again, by the procedure described for the following operating situations cations taken into account:

If the ratio NV settles to a value that is be corresponds to the correct gear, and the gradient is clear small enough, so it is a completed dome operation suspected. Did the speed change due to one neutral coupling process from below or from above to the Approximate synchronous speed of the gear was the detection correct.

The driver intends to accelerate before the end of engagement ganges brought the speed to an overshoot, whereby accidentally a speed value was reached that is synchronous ratio corresponds to a lower gear, was the Ent divorce is not correct, but is followed by a subsequent Falling speed automatically corrected again. The driver maintains the engine speed when the clutch is depressed Accelerating in the range of the synchronous ratio of a gear,  this will in itself be the wrong decision after the end corrected this condition immediately. If no gear is engaged, the clutch will not change determined state, since no frictional connection in the drive strand is present. If the driver engages a gear, this is done automatic detection of the clutch condition and thus the adhesion as indicated above.

Effects of wrong decisions on control the drive unit is therefore not to be feared.

The control unit 10 comprises at least one microcomputer. The procedure described above is implemented in the preferred exemplary embodiment as a computer program of this microcomputer. In Fig. 2, a flow chart is shown, which sketches an example of such a computer program. The program shown is run through at predetermined time intervals (e.g. a few milliseconds).

In the first step 100 , the speed N and the vehicle speed V are read in and in the subsequent step 102 the ratio NV is formed as the quotient of the speed and the vehicle speed. In the subsequent step 104 , the change over time (gradient) dNV / dt is formed on the basis of the measured values of the ratio at different times. A check is then made in step 105 as to whether the force-locking information KUP has the value 1, that is to say that it indicates a closed drive rod and thus force-locking. If this is the case, it is checked in step 106 whether the ratio is outside the tolerance band of a gear or whether the magnitude of the gradient exceeds a predetermined threshold value A0. The ratio is outside the tolerance band if the currently measured ratio value does not match a ratio value stored in a table for the different gears within the scope of a tolerance. If one of the conditions queried in step 106 is met, then in step 108 the counter Tzu used for debouncing the function is set to the value zero for the transition from the open to the closed position of the drive train, while the counter Tauf for the reverse Process is increased by one. In the following step 110 it is checked whether the counter reading Tauf has reached its maximum value. If this is the case, it is assumed that an operating state change has taken place with sufficient certainty so that the adhesion information KUP assumes the value zero. If the counter reading in step 110 did not reach the maximum value, nothing is changed in the current status information. If step 106 has shown that neither of the two conditions is met, in step 114 the two counters Tzu and Tauf are set to the value zero. After steps 110 in the event of a no answer, steps 112 and 114 , the program is run through again at step 100 at the next point in time.

If step 105 has shown that the status information does not have the value 1, but the value zero, it is accordingly checked in step 116 whether the ratio NV lies within the tolerance band of a gear and whether the magnitude of the gradient of the ratio has a threshold value A1 un steps. The check as to whether the ratio lies within a tolerance band of a gear takes place in accordance with the illustration in step 106 , it being checked whether the ratio corresponds to a table value within the tolerance. If this is the case and the amount of the gradient meets the specified condition, the counter Tzu is incremented by one in step 118 and the counter Tauf is set to zero. In the following step 120 it is checked whether the counter Tzu has reached its maximum value. If this is the case, a change of state of the operating state of the drive rod is assumed in step 122 and the force-locking information KUP is set to the value one. In the event of a negative answer in step 120 , the program is repeated at the next point in time, just as in step 122 . If step 116 has shown that at least one of the conditions is not met, the two counters Tzu and Tauf are set to the value zero and the program is repeated with step 100 at the next point in time.

In Fig. 3, an example of a program is shown for evaluating the frictional connection information. After the start of the program part at predetermined times, the adhesion information KUP is read in the first step 200 . A check is then carried out in step 202 as to whether the information has the value one, that is to say it indicates a positive connection. In this case, the load change function is activated in accordance with step 204 and switched to active in the event of a no answer in step 202 in accordance with step 206 . The program will then run again at the next point in time.

Instead of using a mechanical switching element becomes a clutch travel in another embodiment sensor for determining the closed or open dome lung used. The procedure for recognizing the force conclusion and / or the diagnosis in the context of the above Be spelling is indicated accordingly with the sensor's position signal turns.

Instead of or in addition to the application of the described before way as a replacement of the clutch switching element or egg nes clutch travel sensor is the procedure described as stated above for diagnosis or as an additional coupling status information used. That becomes a diagnosis Switching signal or the path signal with the determined force final signal compared and possible error states at un permissible deviations are determined. In an execution case  game will improve detection security Non-positive connection detected when due to the switching element or the clutch travel sensor or based on the ratio a closed clutch can be found while an open drive train is detected when the scarf telement or the clutch travel sensor an open clutch indicates and if out of the ratio an open clutch is derived. In another embodiment Non-positive connection detected when due to the switching element or the clutch travel sensor and based on the ratio a closed clutch can be found while an open drive train is detected when the clutch lungswegensor or the switching element an open clutch display or if an open one from the relationship Clutch is derived.

In one embodiment, as described above Load change function active or in depending on the adhesion activated. In another embodiment, who the parameters of the load change function, e.g. B. at least one Filter constant, switched depending on the adhesion. There at is a reduction in the filtering effect when the stood aimed at without adhesion.

Claims (9)

1. A method for detecting the operating state of a drive train of a motor vehicle, the Betriebszu state indicates whether there is a positive connection or not, with a clutch ( 18 ) and a transmission ( 22 ), it being determined whether there is a positive connection in the drive train and wherein depending on the operating state of the drive train, the drive unit ( 12 ) of the motor vehicle is controlled, characterized in that the operating state in accordance with the relationship (NV) between engine speed (N) and vehicle speed (V) and the temporal change of the ratio is determined. 2. The method according to claim 1, characterized in that a Load change function is carried out when he engages is known while the load change function is inactive if no adhesion is detected, or that parameters of the load change function depending on the detected adhesion modifi be decorated. 3. The method according to any one of the preceding claims, characterized characterized in that no adhesion is detected when the ratio outside of a tolerance band for one located gear, or the change in ratio is greater than a predetermined threshold.   4. The method according to any one of the preceding claims, characterized characterized in that adhesion is recognized when the ver ratio within a predetermined tolerance band for egg is in gear and the change in ratio falls below a predetermined threshold. 5. The method according to any one of the preceding claims, characterized characterized in that a change in the operating state then is assumed when determining the operating status leads to the same result several times in succession. 6. The method according to any one of the preceding claims, characterized characterized in that to generate the clutch operation status information a mechanical switching element or Clutch travel sensor is provided, the switching signal or the path signal with the determined adhesion signal Diagnostic purposes is compared. 7. The method according to any one of the preceding claims, characterized characterized in that to determine the clutch condition a mechanical switching element or a clutch travel sensor is provided, the closed clutch or force then is detected when due to the switching element or the clutch travel sensor or based on the ratio a closed clutch or frictional connection determined can be while an open clutch or an open Neter drive train is detected when the switching element or the clutch travel sensor an open clutch or egg indicates an open drive train and if from the ver ratio an open clutch or an open An powertrain is derived. 8. The method according to any one of the preceding claims, characterized characterized in that to determine the clutch condition  a mechanical switching element or a clutch travel sensor is provided, the closed clutch or force then is detected when due to the switching element or the clutch travel sensor and based on the ratio a closed clutch or frictional connection determined can be while an open clutch or an open Neter powertrain is detected when the clutch paths sor or the switching element an open clutch or egg indicates an open drive train or if from the ver ratio an open clutch or an open An powertrain is derived. 9. A device for detecting the operating state of a drive train of a motor vehicle, wherein the operating state indicates whether there is a positive connection or not, with a clutch ( 18 ) and a transmission ( 22 ) with an electronic control unit ( 10 ), which at least the drive unit ( 12 ) of the motor vehicle controls the basis of a force-locking signal, characterized in that the control unit ( 10 ) has means which represent the operating state on the basis of the ratio (NV) of the speed (N) to the driving speed (V) and its time Detect change.