ITMI991274A1 - PROCEDURE AND DEVICE TO RECOGNIZE THE OPERATING STATE OF THE MOTOR DRIVE TRANSMISSION SECTION OF A VEHICLE - Google Patents

Description

State of the art

A method and a device are described for recognizing the operating state of the drive transmission section of a motor vehicle.

For the control of motor vehicles, especially for the control of the motor vehicle engine, the operating status of the motor vehicle drive transmission section is often of interest, to detect whether or not there is a mechanical constraint, this is especially true for vehicles with manual gearboxes. . From the current state of the art solutions are known in which mechanical switching elements are used to detect the operating state of a clutch and / or the position of the gearbox (see for example DE 34 26 697 C3, patent US 4120 373) . A clutch switch must have its switching flank at a point where the clutch pedal is operated, where the clutch engages without slipping. However, this switching point cannot be set exactly due to tolerances and clutch wear. The result may occur that the clutch, with the clutch pedal being slightly actuated, is still engaged with a mechanical constraint even if the switch already signals a disengaged clutch. Likewise, the clutch, on the other hand, can still be disengaged or slip even if the switch already indicates a clutch engaged. Consequently, the control functions of the motor vehicle are negatively influenced, which work in dependence on the signal of the clutch switch or on a mechanical constraint signal derived therefrom.

Such functions are, for example, idle control, travel speed control or load change function. Load change functions are functions that when passing from the release operation to the traction operation of an internal combustion engine will have the purpose of preventing vibrations in the drive transmission section. For this purpose, the driver request signal is filtered in a particular embodiment (see for example DE-A 43 21 333). With a function of this type, the information regarding the state of the clutches or the mechanical constraint in the drive transmission section is particularly important, since when the drive transmission section is closed, requests for torque variations are limited or filtered to avoid vibrations. to prevent a jolting movement of the vehicle. Unlike this, when the clutch is disengaged, i.e. when the drive transmission section has started, requests for torque variations must be made very quickly, in order to increase the number of revolutions of the engine quickly enough, for example during start-up or to prevent the engine from packing up when the clutch is disengaged when shifting to the higher gears of the gearbox from full load.

Therefore, the invention has the task of indicating expedients for reliably recognizing the operating state of the drive transmission section. This is achieved by the features of the independent claims.

Advantages of the invention.

It is particularly advantageous that the information relating to the operating status of the drive transmission section, specifying whether or not there is a mechanical constraint, is obtained from the ratio between the number of revolutions of the vehicle drive unit (number of engine revolutions) and travel speed (number of output revolutions of the gearbox). This information is independent of the tolerance situation of mechanical switches, especially for clutch switch.

Furthermore, with the solution described below, unlike the clutch switch, not only the operating state of the clutch is determined but the mechanical constraint in the entire drive transmission section, which is of decisive importance especially for the gear change function. load.

It is also advantageous to use the method described for recognizing the operating status of the driving transmission section for diagnostic purposes of a mechanical clutch switch to provide a second information relating to the operating status. By comparison with the switch signal, when the gear is engaged, the respective tolerance situation of the mechanical clutch switch is recognized. In a particularly advantageous way, it can therefore be advantageous in the event of unsatisfactory tolerance situations to switch to the procedure described below.

It is particularly advantageous to use the described method, integrally, in addition to a mechanical switch of the clutch, in the context of the logical correlation two information of the operating state are correlated with each other, where advantageously there is the information "clutch engaged or mechanical constraint" when from one of the two signals of the operating state it is possible to deduce a clutch engaged, while the information "clutch disengaged or no mechanical constraint" exists when a disengaged clutch is inferred from both information. This leads to particular advantages in combination with the load change function outlined above, since in this case a filtration occurs anyway when one of the operating status information indicates a clutch engaged or a closed drive transmission section. This procedure is advantageous when the clutch switch changes its state well in advance after the pedal is operated. If it changes its state very late, it is advisable to choose the inverse procedure, that is the information "clutch engaged or mechanical constraint", exists when from both signals of the operating state it is possible to deduce a clutch engaged, while the information " clutch disengaged or absence of mechanical constraint "exists when it is possible to trace the disengaged clutch from one of the two or both information.

drawing

The invention is illustrated in more detail below based on the embodiments shown in the drawing.

In particular:

Figure 1 shows a block assembly diagram of a unit for controlling a vehicle, in which the method described below is implemented to recognize the operating state, Figure 2 shows a preferred embodiment of this method as an operating diagram schematizing the implementation of the procedure as a program of a calculation element comprising a control unit,

Fig. 3 shows an operating diagram as an example of the evaluation of the operating status signal for the motor control.

Description of the examples of realization

Figure 1 shows the electronic control unit 10 for controlling drive unit 12, especially an internal combustion engine. In addition to the drive unit 12, the drive transmission section 14 comprises a crankshaft 16, a clutch 18 that can be operated by the driver, a gearbox input shaft 20, a gearbox 22 that can be controlled as well as a drive shaft 24 of the gearbox. The torque produced by the drive unit 12, these shafts, the clutch and the gearbox is carried to the drive wheels of the vehicle not shown. The number of revolutions of the crankshaft 16 and thus the number of revolutions of the drive unit 12 are detected by means of a measuring device 26, which carries a corresponding signal N via a control line 28 10. Correspondingly in an embodiment example Preferred by a speed sensor 30, the number of revolutions of the drive shaft 24 of the gearbox via a line 32 is fed to the control unit 10. The number of revolutions of the drive shaft of the gearbox speed in this case represents the driving speed of the vehicle. In another embodiment, the travel speed is inferred from signals from other sensors which, for example, detect the speeds of the wheels. The clutch 18 by means of a mechanical connection 34 must be disengaged by the driver by actuating the clutch pedal 36, or it must be engaged. In one embodiment, a clutch switch 38 is also provided, which can be applied to the clutch itself or to the pedal and when the clutch is engaged it transmits a corresponding switching signal via line 40 to the control unit 10. In another exemplary embodiment this clutch switch 38 is missing and the recognition of the state of the clutch takes place exclusively by means of the method shown below. In addition to the input quantities shown, the control unit 10 is supplied via the input line 42 with a measure for the deflection of an accelerator pedal 44, which can be operated by the driver, and via the lines 46, 50 measuring devices 52 to 56 are additional operating variables of the vehicle or the operating unit or the drive unit, such as the aforementioned wheel speeds, engine temperature, etc. are transmitted. The control unit 10 controls the power, the torque of the drive unit 12, for example by influencing the air supply 58, the fuel injection 60 and / or the ignition angle 62.

The driver's request, preferably a prescribed torque, is derived from the extent of the acceleration pedal deviation in the control unit 10. From this prescribed torque, taking into account the current operating state of the drive unit 12, a control signal is determined for setting the torque per drive unit 12, where the torque supplied by the internal combustion engine approaches the predetermined prescribed torque. The operating variables read from the control unit 10 are used to calculate the control signal. The control unit 1 'also includes a load change function, where the driver request derived from the position of the accelerator pedal is filtered. . This filtration takes place when a passage from release to traction operation of the internal combustion engine has been recognized when the drive transmission section is closed, i.e. the clutch is engaged and the gear is engaged or when, for example, there is a rapid release of the accelerator pedal. In operating states with open drive sections, i.e. with the clutch disengaged, the load change function is not active. In the following, the expressions "clutch engaged and disengaged" are used as synonyms of the expressions "mechanical constraint respectively absence of mechanical constraint".

Information relating to the operating status of the drive transmission section is produced by the ratio NV between the number of revolutions N of the engine and the speed V of the vehicle. The inforation is independent of the tolerance situation of a clutch switch 38 possibly present. In a preferred example of embodiment, the recognition of a crushed clutch, respectively released again, when the gear is engaged, is carried out since the ratio between the number of revolutions of the engine and the speed of the vehicle is used as well as the temporal variation of this ratio. . The transition from a clutch engaged to a clutch disengaged is recognized when the ratio is outside the tolerance band for the current gear, or the amount of the time variation is far greater than a pre-assigned threshold value. Correspondingly, the transition from a disengaged clutch to an engaged clutch is recognized when the amount of the time variation is below the threshold and the ratio is within a predetermined tolerance band of a gear.

To improve the functioning this algorithm is eliminated. A change of state is considered as recognized only when the calculation several times consecutively indicates the same information relating to the state of the clutch.

The input gradient (time variation) is calculated from measured values of the ratio at different instants and filtered with a time constant.

By detecting a newly engaged clutch, the following operating situations are taken into account using the procedure described:

if the ratio NV moves towards a value corresponding to a given gear, and in this regard the gradient is sufficiently small, then at first it is assumed that an engagement operation has been completed. If the number of revolutions, following an actual shifting operation from below or from above, approached the synchronous speed of the gear, the recognition was correct.

If the driver accelerating before the end of the engagement operation made the number of revolutions to an over-rev, where by chance a value of the number of revolutions corresponding to the synchronization ratio of a lower gear was reached, then the decision was not corrected but by a subsequent reduction in the number of revolutions it is corrected again automatically. If the driver maintains the number of revolutions within the synchronization ratio of a gear while accelerating with the clutch pressed, this decision, which is in itself incorrect, is immediately corrected again after the end of this situation. If no gear is engaged then there is no change in the state of the clutch, as there is no mechanical constraint in the drive transmission section. If a gear is engaged by the driver, then automatic recognition of the state of the clutch and therefore of the mechanical constraint takes place as previously indicated. There is therefore no need to fear repercussions of incorrect decisions on the control of the drive unit.

The control unit 10 comprises at least one microcomputer. The method described above is implemented in the preferred embodiment as a calculation program of this microcomputer. Figure 2 shows an operating diagram schematizing an example for a calculation program of this type. The program shown is run at pre-assigned time intervals, for example a few milliseconds.

In the first step 100 the numbers of revolutions N and the speed V of the vehicle are read in the subsequent phase 102 the ratio NV is formed as a quotient between the number of revolutions and the speed of the vehicle. In the subsequent step 104 the temporal variation (gradient) dNV / dt is formed on the basis of the measured values of the ratio at different instants. Subsequently, in step 105 it is checked whether the mechanical constraint information KUP has the value 1, that is, if it indicates a closed drive transmission section and therefore a mechanical constraint. In this case, in step 106 it is checked whether the ratio lies outside the tolerance band of a gear or whether the amount of the gradient exceeds a pre-assigned threshold value AO. The ratio is outside the tolerance band when the currently measured ratio value does not coincide with a ratio value, stored in a gear table, within a tolerance. If one of the conditions interrogated in step 106 is satisfied then in the subsequent step 108 the counter Tzu, serving to eliminate the function, for the passage from the open position to the closed position of the motor transmission section is brought to the value 0 while the counter Tauf for the reverse operation is increased by 1. In the next step 110 it is checked whether the Tauf counting volume has reached its maximum value. If this happens, one starts from the fact that a change of the operating state has occurred with sufficient safety, so that the information KUP relating to the mechanical constraint assumes the value 0. If the counting volume in phase 110 has not reached the maximum value , then nothing is changed in the current state information. If from step 106 it has emerged that neither of the two conditions is satisfied, then in step 114 both counters Tzu and Tauf are set to the value 0. After steps 110 in the case of a negative response, steps 112 and 114, the program in the following instant it is passed again with phase 100.

If it has emerged from step 105 that the status information does not have the value 1 but the value 0, then correspondingly in step 116 it is checked whether the ratio NV is within the tolerance band of a gear and whether amount of the ratio gradient falls below a threshold value Al. The verification of whether the ratio value falls within a tolerance band of a gear, takes place corresponding to the representation in Figure 106, where it is checked whether the value of the ratio within the tolerance corresponds to a tabular value. If this happens and if the gradient amount satisfies the indicated condition, in phase 118 the Tzu counter is increased by 1 and the Auf counter is set to 0. In the next phase 120 it is checked whether the Tzu counter has reached its maximum value. If this occurs then in accordance with step 102, a change in the operating state of the drive transmission state is started and the information of the mechanical constraint KUP is set to the value 1. In the case of a negative response in step 120 as well as after step 122 the program is repeated at the next instant. If from step 116 it has emerged that at least one of the conditions is not satisfied, then the counters Tzu and Tauf are set to the value 0 and the program is repeated in the next instant with step 100.

Figure 3 shows an example for a program for evaluating mechanical constraint information. After starting from the program part at pre-assigned instants, the mechanical constraint information KUP is read in the first phase 200. Subsequently, in phase 202 it is checked whether the information has the value 1, ie the mechanical constraint is indicated. In this case according to step 204 the load change function is activated and in the case of a negative response in step 202 according to step 206 it is deactivated. The program is then run through again at the next instant.

Instead of using a mechanical switching element in another embodiment, a clutch stroke sensor is used to determine the rigidly disengaged engaged clutch. The method for recognizing the mechanical constraint and / or the diagnosis in the context of the foregoing description are used correspondingly with the travel signal of the sensor.

Instead of or in addition to the use of the described method as a substitute for the clutch switching element or a clutch sensor, the method described as described above is used for diagnosis or as additional information on the state of the clutch. During diagnostics, the switching signal or the travel signal is compared with the determined mechanical constraint signal and possible error states are determined in the event of impermissible deviations. In an example of embodiment, to improve recognition safety, a mechanical constraint is recognized when, following the switching element or the clutch stroke sensor or following the ratios, a clutch engaged can be detected, while a drive transmission section is recognized. open when the switching element respectively the clutch sensor indicates a disengaged clutch and when the ratio results in a disengaged clutch. In another embodiment, a mechanical constraint is recognized when, following the switching element respectively the clutch stroke sensor and following the gear ratio, a closed clutch can be detected, while an open drive transmission section is recognized when the clutch travel respectively of the switching element indicates a disengaged clutch or when a disengaged clutch is deduced from the ratio.

In an embodiment example as previously described, the load change function is activated or deactivated depending on the mechanical constraint. In another embodiment, the parameters of the load change function, for example at least one filter constant, are switched depending on the mechanical constraint. In this regard, an attempt is made to obtain a reduction of the filtration effect in a state without mechanical constraint.

Claims (9)

CLAIMS 1. Procedure for recognizing the operating status of a drive transmission section of a motor vehicle, where the operating status indicates whether or not there is a mechanical constraint with a clutch (18) and a gearbox (22) where it is detected whether mechanical constraint in the drive transmission section, where moreover, depending on the operating state of the drive transmission section, the motor vehicle drive unit is controlled, characterized in that the operating state is determined on the basis of the ratio (NV) between number of revolutions (N) of the engine and vehicle speed (V) and based on the temporal variation of the ratio. 2. Process according to claim 1, characterized by the fact that a load change function is performed when the mechanical constraint is recognized, while the load change function is inactive when the absence of a mechanical constraint is recognized, or by the fact that parameters from the function load changes are modified according to the recognized mechanical constraint. 3. Method according to one of the preceding claims, characterized in that no mechanical constraint is recognized when the gear is outside a tolerance band with a gear engaged, or the variation of the force is higher than a pre-assigned threshold value. 4. Method according to one of the preceding claims, characterized in that mechanical constraint is recognized when the ratio is within a predetermined tolerance band for a disengaged gear and the change in the ratio falls below a predetermined value of theshold. Method according to one of the preceding claims, characterized in that a change in the operating state is assumed when the determination of the operating state can lead to the same result consecutively. Method according to one of the preceding claims, characterized in that a mechanical switching element or a clutch stroke sensor is provided for producing the operating status information of the clutch, wherein the switching signal or the stroke signal is compared with the mechanical constraint signal determined for diagnostic purposes. Method according to one of the preceding claims, characterized in that the mechanical switching element or a clutch stroke sensor is provided to determine the state of the clutch, wherein the closed clutch or the mechanical constraint is recognized when following the switching element respectively to the clutch stroke sensor or as a result of the ratio it is possible to detect a clutch engages or mechanical constraint, while a disengaged clutch or an open drive transmission section is recognized, when the switching element or the stroke sensor is recognized of the clutch indicates a disengaged clutch respectively an open drive transmission section, and when the ratio is deduced a disengaged clutch or an open drive transmission section. 8. Method according to one of the preceding claims, characterized in that a mechanical switching element or a clutch stroke sensor is provided for determining the state of the clutch, wherein the engaged clutch or mechanical constraint is recognized when following the switching element respectively to the clutch stroke sensor and following the gear ratio, it is possible to detect a clutch engaged or mechanical constraint, while the clutch disengaged or an open drive transmission section is recognized, when the clutch stroke sensor or the switching element indicates a clutch disengaged respectively an open drive transmission section or when a disengaged clutch can be deduced from the ratio or an open drive transmission section. 9. Device for recognizing the operating status of a motor vehicle drive transmission section, where the operating status indicates whether or not there is a mechanical constraint, with a clutch (18) and a gearbox (22), with a electronic control unit (10), which at least on the basis of a mechanical constraint signal controls the drive unit (12) of the motor vehicle, characterized in that the control unit (10) has means which determine the state of exercise on the basis of the ratio (NV) that is the number of revolutions (N) and the speed of the vehicle (V) and on the basis of its temporal variation.