JP2000352346A - Control method and device for vehicle driving unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable determination of an appropriate required torque of an auxiliary steering system for a vehicle by determining required value of an output variable of a drive unit provided in the auxiliary steering system as a function of variables representing at least a steering angle and its time slope. SOLUTION: In determining a required torque of a power steering unit, a steering angle LW determined based on a wheel speed and the like is processed at a step 200 to obtain its absolute value. A time slope of the steering angle is then determined at a step 202. Then both the absolute value and time slope are transmitted to characteristics curves 204 to determine the required torque. The required torque is corrected as a function of a vehicle speed VFZ at a correction step 206 and a first part MSERVO 1 of the required torque is determined. A second part MSERVO 2 of the required torque as a function of the vehicle speed is determined at a characteristic curve 210. The power steering unit is controlled based on the sum of the first and second parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling a vehicle drive unit.

[0002]

DE-A-43 04 779 (U.S. Pat. No. 5,484,351) describes a method and a device for controlling a vehicle drive unit, in which at least the driver's wishes, for example an acceleration operable by the driver, are described. A target value for the torque of the drive unit is determined based on the pedal stroke. This target value for the torque of the drive unit takes into account the torque demand of the accessory and the losses in the range of the drive unit and is corrected by the correction value of the idle speed controller.
The target value thus adapted is then converted into a control variable for adjusting the torque of the drive unit, taking into account the drive unit and / or other variables of the vehicle, which control variable is Is controlled to a predetermined target value. Loss torque or consumption torque is a predetermined relationship,
For example, it is formed as a function of a measured operating variable, such as an engine speed, an engine temperature, or a state signal of ancillary equipment, based on a characteristic curve or characteristic curves. An adaptation is made to adapt the predetermined relationship to changing ambient conditions, the adaptation correcting the predetermined relationship based on the output signal of the idle control device. In particular, it aims at minimizing the correction value of the idle control device in the steady state, or making this correction value an average value that indicates the optimal determination of the consumption torque or the loss torque.

[0003] An essential consumer in the field of motor vehicles is the steering aid (power steering). Regarding the determination of the torque demand of such a steering assist device, the above-mentioned prior art does not provide this problem.

[0004]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method and a device capable of determining the torque demand of a steering aid in a motor vehicle.

[0005]

The above object is achieved by setting a set value MS.
The output variable of the drive unit is controlled as a function of the OLL, in which case the demand MVER from the consumer to this output variable is determined and the demand is taken into account in the control of the output variable. In the control method, the consumer device is a steering assist device, and a demand value MSERVO for an output variable of the drive unit of the steering assist device is determined as a function of at least a steering angle LW and a variable representing a time gradient thereof. The present invention is achieved by a method for controlling a vehicle drive unit according to the present invention, which is characterized by

[0006] The problem is also solved by at least one program for forming a set value MSOLL for an output variable of a drive unit, a program for determining a demand value MVER for a consumer device for this output variable, and this demand value. Including a program for controlling the drive unit in consideration of the above, comprising a control device having at least one microcomputer, in the control device of the vehicle drive unit, wherein the consumer device is a steering assist device,
A control unit for the vehicle drive unit, characterized in that the control unit includes a model representing the demand value MSERVO for the output variable of the steering assist device as a function of at least the steering angle LW and its time gradient. Achieved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

FIG. 1 shows a control device 10 for operating a drive unit 14 of a vehicle via an output line 12. In a preferred embodiment, the drive unit 14 is an internal combustion engine, which is controlled by a control variable supplied via the output line 12, for example with respect to the fuel supply. In another embodiment, drive unit 14 is an electric motor. The control device 10 consists essentially of various elements, namely an input circuit 16, a microcomputer 18, an output circuit 20, and a communication system 22 connecting these elements. In order to control the drive unit 14, at least one microcomputer 1 of the control device 10
8 outputs the determined control amount to the output line 12 via the output circuit 20. The microcomputer 18 calculates a control variable on the basis of operating variable signals supplied from the corresponding measuring device via the input circuit 16 or on the basis of operating variable values derived from these signals. A signal for the steering angle LW is supplied from the steering angle sensor 26 to the input circuit 16 via the first input line 24. A signal representing the engine speed Nmot is transmitted from an engine speed transmitter 30 via an input line 28. Via an input line 32, a signal representative of the vehicle speed VFZ is supplied from a corresponding measuring device 34. In this case, the measuring device 34 may be another control unit that determines the vehicle speed or an approximate signal of the vehicle speed based on the wheel speed signal. In addition, a signal representing the accelerator pedal stroke by the driver is transmitted via a line 36 from a corresponding pedal value transmitter 38. In addition to these signal values,
Via the input lines 40-44, other operating variable signals are transmitted from the measuring devices 46-50, such as, for example, signals representative of the load of the vehicle, engine temperatures, status signals of other accessories, etc. Are evaluated in combination with the control functions described below or other control functions.

[0009] Instead of determining the steering angle from the steering angle sensor, in other embodiments, it is based on a comparison of the wheel speeds of the steered wheels, or in a lateral acceleration,
The steering angle is determined based on other measured variables such as yaw rate and the like.

Depending on the embodiment, within the control of the drive unit, which may be a diesel engine, an Otto engine or an electric motor, respectively, the torque demand from the consumer, including the steering aid, is determined and the torque of the drive unit is determined. The torque demand is taken into account when determining at least one control variable for controlling the torque consumption such that the amount of torque received by these consumers is compensated. With regard to the steering assist device, the steering movement does not change the drive due to this compensation and does not stall the drive unit when the driver's setpoint is very small in a side-by-side (garage) operation. Therefore,
Determining the torque demand of the steering assist device is crucial for improving vehicle characteristics.

[0011] A steering assist device described below (hereinafter referred to as a steering assist device)
The method of determining the torque demand of the power steering determines the torque demand of the hydraulic, electrohydraulic or electric steering assist device. In particular, the torque demand of the servo pump in a hydraulic or electro-hydraulic steering aid is determined reliably and accurately.

A model is used to accurately and qualitatively and quantitatively determine the power steering torque demand value, whereby the torque demand is calculated based on the measured variables. The most important influence variable of the model is the current steering angle. In addition, another input variable is the vehicle speed, and in a hydraulic or electro-hydraulic steering assist device the rotational speed of the supply pump, the rotational speed of the supply pump depends on the rotational speed of the drive unit and the drive unit and the pump drive. It is determined from the gear ratio with the device.

In a preferred embodiment, the torque demand in power steering is determined from at least two parts. The first part is determined by the characteristic curves as a basic part as a function of the steering angle and its change over time. In a curve running, the required steering force decreases as the curve speed increases, so this basic torque demand value is corrected by the vehicle speed. Correspondingly, the power steering torque demand decreases with increasing speed. The design of the power steering, which is a function of the speed, provides another part, in which, at high running speeds, a smaller force and thus a smaller torque demand is formed.

In hydraulic or electro-hydraulic power steering, furthermore, the mechanical losses of the hydraulic servo pump should be taken into account simultaneously, this mechanical loss being dependent on the engine speed and the speed between the drive unit and the pump. A third portion that is a function of the transmission ratio of In this case, the torque demand of the servo pump increases with the rotation speed of the servo pump.

In another embodiment, the load condition of the vehicle is taken into account as an influencing variable on the torque demand of the power steering. Since the weight on the steering shaft increases due to the load state of the vehicle, the torque demand of the power steering increases with the increase of the vehicle load. Therefore, in determining the torque demand, the corresponding fourth part, which is a function of the load capacity, is taken into account.

The model converts operating variables into torque demand values by means of characteristic curves, characteristic curves or tables or calculation steps. The relationship underlying this conversion has been determined for each vehicle type. During the life of the vehicle, this relationship may change, for example, in the short term due to changes in the coefficient of road friction, in the long term different tires (e.g. winter tires, summer tires), different road tires in different manufacturers. It may change due to a change in adhesion or a change in tread depth due to wear. The adaptation of this relationship and thus the improvement of the accuracy of the torque demand determination is made, for example, by comparing the calculated torque with the actually accepted torque. For example, when power steering is an active consumer that inherently places a load on the drive unit, an indication of the deviation between these two values can be derived from the correction values of the idle speed controller under certain steady-state conditions. Given. An adaptation coefficient is determined from the deviation between the correction value of the idle speed control device and the optimum value, and this adaptation coefficient is taken into account in the determination of the torque demand value.

In modern whole-vehicle control designs, the torque demand values of the consumers are available as aggregate values or separately for individual consumers via the torque interface.

A preferred embodiment is illustrated by the flow charts of FIGS. These figures show programs of at least one microcomputer 18, which processes these programs at predetermined time intervals.

FIG. 2 schematically shows a flow chart which shows a method of compensating for the torque demand value from the consumption equipment and the lost torque, which is known from the state of the art described in part at the outset. First, the microcomputer forms the driver's desired FW representing the target torque, for example, by means of the characteristic curves 100 or selected calculation steps. In the preferred embodiment, the driver's desired FW is determined based on the accelerator pedal stroke β and the engine speed Nmot by the driver. The driver's desired FW is corrected in a first correction step 102 as a function of the determined consumption torque or loss torque, and in a second correction step 104, the idle speed control device 10
6 is corrected to the target torque MSOLL as a function of the output signal. This target torque is then converted by the program 108 in a manner known from the prior art into a control variable used for controlling the drive unit. For example, taking into account the drive unit and / or other operating variables of the vehicle as a function of the target torque, the fuel injection quantity qk, the set air supply and the set ignition angle αz (in Otto engines) are calculated and set. Is output to the drive unit. The idle speed control device 106 forms the correction value ΔMLLR as a function of the engine speed Nmot and a target speed set based on operating variables such as the engine temperature. The consumer torque MVER considered in the correction stage 102 is, according to the model 110 shown in FIG.
It is determined as a function of the steering angle LW, the vehicle speed VFZ, and possibly the engine speed Nmot, possibly taking into account the correction value ΔMLLR of the idle speed control device.
The torque demand of the power steering determined by the model, and for example the transmission converter,
From the torque demand values of other accessory consumers, such as air conditioners, generators, etc., a consumer torque MVER is optionally formed in a coupling step 112, which is then determined by the driver's desired and thus target torque. Is adjusted so as to compensate the torque demand value (increase the target torque when the torque demand increases).

A preferred embodiment for the model used for determining the power steering torque demand is shown in FIG. This figure shows a flowchart for model 110. First, the steering angle LW determined on the basis of the wheel speed signal or the measurement signal is read, and in a first program step 200 the absolute value of this value is formed. This is because the steering direction is not critical for determining the torque demand. Subsequently, in step 202, the time gradient of the steering angle is determined based on the current steering angle value and the previous steering angle value. The steering angle gradient and the current steering angle itself are supplied to a characteristic curve group 204 in which a first part of the power steering torque demand is stored as a function of the input variables mentioned above. ing. The torque demand value thus obtained is then corrected in a correction step 206 as a function of the vehicle speed VFZ. In this way,
First part of power steering torque demand MSE
RVO1 is determined. A correction value, which is a function of the vehicle speed, is determined in the characteristic curve 208 as a function of the vehicle speed, in which case the correction value is provided such that the torque demand value is reduced as a function of the steering angle at increasing speeds. I have.

Furthermore, in the characteristic curve 210, a second part MSERVO2 for the torque demand of the power steering is determined, also as a function of the vehicle speed.
This takes into account the design of the power steering as a function of speed, in which case the torque demand value MSERVO2 decreases with increasing vehicle speed VFZ. Join step 212
In, both parts are combined into a sum MSERVO and preferably added.

In an advantageous embodiment, the power steering is electro-hydraulic or hydraulic steering. Therefore, the essential factor that loads the drive unit is the hydraulic servo pump. This part of the power steering torque demand is the third part MSERVO
3 is determined by the characteristic curve group 214 based on the pump / motor rotation speed. In this case, the pump motor speed is multiplied by the gear ratio Ue between the pump motor and the drive unit (here, "Ue" stands for German U umlaut) (multiplication stage 216). ), Determined from the measured rotational speed Nmot of the drive unit. In this case, the gear ratio Ue is fixedly set and stored in the memory cell 218. Since the mechanical loss of the pump increases with the rotation speed, the partial MSERVO3 increases as the pump rotation speed increases. The third part is added to the above part in the coupling stage 212.

In another embodiment, the vehicle load LAST is determined within the model based on acceleration or as a measured variable and is supplied to a characteristic curve 220 from which the power steering is determined. A fourth part MSERVO4 for torque demand is derived.
In this case, this part rises with increasing load. A fourth part is also added to the above part.

In some embodiments, the partial MSERVO3
And MSERVO4 are not present.

For the adaptation of the fixed characteristic curves or characteristic curve values and their adaptation to various boundary conditions, a further correction step 222 is carried out after step 212 for the determined torque demand value. This value is corrected by the adaptive coefficient A in the correction step 222. The adaptation coefficient A is determined in step 224 from the correction value ΔMLLR of the idle rotation speed control device. Various conditions must exist for determining the adaptation coefficient, for example, the operating state of the vehicle must be stationary and essentially only the power steering as a consumer must be operating. At this time, the adaptive coefficient A may be determined based on the magnitude of the correction value, and the adaptive coefficient A is set so that the correction value of the idle rotation speed control device changes in the direction of the optimum value again. To correct the torque demand value.

In another embodiment, in addition to the torque control of the drive unit, the output of the drive unit is controlled. This method is included in the concept of controlling the output variables of the drive unit.

[0027]

The torque demand of the steering assist device (eg power steering) is determined and this torque demand is taken into account in the control of the drive unit. In this way, the control of the drive unit is improved, since the torque demands of the steering aid which have not been taken into account conventionally are also taken into account in the control of the drive unit.

A qualitatively and quantitatively correct compensation of the torque demand of the steering aid, in particular of the servo pump in hydraulically controlled power steering, is provided. By increasing the torque setting of the driver, the driver no longer has to take into account the load from the steering aid, so that the conversion to the driver's desired drive torque is more accurate. This compensation is of course automatic.

[0029] In the side-by-side (garage putting) operation, it is advantageous that when a large steering motion is performed, the engine stall that occurs when the drive unit is stopped due to a sudden decrease in the rotation speed is also avoided. . When the torque acceptance of the steering assist device is known, the driver can give finer vehicle movements. The running feeling in the sideways (garage) operation is improved.

When determining the torque demand of the power steering, it is particularly advantageous that the load condition of the vehicle is also taken into account. This further improves the compensation for torque demand, since the effective weight on the steered shaft and the effect of this weight on the torque demand of the power steering are taken into account at the same time.

To calculate the torque demand, the parameters are advantageously adapted, for example, on the basis of a correction value of the idle speed controller. This advantageously compensates for changes in road surface adhesion at different tires, different road surface friction coefficients and different tread depths.

[Brief description of the drawings]

FIG. 1 is an overall circuit diagram of a control device for controlling a vehicle drive unit.

FIG. 2 is a flow chart showing the principle method when considering and compensating for the torque demand of the consumer or the lost torque.

FIG. 3 is another flow diagram schematically illustrating the determination of the torque demand of the steering assist device.

[Explanation of symbols]

Reference Signs List 10 control device 14 drive unit 16 input circuit 18 microcomputer 20 output circuit 26 steering angle sensor 30 engine rotation speed transmitter 34 measuring device (vehicle speed) 38 pedal value transmitter 46, 50 measuring device (other operating variables) 100, 204, 214 characteristic curve group 102 first correction step 104 second correction step 106 idle rotation speed controller 108 program 110 model 112, 212 coupling step 200 absolute value forming step 202 time gradient forming step 206, 222 correction step 208, 210, 220 Characteristic curve 216 Multiplication stage 218 Memory cell 224 Adaptation coefficient formation step A Adaptation coefficient FW Driver's request LAST Vehicle load LW Steering angle MSERVO Demand value of steering assist device MSE RVO1, MSERVO4 First to fourth parts of torque demand MSOLL set value (target torque) MVER Consumed equipment torque Nmot Engine speed qk Fuel injection amount Ue Gear ratio VFZ Vehicle speed αz Set ignition angle β Accelerator pedal stroke ΔMLLR Idle rotation Speed controller correction signal

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Rainer Meyer Germany 71263 Weil der Stadt, Hermann-Schnaofer-Strase 33

Claims (10)

[Claims] 1. An output variable of a drive unit is controlled as a function of a set value (MSOLL), in which case a demand (MVER) from a consumer for this output variable is determined and said demand is output variable In the control method of the vehicle drive unit considered in the control of the vehicle, the consumer device is a steering assist device, and the demand value (MS) of the output variable of the drive unit of the steering assist device is
ERVO) is determined at least as a function of a variable representing the steering angle (LW) and its time gradient. 2. The method according to claim 1, wherein the demand value (MSERVO) is determined as a function of a vehicle speed (VFZ). 3. The vehicle according to claim 1, wherein the demand value determined as a function of the steering angle (LW) and a variable representing its time gradient is corrected as a function of the vehicle speed (VFZ). Method. 4. The hydraulic or electrohydraulic power steering according to claim 1, wherein the demand value (MSERVO) is determined as a function of the rotational speed of a hydraulic pump of the power steering. A method according to any one of the preceding claims. 5. The pump rotation speed is determined based on a rotation speed of the drive unit (Nmot) and a speed ratio (Ue) between the drive unit and a pump motor. The described method. 6. The method according to claim 1, wherein the demand value (MSERVO) is determined as a function of a vehicle load (LAST). 7. The method according to claim 1, wherein the demand value (MSERVO) is adapted as a function of the determined actual demand value. 8. The method according to claim 7, wherein the adaptation value (A) is determined as a function of a correction signal (ΔMLLR) of the idle speed control device. 9. The method according to claim 1, wherein the output variable of the drive unit is a torque of the drive unit. 10. At least one program (100) for forming a set value (MSOLEL) for an output variable of a drive unit, a program for determining a demand value (MVER) for a consumer device for this output variable (10). 11
0, 112), and a program (108) for controlling the drive unit in consideration of the demand value.
A control device for a vehicle drive unit, comprising a control device (10) having at least one microcomputer (18), wherein the consumer device is a steering assist device, and the control device (10) is a control device for the steering assist device. And a model (110) representing a demand value (MSERVO) for an output variable as a function of a variable representing at least the steering angle (LW) and its time gradient.