DE4335726B4 - Method and device for controlling the drive power of a vehicle - Google Patents

Abstract

Method for controlling a drive unit of a vehicle,
Wherein the torque of the drive unit is set via at least one setting device,
The at least one adjusting device is set at least in the idling and / or idling operating range on the basis of at least one operating variable of the drive unit and / or of the vehicle,
Wherein the at least one operating variable is the turbine speed of an automatic transmission with a torque converter,
characterized in that
the setting of the adjusting device is dependent on the time course of the turbine speed.

Description

The The invention relates to a method and a device for controlling the drive power of a vehicle according to the preambles of the independent claims.

Such a method and such a device is known from EP 206 091 A2 ( US 4,819,596 A ) known. There, a regulation of the rotational speed of a drive unit, preferably in idle and near-idle area, proposed, which controls the drive power of the vehicle via the control of the air supply to an internal combustion engine as a function of various factors. A first factor is a feedback factor which is determined based on the difference between the actual and a predetermined setpoint speed. In addition, additive correction factors are provided, which are added to form the drive signal for setting the drive power to the feedback factor. To take account of the load of an automatic transmission equipped with a torque converter in the idling or idle region, especially when the vehicle is rolling, one of these correction factors is predetermined as a function of the driving speed of the vehicle.

This Correction factor becomes when gear is engaged with increasing vehicle speed smaller in size, goes to zero. This should counteract speed drops, which can occur as follows. Since the loading effect of the torque converter when rolling Vehicle is lower than when the vehicle is at a constant torque delivered by the engine when the vehicle is rolling a higher one Speed result when the vehicle is stationary. The integrator share of the idle controller would in this operating situation at high speed, the engine torque in Reduce sense of a regulation of the speed to its setpoint. When the rolling vehicle suddenly is decelerated, the integral part in the worst case at its minimum stop or in its area. The made by the braking Speed drop, the controller can then not counteract fast enough, so that the Driving comfort impaired, the engine even goes out. Due to the driving speed-dependent correction factor the idle speed controller is relieved.

So is indeed speed cuts while counteracted the operating situation described above, an accurate Determination of the motor actually required by the torque converter Moments and an exact and fast setting of the speed or the engine torque required to maintain the speed but not achieved. For example, a possible Shifting the transmission or a sharp braking and that then suddenly changing Load torque can not be detected and considered fast enough. This must be done by the Idle speed control itself be compensated. Further, as the Delay Time to build up the cylinder filling and thus the engine torque is not considered, is an unsatisfactory Ride comfort and unsatisfactory control behavior the result.

From the document D3 ( DE 42 10 416 A1 ), a control device for a motor and an automatic transmission is known. The controller controls a start time, an end time, or torque down-ramping operations of the engine during gear shifts. Using stored information such as a turbine speed signal, a gear shift signal, a throttle opening degree, a vehicle speed, an engine speed, and so forth, the controller calculates a suitable torque reduction performed either by retarding the ignition timing or by interrupting a fuel supply to fuel injection valves. According to a preferred embodiment, upon detection of a change ratio or differential value of the turbine speed, a period of the torque reduction is started, stopped, and kept within an appropriate schedule.

From the not previously published German patent application DE 43 04 779 A1 It is known to calculate the torque demand when the gear position of the automatic transmission in dependence on the current turbine speed or output speed in idle or idle state and to consider in the feedforward control of the idle speed controller. Another peculiarity of this non-prepublished patent application is that to control the idle speed to be generated by the engine torque, the indicated engine torque is determined. As part of the feedforward control of the idle speed controller, the torque requirement of units such as an air conditioner is calculated as a function of the corresponding operating variables, determines the engine temperature and engine speed-dependent torque loss and then combined to form a target value for the indicated engine torque. The idle speed controller sets in dependence on the difference of the target speed and actual speed according to one of the known control strategies a momen tenkorrekturwert for correcting the determined by the feedforward indicated torque of the motor available. The thus calculated and corrected target engine torque value is then converted via a setpoint for the engine load to be set in a setting signal for the air supply to the engine, the injection time and / or the ignition.

It It is therefore an object of the invention to provide measures which a Method and device for controlling the drive power improve a vehicle, especially when the vehicle is rolling.

This is achieved by that at the determination of the engine torque to be set the temporal Course of the turbine speed of an automatic transmission with torque converter is taken into account.

Advantages of invention

The inventive approach has the advantage that the Driving behavior of a vehicle when the vehicle is rolling and in idle mode is significantly improved.

It is particularly advantageous that in the braking phase, especially when rolling vehicle speed undershoots be avoided, since the adaptation to the changing Motor loads in this operating condition due to timely construction the filling he follows.

Further is advantageous that the Determination of the filling, this means in the preferred embodiment the Determining the air supply to the engine, by calculating the indicated Moments considering all Motor loads with regard to the realization of a desired Output torque at the wheels he follows. When idling, the desired output torque is essentially Zero.

Advantageous is further that a load Regulation in the sense of an increase in the engine load at the output from the engine Torque immediately while a change the engine load in the sense of a reduction in engine load only filtered comes to effect. This is a strong, the ride comfort affecting change avoiding the supply of air in the operating conditions in which no immediate response is required.

Further is achieved by the procedure according to the invention the idle speed control also in gear freewheel in the optimal control range held.

Further Advantages will become apparent from the following description of exemplary embodiments or from the dependent ones Claims.

drawing

The invention will be explained in more detail below with reference to the embodiments shown in the drawing. It shows 1 an overview block diagram of a device for controlling the drive power of a vehicle while in 2 a block diagram of erfindungsgmäßen approach is shown. The 3 and 4 Finally, flow charts in which the realization of the procedure according to the invention is outlined as a computer program.

description of exemplary embodiments

1 shows an overview block diagram of a device for controlling the drive power of a vehicle, in which the inventive method and the device according to the invention comes into effect. The drive unit 8th comprises a schematically illustrated engine (internal combustion engine 10 ), which via an output shaft (crankshaft 12 ), which is on a torque converter unit 14 an automatic transmission 16 leads. The converter unit 14 consists of a converter 18 in a preferred embodiment, a controllable or controllable lock-up clutch 20 (Converter clutch) is connected in parallel. The wave 22 the transducer unit 14 , the turbine shaft, leads to the actual gear unit 24 whose output shaft 26 which is ultimately acting on the drive wheels output shaft of the drive train of the drive unit.

From the powertrain become a control unit 28 supplied to different operating sizes. A first input line 30 connects the controller 28 with a measuring means 32 for the speed of the shaft 12 , the engine speed, while a line 34 the control unit 28 with a measuring means 36 for the speed of the shaft 26 , the output speed number, connects. Further, in the preferred embodiment, an input line 38 provided which the control unit 28 with a measuring means 40 for detecting the rotational speed of the shaft 22 , which combines turbine speed. In advantageous embodiments, an input line 42 provided which the control unit 28 with the gear unit 24 connects to the transmission of information regarding the inserted translation. Further input lines 50 to 52 connect the controller 28 with measuring devices 54 to 56 For recording further operating variables of the drive unit or the vehicle, such as engine temperature, supply voltage, wheel speed, status of additional consumers, a measure of the engine load (air flow, mass, intake manifold pressure), temperature of the converter oil, etc ..

To control the output power of the drive unit has the control unit 28 over several output lines, of which for clarity in 1 only a few are selected. A first output line 58 connects the controller 28 with an actuator 62 , This is about a mechanical connection 64 with an engine influencing actuator 60 connected. The latter is in a preferred embodiment, an actuator for influencing the air supply to the engine, in particular a throttle or a bypass valve, is. Furthermore, the engine power by influencing the fuel metering and / or ignition individually or in combination (also together with the adjustment of the air supply) be set. To control the transmission 16 indicates the controller 28 Further, an output line 70 on which the controller 28 with the gear unit 24 to adjust the transmission ratio. In the transmission 16 it can be a continuously variable or an automatic multi-step transmission. Furthermore, in an advantageous embodiment, the control device 28 via a line, not shown, with the controllable converter clutch 20 connected.

For controlling the drive power, various known strategies can be followed. On the one hand, the engine output can be specified mechanically by the driver via the setting of the throttle valve, wherein the automatic transmission 24 and the lockup clutch 20 be switched depending on operating variables such as engine speed and engine load. In this case, it is the actuator 62 in preferred embodiments by an actuator in the bypass to the mechanical throttle or in a controllable stop the throttle. Further, a so-called electronic accelerator pedal may be provided, in which the driver's request is determined on the basis of the degree of depression of the accelerator pedal and the engine power is adjusted by electrical adjustment of a throttle valve. Furthermore, a control strategy may be provided, according to which a desired output torque is predetermined as a function of the driver's request and the engine torque to be set is adjusted by setting the transmission ratios and torque losses to provide the desired output torque by adjusting the air supply, fuel metering and / or ignition timing. The procedure according to the invention is presented below in the context of a preferred embodiment in the context of the latter control strategy. At idle or idle operating range, which is in connection with the procedure according to the invention of interest, the output torque setpoint is in the range of zero.

A corresponding application of the procedure according to the invention in the context the other two known control strategies is in other embodiments advantageous and will become apparent from the following description.

at stationary, stalled vehicle with automatic transmission must at engaged stage of the engine against the stationary turbine wheel of the torque converter (driven-side wheel of the converter) Apply torque to maintain idling speed. If the Driver starts to roll the vehicle slowly, without accelerating the turbine wheel of the converter to rotate as a result of the rotation of the drive wheels. The braking effect of the converter on the engine thus decreases, that is, the load the motor through the torque converter is lower. When pressing the Brake when the vehicle is rolling, the drive wheels are braked, the turbine wheel turns slower, the load of the engine increases. Here must the Idling control quickly compensate for the load increase during braking through the increase of the torque output by the engine to undershoot a speed to avoid. This is done by the procedure according to the invention.

In 2 is the control unit 28 shown. This will be input lines 100 to 102 of measuring devices 104 to 106 fed. These input lines lead to a speed setpoint unit 108 , whose output line 110 on a comparison unit 112 or to a calculation unit 114 leads. The comparison unit 112 is from the measuring device 32 The administration 30 fed. The output line 116 the comparison unit 112 leads to a control unit 118 , whose output line 120 to another reference junction 122 leads. This reference junction is a line 124 , the output line of the calculation unit 114 , fed. Furthermore, the cold junction becomes 122 in some advantageous embodiments as shown in phantom another line 126 from a pilot unit 128 fed, which in turn lines 130 to 132 are fed. The output line 134 the reference junction 122 leads to a unity 136 to form the or the drive signals for adjusting the motor torque. In the preferred embodiment, an output line leads 58 the adjusting device 60 - 64 for influencing the air supply to the engine.

The calculation unit 114 are next to the line 110 a line 140 supplied by a determination unit 142 is supplied. The determination unit 142 becomes a conduit 144 from the measuring device 146 fed. Furthermore, the calculation unit 114 from the measuring device 40 The administration 38 fed further to a differentiation stage 148 leads, whose output line 150 also on the calculation unit 114 leads.

The of the measuring device 32 outgoing line 30 is added to the determination unit 152 led, which over the line 154 further with a measuring device 156 connected to the detection of the air flow rate through the internal combustion engine. The output line 155 the determination unit 152 leads to the calculation unit 114 ,

In the presentation after 1 are the in 2 specified measuring devices 104 - 106 . 146 . 156 as well as the input lines 100 - 102 . 130 - 132 . 144 . 154 in the measuring devices 54 - 56 and the input lines 50 - 52 summarized.

The setpoint formation unit 108 forms a setpoint NSoll for the idling speed as a function of the quantities supplied to it. In this case, a map or a table is specified, in which the Solleerlaufdrehzahl is specified as a function of the supplied operating variables. The latter are, for example, engine temperature, which substantially decreases with increasing engine temperature, the target speed, battery voltage, wherein substantially with decreasing battery voltage, the engine speed increases, etc. The set value formed in this way is via the line 110 for comparison element 112 guided. There, the setpoint with the of the measuring device 32 detected actual value of the engine speed Nmot compared to form a control deviation. The difference between the two values, the control deviation, is transmitted via the line 116 the control unit 118 supplied in which on the basis of a predetermined control strategy, such as a PID controller, an output signal is generated whose size and polarity is formed depending on the difference between the setpoint and actual value in the sense of an approximation of the actual value to the desired value. This value is over the line 120 a comparison unit 122 fed in the additional values over the line 124 and in advantageous embodiments in the line 126 be switched on. About the line 126 signal magnitudes are fed into the unit 128 depending on the lines 130 to 132 supplied loads of the engine, eg the status of an air conditioner, a power steering, windshield heater, etc. is formed to increase the engine torque to maintain the idle target speed. The assignment is in the unit 128 in such a way that, for example, when the air conditioning system is switched on, a signal size is transmitted via the line 126 is released, which ultimately causes an increase in the engine torque, which compensates for the torque required by the additional load. That in the comparison unit 122 formed sum signal is over the line 134 the unit 136 supplied to form the drive signal or the drive signals. This is in the context of the embodiment according to 2 a unit that over the line 134 supplied signal in via the line 58 delivered clocked drive signal for the actuator 138 transforms.

It should be noted that in the preferred embodiment, the on the lines 120 . 126 and 124 each signal represents a measure of the engine torque. The setting of the adjusting device 60 - 64 through the unit 136 can also be done by combined control of air supply, injection and / or ignition in other embodiments. This is done via the line 134 the unit 136 supplied target engine torque on the basis of speed and engine load-dependent maps in control signals for the air supply controlling actuator, the fuel metering controlling actuator and / or the ignition device converted.

The calculation unit 114 determined on the basis of their supplied quantities the torque requirement of the converter, which via the line 124 in the summit 122 switched on the signal representing the engine torque to be adjusted and over the line 134 by adjusting the adjusting device 138 provided. To determine the torque requirement of the transducer through the unit 114 becomes this over the line 110 the target speed value NSoll, and also the measured value of the turbine speed Nturb, which in the measuring device 14 determined and over the line 38 is supplied, fed. In the event that the turbine speed can not be detected, a measure of the turbine speed based on the output speed Nab, which is determined by the measuring device 36 is determined, as well as the set gear ratio Ü calculated.

Furthermore, the calculation unit 114 over the line 150 a measure of the time course of the turbine speed, which is based on the measured turbine speed in the unit 148 , in particular by temporal differentiation, is supplied. Furthermore, a measuring device 146 provided for determining the oil temperature TÖl the converter, which via a line 144 to the determination unit 142 leads. There, a factor KT is read out of a predetermined characteristic, which is transmitted via the line 140 to the calculation unit 114 to be led. Further, the determination unit 152 provided in the depending on the over the line 30 supplied engine speed Nmot and the over the line 154 supplied motor load TL a measure of the delay time Tfü for the structure of the filling, that is, the engine torque, is read out at load change. This value is over the line 155 the calculation unit 114 fed. The signal TL representing the engine load is determined as known from the prior art on the basis of the signal from the measuring device 156 determined air flow rate determined by the internal combustion engine and the engine speed.

The general dependence the factor KT of the temperature of the converter oil is such that the factor KT gets colder with colder oil, because by colder oil the inner Friction in the converter, thus the torque requirement of the converter to the Increased torque to be output from the engine. The delay time for the Structure of the filling is essentially with increasing engine speed and increasing Engine load in terms of amount shorter.

The calculation unit 114 then determines according to the following with reference to 3 and 4 illustrated approach, depending on the quantities supplied to the torque requirement of the converter even in the dynamic state, which as a signal via the line 124 the setting of the adjusting device 60 - 64 changed in the sense of a compensation of the torque requirement.

In 3 and 4 are flowcharts outlined, based on the 2 illustrated inventive approach in its realization as a computer program.

In this case, the procedure according to the invention is based on the finding that, when idling with the gear stage engaged, the torque take-up of the converter must be taken into account in the setting of the indicated engine torque for automatic transmissions. The required indexed engine torque Mind is obtained as an addition from the torque pickup of the converter MW, torque loss MV, the consumption torque of Nebenaggretaten (for example, an air conditioner) MK and the correction torque DMllr an idle controller to maintain the idle speed. In particular, the dependence of the torque requirement of the converter on the oil temperature of the converter and the turbine speed at a given sole rolling speed is given by the following equation. MW = KT (Töl) · KMU (Nturb / NSoll) · NSoll · NSoll (1)

Since the structure of filling and thus the structure of the indicated torque requires a certain, substantially dependent on engine speed and engine load time Tfü, it can lead to a very strong braking process that the changed torque requirement of the converter can not be adjusted in time by changing the filling can. This would lead to undershooting the engine speed. In order to avoid this, the calculation of the torque requirement of the converter is modified by inserting a turbine speed-dependent factor Nt as indicated in the following equation. MW = KT (Töl) · KMU (Nt / NSoll) · NSoll · NSoll (2)

In this way, at every negative gradient (braking process), the charge build-up is already initiated at the current time T0 to the value at the time T0 + Tf and the torque necessary for compensating the torque requirement of the converter is provided. In this case, as an extension of the procedure according to the invention, the newly calculated torque demand value of the converter can be used immediately for calculating the indicated torque if the newly calculated value is greater than the value calculated during the previous program run, that is to say when the engine torque for compensating the torque requirement of the converter must be increased. In the other case, to improve the Driving comfort and to avoid strong changes in torque, the new value of the torque requirement are filtered by means of a low-pass filter.

Further can for the transmission state "freewheel", which in some Driven, for example, in first gear occurs when the engine be driven by the drive can not be controlled. In such an operating condition, the negative engine torque request be prohibited because the engine otherwise dies because of freewheeling the gearbox. This means, if the condition "freewheeling" is fulfilled, become negative torque requirements of the converter, that is, for example at an increase the driving speed so that the Turbine speed greater than the target speed is, not performed, the torque demand value rather, the converter is set to zero. The clutch torque (output torque of the engine) thus remains zero.

After starting the program part in 3 at given times is in a first step 200 checks whether the vehicle is in idle or idle operating state. This query is made in the preferred embodiment based on the driving speed and the accelerator pedal position, with an accelerator pedal position in a small amount around the rest position and a vehicle speed below a predetermined limit (eg 10 km / h) reaching the idle or idle range is detected. If the vehicle is in this operating state, the procedure according to the invention is initiated. It is in the step 202 read in the operating variables necessary for carrying out the procedure according to the invention. These are the turbine speed Nturb (alternatively, if this is not to measure, the output speed Nab and the transmission ratio Ü), the temperature of the converter oil Töl, the engine temperature Nmot, the measured air flow rate or the engine load signal TL and other operating variables such as motor temperature Tmot, battery voltage Ubat, etc .. After reading the operating variables in step 204 determined from corresponding maps, characteristics or, by calculation, the following quantities. The idling target speed NSoll is determined on the basis of Tmot, Ubat, etc., the factor KT based on the oil temperature Töl of the converter, a delay time factor TFF to build up the charge upon load change becomes from a map on the basis of engine speed Nmot and load signal TL, the turbine speed Nturb is calculated from the output speed Nab and gear ratio Ü in the event that it is not to be measured, and finally the time course of the turbine speed is determined as the time derivative of the turbine speed value dNturb / dt. After determining the above operating variables, the step 206 the torque correction value DMllr of the idle speed controller is calculated based on the difference between the target speed and the engine speed according to the predetermined control strategy. In the following query step 208 it is checked whether the turbine speed drops, that is, whether the time derivative of the turbine speed is less than zero. If this is the case, then in the next step 210 a factor SME is determined on the basis of the turbine speed, its time history, the delay time and the idling speed according to the following relationship:

In contrast, if the turbine speed is positive or constant, the factor SME will be used in step 212 calculated from the quotient of the turbine speed and the Solleerlaufdrehzahl. Im on the step 210 or 212 following step 214 the torque requirement of the converter MW is calculated as the product of the factors KT, KMU and the square of the nominal idling speed.

After calculation of the torque requirement of the converter, the program part according to 4 with the query step 216 continued, in which it is determined under appropriate boundary conditions, whether freewheeling exists. This is done by checking whether a gear is engaged in the freewheeling state is established. If so, the query step becomes 218 checked, above the currently determined torque demand value MWnew for the converter is greater than or equal to zero (step 218 ). If this is the case, then in step 220 assumed the torque requirement of the converter, while in the opposite case according to step 222 the value for the torque requirement MW of the converter is set to zero. This is because when freewheeling state, a reduction of the engine torque when the vehicle speed is so high that the engine would be dragged from the drive, does not make sense, otherwise a dying of the engine is possible.

Was in the step 216 no free-wheeling state is detected, then in the subsequent query step 224 checks whether the currently determined torque requirement value of the converter MWnew is greater than the value MWalt determined in the previous program cycle. If this is the case, then in the next step 226 the torque demand value of the converter MW is set to the value determined in the current pass, that is to say the change in the torque to be output by the engine is initiated immediately. With a no-decision in step 224 will according to step 228 the torque demand value of the converter on the basis of the determined in the previous program run, the calculated in the current program run and a low-pass function with time constant T2 calculated. After completing these calculations, the next step is 230 the indexed engine torque Mind for the realization of the calculated torque demand values from the sum of the torque correction of the speed controller DMllr and the torque requirement of the converter MW, possibly further variables, such as the torque requirement of an air conditioner MK, loss moments MVetc. calculated. In the following step 232 Finally, the calculated value of the indicated engine torque is converted into a throttle position DK and thus into a drive signal. Thereafter, the program part as well as in non-idle state according to step 200 finished and repeated in due course.

Next the time derivative for calculating the time course Turbine speed can also made a difference formation become. In addition to the illustrated embodiment of a gasoline engine can the procedure according to the invention also advantageously in connection with a diesel engine Find application.

Claims (10)

Method for controlling a drive unit of a vehicle, wherein the torque of the drive unit is adjusted via at least one setting device, the at least one setting device is adjusted at least in idling and / or idling operating range on the basis of at least one operating variable of the drive unit and / or of the vehicle , - wherein the at least one operating variable is the turbine speed of an automatic transmission with torque converter, characterized in that the setting of the adjusting device is dependent on the time course of the turbine speed. Method according to claim 1, characterized in that that the Temporal course of the turbine speed determined by the gradient becomes. Method according to one of the preceding claims, characterized characterized in that depending on turbine speed and the time course of the turbine speed of the torque requirement the torque converter is determined and this for determination the setting of the adjusting device is evaluated. Method according to one of the preceding claims, characterized characterized in that for the idle or an idle speed controller is provided in the area close to the idling, which on the basis of target and actual engine speed, a correction value for the Motor torque determined, which together with the torque requirement the converter and optionally the torque components of others Aggregates and loss moments the adjusted engine torque determine the adjusting device depending on the determined to be set Motor torque is set. Method according to one of the preceding claims, characterized characterized in that Torque requirement of the converter on the basis of the target idling speed, one of the oil temperature dependent of the converter Factor, the turbine speed, the time course and a Delay Time for the Structure of the engine torque, essentially dependent on engine speed and Engine load, is calculated. Method according to one of the preceding claims, characterized characterized in that increasing turbine speed or constant turbine speed the torque requirement of the converter regardless of the time course the turbine speed selected becomes. Method according to one of the preceding claims, characterized characterized in that an increase the torque requirement of the converter, the increased torque demand immediately Adjustment of engine torque comes into effect while at decreasing or constant torque requirement, the change of the torque according to a low-pass filtering is made. Method according to one of the preceding claims, characterized characterized in that Free running state of the gearbox with negative torque requirement of the converter the clutch torque is kept at zero. Method according to one of the preceding claims, characterized characterized in that Adjustment of the engine torque by influencing the air supply to the engine over the adjusting device takes place. Device for controlling a drive unit a vehicle, - With at least one adjusting device for influencing the torque the drive unit, - With Means for adjusting the adjusting device at least at idle and / or idle operating range depending on at least one Operating size of the drive unit and / or the vehicle, - With Means for detecting the turbine speed one with a torque converter equipped gear unit, - wherein the at least one Operating variable the turbine speed is characterized in that - Means are provided, which the setting of the adjusting device depending on the time course make the turbine speed.