DE3314800A1 - Control device for a vehicle driven by a prime mover by way of a stepped transmission - Google Patents

Abstract

A control device for a commercial-vehicle stepped transmission is proposed which has the following devices: a family of engine characteristics 36 for determining the instantaneous drive torque MA delivered by the engine (36); a measuring device (16) for registering the acceleration s of the vehicle; a weight determination (30) for calculating the vehicle weight with the aid of the instantaneous drive torque MA and the acceleration s; a torque monitoring device (24) for calculating a stationary torque Mstat; and a transmission control (18) for comparing the stationary torque Mstat with a predetermined optimum torque Mopt. <IMAGE>

Description

Control device for one of a prime mover

Vehicle driven by a stepped transmission. The invention refers to a control device for one of a prime mover a stepped transmission driven vehicle, according to the preamble of the claim 1.

When manually shifting a transmission for a vehicle, in particular for a commercial road vehicle, it happens that the torque in the newly engaged Gear is not sufficient to drive the vehicle at the speed it was before the gear change to continue driving. It must therefore be switched back again. The appraisal and anticipation of such a situation by the vehicle operator is difficult and inaccurate. Wrong gear change mean, however, that the vehicle uneconomical, in particular with excessive fuel consumption.

The situations described can also occur with automatically working Appear driven. These gears are therefore designed so that only at high Power reserve is switched. This also means an uneconomical one Driving style.

The selection of the most favorable operating point from an engine and a drive unit that is present in a gearbox depends on a large number of factors. Even the definition of the "most favorable operating point" is very difficult because the The point of cheapest consumption in the characteristic field of an engine is usually not the Point of maximum performance. Depending on the requirements and external conditions the gear selection criteria between the various operating points classified as "favorable" can be varied.

The quality of these criteria is also crucial for the constancy depends on the sizes used. If, for example, engine torques are determined, then are these dependent, among other things, on the fuel density, on the altitude, in that the engine is running, the fuel quality, the engine temperature etc. Are now the engine torques using according to theoretical or empirical methods determined constant values are compared, then the result is when a Deviation of one of the many influencing factors have an error.

An obvious solution is to try as many of the most important as possible Record and evaluate influencing variables with your own sensors. But that means a great effort.

The accuracy with which a value is determined is also important in the Determination of switching points, especially for those operated with a high load / empty ratio Commercial vehicles of vital importance. Should, for example, the at constant Speed at the vehicle occurring driving resistances can be determined exactly, then variables such as changes in the drag coefficient Cw due to changes in the structure, Airtightness, changes in the rolling friction of tires on the road at different rates Tire profiles and different wear conditions, road profile, etc. recorded will. In addition, certain parameters such as bearing friction and gear efficiency cannot be determined on series vehicles without great effort.

The invention is based on the object of providing precise switching points for to determine a vehicle transmission, with as few peripheral devices (sensors) as possible should be used.

This object is achieved by the invention specified in claim 1 solved. Advantageous embodiments and developments of the invention are specified in the subclaims.

The invention is based on the following knowledge. Anyone The instantaneous drive torque MA that drives the vehicle is made up at this point in time from a stationary drive torque instead of that to continue driving the vehicle without Acceleration or deceleration of the vehicle is required, and an acceleration or deceleration of the vehicle causing acceleration torque Mb. This means that the stationary drive torque Mstat can be calculated as follows: MA Mstat + Mb Mb = G e f (s staut = MA - G o f (s if the sizes M, G and s are available or can be measured. In detail, mean in the equations: Mstat = stationary Drive torque MA = current drive torque Mb = acceleration torque G = weight of the vehicle s = acceleration of the vehicle The term f (s) means that the vehicle acceleration can be provided with a factor. All sizes can be derived from the actual values.

The stationary moment Mstat can be used as the sum of the driving resistances be taken when driving at a constant speed. These driving resistances are the rolling friction, the air friction and the gradient resistance.

Since the values on the right in the formula for Mstat are easily determined can be, so the cumbersome and imprecise recording of the individual Bypass driving resistance.

The exact vehicle weight needed to evaluate the equation for Mstat can about the vehicle acceleration as in the earlier application P 32 46 201.8 described, can be determined. It is essential that the exact weight is known, and not, as in known applications (e.g.

DE-OS 30 18 032, DE-OS 31 01 056) from an assumed vehicle weight is assumed.

Furthermore, according to the embodiment according to the invention, for the calculation If possible, all required sizes are based on values that have been defined once.

In the proposed case this is done under certain operating conditions determined characteristic field of the motor used, in the motor output torque over Engine speed at various engine control operating points are plotted in stored in a memory. All required sizes such as MA, G and Mstat will be determined from these values, among other things. The theoretically or empirically determined Threshold values Mopt, which are used to create switching criteria with, for example, the Value Mstat are compared, also refer to the values of the stored Characteristic field. This procedure has the great advantage that when there are shifts of the family of characteristics, e.g. due to a change in fuel density or a change in altitude, the ratio of the sizes does not change in the described value comparisons and thus error-free values can be delivered.

For example, the engine torque would be measured directly and theoretically or empirically established values are compared, then would have to change in the event of changes the motor torque is corrected by external influences, to get an error-free result.

The invention avoids these and at the same time a number of others Possible errors.

A comparison of theoretically or empirically determined moments with the stationary moment Mstat with given Values has the following Advantage: If a check is carried out before engaging a new gear, whether it is in the new one Maximum achievable gear or taking into account specified selection criteria (e.g. fuel consumption) greater than the appropriate drive torque to be considered is than the stationary transformed according to the gear ratio Drive torque, it can be predicted how the vehicle will move after a gear change will continue to move, i.e. whether it is at all with the one that was present before the gear change Moving on at speed and with economical fuel consumption. If necessary, the insertion via a locking device is an unfavorable one Ganges prevented.

The mentioned comparison between the transformed stationary drive torque and the appropriate drive torque of the new gear also leaves a prediction the possibly expected acceleration of the vehicle after changing gears.

The engine characteristic field is also to be understood as a characteristic field, which indirectly describe the operating state of the engine, such as the Numerical values of the fuel injection times.

Furthermore, among the "moments" used in the claims also to understand drive sizes in general, for example also power sizes or those comparable quantities that the drive torque is only considered to be one of contain several calculation quantities.

The invention is based on an embodiment that is shown in the drawing is shown, explained in more detail.

The drawing shows the essentials in a simplified representation Elements of a vehicle driven by a prime mover. As a prime mover An internal combustion engine 6 is used, the fuel supply of which can be controlled by means of a sender 1 is. The motor 6 is connected to a coupling 9 via a shaft 8, which in turn is connected to a transmission 12 via a shaft 11.

The gear 12 is used to drive an axle 14, which in turn the Driven vehicle wheels of the vehicle drives. From the driven wheels of the vehicle, only the wheel 15 is shown for the sake of simplicity.

The sender 1 for controlling the fuel supply to the engine 6 has a signal output 3, which via a signal line 4 with a signal input 5 of the motor 6 is connected. The encoder 1 is also provided with a device, which represents the position of the encoder 1 as a signal variable y. This signal quantity is y can be called up at a signal output 2 of encoder 1. In the simplest case, the contains Sensor 1 as a control element for the fuel supply of the engine 6 is a conventional, mechanical one working accelerator. The encoder 1 can, however, also - as in the illustrated embodiment - Be designed as an electrical or electronic encoder if the motor 6 can be controlled accordingly by means of a control signal.

The between the drive-side shaft 8 and the output-side Coupling 9 arranged on shaft 11 can be actuated by means of a control signal which a signal input 10 of the clutch 9 can be fed.

The transmission 12 is also electrically controllable, with signal inputs 13 of the transmission 12 for receiving appropriate control signals for inserting the respective serve the desired or required course. Both the clutch 9 and that In the simplest case, gears 12 can be operated purely mechanically. In this In this case, the signal inputs 10 and 13 symbolically represent the connection of clutch actuation mechanisms and transmission actuation mechanisms with the corresponding actuation devices for the clutch 9 and the transmission 12.

A transmission control 18 is provided to control the transmission 12. In the simplest case, this transmission control 18 works in such a way that the transmission 12 as a function of the speed of the vehicle and thus as a function is automatically switched from the speed nR of the driven wheels. To capture the speed nR of the driven wheel 15 is a sensor 16, the speed signal A signal input 19 of the transmission control 18 is supplied via a signal line 17 is. The transmission control is via signal outputs 22 and corresponding signal lines 23 18 with the signal inputs 13 of the transmission 12 and the signal input 10 of the clutch 9 connected.

If by means of the transmission control 18 as a function of the speed of the vehicle and a new one, taking into account the specified selection criteria Gear is set, the clutch 9 is actuated via its signal input 10 and then, with the clutch disconnected, the transmission 1 via its signal inputs 13 switched by the transmission control 18. Then the clutch 9 is then again closed. The control or actuation of the clutch 9 and the transmission 12 can - as above- indicates - also purely mechanically via servomotors the transmission control 18 take place.

Regarding the selection criteria mentioned above, according to those in the transmission control 18 each time a new gear is set belongs in the illustrated embodiment a check as to whether the motor 6 after inserting the new one selected per se Ganges is even able to allow the vehicle to continue driving without delay or acceleration to apply the required stationary drive torque. This means, that the drive torque range assigned to the new gear selected per se or a corresponding optimal or appropriate drive torque Mopt greater Values or must have a higher value than that for the delay or Steady-state drive torque required for the vehicle to continue to travel without acceleration Mstat The optimal drive torque assigned to the new gear selected Mopt can, for example, also be determined taking fuel consumption into account be.

For the mentioned comparison between the respective stationary drive torque Mstat and the optimal drive torque Mopt for the new gear selected a comparison device 45 is provided, which is integrated in the transmission control 18 is. Also integrated into the transmission control 18 is a device that for storing or computationally determining the individual gears of the transmission 12 associated appropriate or optimal drive torque M is used. It understands opt yourself that in the mentioned comparison of the drive torques not the respective stationary drive torque directly with the appropriate drive torque of the relevant new gear is compared, but that in this comparison the stationary drive torque according to the gear ratio between the switched on and is transformed into the new corridor in question. For this reason is shown in Embodiment specified as a comparison variable M stat stat Mstat. It is natural also possible instead of the stationary drive torque or according to the transmission ratio the value transformed by the gearbox other values derived from the drive torques Quantities such as forces, powers or such comparative quantities that determine the drive torques only included as one of several calculation variables to be compared with one another.

All appropriate drive torques M or M 'beopt opt drag each other always to the values stored in the characteristic map memory 36. For the calculation or determination of the stationary drive torque or one derived therefrom stationary drive variable, a torque control device 24 is provided, the stationary drive size required for the above comparison (e.g. Mstat or M1) delivers stat to the transmission control 18 via signal lines 21, provided that the transmission control 18 via query signal lines 20 the appropriate Size queries. This ensures that the transmission control 18 after Selection of one or more permissible per se according to the speed nR of the wheel 15 new courses for each of these courses the comparison between the required stationary Carries out the drive torque and the drive torque appropriate for the new gear in question. The result of this comparison is then that, for example, the most economical new one Gear is selected that drives the vehicle in each case so that it at least continues to drive without significant delay, or that no new gear is engaged, because the vehicle does not continue to travel in any of the new gears selected per se is guaranteed without any significant delay.

In the torque control device 24, the respective stationary Drive torque Mstat determined by the fact that the difference between the actual The respective instantaneous drive torque MA of the vehicle applied by the engine 6 and such a calculation variable is determined, which is the product of the weight of the vehicle and the calculated value of the current acceleration of the vehicle. In order to be able to calculate the mentioned difference, the torque control device 24 the transformed instantaneous drive torque MA des via a signal input 27 Motor 6, via a signal input 26, the weight G of the vehicle and via a Signal input 25, the speed nR of the driven wheel 15 is supplied.

The signal input 27 of the torque control device 24 is via a line 34 to the signal output 35 of an engine characteristic map - memory 36 connected, which is connected to the aforementioned signal output 35 to the momentary drive torque of the motor 6 provides the corresponding signal. The signal input 26 of the The torque control device 24 is connected to the evaluation device via a signal line 29 30 connected to determine the weight of the vehicle. At this signal output 29 of the evaluation device 30 is a corresponding to the weight of the vehicle Signal available. Finally, the signal input 25 of the torque control device 24 is via the signal line 17 to the speed sensor 16 for detecting the wheel speed nR connected. In the torque control device 24 is calculated by differential calculation the acceleration variable from the time profile of the speed nR of the wheel 15 s' of the vehicle is calculated. The respective instantaneous drive torque MA of the motor 6 is determined from the engine characteristic field 36, which is the dependency of the following Sizes from each other includes: current drive torque MA of the motor 6, speed nR of the motor 6 and position y of the sender (accelerator pedal) 1. Im shown Embodiment contains the memory 36 for different values (Y1, y2, y3) position y of sender 1 has a characteristic curve for the dependence of the momentary Drive torque MA from speed nA Position y of encoder 1 becomes a signal input 39 of the memory 36 is supplied via a signal line 40, which in turn is connected to the Signal output 2 of encoder 1 is connected. The speed nA of the motor 6 is determined by means of a sensor 7 scanning the shaft 8 and via a signal line 38 is fed to a signal input 37 of the memory 36. The characteristic curve memory 36 is designed in such a way that it is the current drive torque for each value pair y / nA MA makes available at its signal output 35. The speed nA of the motor 6 can also be calculated from the wheel speed nR of the wheel 15 if the respective Gear ratio of the transmission 12 is taken into account.

In weight determination 30 for determining the weight of the vehicle becomes the ratio between the instantaneous drive torque MA of the motor 6 and a Difference between two calculation quantities formed, the calculation quantities mentioned in each case contain an acceleration variable corresponding to the acceleration of the vehicle. These two acceleration quantities 5 x2 and 5 become x2 at different times xl is determined, the one acceleration variable being determined at a point in time in which the vehicle is in a non-powered state, e.g. in a switching pause is located. In this non-powered state, the vehicle is not accelerated significantly or delayed.

In order to be able to carry out the aforementioned arithmetic operation, the weight determination 30 the instantaneous drive torque via the signal line 34 and a signal input 33 MA of the motor 6 supplied. The one used to create the acceleration values 5x2 and Exl required time course of the speed nR of the driven wheel 15 is A signal input 32 of the weight determination 30 is supplied via the signal line 17. Finally, via the signal lines 23, a signal input 31 is used to determine the weight 30 communicated the point in time at which the clutch 9 is determined by control signals of the weight determination 30 between such times when the vehicle is being propelled by the engine 6 subject to, and such times when the vehicle is not driving the engine 6 is subject to a distinction. These will also be different times the acceleration values 5.x2 and 5x1 are measured or determined.

The general formula for determining the vehicle weight G is: Values with index 1 are determined at time 1 and values with index 2 are determined at time 2.

In addition to the special case MA2 described above = ° der for the switching pause applies, the special case f (so2) = 0 can also be evaluated. This applies to unaccelerated Journey.

The above equation can of course also be general, without the special cases to be seen to be evaluated. It is always important to ensure that the two The measuring points are not too far apart. However, in order to achieve a sufficient accuracy for the weight size should be the difference between the drive torques MA1 - MA2 should be chosen as large as possible.

The weight determination 30 can also be designed so that different determined weight sizes G to form an average value for the weight sizes are used and that the mean value of the weight sizes determined in this way is in turn is used to display or determine the weight of the vehicle. In this In this case, the torque control device 24 is supplied with an average weight value.

It can also be provided means that only such weight sizes or only allow the mean values of the weight sizes to be evaluated that a predefined deviation from a predefined value or a previously determined one Do not exceed the value of the weight sizes.

To ensure that even if in the evaluation device 30 e.g. because the driving time is too short, a sufficiently precise value for the weight size is not yet available G is present, in the torque control device 24 a useful value for the To be able to determine stationary drive torque Mstat, it is advantageous instead of the The weight variables G determined by the evaluation device 30 are initially an average Use weight size G0, which corresponds e.g. to a half-loaded vehicle.

Suitable for a reliable determination and calculation of the weight size G. In an advantageous manner, a microcomputer provided in the weight determination 30, with which, in particular, the time-dependent computing processes with regard to the acceleration variables can be implemented in a simple manner.

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Claims (20)

Claims 9 control device for one of a motor over a transmission that preferably varies in steps Vehicle characterized by the following features: a) it is an engine characteristic field (36) to determine the instantaneous drive torque MA delivered by the motor (6) intended; b) it is a measuring device (sensor 16) for detecting the acceleration § 'of the vehicle provided; c) there is a weight determination (30) for the calculation the vehicle weight with the aid of the current drive torque MA and the Acceleration s provided; d) there is a torque control device (24) for Calculation of a stationary moment Mstat with the aid of the instantaneous moment MA of the vehicle weight G and the acceleration s provided; e) it is a transmission control (18) provided that the stationary moment Mstat with at least a predetermined optimal moment Mopt compares. 2. Control device according to claim 1, characterized by the following Features: a) a sensor (7) which detects the speed nA of the motor (6) is provided; b) a transmitter is provided for detecting an engine control variable y that corresponds to the position of the control member (1) controlling the motor (6); c) it is a map of the motor characteristics (36) is provided, which contains a family of characteristics showing the mutual dependence of engine speed nA, engine control variable y and instantaneous torque MA; d) a signal output (35) of the engine characteristic field (36) is with the current one Signal input (27) of the torque control device (24) assigned to the torque MA tied together. 3. Control device according to claim 2 for a vehicle, with a designed as an internal combustion engine motor (6), which is controlled by an accelerator pedal is, characterized in that the control member (1) is designed as an accelerator pedal. 4. Control device according to at least one of claims 1 to 3, characterized in that the intended for detecting the vehicle acceleration s Measuring device which detects the speed nR of at least one vehicle wheel (15) Sensor (16) contains the output signal of a differentiating device for determination one derived from the time profile of the speed of the vehicle wheel (15) Acceleration variable can be supplied. 5. Control device according to at least one of claims 1 to 4, characterized in that a weight determination (30) is provided for determining the vehicle weight or a corresponding weight size, which has the following features: a) the weight determination (30) determined using the current moment MA and several values of the vehicle acceleration determined at different points in time X1, X2 § a weight size G corresponding to the weight of the vehicle according to the formula: b) a control device is provided which is designed so that at least one of the values of the acceleration variable s to be used by the weight determination (30) is determined at a point in time at which the vehicle is driven by the motor (6), and that at least one of the values of the acceleration variable s to be used by the weight determination (30) is determined at a point in time at which the vehicle is in a non-powered state. 6. Control device according to claim 5, characterized in that the weight determination (30) a computing circuit for forming the ratio of instantaneous drive torque MA to the difference between two determined at different times Acceleration sizes 5 included. 7. Control device according to claim 6 for a vehicle with a Coupling to separate the driven vehicle wheels from the drive train of the vehicle, characterized by the following features: a) the coupling (9) is provided with a control input (10) for controlling the clutch actuation; b) the The control input of the clutch (9) is connected to a control output (22) of the transmission control (18) connected; c) the transmission control (18) is designed so that it then a Control signal for separating the clutch (9) is generated when the non-powered state the value of the acceleration variable assigned to the vehicle is determined. 8. Control device according to at least one of claims 5 or 6, characterized in that the weight size G is determined repeatedly will. 9. Control device according to claim 8, characterized in that various determined weight sizes G to form an average value for the Weight size G are used and that the mean value of the weight sizes determined in this way G in turn used to display or determine the weight of the vehicle will. 10. Control device according to claim 8 to 9, characterized in that that means are provided that only such weight sizes G or only such mean values the weight variables G can come to the evaluation, which a predetermined deviation from a predetermined value or a previously determined value of the weight sizes Do not exceed G. 11. Control device according to claim 8 to 10, characterized in that that especially after a change of the vehicle weight for the first determination of the weight variables G is a fixed predetermined value of the Weight size G is used. 12. Control device according to at least one of claims 1 to 11, characterized in that the torque control device (24) is a computing device to calculate the difference between the drive torque MA of the motor on the one hand and the product of weight G and acceleration s on the other hand according to the formula: Mstat = MA - G. f (contains s, where Mstat denotes the stationary drive torque. 13. Control device according to at least one of claims 1 to 12, characterized in that the steady-state drive torque Mstat is continuously determined will. 14. Control device according to at least one of claims 1 to 13, characterized in that the stationary drive torque Mstat for further Gears taking into account the gear ratio according to the formula Mstat (new) = Mstat 1 i (new) is calculated, where: Mstat (new) = stat. Moment in the new Gear i = ratio in old gear i (new) = ratio in new gear 15th Control device according to at least one of Claims 1 to 14, characterized by the following features: a) a transmission control (18) is provided which is used for Storage or determination of threshold values of optimal drive torques M is used, the unopt ter application of given selection criteria for the different courses of the transmission are specified as appropriate; b) it is a comparison device (45) are provided, which are used to compare the respective stationary drive torque M stat is used with the drive torque Mopt of the same or a different gear. 16. Control device according to at least one of claims 1 to 15, characterized in that the predetermined optimal moments Mopt, pt are matched are based on the values stored in the motor characteristic field (36). 17. Control device according to at least one of claims 15 to 16, characterized in that the output signal of the comparison device (45) to display a gear recommended according to the specified selection criteria serves. 18. Control device according to at least one of claims 15 to 17, characterized in that a locking device is provided that the insertion a new gear is prevented if the one determined in the comparison device (45) Difference between the stationary drive torque Mstat and that for the new gear optimal drive torque Mopt exceeds or falls below a specified amount. 19. Control device according to at least one of claims 15 to 18, characterized in that the comparison device (45) is designed so that first those gears are determined for an existing driving condition, for which the optimal drive torque Mopt is greater than the stationary drive torque Mstat and that then of the courses selected in this way with respect to predetermined selection criteria the cheapest gear is selected. 20. Control device according to claims 1 to 19, characterized in that that at least one microcomputer is used to perform the calculations.