FR2827340A1 - On-demand control and torque generating circuit for road vehicle engine, has processor which evaluates engine rotational speed and position of accelerator pedal to determine engine torque - Google Patents

Abstract

On demand torque (10) generating system including:- (a) A processor for input values including engine (12) rotational speed and accelerator pedal relative position (14), and; (b) A system to deliver the required torque as a function of the input values. The processing of the accelerator position includes a line (16) transforming the value into a parameter (18) used to regulate engine power. The engine power domain can be regulated between maximum (20) and low (24) determined from minimum torque (22) depending upon real engine rotational speed. The regulation of engine power can be subject to variation as a function of rotational speed by means of a stability factor (26). An Independent claim is also included for: a method of torque generation.

Description

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 The invention relates to a device for generating torque demand in the context of a motor control, comprising means for processing input quantities, the input quantities comprising a motor rotation speed and a quantity representing a driver request, and means used to deliver the torque request as a function of the input quantities.

The invention further relates to a method for generating a torque request in the context of a motor control, according to which input quantities are processed, the input quantities comprising a motor rotation speed and a quantity representing a conductor request, and the conductor request is delivered according to the input quantities.

 Devices and methods conforming to generic types are used in the case of the interpretation of a driver request in the context of electronic load regulation of an internal combustion engine. A quantity representing the driver demand, which depends for example on an accelerator pedal position, and the current engine speed is sent to at least one characteristic table with several dimensions, so that, finally, at using an average formation from the characteristic table, a torque request can be issued according to the input quantities indicated and possibly other parameters.

 During a progressive improvement of the driving behavior of motor vehicles, increasingly strict conditions are also applied to the indicated determination of the torque demand. This request can be taken into account by increasing the characteristic multi-dimensional table indicated more and more. As a result, it is finally possible to execute increasingly precise transpositions of the driver demand, even taking into account other variables and parameters, to obtain the desired torque.

 However, the provision of increasingly larger characteristic tables also brings with it many problems. First of all, the more memory locations are needed for the data stored in a characteristic table, the larger the characteristic tables are designed. In addition, to exploit the input data by means of the larger characteristic tables, increased calculation means are necessary.

These two problems indicated are generally still bearable within the framework of a development of the technique, given, on the one hand, that the capacity of the memory components increases more and more and can be made available in an economical manner and given, on the other hand, that the computing power of

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 Modern control units can handle even complex calculation tasks thanks to large, multi-dimensional characteristic tables.

 However, another problem in determining a torque demand on the basis of multidimensional characteristic tables lies in the fact that it is increasingly difficult to suitably adapt the characteristic tables to the properties of desired driving of a vehicle. This must above all be attributed to the dependencies between the different quantities which must be taken into account in the characteristic table, so that due to the mutual influence of the quantities, the adjustment, related to an application, of a characteristic table results often instead a shift in the desired driving properties of a vehicle.

 The object of the invention is to provide a device and a method for generating a torque request which eliminates the drawbacks and problems indicated in the prior art. In particular, it is desired to reduce the means of adaptation of a control device with electronic charge regulation.

 To this end, the subject of the invention is a device, of the generic type considered, characterized in that the means serving to process the quantity representing the driver request comprise at least one characteristic line, the characteristic line transforming the quantity representing the demand driver in a parameter used to adjust the engine power.

The invention is therefore based on the fact that we turn away from a characteristic table with several dimensions in favor of a characteristic line with one dimension. Due to this diversion, the driving behavior of the vehicle can be ascertained and adapted in a simple manner. The multiple tasks which are supported by the multi-dimensional characteristic tables of the state of the art are replaced, in accordance with the invention, by calculation algorithms which in any case use quantities available in a motor control. Since the quantity representing the driver demand is transformed into a parameter used to regulate the engine power, it is possible to have a desired constant power control which also provides a constant vehicle speed in most driving situations in the case of a constant driver demand.

 In a particularly advantageous manner, according to a development of the device according to the invention, the quantity representing the driver's demand is the relative position of an accelerator pedal. It is possible to imagine numerous output quantities of sensors which can be used as input quantities for the characteristic line, this essentially depending on the type of vehicle. Using the relative position of an accelerator pedal while

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 as long as the quantity which represents the driver demand is for example useful in the case of passenger vehicles. In this case, the position relative to the not depressed state of the accelerator pedal is designated by 0% and in the fully depressed state of the accelerator pedal, by 100%.

 In addition, in a particularly preferred manner, the parameter used to adjust the motor power indicates the ratio of the desired motor power to the motor power range which can be adjusted. The output value of the characteristic line is therefore here also a relative value which is related to the entire power domain. If the parameter is 100%, work with maximum motor power. If the value is 0%, then a minimum engine power must be present.

 From this point of view, the device is particularly useful when the range of motor power which can be adjusted can be limited upwards by the maximum motor power and downwards by a power determined from a minimum torque dependent on the actual engine speed. The minimum torque is then generally chosen in such a way that, for an accelerator pedal that is not actuated, there is still always a certain torque. By means of this, on the one hand, a certain braking action must be exerted by the engine. On the other hand, when users are connected, an engine stall must be prevented.

 According to a particularly preferred embodiment of the device according to the invention, it is provided that the adjustment of the motor power can be subject to a variation as a function of the speed of rotation by means of a stability factor. . The stability factor is then usefully prefixed as a constant. The dependence on the speed of rotation is achieved by modifying the motor power more strongly for low speeds of rotation than for high speeds of rotation. This is used to correct the control at constant power using the stability factor, especially for low rotational speeds. Therefore, for example, the following driving situation is taken into account. If driving at a low speed on a plane and at constant speed, control at constant power is then desired. If we then arrive in any case at a hill location, the speed of rotation would then decrease and sometimes drop below a minimum speed value, which could ultimately cause the engine to stall. This situation is opposed by the fact that the power is increased for low rotational speeds on the basis of the stability factor. Such an increase is generally worth a few percent, for example 2% to 4%.

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 According to another preferred embodiment of the device, there are provided several characteristic lines awaiting different driving behaviors.

Thus, the driver can for example choose between a quiet driving behavior and a sporty driving behavior, the characteristic line each corresponding time being in fact activated in the engine control.

 For the same purpose indicated above, the invention also relates to a process, of the generic type defined in the introduction, characterized in that the quantity representing the demand for the driver is treated by means of a characteristic line, the characteristic line transforming the quantity representing the driver demand in a parameter used to adjust the engine power. In this way, the advantages and particularities of the device according to the invention are also realized within the framework of a process. This also applies to the preferred embodiments of the process which are indicated below.

 In a particularly advantageous manner, according to a development of the method according to the invention, the relative position of an accelerator pedal is used as a quantity representing the driver's demand. The accelerator pedal position is, for example in the case of passenger and utility vehicles, an appropriate size which represents the driver demand.

 In addition, in a particularly preferred manner, the parameter used to adjust the motor power indicates the ratio of the desired motor power to the motor power range which can be adjusted. The initial value of the characteristic line is therefore a relative value which is related to the entire power domain.

 From this point of view, the method is particularly useful when the range of engine power which can be adjusted is limited upwards by the maximum engine power and downwards by a power determined from a minimum torque dependent on the actual motor speed. The minimum torque is then generally adapted in such a way that, when the accelerator pedal is not actuated, there is still always a certain minimum torque. Thanks to this, on the one hand, a certain braking action must be exerted by the engine. On the other hand, when users are connected, an engine stall must be prevented.

 According to a particularly preferred embodiment of the method according to the invention, it is provided that the adjustment of the motor power is modified as a function of the speed of rotation by means of a stability factor. Usefully, the stability factor is prefixed as a constant. The

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 dependence on the speed of rotation is achieved by the fact that the motor power is modified more strongly for low speeds of rotation than for high speeds of rotation. This makes it possible, in particular in the case of low rotational speeds, to correct the control at constant power by means of the stability factor. Therefore, account is taken, for example, of a driving situation in which increased resistance to driving suddenly occurs. If this increased resistance to driving appears at low rotational speeds, it is then advisable to increase the engine power, in order to avoid an undesired excessive reduction in the engine rotational speed.

 According to another preferred embodiment of the method, it is expected that several characteristic lines are used pending different driving behaviors. Thus, the driver can for example choose between a quiet driving behavior and a sporty driving behavior, the characteristic line each corresponding time being in fact activated in the engine control.

 At the basis of the invention is the observation that the adaptation of a torque-based motor control can be greatly simplified by replacing a characteristic table with several dimensions by a characteristic line, while it is possible to overcoming the other tasks of the multi-dimensional characteristic tables of the state of the art by means of calculation algorithms located in the control device. The invention allows constant power control, stability corrections, in particular as regards driving behavior for low rotational speeds, which can be applied in the context of preferred embodiments.

 The invention is set out below by way of example with the aid of preferred embodiments and with reference to the accompanying drawings.

 We see: in Figure 1, a schematic representation of a device used to produce a torque request which conforms to the state of the art and, in Figure 2, a schematic representation of a device used to produce a torque request torque request which is in accordance with the present invention.

 Figure 1 is a schematic representation of a device for producing a torque request which conforms to the state of the art. In this example, the current engine speed 112, which is usually indicated in revolutions per minute, and the relative accelerator pedal position 114, which has a value between 0 and 100% of the accelerator pedal. fully pressed, are entered in function block 200. In this function block 200, the variables

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 Input 112,114 are processed mainly by means of a characteristic table with several dimensions. The function block 200 delivers, as an output value, a signal which represents a request for torque 110, for example a required clutch torque. Since the transformation of the input quantities 112, 114 in the function block 200 takes place essentially by means of a characteristic table with several dimensions, this must be adapted in an appropriate manner in order to deliver, for different applications, the appropriate torque request 110. Not only is this complex, but it also leads to problematic or critical adjustments, since the participating parameters influence each other.

 Figure 2 is a schematic representation of a device for generating a torque demand which is in accordance with the present invention. The device according to the invention uses, as input quantities, the speed of rotation of the motor 12, which is generally indicated in revolutions per minute, the relative position of the accelerator pedal 14, which can be indicated in percent of the maximum value, and the current setpoint idle speed 28, also in revolutions per minute. Other input quantities are the maximum motor power 20, which is generally indicated in kW, the maximum motor rotation speed 30, indicated in revolutions per minute, and a dimensionless stability factor 26. As an output quantity, the device provides a torque request 10, more precisely the required clutch torque.

 In order to arrive at the input quantities indicated at the output quantity, characteristic lines 16, 32 are used on the one hand and algorithms which process the primary quantities, the output quantities of the blocks, are used on the other hand. characteristic line sixteen, 16.32 or calculation blocks connected upstream of the output quantities.

 In particular, the motor rotation speed 12 is introduced into a characteristic line block 32 in which the motor rotation speed is transformed into a minimum torque 22 which can be adapted. The minimum torque 22 is multiplied in a first product block 40 by the speed of rotation of the motor 12 and by a constant 34, so as to thus calculate the minimum power 24 as the output value of the first product block 40. In the units indicated, which means that the speed of rotation is indicated in revolutions per minute and the torque in Nm, the constant 34 has the value Tr / 30. 000. The minimum power 24 is then subtracted from the maximum motor power 20 in a first difference block 36. This gives the available power interval 38 on the basis of which the motor control at constant power can work.

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 The value of the available power interval 38 is introduced into a second product block 42. A parameter 18 used to adjust the motor power is introduced as a second quantity in the second product block 42.

This parameter 18 is produced as the output value of the characteristic line 16 and it represents the driver demand interpreted by means of the characteristic line 16. The relative position of the accelerator pedal 14 serves as input value of the characteristic line 16.

 The available power range scaled using parameter 18 in the second product block 42 is added, as scaled power 44, to the minimum power 24 in a first addition block 46 to produce a preliminary power value 48.

 Then, the preliminary power value 48 is multiplied in a third product block 50 by a stability factor 26 which can for example be set to a value of 1.02. The preliminary power value 48 is subtracted from the output value of the product block 50 in a second difference block 52, so that a preliminary correction power 54 is available.

 To transform this preliminary correction power into a correction power dependent on the speed of rotation, a fourth product block 56, a fifth product block 58 and a second addition block 60 are provided.

 The input quantities of the current nominal idle speed 28 and of the motor speed 12 are also used to calculate the correction power dependent on the speed. The maximum motor speed 30 is subtracted from the current setpoint idle speed 28 in a third difference block 62. The output value of the third difference block 62 is entered in an inverse value block 64 so that a reference quantity 66 is available for multiplication with the preliminary correction power 54 in the product block 56. In addition, the current nominal idle speed 28 is subtracted from the motor speed 12 in a fourth difference block 68. Thus, a rotation speed influence quantity 70 depending on the current motor rotation speed 12 is produced as the output value of the fourth difference block 68. The output value of the fourth product block 56 is then multiplied by the influence quantity of rotation speed 70 in the fifth product block 58, so that a correction power 72 is output as the output value of the fifth product block 58.

 Finally, the product blocks 50, 56, 58 and the other function blocks associated with them therefore serve to divide the preliminary correction power 54

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 by a rotation speed reference quantity 66 depending on the current nominal idle rotation speed 28 and then multiplying this quotient by the rotation speed influence quantity 70 depending on the current engine rotation speed 12. As a result, a correction power 72 is obtained which forms a greater correction value for low speeds of rotation than for high speeds of rotation.

 In this way, the constant power motor control, which is based on the interpretation of the pedal value, is corrected on the basis of the stability factor 26. As a result, the driving behavior of the vehicle is stabilized.

 In this sense, in the second addition block 60, the preliminary power 48 is added to the correction power 72 with the result of a final power value 74. In the sixth product block 76, by means of a transmission of the second block of inverse value 78 and of the third block of inverse value 80, the final power value 74 is transformed by calculation, by division by the speed of rotation of motor 12 and by the constant 34 having the value Tr / 30. 000, to give the required clutch torque or the torque request 10.

 The features of the invention disclosed in the foregoing description, the drawings and the claims may be important both individually and in any combination for the practice of the invention.

Claims (12)

1. Torque demand generation device (10) in the context of a motor control, comprising - means for processing input quantities, the input quantities comprising a motor rotation speed (12) and a quantity representing a driver request (14), and - means serving to deliver the torque request (10) as a function of the input quantities, characterized in that the means serving to process the quantity representing the driver request (14) comprise at least one characteristic line (16), the characteristic line (16) transforming the quantity representing the driver demand (14) into a parameter (18) serving to adjust the motor power.  2. Device according to claim 1, characterized in that the quantity representing the driver demand is the relative position of an accelerator pedal (14).  3. Device according to any one of claims 1 and 2, characterized in that the parameter (18) for adjusting the engine power indicates the ratio of the desired engine power to the engine power range that can be adjusted.  4. Device according to any one of claims 1 to 3, characterized in that the adjustable motor power range can be limited upwards by the maximum motor power (20) and downwards by a power ( 24) determined from a minimum torque (22) depending on the actual engine speed.  5. Device according to any one of claims 1 to 4, characterized in that the adjustment of the motor power can be subject to a variation as a function of the speed of rotation by means of a stability factor ( 26).  6. Device according to any one of claims 1 to 5, characterized in that there are provided several characteristic lines awaiting different driving behaviors.  7. Method for generating a torque request (10) within the framework of a motor control, according to which - input quantities are processed, the input quantities comprising a motor rotation speed (12) and a quantity representing a driver request (14), and - the driver request (10) is delivered as a function of the input quantities, <Desc / Clms Page number 10>  characterized in that the quantity representing the demand for the conductor (14) is processed by means of a characteristic line (16), the characteristic line (16) transforming the quantity representing the demand for the conductor (14) into a parameter (18) used to adjust engine power.  8. Method according to claim 7, characterized in that the relative position of an accelerator pedal (14) is used as a quantity representing the driver demand.  9. Method according to any one of claims 7 and 8, characterized in that the parameter (18) for adjusting the engine power indicates the ratio of the desired engine power to the engine power range that can be adjusted.  10. Method according to any one of claims 7 to 9, characterized in that the adjustable motor power range is limited upwards by the maximum motor power (20) and downwards by a power determined at from a minimum torque (22) depending on the actual engine speed.  11. Method according to any one of claims 7 to 10, characterized in that the adjustment of the motor power is modified as a function of the speed of rotation by means of a stability factor.  12. Method according to any one of claims 7 to 11, characterized in that several characteristic lines are used pending different driving behaviors.