DE102011086360A1 - Method for determining torque maximum realizable with drive motor of motor system, involves simulating allowable torque, where allowable torque is impinged with offset for maximum realizable torque - Google Patents

Abstract

The method involves simulating an allowable torque (34). The allowable torque is impinged with an offset for maximum realizable torque. The offset is dependent on the system tolerance of a drive motor (4). The offset is reduced when a desired torque (30) is driver request independent for a predetermined time. The reduction of the offset is time limited in the predetermined operating state. Independent claims are included for the following: (1) a device, particularly computer unit for determining a torque maximum realizable with a drive motor; (2) a computer program with a program code unit; and (3) a computer program product with a program code.

Description

Technical area

The invention generally relates to drive motors, in particular measures for determining a maximum torque that can be converted with a vehicle engine.

State of the art

Methods for determining a torque to be converted by a drive motor are well known.

The DE 10 2006 061 561 A1 discloses, for example, such a method in which, in particular in response to a fault in the control of the drive motor, a setpoint torque to be converted by the drive motor is limited to a predefinable torque. In this case, a rotational speed of the drive motor is determined as a function of at least one operating variable of the drive motor and the predefinable torque is modified as a function of the determined rotational speed.

Disclosure of the invention

According to the invention, a method for determining a maximum torque which can be converted with a drive motor according to claim 1 as well as the device, the vehicle and the computer program product according to the independent claims are provided.

Further advantageous embodiments of the present invention are specified in the dependent claims.

According to one aspect of the invention, a method according to the invention for determining a maximum torque which can be converted with a drive motor comprises the steps of specifying an allowable torque and applying the permissible torque with an offset, dependent on the system tolerances of the drive motor, to the maximum convertible torque. In this case, the offset is applicably reduced, if a desired torque is driver-independent.

The invention is based on the finding that in current engine control systems, a faulty torque request in the torque structure can lead to undesirable speed increases. These speed increases can come about due to a faulty torque request, which is so great that the speed controller abuts its limit during balancing. In addition, a component drift of the accelerator pedal value transmitter within the component tolerances or an incorrect specification of the desired torque of the speed controller can also lead to an undesired increase in the rotational speed.

To avoid this undesirable speed increase, the invention is based on the consideration that the desired torque is limited to a maximum convertible torque when it is too high. The maximum torque that can be converted consists of the sum of the above-mentioned permissible torque and the above-mentioned offset. The offset corrects system tolerances that have been included in the allowable torque during the calculation. In this way, the vehicle is not unnecessarily limited in its retrievable power.

The idea of the invention is to use the offset in the maximum retrievable torque not only as a corrective for system tolerances flowed in but also to avoid the above-mentioned unwanted speed increases. This idea is based on the recognition that it is irrelevant without a driver torque, whether the vehicle is unnecessarily limited in its retrievable power or not, because the driver can counteract even by driving his own behavior of the unwanted speed increase, for example by throttling the requested driver torque. The situation is different if the engine control sets the desired torque. In this case, an undesirable increase in speed leads to indefinite operating conditions of the vehicle, in which it can become unstable in the worst case. If there is no request for a driver-requested torque, the system tolerances considered in the maximum retrievable torque are therefore counteracted by the offset being reduced in accordance with the invention.

In a further development, the offset can be applied in an administrable manner if the desired torque is driver-independent for a predetermined time. By this measure, it can be avoided that the driver experiences a noticeable loss of power, just because he takes his foot off the accelerator pedal, for example, when braking on a highway.

In another refinement, the offset can be applied in an administrable manner if the desired torque is determined by the engine control. This embodiment is based on the consideration that if, for example, a speed calculated by the engine control does not lead to the effect expected by the engine control during the intervention of the electronic stability program, this can lead to uncontrollable and life-threatening vehicle conditions. In extreme cases, the vehicle may become unstable. The reduction of the offset therefore stabilizes the control loop with the engine control.

In an alternative development, the offset is applied administered reduced when the drive motor is in a predetermined operating condition. This operating state can be any operating state in which the offset can exert a negative influence on the vehicle. For example, these operating conditions may affect the idling of the drive motor to conserve engine components or reduce exhaust emissions. Exemplary determinations of further operating states are the subject of the subclaims.

In an additional development, the reduction of the offset in the predetermined operating state is limited in time. In this way, it is ensured that the drive motor settles in the predetermined operating state.

After this transient phase, the power increased by the offset is available again for the drive motor.

In a preferred embodiment, no gearshift of the drive motor is active in the predetermined operating state, so that a speed harmonization in a gear change by the engine control is not affected by the invention.

In another preferred embodiment, all measures for heating a catalyst of the drive motor have expired in the predetermined operating state, so that a wrong operating temperature of the catalyst is avoided by the invention and thus damage desselbigen.

In a further preferred development, a starting operation of the drive motor has expired in the predetermined operating state, so that the motor can be transferred in a timely manner into a ready-to-operate state.

According to a further aspect of the invention, the device, in particular a computing unit, is designed to carry out a specified method according to the invention. The apparatus may comprise a memory and a processor, wherein in the memory a program code is stored, which contains the method steps of the specified method and the processor is designed to execute the specified method, when the method steps are loaded from the memory into the processor.

In another aspect, an engine system includes a drive motor and the above device.

According to a further aspect, a computer program with program code means is provided to perform all the steps of the above method when the computer program is executed on a computer or a corresponding computing unit, in particular in the above apparatus.

In another aspect, a computer program product is provided that includes program code stored on a computer-readable medium and that, when executed on a data processing device, performs the above method.

Brief description of the drawings

Preferred embodiments of the present invention will be explained in more detail with reference to the accompanying drawings. Show it:

1 a control circuit for driving a drive motor with an apparatus for carrying out the method according to the invention;

2 a logic diagram of a device 1 according to a first embodiment of the invention;

3 a logic diagram of a device 1 according to a second embodiment of the invention; and

4 a logic diagram of a control for controlling the devices from the 2 or 3 ,

Description of embodiments

It will open 1 Reference is made to a control loop 2 for controlling a drive motor 4 shows. The drive motor may be any desired drive motor, such as an internal combustion engine or an electric motor.

The control loop 2 In the present embodiment, it becomes a memory 6 a setpoint speed 8th for the drive motor 4 specified. About a target-actual-value comparison 10 becomes a control speed difference 12 between the setpoint speed 8th and one on the drive motor 4 and to the target actual value comparison 10 guided actual speed 14 certainly. A torque structure 16 determined from the control speed difference 12 a control torque 18 that at the drive motor 4 necessary to the setpoint speed 8th adjust. Thus the control loop is closed.

The torque structure 16 includes a speed controller 20 , the regulator output is a regulator torque 22 outputs. In a target torque structure 24 is based on the controller torque 22 , a driver request torque 26 and a battery management torque 28 a target torque 30 determined below as the desired torque 30 referred to as. The desired torque 30 will be described in a limiting device to be described 32 to a permissible torque 34 limited. For this purpose, the limiting device receives in addition to the desired torque 30 the actual speed 14 of the drive motor 4 and a control signal 38 from a control device to be described later 36 ,

To calculate the control signal 38 receives the control device 36 several status signals to the drive motor 4 , These include, inter alia, a request signal 40 , which indicates whether currently a driver's desired torque 28 requested by a driver, a catalyst signal 42 , which indicates whether the catalyst of the vehicle with the drive motor 4 currently being heated, a circuit signal 44 , which indicates whether currently the gear shift of the vehicle with the drive motor 4 is active, a start signal 46 , which indicates whether the drive motor is currently in a starting phase and an idle signal 48 indicating the torque at which the drive motor is idling. These signals can optionally be further signals 50 be supplemented.

In 2 is a first embodiment of the limiting device 32 shown. In 2 become too 1 the same elements with the same reference numerals and not described again.

The desired torque 30 is first in a filter 52 filtered, which may be designed as a low-pass filter with deadtime behavior, for example. The filtered desired torque 54 eventually becomes an adder 56 with a corrected offset 58 applied and as a permissible torque for limiting the torque 34 connected to the drive motor 4 is spent.

The corrected offset 58 consists of a basic offset 59 and a correction offset 61 together.

The basic offset 59 is in a first offset table 60 deposited. The first offset table 60 in the present embodiment depends on the filtered desired torque 54 and the actual speed 14 of the drive motor 4 , About a switch 62 can the basic offset 59 directly as a corrected offset 58 for applying the filtered desired torque 54 be issued. An exemplary first offset table 60 is given below:

In the first offset table 60 the values are given dimensionless.

The correction offset 61 is in a second offset table 64 deposited. Also the second offset table 64 in the present embodiment depends on the filtered desired torque 54 and the actual speed 14 of the drive motor 4 , About the switch 62 can the correction offset 61 from the basic offset 59 deducted and as a corrected offset 58 for applying the filtered desired torque 54 be issued. An exemplary second offset table 64 is given below:

Also in the second offset table 64 the values are dimensionless stored.

A brief comparison of the two tables shows that an imposition of the base offset 59 with the correction offset 61 only at high actual speeds 14 to a reduction of the basic offset 59 , in this case to zero, leads. At low actual speeds 14 becomes the basic offset 59 unchanged regardless of the position of the switch 62 output. For the sizing of the table in the present embodiment, it was assumed that the drive motor 4 at standstill and without driver's request torque 26 not with too high actual speeds 14 allowed to run. Therefore, the basic offset 59 at high actual speeds 14 corrected, at low actual speeds 14 However not.

In 3 an alternative way is shown, the basic offset 59 with the correction offset 61 to act on. In 3 become too 1 and 2 the same elements with the same reference numerals and not described again.

As in 3 shown, the switch can 62 also directly into the branch of the correction offset 61 be used. In this way, although the complexity of the resulting algorithm can be reduced, the delaying subtraction operation is steadily needed.

In 4 is an embodiment of the control device 36 for generating the control signal 38 shown. In 4 become the 1 to 3 the same elements with the same reference numerals and not described again.

In the generation of the control signal flow, as already mentioned, the request signal 40 , the catalyst signal 42 , the circuit signal 44 , the start signal 46 , and the idle signal 48 one.

About a first and-member 66 is verified, whether in each case the catalyst signal 42 , the circuit signal 44 and the start signal 46 are turned off, and whether since their shutdown a predetermined time has not yet elapsed. This should be exemplified by the processing of the catalyst signal 42 to be discribed. For the other two signals, the following statements apply analogously.

A first negator 68 only gives a positive signal when the catalyst signal 42 is turned off less than a predetermined time. This is about a second and-member 70 achieved that only then outputs no signal, what at the negator 68 to a positive catalyst signal 42 leads when the catalyst signal 42 is switched off and if since the switch-off time, a delay element 72 has not expired yet. Will the catalyst signal 42 switched off, it triggers the delay element 72 after a predetermined time also his output signal also turn off. As the output of the delay element 72 but over a second negator 74 is negated lie on the second and-member 70 only as long as no signals, as since switching off the switch-off signal 30 a predetermined, in the delay element 72 deposited time has not yet elapsed.

A third and limb 76 Checks if the output signal of the first AND gate 70 is active and whether at the same time the drive signal 40 has lapsed for at least a predetermined time. This is accomplished by a third inverter in the present embodiment 78 ensured, whose output signal with a second delay element 80 is delayed. Gives the third and-member 76 an active output signal, this is as a control signal 38 over an OR link 82 output.

Alternatively, the control signal may also be from a fourth AND gate 86 generated and over the OR gate 82 be issued. In addition to the condition that the second delay element 80 outputs an output signal, ie the drive signal 40 has been extinguished for a predetermined time, must also by the idle signal 48 indicated torque a predetermined threshold 84 have exceeded what is in the comparison unit 88 is checked.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006061561 A1 [0003]

Claims (12)

Method for determining a drive with a motor ( 4 ) maximum convertible torque ( 34 ), comprising the following steps: - Specifying a permissible torque ( 30 ), and - applying the permissible torque ( 30 ) with one of the system tolerances of the drive motor ( 4 ) dependent offset ( 58 ) to the maximum convertible torque ( 34 ), where the offset ( 58 ) is applied administrable when a desired torque ( 30 ) is driver independent. Method according to claim 1, wherein the offset ( 58 ) is applied administrable when the desired torque ( 30 ) is driver-independent for a predetermined time. Method according to claim 1 or 2, wherein the offset ( 58 ) is applied administrable when the desired torque ( 30 ) is determined by the engine control. Method according to one of the preceding claims, wherein the offset ( 58 ) is applied administered when the drive motor ( 4 ) in a predetermined operating condition ( 50 ) is located. Method according to claim 4, wherein the reduction ( 61 ) of the offset in the predetermined operating state ( 50 ) is limited in time. Method according to claim 4 or 5, wherein in the predetermined operating state no gearshift ( 44 ) of the drive motor ( 4 ) is active. Method according to one of claims 4 to 6, wherein in the predetermined operating state all measures ( 42 ) for heating a catalyst of the drive motor ( 4 ) have expired. Method according to one of claims 4 to 7, wherein in the predetermined operating state, a starting operation ( 46 ) of the drive motor ( 4 ) has expired. Device, in particular a computing unit, for determining one with a drive motor ( 4 ) maximum convertible torque ( 34 ), wherein the device is designed to - an allowable torque ( 30 ), and - the permissible torque ( 30 ) with one of the system tolerances of the drive motor ( 4 ) dependent offset ( 58 ) to the maximum convertible torque ( 34 ), whereby the offset ( 58 ) is applied administrable when a desired torque ( 30 ) is driver independent. Motor system comprising a drive motor ( 4 ) and a device according to claim 9. Computer program with program code means for carrying out all steps of the method according to one of claims 1 to 8, when the computer program is executed on a computer or a corresponding computing unit, in particular in a device according to claim 9. A computer program product containing program code stored on a computer-readable medium and which, when executed on a data processing device, performs the method of any one of claims 1 to 8.

Images