Method for determining a change in a torque requirement to a drive motor of a work machine

Abstract

Method for determining a change in an engine torque requirement to a drive motor (10) of a work machine due to a change in the state of respective auxiliary consumers (16), the method comprising at least the following steps; - detecting (30) a change in engine torque; - detecting (32) a change in driving condition; - determining (34) a change in state of respective auxiliary consumers (16) as a function of the detected engine torque change and the detected driving state change; and - Determining (36) the changed engine torque requirement to the drive motor (10) by the respective auxiliary consumers as a function of the determined change in state of the respective auxiliary consumers (16).

Description

Technical FieldThe present invention relates to a method for determining a change in torque demand to a drive motor of a work machine due to a change in state of an auxiliary load. The invention also relates to a working machine having a drive motor, a drive transmission and at least one auxiliary consumer.Prior ArtIn a drive train of a work machine, it is usually known which torque is generated by a drive motor. In a working machine, however, this torque is not made completely available to a drive output in every usage state. Instead, a portion of the torque may be directed to respective auxiliary consumers of the work machine. A outlay for recording a number and type of active secondary consumers and their respective torque requirement can be very high in this case. Therefore, it is usually not known how much of the torque generated by the drive motor is conducted to the respective auxiliary consumers. Accordingly, it may be unknown, for example, which torque is actually made available to a drive transmission. For vehicle control, however, it is desired to know this torque actually applied to an input of the transmission. For example, this torque, if available, is used for the control of the transmission. As a result, a transmission control can be substantially more efficient and convenient.In some working machines, a signal is actually present in an internal bus system, which indicates a removal of torque by secondary consumers. However, this signal usually permits only a very inaccurate estimation of the torque required by the respective secondary consumers. The actual removal of torques by secondary consumers can deviate by a few hundred Newton-meters, for example. As a result, a drive transmission control can be uncomfortable and also inefficient.DE 10 2018 111 022 A1 describes an agricultural working machine and a method for operating an agricultural working machine.DE 10 2014 113 335 A1 describes an agricultural working machine with predictive regulation of a drive power and / or a drive train.DE 10 2019 200 125 A1 describes a method for operating a drive train of a vehicle.DE 10 2015 221 159 A1 describes a method for controlling a commercial vehicle.DE 10 2010 030 247 A1 describes a method for operating a drive train.DE 10 2017 220 029 A1 describes a method for operating a working machine with a torque measuring device.DE 10 2020 215 661 A1 describes a method for operating a motor vehicle with an auxiliary power take-off.SUMMARY OF THE INVENTIONA first aspect relates to a method for determining a change in an engine torque request to a drive engine of a work machine on the basis of a change in state of respective secondary consumers. A drive motor can be designed, for example, as a traction motor. The drive motor can be designed, for example, as an internal combustion engine or an electric machine. A torque may be a torque provided on a shaft. An engine torque request to the drive engine may correspond to a drive power required to drive a traction drive and respective auxiliary consumers of the work machine. A working machine can be designed, for example, as an agricultural machine or construction machine. An example of a agricultural machine is a tractor. An example of a construction machine is a wheel loader. An auxiliary consumer can be, for example, a fan, an air conditioning compressor, an air compressor, an alternator, a control hydraulic system or else a working device on a power take-off shaft.The method includes a step of detecting an engine torque change. The engine torque can be calculated, for example, by an engine controller for detecting it. The engine torque can also be detected, for example, by a torque sensor. The motor torque may be a torque provided by the drive motor on a motor shaft. The engine torque changes, for example, when an applied load on the engine increases or decreases. The load present can change, for example, by activating or deactivating an auxiliary consumer. The engine torque may also change as a result of a driver's request. For example, engine torque may increase by applying an accelerator pedal. The engine torque can be controlled, for example, by an engine controller. An engine torque change may be a gradient of engine torque.The method has a step of detecting a change in the driving state. A change in the driving state can be, for example, an acceleration or a deceleration of the working machine. This can be detected, for example, by an acceleration sensor. A change in the driving state can also be, for example, a change in the rotational speed at an output shaft of the working machine. For example, a torque sensor may detect the change in speed at a driven axle of the work machine. For example, the output speed may change as the work machine accelerates. The detected change in the driving state can allow conclusions to be drawn as to whether the vehicle is accelerated or braked by a change in engine torque or whether the change in engine torque has been caused, for example, by a state lowering of an auxiliary consumer.The method has a step of determining a change in state of respective secondary consumers as a function of the detected engine torque change and of the detected change in driving state. For example, a change in state of an auxiliary consumer can be an activation or deactivation of the auxiliary consumer. For example, a state of respective secondary consumers can change by switching them on or off. A change of state from an auxiliary consumer can, however, also relate to its torque request. For example, a fan can change its rotational speed and thus require more torque. On the basis of the detected engine torque change and the detected driving state change, it can be concluded whether a respective one of the secondary consumers has changed its state. For example, if the engine torque is increased in the case of a constant driving state, it can be assumed that at least one of the secondary consumers has caused this engine torque change. From this, it is then possible to infer a drive torque actually made available to the drive transmission.The work machine can have only one or more auxiliary consumers. The change of state can be determined for a plurality of secondary consumers for each of these secondary consumers or also only for a few selected ones of these secondary consumers. For example, changes in state of secondary consumers with a very low torque requirement can be ignored in the method. For example, it is possible instead to restrict itself to secondary consumers with the highest torque requirements. This can simplify the identification of which accessories have changed state. Each secondary consumer may be assigned a torque request. Thus, a system reaction can allow a conclusion to be drawn as to which of the secondary consumers has been activated or deactivated. For example, in the case of an engine torque increase at a first level, it can be assumed that a first secondary consumer has been activated, and in the case of an engine torque increase at a second level, it can be assumed that a second secondary consumer has been activated.The method has a step of determining the changed engine torque request to the drive engine by the respective auxiliary consumers as a function of the determined change of state of respective auxiliary consumers. In this case, for example, recourse can be made to a torque request from respective secondary consumers stored in tabular form as a function of their state. For example, a torque request of an auxiliary consumer now determined as activated can be subtracted from the detected engine torque in order to determine the drive torque made available to a drive transmission for an output of the working machine. The changed torque request to the drive motor can be estimated for the determination thereof, for example. This estimation can be significantly more precise than is possible, for example, only with a signal in a bus system of a vehicle controller. This makes it possible to provide much more precise information for controlling systems of the drive machine. For example, a net actual drive shaft torque at an input shaft of the transmission may be calculated or otherwise determined. If no state of an auxiliary consumer has changed, it can be assumed, for example, that an engine torque change also corresponds to a torque change at the drive transmission.In a further embodiment of the method, it is provided that the detection of the change in the driving state comprises a detection of a change in the output rotational speed. For example, a rotational speed sensor can be provided on an output shaft of the transmission or on a driven shaft of the working machine. This detection makes it possible to detect particularly precisely whether an engine torque change influences an engine torque provided to the transmission or whether this engine torque change is rather supplied to one of the secondary consumers.In a further embodiment of the method, it is provided that the detection of the change in the driving state comprises a detection of a vehicle acceleration. For this purpose, the working machine can have an acceleration sensor, for example. As a result, it is possible to detect in a particularly simple manner whether the engine torque change is attributable, for example, to a driver's wish and is therefore not attributable to a change in state of an auxiliary consumer.If both an output speed change and a vehicle acceleration are detected, the method can also detect, for example, whether a driving state change and thus an engine torque change is attributable to a change in a subsurface on which the working machine is driving. For example, a driving resistance may change due to a ground condition and thus require a change in engine torque. For example, an inclination of a driving plane can also change and thus cause a change in engine torque.In a further embodiment of the method, it is provided that a change in state of respective secondary consumers is determined only if a detected engine torque change is greater than a first threshold value. By taking into account the first threshold value, it can be avoided that the method reacts unnecessarily sensitively. In addition, it is thus possible to prevent the usual fluctuation in the engine control, for example due to environmental influences, vibrations, shocks and the like, from being undesirably identified as a change in state of respective secondary consumers. Respective data on which the method is based can thus be filtered.In a further embodiment of the method, it is provided that the first threshold value corresponds to a torque request of an auxiliary consumer of the work machine with a lowest torque request. This makes it possible to particularly reliably prevent engine torque changes being taken into account, which changes cannot correspond at all to a change in state of an auxiliary consumer.In a further embodiment of the method, it is provided that a change in state of respective secondary consumers is determined only if a detected change in engine torque is longer than a second threshold value. Short-term fluctuations can also be filtered from the data for the method. For example, it can be taken into account that an auxiliary consumer remains permanently activated and only then is an actual change in an input torque for the transmission actually caused. In the case of an engine torque change longer than a certain period of time, it can be assumed with a high probability that this was caused by a change in state of respective secondary consumers.In a further embodiment of the method, it is provided that a change in state of respective secondary consumers is determined only if oscillations of the change in driving state are below a significance threshold. The significance threshold can be defined by a predefined oscillation amplitude, by a predefined oscillation frequency and alternatively or additionally by a predefined oscillation shape. The significance threshold can likewise be used to filter changes in engine torque on the basis of external influences and respective working processes of the working machine. As a result, the accuracy of the determination of state changes of respective secondary consumers can be improved.In a further embodiment of the method, it is provided that a change in state of respective secondary consumers is determined only if a detected change in driving state does not increase over a predetermined period of time. This makes it possible to detect when the working machine continuously changes its driving state. For example, a continuous acceleration or deceleration can thus be filtered. As a result, the accuracy of the determination of state changes of respective secondary consumers can be improved.In a further embodiment of the method, it is provided that the determination of the change in state of respective secondary consumers comprises identifying that one of a plurality of secondary consumers of the working machine whose state has changed. For example, the identification can take place as a function of the detected engine torque change and optionally additionally of the detected driving state change. For example, each secondary consumer of the plurality of secondary consumers may be assigned a torque request. If a change in state has been determined by a respective one of the secondary consumers, that one of the plurality of secondary consumers whose torque request is closest to or identical to the detected engine torque change can be identified as responsible for this. This makes it possible to improve the accuracy of the determination of a drive torque actually made available to the drive transmission, since the auxiliary consumer actually responsible for the torque change can be known by identifying the latter.In a further embodiment of the method, it is provided that the determination of the changed engine torque request to the drive engine is carried out by the respective secondary consumers as a function of the identified secondary consumer of the plurality of secondary consumers whose state has changed. For this purpose, a tabular comparison can be made, which is based on a torque request of respective secondary consumers. The torque request of the respective secondary consumers can be stored in a database, for example. The torque requirement of the respective secondary consumers can have been determined, for example, by previous driving experiments or other experiments.In a further embodiment of the method, it is provided that the detection of the change in the driving state takes place with a time offset before the detection of the change in the engine torque. An engine torque can be determined, for example, as a function of stored engine characteristic curves. The engine torque determination may therefore require a calculation that takes time. In addition, a transmission of the engine torque, for example to a transmission control, can cause a time delay. Overall, therefore, the engine torque and, accordingly, also the change in engine torque can be subject to a time delay. This can be greater than in the case of the driving state change detection, which can be carried out directly by sensor means, for example. As a result, the detected engine torque change and the detected driving state change can relate to different time periods or points in time. As a result of a delay in data acquisition, the acquisitions of the change in the driving state and the change in the engine torque can better correspond to the same period of time, as a result of which precision can be carried out in the determination of changed engine torque request to the drive engine. For example, the detected engine torque at a first point in time and a detected driving state at an earlier second point in time may each correspond to the same real point in time.A second aspect relates to a working machine. The working machine has a drive motor, a drive transmission and at least one auxiliary consumer. The drive motor can be designed to generate a drive torque which is supplied to the drive transmission. The color transmission can be designed to forward drive torque to an output of the work machine. The drive transmission can be designed, for example, to transmit the torque with different transmission ratios. The transmission can have, for example, a plurality of gears. The transmission may also provide idle. The drive motor can be designed to drive the respective auxiliary consumers of the working machine. For this purpose, a portion of the torque generated by the drive motor can be conducted to the secondary consumers upon their activation. The working machine can have a plurality of different auxiliary consumers.The working machine can be configured to carry out the method according to the first aspect. Respective advantages and further features can be gathered from the description of the first aspect, wherein configurations of the first aspect also form configurations of the second aspect and vice versa.The work machine may include a detection device configured to detect an engine torque change and a driving state change. For this purpose, the detection device can have respective sensors. The detection device can also be connected to a vehicle bus on which corresponding data are transmitted to the detection device, for example from a vehicle controller. The working machine can have a determination device which is designed to determine a change in state of respective secondary consumers as a function of the detected engine torque change and of the detected change in driving state, and to determine a changed engine torque request to the drive engine by the respective secondary consumers as a function of the determined change in state of respective secondary consumers. The determination device can be designed, for example, as a microcontroller or onboard computer.In a further embodiment of the working machine, it is provided that the working machine has a transmission control. The transmission controller may be configured, for example, to actuate respective shift elements of the transmission. For example, the transmission controller can automatically adjust the respective clutch and brakes of the transmission as a function of an input torque at the transmission and thus adapt a gear of the transmission to a current driving state. The transmission controller may be configured to control the transmission as a function of an engine torque and the determined changed torque request to the drive engine by the respective auxiliary consumers. For example, an input shaft torque for the transmission is determined by the respective auxiliary consumers as a function of the engine torque and the determined changed torque request to the drive engine. This allows improved control of the transmission, since it can now be based on a precisely determined input torque.Brief Description of the FiguresFIG. 1 schematically illustrates a method for determining a change in torque demand to a prime mover of a work machine due to a change in state of an accessory. FIG. 2 schematically illustrates the work machine when performing the method according to FIG. 1.Detailed Description of EmbodimentsFIG. 1 schematically illustrates a method for determining a change in a torque request to a drive motor 10 of a working machine on the basis of a change in state of an auxiliary consumer 16. In addition, the working machine has respective secondary consumers 16, which can likewise be supplied with a drive power by the drive motor 10.In a step 30, a motor torque change of the drive motor 10 is detected by means of a part 20 of a detection device 18 of the working machine. The change in engine torque may have been caused by an activation or deactivation of one of the secondary consumers 16 or else by a changed driver's wish. In a step 32, a change in the driving state of the working machine is detected by means of a part 22 of the detection device 18 of the working machine. The detection device 18 is designed to detect both a change in the output rotational speed of the driven axle 14 and a vehicle acceleration as part of the change in the driving state.In a step 34, a determination of a change in state of respective auxiliary consumers 16 is carried out as a function of the detected engine torque change and of the detected change in driving state by means of a determination device 24, which makes a decision as to whether a respective auxiliary consumer 16 has been switched on or switched off. The determination that a state of an auxiliary consumer 16 has been changed is carried out on a rule-based basis. Only if a detected engine torque change is greater than a first threshold value is it decided that a state of a respective secondary consumer 16 has been changed. The first threshold value corresponds to a torque request of that one of the secondary consumers 16 which has the lowest torque request from all secondary consumers 16. In addition, the detected change in engine torque must be longer than a second threshold value and thus a minimum duration. In addition, an oscillation of the change in the driving state must be below a significance threshold. The driving state change may not increase over a predetermined period of time. As a result, engine torque changes and driving state changes are filtered, which are very likely not to be attributed to a state change of respective secondary consumers 16, but, for example, to a driver's wish or external influences.If a change in state of respective secondary consumers 16 has been determined in step 34, in one embodiment, the one of secondary consumers 16 whose state has changed is identified on the basis of a comparison of the detected engine torque change with torque requests of the respective secondary consumers 16 stored in tabular form. On the basis of this information, starting from a current engine torque, the input torque at the transmission 12 is then estimated and the transmission control is based on it. For this purpose, in step 36, the changed engine torque request to the drive engine 10 is determined by the respective auxiliary consumers as a function of the determined state change of respective auxiliary consumers 16 by means of the determination device 24. The determination device 24 is part of a transmission control system which is designed to control the transmission 12 as a function of an engine torque and the determined changed engine torque request to the drive engine 10.Step 30 and step 32 can be performed with a time offset. This can take account of the fact that the detection of the engine torque change is subject to a greater delay than the detection of the driving state change. It can thus be achieved that the actually detected changes of engine torque and driving state correspond in each case in real time.Reference numerals denote reference numerals10 Drive motor 12 Transmission 14 Axle 16 Auxiliary consumer 18 Detection device 20 Part 22 Part 24 Determination device 30 Step of detecting an engine torque change 32 Step of detecting a driving state change 34 Step of determining a state change 36 Step of determining the changed engine torque request

Claims

Method for determining a change in an engine torque request to a drive motor (10) of a working machine on the basis of a change in state of respective secondary consumers (16), wherein the method has at least the following steps; - detecting (30) an engine torque change; - detecting (32) a change in driving state; - determining (34) a change in state of respective secondary consumers (16) on the basis of the detected engine torque change and on the basis of the detected change in driving state; and - determining (36) the changed engine torque request to the drive motor (10) by the respective secondary consumers on the basis of the determined change in state of respective secondary consumers (16).Method according to Claim 1, characterized in that the detection (32) of the change in the driving state comprises a detection of a change in the output rotational speed.Method according to Claim 1 or 2, characterized in that the detection (32) of the change in the driving state comprises a detection of a vehicle acceleration.Method according to one of the preceding claims, characterized in that a change in state of respective secondary consumers (16) is determined only if a detected change in engine torque is greater than a first threshold value.Method according to Claim 4, characterized in that the first threshold value corresponds to a torque request of an auxiliary consumer (16) of the working machine with a lowest torque request.Method according to one of the preceding claims, characterized in that a change in state of respective secondary consumers (16) is determined only if a detected change in engine torque is longer than a second threshold value.Method according to one of the preceding claims, characterized in that a change in state of respective secondary consumers (16) is determined only if oscillations of the change in driving state are below a significance threshold.Method according to one of the preceding claims, characterized in that a change in state of respective secondary consumers (16) is determined only if a detected change in driving state does not increase over a predetermined period of time.Method according to one of the preceding claims, characterized in that the determination (34) of the change in state of respective secondary consumers (16) comprises identifying that one of a multiplicity of secondary consumers (16) of the working machine whose state has changed.Method according to Claim 9, characterized in that the changed engine torque request to the drive engine (10) is determined (34) by the respective secondary consumers as a function of the identified secondary consumer (16) of the multiplicity of secondary consumers (16), the state of which has changed.Method according to one of the preceding claims, characterized in that the detection (32) of the change in the driving state takes place with a temporal offset before the detection (30) of the change in the engine torque.A working machine having a drive motor (10) and a drive transmission (12) and at least one auxiliary consumer (16), wherein the working machine further has a detection device (18) which is designed for detecting (30, 32) an engine torque change and a driving state change, a determination device (24) which is designed for determining (34) a state change of respective auxiliary consumers (16) as a function of the detected engine torque change and of the detected driving state change and for determining (36) a changed engine torque request to the drive motor (10) by the respective auxiliary consumers as a function of the determined state change of respective auxiliary consumers (16).Working machine according to Claim 12, characterized in that the working machine has a transmission controller which is designed to control the transmission (12) as a function of an engine torque and the determined changed engine torque request to the drive engine (10).

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