Method for operating drive device of work machine

Abstract

The invention relates to a method for operating a drive of a work machine. The drive has a conventional maximum traction profile in which the maximum permissible traction of the drive increases as the output rotational speed of the drive decreases. The method includes receiving an activation signal for activating a grader operation of the work machine, where the grader operation has a limited maximum traction profile. The maximum permissible traction force of the drive device is less intensively increased with a decrease in the output rotational speed of the drive device in the case of a limited maximum traction force curve than in the case of a conventional maximum traction force curve. In addition, the method includes determining a current maximum allowable traction based on the limited maximum traction profile and comparing the current traction with the current maximum allowable traction. In addition, the method comprises adjusting the transmission ratio of the transmission mechanism towards a lower output speed of the driving device based on the comparison.

Description

Technical Field

[0001] This invention relates to a method for operating a drive unit for a work machinery. The work machinery may be a grader. Furthermore, this invention relates to a control device configured to perform this method, a drive unit having such a control device, and a work machinery having such a drive unit. Background Technology

[0002] In the field of construction machinery, drive units with an engine and a power-split transmission mechanism are used. This power-split transmission mechanism can have a continuously variable transmission (CVT), allowing for stepless adjustment of the transmission ratio. In graders (also known as leveling machines), conventional transmission mechanisms with fixed transmission ratios in the corresponding gears are used, where the output speed and consequently the travel speed are fixedly related to the engine speed. When a load is applied to the grader, the operator receives feedback through a decrease in engine power and a deceleration of the vehicle. Summary of the Invention

[0003] This invention relates to a method for a drive mechanism for operating construction machinery. The construction machinery can be construction machinery, agricultural machinery, or forestry machinery. For example, the construction machinery is a grader, also known as a leveling machine. The grader may have a grader blade, which can be arranged between the front and rear axles of the grader. The grader blade can be rotatable, tiltable, and alternatively or additionally adjustable to approximately 90° on both sides, so as to also be able to process inclined surfaces. The drive mechanism has an engine and a power-split transmission mechanism. The engine can be an internal combustion engine and alternatively or additionally an electric motor. The power-split transmission mechanism can be a hydrostatic mechanical power-split transmission mechanism and alternatively or additionally an electromechanical power-split transmission mechanism. The power-split transmission mechanism can have a mechanical power branch and a hydrostatic branch, and alternatively or additionally an electrical power branch. The power-split transmission mechanism has a continuously variable transmission (CVT) so that the transmission ratio of the transmission mechanism can be continuously adjusted. The power-split transmission mechanism can be designed, for example, such that different fixed speed ratios can be switched between the drive end and the output end of the transmission mechanism through the mechanical power branch. Different speed ratios can constitute the speed range of the working machinery. Within these speed ranges, the transmission ratio can be continuously adjusted using a continuously variable transmission (CVT). A CVT can be designed as a hydrostatic transmission and have two hydraulic motors that are hydraulically connected to each other. Alternatively or additionally, a CVT can also have two electric motors that are electrically connected to each other.

[0004] The drive unit has a conventional maximum traction force curve, in which the maximum permissible traction force of the drive unit increases as the output speed of the drive unit decreases. Here, the output speed of the drive unit can be in a fixed relationship with the reciprocal of the transmission ratio of the power-split transmission mechanism and, alternatively or additionally, with the travel speed of the working machinery. Therefore, the conventional maximum permissible traction force curve can be formed such that the maximum permissible traction force increases as the travel speed decreases. The drive unit can have different maximum permissible traction force curves for different engine speeds, and these curves can be identical in their direction. However, different maximum permissible traction force curves can assign different maximum permissible traction forces to different output speeds of the drive unit. Here, the engine speed can, for example, be in the range of 1000 rpm to 2500 rpm. Here, the conventional maximum permissible traction force curves can be formed such that, in the lower travel speed range, they decrease moderately, for example linearly, as the travel speed increases, so as to subsequently decrease more drastically, for example exponentially.

[0005] The method includes receiving an activation signal for activating the grader operation of the work machinery. Here, the grader operation can be activated by the operator of the work machinery via a switch based on defined state parameters, or it can be activated automatically. The grader operation can be a process in which the ground should be leveled and therefore wheel slippage should be prevented. Here, the grader operation has a limited maximum traction curve, where, compared to a conventional maximum traction curve, the maximum permissible traction force of the drive unit does not increase as drastically as the output speed of the drive unit decreases. In other words, the grader operation is designed such that, compared to conventional operation, the traction force of the drive unit reaches a smaller value when the work machinery decelerates. Therefore, the risk of wheel slippage during grader operation can be reduced. Here, compared to a conventional traction curve, the limited maximum traction curve can result in lower traction force in a segmented manner or entirely.

[0006] Here, the restricted maximum traction curve can include a linear curve, a quadratic curve, an exponential curve, or other types of curves, as long as it has a smaller value than the conventional traction curve when the output speed of the drive unit decreases. The restricted maximum traction curve can be shaped such that it generally rises as the output speed of the drive unit decreases, yet a reduction in traction is permissible within a defined range. Enabling grader operation can be associated with various conditions, such as the operator of the work machinery explicitly activating grader operation. Alternatively or additionally, it may be necessary that the maximum speed of the work machinery set by the operator (e.g., via a predetermined virtual gear) is lower than a predetermined maximum speed, such as lower than a predetermined virtual gear. This ensures that grader operation is only activated at a suitable speed for grading and at the operator's explicit intention. In alternative embodiments, only one of these conditions may be required to activate grader operation. The drive unit can have different restricted maximum traction curves for different engine speeds, which can be formed as described above in conjunction with conventional maximum traction curves.

[0007] Furthermore, the method also includes determining the current maximum permissible traction force based on a restricted maximum traction force curve (e.g., a restricted maximum traction force curve belonging to the current engine speed). For this purpose, the current driving speed, the current gear ratio (e.g., the reciprocal of the current gear ratio), and alternatively or additionally, the current output speed at the output of the drive unit can be detected. The current maximum permissible traction force under these detected parameters can now be determined based on the restricted maximum traction force curve. Furthermore, the current traction force of the drive unit can be determined, for example, based on a sensor device in the continuously variable transmission (CVT) of the drive unit. This sensor device can, for example, determine pressure parameters in the CVT, which can be in a fixed and defined relationship with the traction force provided by the drive unit. In one embodiment, the current traction force is determined based on the pressure difference in the CVT.

[0008] Furthermore, the method includes comparing the current traction force with the current maximum permissible traction force. If the current traction force exceeds the current maximum permissible traction force (based on a limited maximum traction force curve already known), the method adjusts the transmission ratio towards a lower output speed of the drive unit. For example, a continuously variable transmission (CVT) with a power-split transmission can be adjusted to reduce the inverse of the transmission ratio, i.e., increase the transmission ratio. By adjusting the transmission ratio towards a lower output speed and thus a lower travel speed, the work machinery is slowed down. Thus, if the work machinery is, for example, in the process of leveling and the load acting on the work machinery is increasing, the traction force can be increased to the current maximum permissible level. Subsequently, the transmission is adjusted such that the vehicle is slowed down accordingly until the applied load no longer exceeds the maximum permissible traction force at its respective point in time. By limiting the traction force based on the limited maximum traction force curve, even in a power-split transmission with a CVT, a moderate increase in traction force can be provided when the output speed at the output end of the drive unit decreases. Therefore, wheel slippage of the work machinery can be effectively prevented, resulting in improved processing results and more comfortable machine operation.

[0009] In one embodiment, the method includes determining the maximum speed of the operating machinery. The maximum speed can be predetermined, for example, by the operator of the operating machinery, who sets the operating speed. In one embodiment, the maximum speed can be achieved by setting a so-called virtual gear, which can correspond to the determined maximum speed. Furthermore, the method can include reading in a permissible traction increase and, alternatively or additionally, reading in a traction gradient. The permissible traction increase can be an absolute value, allowing the torque to increase to the maximum absolute value during grader operation as the operating machinery decelerates to a stop. The traction gradient can be the slope of the traction increase as the operating machinery decelerates. Within the scope of this embodiment, the method also includes defining a restricted maximum traction curve based on the known maximum speed and the read-in permissible traction increase and, alternatively or additionally, the read-in traction gradient. Here, if a traction gradient is predetermined, it is advantageous that the operator always obtains the same torque increase with the same speed loss, regardless of the selected gear. Therefore, within the scope of this embodiment, the shape of the restricted maximum traction curve can be personalized and adjusted by the operator as needed.

[0010] For example, the traction support point can be determined based on the known maximum speed and a conventional maximum traction curve. In one embodiment, the traction support point is determined based on the conventional maximum traction curve as follows: the maximum traction value corresponding to the known maximum speed is read from the curve. Furthermore, the slope of the restricted maximum traction curve is determined based on the read-in allowable traction increase and / or traction gradient. If a traction gradient is read, the slope of the restricted maximum traction curve is independent of the known maximum speed and the traction support point. However, if the maximum allowable traction increase is read, the slope of the traction curve can depend on the known maximum speed and therefore on the determined traction support point. For example, the slope at a larger maximum speed may be smaller than the slope at a smaller maximum speed. Within the scope of this embodiment, the traction straight line can now also be determined based on the traction support point and the traction slope. In this embodiment, the traction straight line can pass through the traction support point and rise with the determined traction slope as the output speed decreases and thus the travel speed decreases until it stops. Here, the permissible traction increase and the alternative or additional traction gradient can be given not only as an absolute value but also as a percentage value.

[0011] In one embodiment, the method includes knowing the maximum speed of the working machinery, which can be achieved according to the embodiment described above. Furthermore, the method includes selecting a limited maximum traction force curve from a plurality of stored limited maximum traction force curves based on the known maximum speed. Thus, within the scope of this embodiment, different limited maximum traction force curves can be stored for different grader gears and therefore for different travel speeds of the working machinery when grading. Additionally, different limited maximum traction force curves can also be stored for different engine speeds in different grader gears, as described above. The stored limited maximum traction force curves can all have a shape that shows an upward trend as the output speed of the drive unit decreases and therefore as the travel speed decreases. Within the scope of this embodiment, one of the stored limited maximum traction force curves can now be selected based on the known maximum speed. The advantage of this embodiment is that, during grader operation, traction can be automatically and as needed limited to an acceptable level without further operator intervention. This reduces the risk of misoperation and thus improves reliability.

[0012] Within one embodiment, the method includes determining the current maximum permissible engine speed based on a limited maximum speed curve of the engine. Here, the limited maximum speed curve exhibits a decreasing trend as the output speed of the drive unit decreases, and therefore as the travel speed decreases. The method of this embodiment includes comparing the current engine speed with the current maximum permissible engine speed. If the current engine speed exceeds the current maximum permissible engine speed, the engine speed is reduced within the scope of this embodiment. If the work machinery is operating as a grader and a load is applied to the work machinery, the drive unit's transmission mechanism can be adjusted towards a lower output speed, as described above. This can result in deceleration of the work machinery. If such deceleration of the work machinery occurs, the maximum permissible engine speed can be reduced within the scope of this embodiment, which can lead to a decrease in engine speed. Through this simulated decrease in engine power, the operator of the work machinery receives feedback regarding the load increase, allowing the operator to react accordingly, for example, by adjusting the grader blade. As a result, within the scope of this embodiment, improved operation of the grader with a power-split transmission mechanism can be achieved through load feedback regarding the decrease in engine power.

[0013] Within the scope of one embodiment, the method includes determining the maximum engine speed. Here, the maximum engine speed can be determined based on the known maximum speed of the working machinery. Furthermore, within the scope of this embodiment, the method may include reading in a permissible decrease in engine speed and alternatively, additionally, reading in an engine speed gradient. Additionally, the method of this embodiment may include defining a restricted maximum speed curve based on the maximum engine speed and the read-in permissible decrease in engine speed and / or engine speed gradient. Within the scope of this embodiment, for example, an engine speed straight line can be determined, which starts from the maximum engine speed and then decreases at a constant slope as the output speed of the drive unit decreases until the working machinery stops. Here, the slope (the rate at which the engine speed straight line decreases) may depend on the read-in permissible decrease in engine speed and / or engine speed gradient.

[0014] Simultaneously, within the scope of this implementation scheme, adherence to the minimum engine speed can be ensured. If, for example, a linear increase in engine speed results in an engine speed lower than this minimum engine speed, then within the scope of this implementation scheme, the minimum engine speed can be predetermined as the maximum permissible engine speed. Therefore, within the scope of this implementation scheme, the operator of the working machinery can set the engine power reduction as needed by presetting the maximum permissible engine speed reduction and / or engine speed gradient. Here, presetting the engine gradient has the advantage that, as long as the engine speed is higher than the minimum engine speed, the operator will always obtain the same engine speed reduction with the same speed loss, regardless of the selected gear. Here, the permissible engine speed reduction and engine speed gradient can be input not only as absolute values ​​but also as percentage values.

[0015] Within the scope of one implementation, the method includes knowing an engine speed limit class, also known as an Engine Speed ​​Limitation Class. Different limited maximum engine speed profiles can be stored for different maximum speeds, such as the different virtual gears described above. Similarly, different limited maximum engine speed profiles can also be stored for a single virtual gear. Here, the different limited maximum engine speed profiles for a single virtual gear can differ from each other at higher driving speeds (i.e., at higher output speeds of the drive unit), but decrease to the same maximum engine speed at lower output speeds. In an alternative implementation, the different limited maximum engine speed profiles for a single gear decrease to different maximum engine speed levels, so that they can differ from each other even at very low driving speeds. Here, the limited maximum engine speed profiles can be configured such that they maintain a constant maximum engine speed at lower driving speeds, for example, at approximately 25% of the known maximum speed.

[0016] A maximum speed curve can now be selected from multiple restricted maximum speed curves of the engine based on the known engine speed limit level. If, for example, a higher engine speed limit level is known, a maximum speed curve that allows for a higher maximum speed at higher travel speeds can also be selected. Correspondingly, in the case of a lower engine speed limit level, a maximum speed curve that allows for a lower maximum engine speed at higher travel speeds can be selected. The engine speed limit level can be set by the operator of the work equipment. Alternatively or additionally, the engine speed limit level can also be automatically set based on determined parameters. This embodiment has the advantage that the restricted maximum speed curve can be selected automatically and as needed without being set by the operator of the work equipment. This allows for a reliable and stable range of operation for the work equipment.

[0017] Furthermore, the present invention relates to a control device configured (i.e., specifically configured for), for example, programmed for, executing a method according to one of the previously described embodiments. The control device may have one or more interfaces for communicating with respective components of a drive unit, the interfaces being designed as input and / or output interfaces respectively. The control device may be a transmission control device, designed for controlling a transmission mechanism and optionally additionally for controlling an engine. Furthermore, the present invention relates to a drive unit having an engine and a power-split transmission mechanism equipped with a continuously variable transmission (CVT) for continuously adjusting the transmission ratio of the transmission mechanism. The drive unit also has a control device according to the previously described embodiment for controlling the engine and the power-split transmission mechanism. Furthermore, the present invention relates to a working machine having such a drive unit. Regarding the embodiments and advantages of the various components, reference is made to the above embodiments in conjunction with the method of the present invention. Attached Figure Description

[0018] Figure 1 The illustration schematically depicts a working machine according to one implementation scheme.

[0019] Figure 2 Schematic illustration based on Figure 1 The drive unit of the operating machinery.

[0020] Figure 3 This schematically illustrates a method for operation according to one implementation scheme. Figure 2 A flowchart of a method for driving a device.

[0021] Figure 4a and Figure 4b This illustrates the operation of a grader according to one implementation scheme. Figure 2 The traction force curve and engine speed curve of the drive unit.

[0022] Figure 5a and Figure 5b This illustrates the operation of a grader according to another embodiment. Figure 2 The traction force curve and engine speed curve of the drive unit. Detailed Implementation

[0023] Figure 1 A work machine 100 with a drive unit 1 according to one embodiment of the present invention is shown. In this embodiment, the work machine 100 is a grader. The work machine 100 includes a plurality of wheels (not shown) that are driven by the drive unit 1. In addition, the work machine 100 includes a grader shovel (not shown) arranged here between the front and rear axles of the grader. Figure 2The structure of the drive unit 1 is schematically shown. The drive unit 1 includes an engine 2, which in this embodiment is designed as an internal combustion engine. Furthermore, the drive unit 1 includes a power-split transmission mechanism 3, which has a mechanical power path 4 and a hydraulic power path with a continuously variable transmission 5. The power-split transmission mechanism 3 has a drive end 6 and an output end 7. The drive end 6 is mechanically connected to the engine 2. The output end 7 of the power-split transmission mechanism 3 is mechanically connected to a wheel (not shown) of the working machine 100. Here, the output speed of the drive unit 1 at the output end 7 is in a fixed and defined relationship with the wheel speed and, consequently, with the travel speed v of the working machine 100.

[0024] Different fixed speed ratios and thus different speed ranges can be switched between the drive end 6 and the output end 7 of the power-splitting transmission mechanism 3 via the mechanical power path 4 (which has multiple shifting elements not shown in this embodiment). Within these speed ranges, the transmission ratio can be steplessly adjusted by the continuously variable transmission 5. In this embodiment, the continuously variable transmission 5 is designed as a hydrostatic transmission with two hydraulic units hydraulically connected to each other. By adjusting the flow rate of the continuously variable transmission 5, the transmission ratio of the hydraulic power path and thus the transmission ratio of the transmission mechanism 3 can be steplessly adjusted.

[0025] Furthermore, the drive unit 1 includes a control device 8 for controlling the drive unit 1, which in this embodiment is designed as a transmission mechanism control device. The control device 8 includes an engine interface 9 for operating the engine 2. Additionally, the control device 8 includes a transmission mechanism interface 10 for operating the power-split transmission mechanism 3, particularly for switching the speed range of the mechanical power branch 4 and for adjusting the hydraulic power branch of the transmission mechanism 3. Here, different measurement parameters of the power-split transmission mechanism 3 can also be read through the transmission mechanism interface 10. Therefore, the continuously variable transmission 5, designed as a hydrostatic transmission, has a sensor device through which pressure parameters in the continuously variable transmission 5 can be read. In this embodiment, the pressure parameters are in a fixed relationship with the torque at the output end 7 and thus with the traction force Z of the drive unit 1.

[0026] The control device 8 stores a conventional maximum traction force curve hZ, which allocates different maximum permissible traction forces Z to the drive unit 1 based on the travel speed v of the working machinery 100. The conventional maximum traction force curve hZ... Figure 4a and 5a As shown in the diagram. As described above, the driving speed v and the output speed at output terminal 7 are in a fixed relationship. In this embodiment, the output speed at output terminal 7 is also in a fixed relationship with the reciprocal of the transmission ratio of the power split transmission mechanism 3. Figure 4a and5a As shown, the conventional maximum traction force curve hZ is formed such that the maximum permissible traction force Z decreases with increasing travel speed v (i.e., with increasing output speed at output terminal 7). For smaller travel speeds v, the maximum permissible traction force Z is initially approximately constant, and then decreases approximately exponentially with increasing travel speed v. In this embodiment, the drive unit 1 has different maximum permissible traction force curves hZ for different engine speeds of the engine 2, wherein, at... Figure 4a and 5a Only one maximum permissible traction force curve hZ is shown. Different maximum permissible traction force curves hZ differ from one another, but they all generally possess the following characteristics. Figure 4a and 5a The direction shown is as indicated.

[0027] If the work machinery 100 moves at a defined travel speed v and builds a load, the drive unit 1 increases the traction force Z and attempts to maintain a constant travel speed v. If the traction force Z reaches the maximum permissible traction force hZ at the current travel speed v, the control unit 8 adjusts the power split transmission mechanism 3 to a smaller reciprocal of the transmission ratio, thereby slowing down the work machinery 100. This process is repeated until the applied load no longer exceeds the maximum permissible traction force hZ at its respective travel speed v and its respective engine speed n.

[0028] Control device 8 is configured to perform the following reference Figure 3 The method described. In the first step I, the control device 8 learns the maximum speed vmax1 or vmax2 of the operating machinery 100. The maximum speed vmax1 or vmax2 can be input by the operator of the operating machinery 100, specifically, the operator pre-sets the operating speed, for example, through a virtual gear limit. Figure 4a and 4b Two examples of the known maximum speeds vmax1 and vmax2 are shown in the diagram. The operator of the working machine 100 can input the maximum speed vmax1 or vmax2 through the corresponding shift element.

[0029] In subsequent step II, control device 8 now receives an activation signal for initiating grader operation of grader 100. In this embodiment, control device 8 receives the activation signal when the virtual gear predetermined by the driver, and consequently the maximum speed vmax1 or vmax2 of the working machine 100 predetermined by the driver, is less than or equal to the maximum permissible virtual gear for grader operation. Therefore, in this embodiment, control device 8 compares the virtual gear selected by the driver with the maximum permissible virtual gear for grader operation in step II. If this condition is met and the driver of the working machine 100 additionally inputs a command to initiate grader operation of grader 100, for example, via a switch, control device 8 receives the activation signal for initiating grader operation.

[0030] exist Figure 4a In the illustrated embodiment, the control device 8 then reads the permissible traction force increase ΔZ or traction force gradient in subsequent step III.1, which is correspondingly input by the operator of the work machinery 100. Subsequently, in subsequent step III.2, a restricted traction force curve lZ is defined based on the maximum speed vmax1 or vmax2 obtained in step I and the permissible traction force increase ΔZ or traction force gradient read in step III.1. Within the scope of step III.2, the traction force support point ZP1 or ZP2 is first determined based on the known maximum speed vmax1 or vmax2 and the conventional maximum traction force curve hZ. More specifically, the traction force support point ZP1 or ZP2 is determined as follows: the maximum permissible traction force Z at the maximum speed vmax1 or vmax2 is determined according to the conventional maximum traction force curve hZ. Subsequently, the traction force slope is determined based on the permissible traction force increase ΔZ or the read traction force gradient obtained in step III.1. Next, we will use the traction slope to determine the traction line lZ1 or lZ2 that passes through the traction support point ZP1 or ZP2.

[0031] If the driver of the work machinery 100 has predetermined a permissible traction increase ΔZ in step III.1, a restricted maximum traction line lZ1 is obtained, the slope of which depends on the known maximum speed vmax1 or vmax2. At a smaller maximum speed vmax1, the traction line lZ1 has a larger slope in absolute value compared to the larger maximum speed vmax2. If the driver inputs a traction gradient, a traction line lZ2 with the same slope is obtained; however, they also have different traction increases with respect to the travel speed range of the work machinery 100. All these restricted maximum traction curves lZ1 and lZ2 have in common that they extend through their respective traction support point ZP and their increase is less pronounced than that of the conventional maximum traction curve hZ as the travel speed v decreases, i.e., as the output speed at the output end 7 decreases.

[0032] exist Figure 5a In one alternative embodiment shown, the control device 8 stores different limited maximum traction force curves lZ for different grader gears. G Therefore, in this embodiment, the control device 8 stores a limited maximum traction force curve lZ for the first grader gear. G1 The limited maximum traction force curve lZ for the second gear of the grader G2 The limited maximum traction force curve lZ for the third gear of the grader G3 The limited maximum traction force curve lZ for the fourth gear of the grader G4 And the limited maximum traction curve lZ for the fifth grader gear G5 Used for different grader gears (except for the first grader gear lZ). G1 All of these fixedly stored maximum traction force curves (lZ) on the control device 8 (external) G All exhibit the following trend, in which the increase in maximum permissible traction force Z with decreasing speed v and consequently with decreasing output speed at the output terminal 7 of drive unit 1 is less pronounced compared to the conventional maximum traction force curve hZ. Here, the limited maximum traction force curve lZ... G The traction increase when moving towards a lower speed range v is initially moderate and then strong, in order to avoid the vehicle coming to a stop within the so-called stall point range. In an alternative embodiment, the limited maximum permissible traction can also initially increase moderately towards a lower travel speed v and then decrease moderately.

[0033] Regardless of Figure 4a The implementation scheme shown is still in Figure 5aIn the illustrated embodiment, the control device 8 stores different limited maximum traction force curves lZ1, lZ2, and lZ for different engine speeds of the engine 2. G These different limited maximum traction force curves lZ1, lZ2, and lZ G They have roughly corresponding directions, however they differ slightly from each other in terms of their permissible traction force Z.

[0034] exist Figure 4a and 4b In the illustrated embodiment, in step IV.1, the maximum engine speed nmax1 or nmax2 is determined for the maximum speed vmax1 or vmax2 obtained in step I. Furthermore, in step IV.2, the allowable engine speed decrease Δn or engine speed gradient is read in by the control device 8, which is correspondingly predetermined by the operator of the work machinery 100. Based on the maximum engine speed nmax1 or nmax2 determined in step IV.1 and the allowable engine speed decrease Δn or engine speed gradient read in step IV.2, a restricted maximum speed curve ln for the engine 2 is defined in step IV.3. According to... Figure 4a In the implementation scheme, the limited maximum speed curve ln is defined as follows: a straight line is established through the maximum permissible engine speed nmax1 or nmax2, and its slope is determined based on the permissible engine speed decrease Δn or engine speed gradient read in step IV.2. All these permissible maximum speed curves ln share the common feature that they continuously decrease from the maximum speed nmax1 or nmax2 as the driving speed v decreases and then as the output speed at output terminal 7 decreases, as... Figure 4b As shown.

[0035] If the driver predetermines a permissible engine speed decrease Δn, then a restricted maximum speed curve ln1 with different slopes for engine 2 is obtained based on the maximum speed vmax1 or vmax2 obtained in step I. Here, compared to when the known maximum speed vmax2 is larger, the restricted maximum speed curve ln1 has a larger slope in absolute value at the known smaller maximum speed vmax1. If an engine speed gradient is predetermined, the restricted maximum speed curve ln2 for engine 2 has the same slope, but with different engine speed decreases within the travel speed range of the working machinery 100.

[0036] And in Figure 5a and 5b In the embodiment shown, the control device 8 stores different limited maximum speed curves ln of the engine 2 for different grader gears. G3 and ln G4All these curves ln G What they have in common is that they also decrease as the driving speed v decreases, and thus as the output speed of output terminal 7 decreases, such as... Figure 5b As shown. Here, multiple limited maximum speed curves ln are stored for each grader gear. G Different limited maximum speed curves ln G It can be reduced to the same engine speed n, such as ln G4 As shown in the example, or it can be reduced to different engine speeds n, such as ln. G3 As shown in the example. In one embodiment, the limited maximum speed curve of engine 2 is formed such that it maintains engine speed n at approximately 25% below the maximum driving speed v of the selected gear and does not decrease further. In an alternative embodiment, the limited maximum speed curve of engine 2 is ln G It can also be constructed as follows, that is, it rises towards a smaller travel speed v, such as... Figure 5b As shown by the dashed line in the image.

[0037] exist Figure 5a and 5b In the illustrated implementation, control device 8 first learns the engine speed limit level in subsequent step IV.4, which can be set by the driver or automatically by control device 8. Subsequently, in subsequent step IV.5, control device 8 retrieves the engine speed from multiple limited maximum speed curves stored in control device 8 at the respective grader gears. G A restricted maximum speed curve is selected. Compared to the case with a lower engine speed limit level, when the engine speed limit level is set higher, the restricted maximum speed curve ln of engine 2 with a higher maximum permissible engine speed n is selected. G .

[0038] In subsequent step V, the current traction force Z of the drive unit 1 is now known by the control device 8. For this purpose, the aforementioned sensor device in the continuously variable transmission 5 is utilized in this embodiment. Furthermore, in step V, the limited maximum traction force curves lZ1, lZ2, or lZ... G To determine the current maximum permissible traction force Z. In subsequent step VI, the current traction force Z is now compared with the current maximum permissible traction force Z. If the current traction force Z exceeds the maximum permissible traction force Z (which is based on the limited maximum traction force curves lZ1, lZ2, or lZ), then... G(As already known), the control device 8 then adjusts the transmission ratio of the power-split transmission mechanism 3 in step VII. Here, the transmission ratio is adjusted towards a smaller output speed at the output end 7 of the drive device 1. For example, within the scope of this embodiment, the continuously variable transmission 5 of the power-split transmission mechanism 3 is adjusted for this purpose. This results in a reduction in the speed of the working machine 100 and thus a smaller travel speed v.

[0039] In step VIII, control device 8 now bases its operation on the previously determined limited maximum speed curves ln1, ln2, or ln... G To determine the current maximum permissible engine speed n. Furthermore, in this step, control device 8 determines the current engine speed n. In subsequent step IX, control device 8 compares the current engine speed n with the current maximum permissible engine speed (which is based on the limited maximum speed curve ln1, ln2, or ln...). G (As determined) a comparison is made. If the current engine speed n exceeds the maximum permissible engine speed, the control device 8 reduces the engine speed n via the engine interface 9 in subsequent step X. The method then returns to step V.

[0040] List of reference numerals

[0041] 100 Operating Machinery

[0042] 1. Drive unit

[0043] 2 Engines

[0044] 3. Power split transmission mechanism

[0045] 4. Mechanical Power Path

[0046] 5. Continuously Variable Transmission (CVT)

[0047] 6. Driver end

[0048] 7 Output terminal

[0049] 8. Control device

[0050] 9. Engine Interface

[0051] 10. Transmission mechanism interface

[0052] I know the maximum speed

[0053] II. Receive enable signal

[0054] III.1 Read in the permissible traction increase and / or traction gradient

[0055] III.2 Limiting Maximum Traction Force Curve

[0056] III.3 Select one traction curve from multiple stored traction curves

[0057] IV.1 Determine the maximum engine speed

[0058] IV.2 Read in the allowed engine speed drop and / or engine speed gradient

[0059] IV.3 Limiting Maximum Speed ​​Curve

[0060] IV.4 Obtain the engine speed limit level

[0061] IV.5 Select one maximum speed curve from multiple stored maximum speed curves.

[0062] V obtains the current maximum permissible traction force.

[0063] VI. Compare the current traction force with the current maximum permissible traction force.

[0064] VII. Adjusting the transmission ratio of the transmission mechanism

[0065] VIII. Obtain the current maximum permissible engine speed.

[0066] IX compares the current engine speed with the current maximum permissible engine speed.

[0067] X Reduce engine speed

[0068] Z traction force

[0069] v Driving speed

[0070] n Engine speed

[0071] lZ1, lZ2, lZ G Limited maximum traction curve

[0072] hZ Typical maximum traction curve

[0073] ZP1, ZP2 traction support points

[0074] maximum speeds of vmax1 and vmax2

[0075] ΔZ is the allowable decrease in traction force.

[0076] Δn is the allowable decrease in engine speed.

[0077] nmax1 and nmax2 are the maximum permissible engine speeds.

[0078] ln1, ln2, ln G Limited maximum speed curve

Claims

1. Method for operating a drive arrangement (1) of a work machine (100), wherein The drive device (1) has an engine (2) and a power-split transmission (3) having a continuously variable transmission (5) for continuously adjusting the transmission ratio of the transmission (3), wherein the drive device (1) has a regular maximum tractive force curve (hZ) in which the maximum permissible tractive force (Z) of the drive device (1) increases with a reduction of the output rotational speed of the drive device (1), the method comprising: receiving (II) an activation signal for activating a motor grader operation of the working machine (100), wherein the motor grader operation has a limited maximum tractive force curve (IZ1; IZ2; IZ G ) in which the maximum permissible tractive force (Z) of the drive device (1) does not increase as strongly with a reduction of the output rotational speed of the drive device (1) as in the case of the regular maximum tractive force curve (hZ); ascertaining (V) a current maximum permissible tractive force (Z) on the basis of the limited maximum tractive force curve (IZ1; IZ2; IZ G ); comparing (VI) the current tractive force (Z) with the current maximum permissible tractive force (Z); adjusting (VII) the transmission ratio of the transmission (3) towards a lower output rotational speed of the drive device (1) on the basis of the comparison.

2. The method of claim 1, wherein, The method comprises: ascertaining (I) a maximum speed (vmax1; vmax2) of the working machine (100); reading in (III.1) an allowed traction force rise (ΔZ) and / or a traction force gradient; defining (III.2) the limited maximum traction force curve (IZ1; IZ2) on the basis of the ascertained maximum speed (vmax1; vmax2) and the read-in allowed traction force rise (ΔZ) and / or traction force gradient.

3. The method of claim 2, wherein, Defining (III.2) the limited maximum traction force curve (IZ1; IZ2) comprises: determining a traction force support point (ZP1; ZP2) on the basis of the ascertained maximum speed (vmax1; vmax2) and the regular maximum traction force curve (hZ); determining a traction force slope on the basis of the read-in allowed traction force rise (ΔZ) and / or traction force gradient; and determining a traction force straight line through the traction force support point (ZP1; ZP2) using the traction force slope.

4. The method of claim 1, wherein, The method comprises: learning (I) a maximum speed (vmax1; vmax2) of the working machine (100) and selecting (III.3) one limited maximum traction force curve (IZ G ) from a plurality of stored limited maximum traction force curves (IZ G ) on the basis of the learned maximum speed (vmax1; vmax2).

5. The method according to any of the preceding claims, characterized in that, The method includes: based on the limited maximum speed curve (ln1; ln2; ln...) of the engine (2) G (VIII) The current maximum permissible engine speed (n) is known, and the restricted maximum speed curve has a downward trend as the output speed of the drive unit (1) decreases; the current engine speed (n) is compared with the known current maximum permissible engine speed (n) (IX); and the engine speed (n) is reduced (X) based on the comparison.

6. The method of claim 5, wherein, The method comprises: setting out (IV.1) a maximum engine speed (nmax1; nmax2) of the engine (2); reading in (IV.2) an allowed engine speed drop (Δn) and / or an engine speed gradient; and defining (IV.3) the limited maximum speed curve (In1; In2) on the basis of the maximum engine speed (nmax1; nmax2) and the read-in allowed engine speed drop (Δn) and / or engine speed gradient.

7. The method of claim 5, wherein, The method comprises: ascertaining (IV.4) an engine speed limitation class; and selecting (IV.5) a limited maximum speed curve (ln G ) for the engine (2) from a plurality of stored limited maximum speed curves (ln G ) on the basis of the ascertained engine speed limitation class.

8. Control device (8) which is set up to carry out the method according to any one of the preceding claims.

9. Drive device (1) which has an engine (2), a power-split transmission (3) with a continuously variable transmission (5) for continuously adjusting the transmission ratio of the transmission (3), and a control device (8) according to claim 8 for controlling the engine (2) and the power-split transmission (3).

10. Working machine (100) which has a drive device (1) according to claim 9.

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