Method and device for the transmission control of a working machine

Abstract

Method for controlling the transmission of a working machine (1), wherein at least one specific parameter is provided by at least one sensor (8) of the working machine (1) and supplied to a control unit for transmission control, and wherein the working machine (1) has a lifting mechanism (2) and the at least one specific parameter characterizes an actuation state of the lifting mechanism (2), wherein a predetermined switching strategy is adapted depending on the at least one specific parameter, characterized in that an adaptation of a switching dynamic of a transmission change takes place.

Description

[0001] The present invention relates to a method and a device for controlling a transmission in the drive train of a machine. Machines typically have attachments or other hydraulic systems that require power from a drive element. Thus, the drive element (electric motor, internal combustion engine) of the machine not only provides sufficient power for the driving function, but must also ensure the power supply for the attachments / hydraulics. Simultaneously, it must be ensured in every operating state that an optimal transmission ratio is provided by the drive element, particularly through a transmission. In particular, overloading of the drive element must be prevented during operation of the hydraulics and the driving function.

[0002] The attachments can be powered by a hydraulic system or electrically by a motor / generator unit, in which case the generator is driven by the hydraulic system or directly by the drive element. Specifically, in the case of a wheel loader, the attachment might be the lifting mechanism with a bucket, while in the case of a forklift, it could be, for example, a lifting mast with corresponding attachments (forks).

[0003] German patent application DE 10 2016 224 076 A1 discloses a method for determining the position of an excavator arm using a LiDAR system. The position data can be used to record the excavator arm's movements. Furthermore, the LiDAR system can be used to detect the excavator's surroundings, enabling semi- or fully automated control of the excavator arm.

[0004] Furthermore, DE 10 2015 115 704 A1 discloses an agricultural machine with a sensor system and an evaluation unit arranged thereon, wherein the position of an implement relative to the body of the machine can be determined by the sensor system. The sensor system can detect an elongated measuring range. This has the advantage that the front loader can be reliably detected by the sensor units regardless of the exact vertical arrangement of, for example, its arms, since their measuring ranges cover a vertical strip. Furthermore, a steering system connected to the sensor system is provided, by which the machine can be automatically steered and / or driven based on the distances determined by the sensor system when the implement is picked up and / or detached.

[0005] US Patent 10,041,229 B2 discloses a system for controlling a machine, such as a wheel loader. The system comprises an image acquisition device and a controller, the controller communicating with the image acquisition device. The controller detects the wheel loader's work cycles, which include scooping material with a bucket and emptying the bucket. The controller also identifies a stockpile in the vicinity of the machine and the distance between the wheel loader and the stockpile. The controller issues a shift request to downshift a transmission system of the wheel loader when the distance falls below a predefined value and the bucket was emptied in the previous work cycle.

[0006] DE 11 2013 005 124 T5 discloses a machine drive train with a gearbox and a control device. This control device selectively varies the gear ratio of a gearbox depending on a corresponding switching signal. A control device monitors stroke and travel speed signals, compares them with predetermined values, and initiates a gear ratio change if a current value is within a defined range, specifically by downshifting.

[0007] US 2017 / 0073923A1 discloses a work vehicle that is trained to determine the height of a work tool as a control threshold for a ride comfort device or an automatic transmission control device.

[0008] A driving control device for a forklift truck is known from US patent 2007 / 0080025A1. Based on a load condition, it determines whether the maximum vehicle speed as well as the acceleration or deceleration during the forklift's journey should be limited.

[0009] The object of the present invention is to provide an improved method for the transmission control of a working machine. In particular, it aims to increase comfort during the operation of the working machine and to avoid wear and unsafe operating conditions.

[0010] To solve the problem, a method according to claim 1 is proposed, wherein at least one specific parameter is provided by at least one sensor of the working machine and supplied to a control unit for transmission control. The working machine has a lifting mechanism, wherein the at least one specific parameter characterizes an actuation state of the lifting mechanism. Depending on the at least one specific parameter, a predetermined shifting strategy of the transmission is adapted.

[0011] The at least one sensor can be a displacement, angle, acceleration, position, height, or pressure sensor, as well as a suitable radar, lidar, or other imaging sensor (for example, a camera). Suitable load sensors are also conceivable, particularly for detecting the load on the lifting equipment. The at least one sensor is mounted on the machine. This includes, in particular, mounting in and / or on the lifting mechanism. However, the at least one sensor can also be mounted in and / or on the working hydraulics. When using a radar, lidar, or imaging sensor, mounting in and / or on the machine is suitable, especially on the machine's cab.

[0012] An operating state can refer, for example, to whether the lifting mechanism is in a retracted or extended position, a load state (partially loaded, loaded, empty), or information about whether a change in the operating state is expected. Such a change in the operating state can be detected, for example, by a change in the value of at least one specific parameter. In addition to the at least one specific parameter for characterizing the operating state, other parameters can also be considered, in particular those that describe the vehicle dynamics parameters of the machine (for example, speed, cornering, speed changes, navigation instructions, condition / performance parameters of the drive element and / or the transmission) or environmental parameters (temperature, road surface condition, humidity).

[0013] In combination with at least one of these additional parameters, particularly accurate estimates of expected changes in operating state can be made. For example, if a load is detected on the hoist, a lifting mast is retracted, and the machine's travel speed is reduced, this could indicate an impending unloading operation.

[0014] The control unit to which at least one specific parameter is supplied can be, in particular, a transmission control unit. Alternatively, it can be a higher-level vehicle control unit of the work machine, a so-called vehicle control computer. The control unit can be located centrally on the transmission or decentrally at another location on the work machine.

[0015] A lifting device is, for example, a boom or mast to which suitable lifting attachments are mounted for picking up a load. These can be forks (especially on a forklift or telehandler) or buckets (especially on a wheel loader). Other lifting attachments are also included, particularly those suitable for picking up individual items or bulk goods.

[0016] With regard to the method according to the invention, a shift strategy is understood to be a predefined logic for setting a transmission ratio of the transmission of the working machine. The transmission can be a powershift transmission, a dual-clutch transmission, a continuously variable transmission (CVT), or a power-split transmission (mechanical, hydraulic, mechanical / hydraulic, electric / hydraulic). Accordingly, a transmission ratio is understood to be either a specific transmission gear, a driving range, or, more generally, a ratio between a transmission input and a transmission output (especially in the case of continuously variable and / or power-split transmissions). Accordingly, taking into account a driving requirement and the operating state of the attachment or the lifting mechanism, an optimal transmission ratio is set.Changing requirements may therefore necessitate an adjustment of the translation ratio.

[0017] In addition to the other parameters, the invention allows at least one specific parameter to be considered alone or in combination with the other parameters. This sometimes results in a switching strategy that deviates from the intended switching strategy being implemented due to the at least one specific parameter. In other words, a different gear ratio can be set, or a gear ratio change can be suppressed. Besides a gear ratio change, it can also be provided that, depending on the at least one specific parameter, the drive train is opened (for example, by opening one or more clutches), or in other cases, the opening of clutches is suppressed.

[0018] On the one hand, preventing a change in gear ratio can contribute to increased comfort; on the other hand, a predetermined shifting strategy can also be adjusted if, based on knowledge of at least one specific parameter, a critical condition of the machine is to be expected. This would be the case, for example, if the lifting mechanism is in an extended position, which increases the machine's tendency to tip over. A downshift could therefore lead to a sudden reduction in speed, with such an impulse increasing the tendency to tip over. An upshift could also promote a tendency to tip over, as it sometimes involves a change in the acceleration of the forward motion.In this context, a downshift refers to a change to a lower gear or a shift to a higher gear ratio, while an upshift describes a change to a higher gear or a shift to a lower gear ratio. This is particularly relevant when a significant change in the gear ratio is involved, such as downshifting several gears.

[0019] In a further training course, the shift strategy is adapted by adjusting the shift dynamics rather than directly influencing the gear ratio itself. This means, for example, that a less pronounced gear ratio change is implemented. The execution of the gear ratio change can also be adjusted. For instance, the duration of a gear change, as well as the opening and / or closing behavior of the clutches, can be modified.

[0020] Instead of adjusting the switching dynamics, a planned gear ratio change can also be suppressed. This means that, depending on the actuation state / position of the lifting mechanism, a gear ratio change may be completely suppressed or delayed. For example, switching points or switching times can be represented by a different characteristic curve than would be intended for a different actuation state / position of the lifting mechanism. However, instead of a delayed gear ratio change, it is also conceivable to bring forward a planned gear ratio change in other situations, i.e., to implement it at an earlier time.This could, for example, be designed in such a way that a change in translation occurs earlier if, due to an actuation request, the lifting mechanism is to be moved into an extended position, or if such a change in actuation state can be inferred from a change in the value of at least one specific parameter.

[0021] The operating state of the lifting mechanism can also be inferred from the value of at least one specific parameter. For example, it's possible to differentiate between a loading or unloading process, an unloading process, or a transport mode. Particularly with a wheel loader equipped with a bucket on the lifting mechanism, it can be assumed that lowering the lifting mechanism and tilting the bucket accordingly will very likely result in a loading process, i.e., the picking up of bulk material.

[0022] Especially when driving a wheel loader into a pile of material, it is crucial that the machine maintains forward momentum. In this case, the opening of one or more clutches (clutch cut-off function) should be prevented. Conversely, opening one or more clutches can be advantageous when the lifting mechanism / mast is extended, particularly because it allows the machine to approach the loading / unloading point smoothly.

[0023] According to a further aspect of the present invention, a device for controlling the transmission of a machine is proposed. The device comprises at least one control unit and at least one sensor. The sensor and the control unit are interconnected for signal transmission. The control unit is configured to execute the method according to the invention and to output a signal for adapting the shifting strategy. Furthermore, a computer program may be included, wherein the method is implemented when the source code is executed on a computer, in this case, the control unit.

[0024] Furthermore, the invention relates to a drive train of a working machine. This comprises a drive element and a gearbox of the type described above, as well as a device according to the invention for gearbox control.

[0025] The invention is described in more detail with reference to the following figures. These show Fig. 1: a schematic representation of a working machine in a first operating state; Fig. 2: a schematic representation of a working machine in a second operating state.

[0026] Fig. Figure 1 shows a schematic representation of a work machine 1, which in this case is designed as a forklift truck. The work machine 1 has a lifting mechanism 2, which is arranged at the front of the work machine 1. The lifting mechanism 2 essentially consists of a lifting device 3 in the form of a fork and a lifting mast 4. A sensor 8 is attached to the lifting device 3, which is intended for detecting and providing at least one specific parameter. A working hydraulic system and operating elements for the lifting mechanism 2 are not shown, nor are a drive element and a gearbox.

[0027] The machine 1 moves along a track 5, which could, for example, represent a depot, a hall, or a construction site. The mobility of the machine 1 is primarily described by movement in a forward or backward direction F. The movement of the machine 1 in the direction F is not limited to straight-line travel; it also includes cornering and shunting operations, sometimes even on the spot.

[0028] The lifting device 3 enables the machine to pick up, transport, and unload cargo 6, in this case, general cargo. In the depicted state, the lifting mast 4, or rather the lifting mechanism 2, is in a retracted position.

[0029] Fig.Figure 2 shows the previously described machine 1 in a different situation, specifically in a different operating state of the lifting mechanism 2. In this case, the lifting mechanism 2 is in an extended position. This shifts the center of gravity of the machine 1, resulting in a greater tendency to tip K, as indicated by the arrow. The tendency to tip K describes the inclination of the machine 1 to tip over a transverse vehicle axis (not shown). The vehicle's transverse axis is orthogonal to both the travel path 5 and the lifting mast 4.

[0030] The tendency to tip K is further increased as soon as the load 6 is picked up or unloaded by the machine 1. In the example shown, the load 6 is located in a storage element 7, which here represents a (high) rack. However, the storage element 7 could also be a means of transport, for example a truck.

[0031] The higher the tilting tendency K of the working machine 1, the more important the adaptation of the switching strategy becomes. Therefore, in this case, the sensor 8 determines and provides the signal for at least one specific parameter, here the position of the lifting mechanism 2 (or the receiving device). Reference sign 1 working machine 2 hoist 3. Absorption devices 4 lifting mast 5 Route 6 charges 7 Bearing element 8 Sensor F Direction of travel K tilt tendency

Claims

[1] Method for controlling the transmission of a working machine (1), wherein at least one specific parameter is provided by at least one sensor (8) of the working machine (1) and supplied to a control unit for transmission control, and wherein the working machine (1) has a lifting mechanism (2) and the at least one specific parameter characterizes an actuation state of the lifting mechanism (2), wherein a predetermined shifting strategy is adapted depending on the at least one specific parameter, characterized by , that an adjustment of the switching dynamics occurs in response to a change in the translation. [2] Method according to claim 1, characterized by , that priority is given to adapting the predetermined switching strategy if, in knowledge of the specific parameter, a critical condition of the working machine (1) is to be feared if a translation change is carried out in an unadapted manner. [3] Method according to any one of claims 1 to 2, characterized bythat the translation change is a downshift or an upshift. [4] Method according to any one of the preceding claims, characterized by , that a clutch cut-off function is activated. [5] Method according to any one of the preceding claims, characterized by , that a clutch cut-off function is deactivated. [6] Device for the transmission control of a working machine (1), comprising at least a control unit and at least one sensor (8), wherein the control unit and the sensor (8) are connected to each other for signal transmission, characterized by that the control unit is configured to execute the method according to one of the preceding claims and to output a signal for adjusting the switching strategy. [7] Drive train of a working machine (1) comprising a drive element, a transmission and a device for transmission control according to claim 6.

Images