Gearbox control depending on the surface condition of a vehicle's terrain

Abstract

Method for controlling at least one transmission (105) of a vehicle; characterized in that by comparing at least one value of a gradient of a rotational speed of an input or output shaft of the transmission (105) with at least one value of a longitudinal acceleration of the vehicle, it is determined whether slip occurs at one or more wheels (113) of the vehicle; wherein The evenness of a surface traversed by the vehicle is assessed by means of one or more extreme values ​​of a vertical acceleration of the vehicle; and wherein the transmission (105) is controlled depending on the occurrence of slippage and the assessment of the evenness.

Description

[0001] The invention relates to a method according to claim 1, a computer program according to claim 6 and an arrangement according to the preamble of claim 7.

[0002] Knowledge of the surface properties of the road surface is of great importance for construction and agricultural machinery, as different surfaces place different demands on the respective drive control. Knowing the road surface properties allows for the appropriate adjustment of the driving or working profiles of the construction or agricultural machine. This is particularly important for the transmission control.

[0003] DE 10 2020 206 128 A1 discloses an acceleration sensor whose triggering pattern is monitored. The triggering pattern correlates with irregularities in the road surface.

[0004] DE 35 45 012 A1 relates to the determination of wheel slip. For this purpose, an acceleration value supplied by an accelerometer is compared with a wheel acceleration measured at the vehicle wheels to generate a control signal that corresponds to the difference between the accelerations. Each control signal is used to act on the engine or the vehicle's braking system in such a way that the higher wheel acceleration is adjusted to match the actual vehicle acceleration measured by the accelerometer.

[0005] US Patent 7,739,019 B2 discloses a system for detecting road irregularities in a vehicle. The system includes a first acceleration sensor that measures the vertical acceleration of a vehicle component. An adaptive acceleration limit module determines a first acceleration limit based on the vehicle's speed. A limit comparison module generates a road irregularity signal by comparing the first acceleration limit from the adaptive acceleration limit module with the acceleration measured by the first acceleration sensor.

[0006] The invention is based on the objective of improving the control of a vehicle's transmission. This objective is achieved by a method according to claim 1, a computer program according to claim 6, and an arrangement according to claim 7. Preferred embodiments are included in the dependent claims and are described below.

[0007] The method according to the invention serves to control at least one transmission of a vehicle. The transmission can be a reduction gear or a differential / compensating transmission. Preferably, the transmission ratio is variable. In particular, the transmission can be a manual transmission or a transmission with a continuously variable ratio.

[0008] The transmission is part of the vehicle's drivetrain. As a transmission, it translates the input speed of an output shaft from the vehicle's drive motor into the speed of an output shaft. The output shaft is then connected to one or more driven wheels of the vehicle. This connection can be made via the differential.

[0009] The invention provides for a comparison of at least one value of a gradient or a derivation of a rotational speed of an input or output shaft of the transmission with at least one value of a longitudinal acceleration of the vehicle.

[0010] Longitudinal acceleration refers to the acceleration of a vehicle along its longitudinal axis. This is identical to the acceleration of a vehicle in the direction of travel when driving straight ahead.

[0011] If no wheel of the vehicle is slipping, the two compared values ​​will correlate or match. However, if slippage is occurring, the values ​​will differ. By comparing the values, it can be determined whether slippage is occurring at one or more wheels of the vehicle.

[0012] The invention further provides for an assessment of the evenness of the surface traversed by the vehicle. Specifically, the evenness of the surface is assessed along a section of the route traveled by the vehicle. This involves the evenness of a longitudinal profile of the surface defined by the traversed route. The evenness is defined, for example, in "Longitudinal Evenness Evaluation Method 'Evaluated Longitudinal Profile' - Further Development of Longitudinal Evenness Evaluation for Condition Assessment and Evaluation" (Günther Maerschalk, Andreas Ueckermann, Slawomir Heller; in: Reports of the Federal Highway Research Institute, Issue S73, 2011).

[0013] The evenness of the surface traversed by the vehicle correlates with the vehicle's vertical acceleration, that is, its acceleration along its vertical axis. Unevenness of the surface is associated with extreme values, i.e., maxima and minima, of the vertical acceleration. Accordingly, the invention provides for evaluating the evenness by means of one or more extreme values ​​of the vehicle's vertical acceleration.

[0014] According to the invention, the transmission is controlled depending on the occurrence of slip and the assessment of the surface's evenness. This dependency manifests itself in the fact that the transmission is controlled differently when slip occurs than in situations where no slip occurs. Similarly, the surface's evenness influences the transmission's control. Thus, the transmission is controlled differently on level and uneven surfaces.

[0015] By taking into account both wheel slip and the evenness of the surface, it is possible to control the transmission appropriately for the situation. Furthermore, the method according to the invention is advantageous because a transmission control unit already has information about the speeds of the input and output shafts as well as accelerations available to it via corresponding sensors. Therefore, the method according to the invention can be implemented in a transmission control unit without any additional hardware requirements.

[0016] In a preferred embodiment, a difference between the two values ​​is calculated to compare at least one value of the speed gradient of the input or output shaft of the transmission with at least one value of the longitudinal acceleration of the vehicle. The magnitude of the difference correlates with the wheel slip.

[0017] Preferably, the slip is classified in a further development of the method. Classification means assignment to one of several classes. The slip is thus assigned to one of several slip classes. Preferably, the slip is quantified for this purpose, with the assignment to the slip classes depending on the magnitude of the slip. The classification according to the further development is advantageous because the method is simplified. Accordingly, the demands on the computing capacity of the control unit are reduced. This allows the use of simpler and therefore more cost-effective control unit hardware.

[0018] Similarly, in a preferred further development, flatness is classified. The flatness is thus assigned to one of several flatness classes. Preferably, the flatness is quantified for this purpose. Assignment to the flatness classes then depends on a flatness measure. Suitable flatness measures can be derived, for example, from the definition of flatness mentioned above. Classifying the flatness also simplifies the process, thus reducing the demands on the control unit's computing capacity and allowing for more cost-effective implementation of the control unit hardware.

[0019] In a preferred advanced design, the transmission is controlled according to one of several driving programs. The driving program is selected based on the occurrence of slip and the assessment of road surface smoothness. Specifically, the driving program can be selected based on the slip and / or smoothness classifications described above. Selecting driving programs allows the transmission to be controlled appropriately for the situation, while simultaneously conserving the processing power of the transmission control unit.

[0020] A computer program according to the invention implements the method according to the invention or a preferred embodiment thereof. The computer program thus comprises instructions for executing the method according to the invention or a preferred embodiment and is therefore configured to execute the method according to the invention or a preferred embodiment. This means that the computer program causes a computer, such as a transmission control unit, to execute the method according to the invention or a preferred embodiment when the computer program is executed by the computer. The computer program can be stored on a storage medium or encoded in one or more transmittable or transmitted signals. In particular, the computer program can be in the form of a computer program product, that is, a tradable unit or a unit that serves the purpose of transferring ownership of the computer program.

[0021] The arrangement according to the invention comprises the transmission control unit described above, the speed sensor, and the acceleration sensor. According to the invention, the transmission control unit includes the computer program according to the invention or a preferred embodiment thereof. Furthermore, it is configured to determine the value of the gradient of the rotational speed of the input or output shaft of the transmission based on a signal from the speed sensor. For this purpose, the speed sensor is connected to the transmission control unit via a signal conductor. The rotational speeds of the input or output shaft of the transmission are encoded in a signal transmitted from the speed sensor to the transmission control unit.

[0022] The transmission control unit is also designed to determine the vehicle's longitudinal acceleration using a signal from the acceleration sensor. The acceleration sensor is connected to the transmission control unit via a signal conductor. The longitudinal acceleration values ​​of the vehicle are encoded in a signal transmitted from the acceleration sensor to the transmission control unit.

[0023] A preferred embodiment of the invention is described in Fig. 1 shown. In detail: Fig. 1 a drivetrain.

[0024] The in Fig. The drive train 101 shown comprises a motor 103, a gearbox 105 and a differential 107.

[0025] The transmission 105 has a control unit 111. It directs a torque flow from the motor 103 to the differential 107. The differential 107 splits the torque flow so that wheels 113 are driven.

[0026] By comparing longitudinal acceleration with an output speed gradient, the transmission control unit 111 determines whether the wheels 113 are slipping. It also monitors the acceleration profile along a vertical axis. From this, the transmission control unit 111 deduces whether the surface is level or uneven. Based on the result, the transmission control unit 111 selects one of the following four categories: - First category: Slippage with uneven ground; - Second category: Slip with a level surface; - Third category: no slippage with uneven ground; and - Fourth category: no slippage with a level surface.

[0027] Depending on the selected category, the transmission control unit 111 makes adjustments to the driving program. If the first category is selected, for example, differential locks can be engaged and gear changes of the transmission 105 can be prevented, or the engine speed 103 can be kept high to provide maximum power. Furthermore, the pressure in the tires 113 can be reduced to decrease ground pressure. It is also possible to activate targeted slip control to maintain a desired level of wheel slip 113.

[0028] If the second category is present, a gradient can be limited, allowing the engine's power output to follow a corresponding signal indicating the driver's request, such as a position signal from the accelerator pedal. This results in a more sensitive response from the engine 103. It is also advisable to engage differential locks and / or activate a shift prevention function depending on the second category. During the filling process of a wheel loader's bucket, the engine power can be reduced as soon as wheel slippage 113 is detected on level ground, thus indicating the presence of the second category.

[0029] If the surface is uneven, but the wheels 113 do not slip according to the third category, the pressure in the wheels 113 can be increased, for example. It may also be useful to increase the available power of the engine 103 to cope with the unevenness, as in the first category.

[0030] If the fourth category is selected and the wheels 113 have no slippage on level ground, a transport mode can be selected for efficiently covering long distances. For this, as in the third category, a high pressure is selected in the wheels 113. Furthermore, the transmission control unit 111 instructs the transmission 105 to shift up early. Reference sign 101 Powertrain 103 Engine 105 gearbox 107 Differential 111 Transmission control unit 113 wheel

Claims

[1] Method for controlling at least one transmission (105) of a vehicle; characterized by , that by comparing at least one value of a gradient of a rotational speed of an input or output shaft of the transmission (105) with at least one value of a longitudinal acceleration of the vehicle, it is determined whether slip occurs at one or more wheels (113) of the vehicle; wherein the evenness of a surface traversed by the vehicle is assessed by means of one or more extreme values ​​of a vertical acceleration of the vehicle; and wherein the transmission (105) is controlled depending on the occurrence of slip and the assessment of the evenness. [2] Method according to claim 1; characterized by , that at least a difference is formed between a value of the gradient of the rotational speed of the input or output shaft of the transmission (105) and a value of the longitudinal acceleration of the vehicle. [3] Method according to any of the preceding claims; characterized by , that the hatching is classified. [4] Method according to any of the preceding claims; characterized by , that the flatness is classified [5] Method according to any of the preceding claims; characterized by , that one of several driving programs for controlling the transmission (105) is selected depending on the occurrence of slip and the assessment of the evenness. [6] Computer program for carrying out a method according to any of the preceding claims. [7] Arrangement comprising a transmission control unit (111), a speed sensor and an acceleration sensor; characterized by , that the transmission control unit (111) comprises a computer program according to the preceding claim; wherein the transmission control unit (111) is designed to determine the value of the gradient of the rotational speed of the input or output shaft of the transmission (105) using a signal from the speed sensor and the value of the longitudinal acceleration of the vehicle using a signal from the acceleration sensor.

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