Method and system for controlling the change in the gear ratio in a vehicle

Abstract

Method for controlling the change of the gear ratio in a transmission (103) of a vehicle (100), wherein the transmission (103) is provided for transmitting energy from an energy source (101) to at least one drive wheel (113, 114) of the vehicle (100), wherein the transmission (103) comprises a plurality of selectable gear ratios, wherein the change of the gear ratio is controlled by a vehicle control system, wherein the vehicle further comprises a device operable by the driver for requesting energy from the energy source, wherein the method comprises the steps of: - Detection of reduced traction of at least one drive wheel of the vehicle, - Determine whether the driver's use of the power-requesting device indicates reduced liability, and - Influencing a process of changing the gear ratio in the transmission (103) when the activation of the driver-operated device for requesting energy by the driver indicates reduced liability, wherein the step of influencing a process of changing the gear ratio in the transmission (103) comprises a step of: -- Changing a gear shift criterion with respect to speeds of the energy source and gear ratios, so that driving at an instantaneous gear ratio is permitted at higher and / or lower speeds of the energy source, compared to the case where no reduced adhesion of at least one drive wheel is detected.

Description

Field of invention

[0001] The present invention relates to vehicles, in particular a method and system for controlling a change in the gear ratio in a vehicle. The present invention also relates to a vehicle, a computer program, and a computer program product that implement the method according to the invention. Background of the invention

[0002] There are various types of vehicle powertrains. For example, vehicle transmissions can be automatic, with a vehicle control system fully managing the process of changing the gear ratio. The transmissions used in these systems can include conventional automatic transmissions with torque converters, as well as automated manual transmissions.

[0003] Automatic gear shifting in commercial (heavy) vehicles, especially long-haul vehicles, often involves control system-controlled gear shifting of manual transmissions, i.e., automatic control of transmissions with a discrete number of fixed gear ratios (i.e., gears). During operation of such vehicles, the transmission is often controlled by the vehicle's control system to select the gear ratio depending on the current driving conditions.

[0004] Generally, it is often desirable to drive the vehicle in the highest possible gear (i.e., the lowest possible gear ratio, considering the circumstances) to reduce the rotational speed of the power source, often an internal combustion engine, and thus lower fuel consumption. Therefore, fuel consumption is often a consideration when choosing the gear ratio. However, the vehicle should also generally be driven with a gear ratio capable of propelling it in the desired manner. This is generally the case, but when the vehicle accelerates or decelerates, it is often necessary for the transmission to be set to a gear ratio suitable or capable of providing sufficient power to propel the vehicle without undesirable hesitation, for example, when driving uphill.It is often desirable that the gear shifting process is not carried out in situations where shifting gears could have a negative impact on the vehicle's propulsion.

[0005] DE 41 05 100 A1 describes a slip control system for a motor vehicle, and in particular a slip control system with an automatic transmission and a traction control system that regulates the driving force transmitted by a drive wheel. The slip control system includes a traction control system. The traction control system comprises an engine control system that reduces the opening degree of a throttle valve, retards the ignition timing, and interrupts the fuel supply to the engine in order to reduce excessive engine power, and / or a brake control system that continuously increases the brake fluid pressure to increase the braking force acting on the drive wheels.

[0006] US Patent 2002 / 0157888A1 describes a traction control system for a vehicle with an automatic transmission that eliminates wheel slip during acceleration by interrupting the fuel supply to the engine when slip occurs. The automatic transmission is prevented from shifting gears when slip occurs, thus maintaining the current gear range, preventing the engine speed from dropping to a regenerative braking speed, and thereby avoiding traction control sticking. Brief description of the invention

[0007] An object of the present invention is to provide a method and system that improves the control of changes in the gear ratio, particularly in situations where a change in the gear ratio can impair the vehicle's propulsion, e.g., by reducing a vehicle's ability to traverse an uphill section of the road. This object is achieved by a method according to claim 1.

[0008] According to the present invention, a method for controlling the change of the gear ratio in a vehicle transmission is provided, wherein the transmission is provided for transmitting energy from an energy source to at least one drive wheel of the vehicle, wherein the transmission comprises a plurality of selectable gear ratios, wherein the change of the gear ratio is controlled by a vehicle control system, wherein the vehicle further comprises a device operable by the driver for requesting energy from the energy source, wherein the method comprises the steps of: - Detection of reduced traction of at least one drive wheel of the vehicle, - Determine whether the driver's use of the power-requesting device indicates reduced liability, and - Influencing a process of changing the transmission ratio in the gearbox when the activation of the driver-operated device to request energy by the driver indicates reduced liability.

[0009] Modern vehicles generally use transmissions of the type previously used in manual transmission vehicles, but with gear changes performed automatically by the vehicle's control system. This applies, for example, to both heavy vehicles and passenger cars. Such transmissions are typically designed to include a discrete number of different gear ratios (gears), with the ratios in heavy vehicles often distributed such that one or more of the lowest ratios (highest gears) are capable of propelling the vehicle at a constant speed when traveling on essentially level terrain.

[0010] When such vehicles, especially when heavily loaded, travel uphill, shifting to a higher gear ratio (lower gear) is often necessary to provide sufficient power to properly manage the uphill section of the road. Particularly when driving uphill, there is often a minimum gear ratio below which the vehicle loses speed due to insufficient drive power. This places demands on how gears are selected when a gear change is required.

[0011] If a gear change is not performed at least to the highest gear (lowest gear ratio) where this criterion is met, the vehicle will continue to decelerate. Strategies exist for executing such gear selections to avoid situations where the vehicle loses too much speed, and the gear change is often performed when one or more criteria are met. For example, a gear change to a lower gear (higher gear ratio) may be designed to occur when it is determined that the engine speed after the gear change will not exceed a predetermined, calibrated speed limit that must not be exceeded.

[0012] However, there are situations that can make gear shifting difficult. The present invention relates in particular to situations in which it is detected that at least one drive wheel of the vehicle has reduced traction, i.e., the friction between at least one drive wheel (tire) and the surface on which the vehicle travels may not be sufficient to transmit the power required to propel the vehicle. The reduced traction can be due, for example, to slippery conditions such as snow, ice, and / or loose gravel.The detection of reduced traction can be carried out, for example, by measuring the rotational speed of the vehicle's drive wheels, and if one or more wheels begin to rotate or spin at speeds that exceed the speeds of non-driven wheels of the vehicle or other drive wheels by more than a predetermined amount, it can be determined that the traction is reduced and one or more wheels are slipping.

[0013] Shifting gears in such situations, particularly when the vehicle is traveling uphill, can adversely affect the vehicle's ability to actually manage the uphill section of the road. For example, if a gear change is performed when one or more drive wheels are spinning, or when the vehicle's drive wheels have barely sufficient traction, the interruption of the motive power applied to the drive wheels during the gear change, and the subsequent increase in motive power after the shift, can often result in a complete loss of traction. This can cause the vehicle to lose speed and may necessitate further gear changes, ultimately leading to the vehicle stalling on an uphill section of the slippery road.

[0014] For this reason, gear shifting can be suspended, i.e., not permitted, when wheel slip is detected and one or more wheels are spinning, in order to reduce the risk of such situations. Conversely, when wheel slip is no longer detected, gear shifting operations are again controlled according to the general criteria that prevailed before wheel spin was detected. However, it has been found that the mere fact that the vehicle's drive wheels are no longer spinning may not be sufficient to guarantee that slippery conditions no longer exist, and thus situations of the aforementioned type can still occur. Even if gear shifting is suspended as soon as wheel slip is detected, gear shifting operations may be suspended in situations where the reduction in traction is very temporary and the suspended gear shifting is not actually justified.

[0015] According to the present invention, the processes of changing the transmission ratio in situations where reduced adhesion of at least one drive wheel is detected can be influenced, but only depending on the actual prevailing conditions.

[0016] According to the invention, the mere detection of reduced traction, which may include a step to detect wheel slip of at least one drive wheel of the vehicle, is not sufficient to suspend or otherwise influence a gear shifting process. Instead, the invention also determines whether the driver's activation of the power request device also indicates reduced traction. That is, the driver's behavior is taken into account to determine whether the detected wheel slip can be considered temporary and no further action is required, or whether slippery conditions are likely to persist. Therefore, if the driver's activation of the power request device also indicates reduced traction, the gear ratio change processes are affected.

[0017] DE 37 84 577 T2 describes a slip control device for a motor vehicle to prevent excessive slippage of a vehicle drive wheel on the road surface, comprising a device for adjusting the output torque, a device for adjusting the braking force, a slip detector device for detecting the slippage of the drive wheel, a first control device which subjects the output torque setting device to feedback control in order to reduce the slippage to a first target slip value, and a second control device which subjects the braking force setting device to feedback control in order to reduce the slippage to a second target slip value. Preferably, the engagement state of the clutch or the gear ratio of the transmission, as well as the engine, can be adjusted to set the output torque of a drive system.To detect the state of slippage or wheel spin, this can be detected either directly from the rotational speeds of the drive wheels, as in the embodiment described above, or indirectly by predicting a state of slippage or wheel spin from the vehicle state. Such a vehicle state can include, for example, an increase in the output torque of a power source or the rotational speed, a change in the degree of accelerator pedal depressor, a change in the rotational speed of the drive shaft, the state of the steering wheel (cornering), the state of the vehicle body tilt (acceleration), and a load.

[0018] According to the invention, the processes of changing the transmission ratio are only affected if the driver's activation of the power request device indicates reduced traction. That is, the way the driver activates the power request device can indicate whether the driving conditions are indeed slippery and whether a gear shift should be adjusted accordingly. For example, if wheel slip is detected and the driver reduces the power demand in this context, e.g., simultaneously or subsequently, by at least partially releasing the accelerator pedal, this can be used as confirmation that the conditions are still slippery and that a gear shift should be avoided if possible.At least in such situations, shifting into a higher gear (lower gear ratio) should be avoided, since, for example, a possible loss of speed of the vehicle due to the slippery conditions may essentially immediately necessitate another gear shift into a lower gear, whereby the process of changing the gear ratio only reduces the vehicle's ability to cope with the uphill section of road.

[0019] With regard to the activation of the power request device by the driver, the step of determining whether the activation of the driver-operated power request device by the driver indicates reduced liability may not only involve the step of detecting a request to reduce energy from the power source.

[0020] Alternatively, it can also be determined how, for example, the way in which the energy demand follows a pattern, such as the driver first reducing the energy demand from the energy source, e.g., rapidly, followed by a comparatively slower increase in the energy demand, can be interpreted as the driver activating the device for demanding energy in order to achieve the highest possible tractive force. According to embodiments of the invention, it is determined whether, after detecting a decrease in the energy demand from the energy source, an increase in the energy demand from the energy source to a level of less energy than was demanded before the decrease is observed, in which case the processes of changing the transmission ratio according to the invention are affected.

[0021] According to the invention, processes of changing the gear ratio can be designed to be influenced for at least a predetermined period of time, starting from the point at which reduced traction of the at least one drive wheel is no longer detected, or from the point at which the driver's activation of the driver-operated device indicates slippery conditions. That is, the gear-shifting process can be designed to be influenced for at least a suitable period of time to avoid situations in which the vehicle loses traction again if the gear-shifting process is allowed too soon after reduced traction is detected.

[0022] The step of influencing the processes of changing the transmission ratio can also be designed so that these processes are terminated when the activation of the device to request energy by the driver no longer indicates reduced adhesion, such as when the driver requests a high amount of energy from the energy source, which can be interpreted as an indication that the driver no longer considers the conditions to be slippery.

[0023] Furthermore, according to the embodiments of the invention, it is not necessary to detect wheel slip, while the simultaneous activation of the device for requesting energy from the energy source by the driver also indicates slippery conditions. Instead, it can be determined whether the activation of the device for requesting energy by the driver within a predetermined time period before and / or after the start and / or end of the wheel slippage indicates slippery conditions, and if so, the gearshifting process according to the invention can be designed to be influenced as soon as such an indication is detected.

[0024] Furthermore, the device operated by the driver to request energy from the energy source can include, for example, an accelerator pedal or another device operated by the driver, such as a lever or button to regulate the energy supplied by the vehicle's energy source. The energy source, in turn, can include an internal combustion engine, one or more electric motors, or a combination thereof.

[0025] The gear-shifting process can be influenced in various ways. For example, the change in the gear ratio can be delayed or suspended. Furthermore, the change to a lower gear ratio can be delayed or suspended, while according to embodiments of the invention, the change to a higher gear ratio can still occur unaffected; that is, only a change to a lower gear ratio is delayed or suspended.

[0026] Gear shifting is delayed by altering the dependence of the energy source's rotational speed on the gear change, thus allowing the vehicle to maintain a current gear for longer periods. This is achieved by allowing the internal combustion engine to operate at higher speeds before shifting into a higher gear (lower gear ratio), or by allowing the internal combustion engine to reach lower speeds before shifting into a lower gear (higher gear ratio) than the limitations present at the start of the modification process according to the invention. For example, the vehicle can be forced to maintain the vehicle's current gear as long as the energy source's rotational speed does not fall below a minimum speed limit. Gear shifting can also be prevented altogether, as long as continued driving in a current gear is possible.

[0027] According to the embodiments of the invention, it is also necessary for the driver to perform at least one further action. For example, it may be necessary for the driver to change the load acting on the drive shaft, e.g., to increase the pressure on the drive shaft and thus improve traction. Furthermore, or alternatively, it may be necessary for the driver to, for example, lock a differential to indicate that slippery conditions actually exist.

[0028] Further features of the embodiments of the present invention and their advantages are given in the detailed description of the exemplary embodiments listed below and the accompanying drawings. Brief description of the drawings Fig. Figure 1A shows a powertrain of an exemplary vehicle; Fig. 1B shows an example of a control unit in a vehicle control system; Fig. Figure 2 shows an exemplary method according to an embodiment of the present invention; Fig. Figure 3 shows, by way of example, the influence of changing the translation ratio. Detailed description of exemplary embodiments

[0029] Fig. Figure 1A schematically represents the powertrain of an exemplary vehicle 100. The powertrain comprises a power source, in this example an internal combustion engine 101, which is conventionally connected to a transmission 103 via a clutch 106 through an output shaft of the internal combustion engine 101, normally via a flywheel 102. An output shaft 107 from the transmission 103 drives drive wheels 113, 114 via a final drive 108, such as a common differential, and drive axles 104, 105, which are connected to the final drive 108.

[0030] The internal combustion engine 101 is controlled by the vehicle control system via a control unit 115. The clutch 106 and the transmission 103 are also controlled by the vehicle control system via a control unit 116.

[0031] The 103 transmission can be set to a number of different (discrete) gear ratios, with the vehicle control system selecting a suitable gear ratio for each driving situation.

[0032] Generally, a gear shift is performed when the engine speed reaches a level at which the conditions for a gear shift are met. When shifting to a lower gear (higher gear ratio), one condition for performing a gear shift may be that the engine speed after the shift is complete must not exceed a certain limit, often a calibrated maximum engine speed. This maximum calibrated engine speed may vary for different gears and / or vehicle speeds. Consequently, a gear shift to a lower gear is generally performed as soon as it is determined that the engine speed in the new gear will not exceed this limit.Alternatively or additionally, the rev limits can be set for the speed of a current gear.

[0033] As discussed above, there are situations in which shifting gears according to such criteria can have a negative impact on the propulsion of the vehicle, and embodiments of the invention provide a method for controlling the change in the transmission ratio in a way that can, for example, make it easier for a vehicle to cope with an uphill section of road by reducing the adhesion between the vehicle's drive wheels and the surface on which the vehicle is traveling.

[0034] An exemplary method 200 according to embodiments of the present invention, which can be implemented at least partially, e.g., in the control unit 116 for controlling the clutch 106 and the transmission 103, is described in Fig. Figure 2 illustrates this. As stated above, the functions of a vehicle are generally controlled by a number of control units, and control systems in vehicles of the disclosed type generally include a communication bus system with one or more communication buses for connecting a number of electronic control units (ECUs) or control devices to various components on board the vehicle. Such a control system can comprise a large number of control units, and the control of a particular function can be divided between two or more of them.

[0035] For the sake of simplicity, Fig. Figure 1A shows only the control units 115-116, but vehicles of the type shown are often equipped with significantly more control units, as the person skilled in the art will understand. The control units 115-116 are designed to communicate with each other and with various components via the communication bus system and other lines. Fig. 1 are partially characterized by connecting lines A.

[0036] Embodiments of the present invention can be implemented in any suitable control unit in the vehicle 100 and therefore do not necessarily have to be implemented in the control unit 115. The control of the transmission 103 according to embodiments of the present invention generally depends on receiving signals from other control units and / or vehicle components, and it is generally the case that control units of the disclosed type are normally configured to receive sensor signals from various parts of the vehicle 100. The control unit 116, for example, receives signals from the engine control unit 115, where these signals may include signals relating to engine operation as well as to the driver's demand for energy and thus to the driver's actuation of, for example, an accelerator pedal. The control unit 116 also supplies signals to the control unit 115, e.g.for controlling the engine speed and the power supplied during gear changes. The control unit 116 also receives signals, e.g., from one or more other control units relating to detected wheel slip. Control units of the type shown are generally also designed to supply control signals to various parts and components of the vehicle, e.g., for controlling the clutch 106 and the transmission 103.

[0037] Such control is often implemented by programmed instructions. The programmed instructions typically comprise a computer program which, when executed in a computer or control unit, causes the computer / control unit to perform the desired control action, such as process steps according to embodiments of the present invention. The computer program generally constitutes part of a computer program product, the computer program product comprising a suitable storage medium 121 (see Fig. 1B) with a computer program 126 stored in the storage medium 121. The computer program can be stored non-volatilely in the storage medium. The digital storage medium 121 can, for example, comprise one of the following: ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), Flash memory, EEPROM (Electrically Erasable PROM), a hard disk unit, etc., and can be provided in or in conjunction with the control unit, whereupon the computer program is executed by the control unit. The behavior of the vehicle in a particular situation can thus be adapted by changing the instructions of the computer program.

[0038] An exemplary control unit (the control unit 116) is shown schematically in Fig. Figure 1B shows the control unit, which can include a processing unit 120, which can be, for example, any suitable type of processor or microcomputer, such as a digital signal processor (DSP) or an application-specific integrated circuit (ASIC). The processing unit 120 is connected to a storage unit 121, which provides the processing unit 120 with, for example, the stored program code 126 and / or the stored data that the processing unit 120 needs to perform calculations. The processing unit 120 is also configured to store partial or final results of calculations in the storage unit 121.

[0039] Furthermore, the control unit 112 is equipped with devices 122, 123, 124, and 125 for receiving and transmitting input and output signals. These input and output signals can include waveforms, pulses, or other attributes that the devices 122 and 125 can capture as information for processing by the processing unit 120. The devices 123 and 124 for transmitting output signals are designed to convert calculation results from the processing unit 120 into output signals that are transmitted to other parts of the vehicle control system and / or the component(s) for which the signals are intended.Each of the connections to the devices for receiving and sending the respective input and output signals may include one or more cables, a data bus such as a CAN bus (Controller Area Network Bus), a MOST bus (Media Oriented Systems Transport) or another bus configuration, or a wireless connection.

[0040] Again with reference to the in Fig. In the exemplary method 200 shown, the process begins in step 201, where it is determined whether a reduced adhesion is detected with respect to one or more vehicle drive wheels, e.g. by detecting wheel slip, which can be determined in any suitable way, e.g. by detecting a sudden increase in the wheel speed of one or more drive wheels and / or a corresponding increase in the speed of the internal combustion engine.

[0041] The method according to the invention can be configured to be performed whenever reduced traction is detected, or, for example, only when the vehicle is traveling uphill. Further criteria, such as road gradient and / or the vehicle's current weight, can influence whether or not the gear-shifting process according to the invention should be affected. For instance, vehicle deceleration can be determined if the method according to the invention is configured to be performed only when the vehicle deceleration exceeds a certain threshold. If the vehicle deceleration is low, the effect of a gear-shifting process is less detrimental to the vehicle's propulsion than if the vehicle deceleration is high, as might be the case when a heavily loaded vehicle is traveling uphill.

[0042] Therefore, according to embodiments of the invention, the method can include the further step of determining an instantaneous deceleration of the vehicle 100, wherein the vehicle deceleration can be determined by any suitable device known per se. According to these embodiments, if it is determined that the vehicle deceleration exceeds a deceleration limit, the method can be provided such that it continues according to the following steps, while otherwise the method can be terminated.

[0043] If it is determined that the vehicle is experiencing reduced adhesion, for example due to wheel slip, the procedure continues with step 202, in which the vehicle's adhesion is further evaluated by determining whether any action by the driver, in this example the accelerator pedal, also indicates reduced adhesion. This can be determined in various ways, for example by determining whether the driver, in conjunction with the detection of, for example, wheel slip, reduces the energy demand from the internal combustion engine. Generally, if a driver notices that conditions of reduced adhesion exist, they will reduce the energy demand from the internal combustion engine in order to restore adhesion.Conversely, it is highly unlikely that the driver will maintain a high energy demand when the wheels begin to spin, unless the driver recognizes that the reduced traction is very temporary and that traction will be restored immediately. Therefore, according to embodiments of the invention, a reduction in the energy demand from the internal combustion engine, detected, for example, by sensing a released accelerator pedal, can be used as an indication that traction has indeed been, and still is, reduced.

[0044] According to embodiments of the invention, it is not only determined whether the energy demand from the internal combustion engine is reduced, but also whether the reduction is followed by an increase in the energy demand. It can be determined whether the increase is at most an increase to, for example, a certain percentage of the demand that existed before the detection of reduced traction. Such behavior can be interpreted as an indication that the driver is seeking traction and attempting to maximize the power transmitted to the vehicle's drive wheels. According to embodiments of the invention, it can be determined whether the increase is followed by a further reduction in the energy demand, in order to ascertain that the conditions are such that traction is still reduced and gear shifting should be influenced.

[0045] If, in step 202, it is determined that the vehicle's propulsion is experiencing reduced traction, the method proceeds to step 203, in which gear shifting is influenced. Otherwise, the method may be designed to return to step 201. According to embodiments of the invention, the processes of changing the gear ratio are influenced if the driver's actuation of the accelerator pedal indicates reduced traction within a first time interval after the detection of reduced traction of the at least one drive wheel. That is, it is not necessary for the driver's actuation of the accelerator pedal to occur simultaneously with the detection of wheel slip, but the actuation of the accelerator pedal by the driver can occur within a time interval after the detection of wheel slip. For example, a suitable number of seconds can be used as a time limit.In this way, the driver is given time to react if one or more wheels begin to slip, and as long as the driver actually reacts accordingly within a specified time period, the gear shifting is affected according to the invention.

[0046] Therefore, in step 203, the control of gear shifting, i.e., the gear shifting operations, are influenced as a result of the double indication of reduced vehicle grip. The gear shifting operations can be designed to be influenced in various ways. According to embodiments of the invention, any changes in the gear ratio are delayed or suspended. According to embodiments of the invention, changes in the gear ratio to lower gear ratios can be delayed or suspended, while changes in the gear ratio to higher gear ratios may still be permitted. If, in step 204, it is determined that no more slippery conditions prevail, e.g.,If slippery conditions are indicated by the driver pressing the accelerator pedal or by the absence of any further indications within a specified time period, the influence according to the invention is suspended and the normal control of gear shifting is resumed in step 205 and the method is terminated in step 206.

[0047] As discussed above, according to the invention, influencing processes of changing the gear ratio also includes changing a criterion regarding when a gear shift should be performed. This criterion relates to when a gear shift is performed in relation to the rotational speed of the internal combustion engine, whereby a gear shift is influenced in such a way that driving at an instantaneous gear ratio is permitted at higher and / or lower rotational speeds of the energy source, compared to the case where there is no reduced traction. This may be necessary, for example, in situations where the vehicle is decelerating due to insufficient energy for driving the vehicle, or where the vehicle speed otherwise changes in such a way that normal gear shift criteria would otherwise trigger a change in the gear ratio.

[0048] This is in Fig. 3 shown. Fig. Figure 3 shows a situation in which the vehicle is decelerated by 100 and forced to be driven in a single gear for a longer period than normal. The x-axis represents time and the y-axis the rotational speed n of the internal combustion engine.

[0049] The solid line 301 represents the change in the rotational speed n of the internal combustion engine for a situation in which the vehicle is driven at 100 km / h on an uphill section and in a situation in which the vehicle is losing speed. The dashed line 302 represents a rotational speed limit n. lim of the internal combustion engine, which must not be exceeded after shifting into a lower gear (i.e., changing the gear ratio to a higher gear ratio).

[0050] Starting from time t0, in the situation represented by solid line 301, vehicle 100 continuously loses speed (deceleration), and thus the rotational speed n of the internal combustion engine 101 is also continuously reduced. The requirements of a gear shift operation in the general case are met at time t1, e.g., that the rotational speed of the internal combustion engine after the gear shift exceeds the rotational speed limit n. lim does not exceed and / or a minimum rotational speed n change achieved. If the gear-shifting process is not influenced according to the present invention, a gear-shifting process would normally be carried out at this time, corresponding to the dashed line 303. However, when influencing processes of changing the gear ratio according to the invention, the gear-shifting process is not carried out, but delayed. This can be achieved, for example, by reducing the maximum permissible speed of the internal combustion engine.lim after shifting gears to a second speed limit n lim_slip This can be achieved so that the criteria for the gear shift are no longer met at time t1. Alternatively or additionally, the criterion can instead be set so that the vehicle is forced to continue driving in its current gear until the engine speed n of the internal combustion engine 101 reaches the engine speed n change_slip is reduced, which is lower than the rotational speed of the internal combustion engine n change , during which the gear shifting process is normally carried out. In this way, the criteria for carrying out the process of changing the gear ratio are only met when the vehicle is decelerated further and is thereby driven in the current gear for a longer period of time.

[0051] Consequently, in the situation corresponding to solid line 301, when vehicle 100 reaches time t1, no gear shift is performed because the new gear shift criteria are not met due to the detected wheel slip. Instead, vehicle 100 is controlled to continue in its current gear while the vehicle speed, and thus the engine speed n, continues to decrease, thereby at least delaying the gear shift. However, the engine speed in a given gear may eventually, as the vehicle continues to decelerate, reach a point where a gear shift can no longer be avoided, for example, because the engine speed exceeds the minimum permissible speed n. change_slipThe engine reaches a speed close to its idle speed. According to the present example, this occurs at time t2, which is why a gear shift is performed, but with a delay according to the invention.

[0052] Furthermore, according to embodiments of the invention, the process of changing the transmission ratio is only affected if the driver takes at least one other measure that indicates reduced liability.

[0053] Such measures could, for example, include detecting that the driver is changing the load applied to the wheel axles, e.g., by reducing the load applied to an auxiliary axle in order to increase the load applied to the drive wheels and thus improve the chances of achieving sufficient traction. The driver could also take other measures, such as locking a differential, to increase the ability to overcome a section of road with reduced traction. Consequently, according to embodiments of the invention, the gear-shifting process is only affected if at least one of these further indications of reduced traction is detected.

[0054] Finally, embodiments of the invention have been described above by way of example for a specific vehicle, but apply to any vehicle in which the vehicle control system controls the gear shifting process. The invention also includes a vehicle with a system that implements the invention.

Claims

[1] Method for controlling the change of the gear ratio in a transmission (103) of a vehicle (100), wherein the transmission (103) is designed to transmit energy from an energy source (101) to at least one drive wheel (113, 114) of the vehicle (100), wherein the transmission (103) comprises a plurality of selectable gear ratios, wherein the change of the gear ratio is controlled by a vehicle control system, wherein the vehicle further comprises a device operable by the driver for requesting energy from the energy source, wherein the method comprises the steps of: - Detection of reduced traction of at least one drive wheel of the vehicle, - Determine whether the driver's use of the power-requesting device indicates reduced liability, and - Influencing a process of changing the gear ratio in the transmission (103) when the activation of the driver-operated device for requesting energy by the driver indicates reduced adhesion, wherein the step of influencing a process of changing the gear ratio in the transmission (103) comprises a step of: -- Changing a gear shift criterion with respect to speeds of the energy source and gear ratios of the transmission, so that driving at an instantaneous gear ratio is permitted at higher and / or lower speeds of the energy source, compared to the case where no reduced adhesion of at least one drive wheel is detected. [2] Method according to claim 1, wherein the step of detecting the reduced adhesion of at least one drive wheel of the vehicle comprises a step of: - Detection of wheel slippage of at least one drive wheel of the vehicle. [3] Method according to claim 1 or 2, wherein the step of influencing a process of changing the transmission ratio in the transmission (103) comprises a step of: - Delaying or suspending a change in the translation ratio to a lower translation ratio. [4] Method according to any one of claims 1-3, wherein the step of influencing the process of changing the transmission ratio in the transmission (103) comprises a step of: - Delaying or suspending a change in the translation ratio. [5] Method according to any one of claims 1-4, wherein the step of influencing a process of changing the transmission ratio in the transmission (103) comprises: - Influencing a process of changing the transmission ratio in the gearbox (103) when the activation of the driver-operated device for requesting energy by the driver within a first time period after the detection of a reduced adhesion of at least one drive wheel indicates a reduced adhesion. [6] Method according to any one of claims 1-5, wherein the step of influencing a process of changing the transmission ratio in the transmission (103) comprises: - Influencing the process of changing the translation ratio during at least a second period of time, from when a reduced adhesion of at least one drive wheel is no longer detected. [7] Method according to any one of claims 1-5, comprising a step of: - Terminating the step to influence the process of changing the transmission ratio when the driver's activation of the power request device no longer indicates reduced liability. [8] Method according to any one of claims 1-7, wherein the step of determining whether the activation of the driver-operated device for requesting energy by the driver indicates reduced liability comprises a step of: - Capturing a requirement to reduce energy from the energy source. [9] Method according to any one of claims 1-8, wherein the step of determining whether the activation of the driver-operated device for requesting energy by the driver indicates reduced liability comprises the steps of: - Detecting a decrease in the requested energy from the energy source and - Detecting an increase in the energy requested from the energy source to a requirement for less energy than was requested before the decrease in the requested energy. [10] Method according to any one of claims 1-8, comprising, prior to the step of influencing a process of changing the transmission ratio in the transmission (103), a step of: - Recording at least one other action taken by the driver that indicates reduced liability. [11] Computer program comprising program code which, when the program code is executed in a computer, enables the computer to execute the method according to any one of the preceding claims 1-10. [12] Computer program product comprising a computer-readable medium and a computer program according to claim 11, wherein the computer program is contained in the computer-readable medium. [13] System for controlling the change of the gear ratio in a transmission (103) of a vehicle (100), wherein the transmission (103) is designed to transmit energy from an energy source (101) to at least one drive wheel (113, 114) of the vehicle (100), wherein the transmission (103) comprises a plurality of selectable gear ratios, wherein the change of the gear ratio is controlled by a vehicle control system, wherein the vehicle further comprises a device operated by the driver for requesting energy from the energy source, wherein the system characterized by is that it includes: - a device designed to detect reduced adhesion of at least one drive wheel of the vehicle, - a device designed to determine whether the driver's activation of the power-requesting device indicates reduced liability, and - a device designed to influence a process of changing the transmission ratio such that when the activation of the driver-operated device to request energy by the driver indicates reduced traction, a change in a gear shift criterion with respect to speeds of the energy source and transmission ratios occurs, so that propulsion at an instantaneous transmission ratio is permitted at higher and / or lower speeds of the energy source, compared to the case where no reduced traction of at least one drive wheel is detected. [14] vehicle, characterized by that it comprises a system according to claim 13.

Images