DE102020005812A1 - Method for controlling the tire pressure of a self-propelled soil compaction machine with pneumatic tires and self-propelled soil compaction machine - Google Patents

Abstract

Method for controlling the tire pressure of a self-propelled soil compacting machine (1) with pneumatic tires, in particular a rubber-tyred roller or a combination roller, and a self-propelled soil compacting machine (1) with a control device (9) for carrying out the method. The method comprises the steps: Determining the weight (G, G1) of the soil compaction machine or the partial weight that weighs on at least one wheel (8) from at least one operating parameter that is dependent on the weight (G, G1) of the soil compaction machine and detected by a sensor soil compacting machine (s1) while it is being driven and determining a target tire pressure based on the determined weight (G, G1) of the soil compacting machine or based on the partial weight that weighs on at least one wheel (8) (s2). The method also includes the steps: Determining the actual tire pressure of at least one wheel (8) of the soil compacting machine (1) (s3) and changing the actual tire pressure of the at least one wheel (8) so that the actual tire pressure approaches the target tire pressure (s4).

Description

The invention relates to a method for controlling the tire pressure of a self-propelled soil compacting machine with pneumatic tires, in particular a soil compacting machine, especially a rubber-tyred roller or a combination roller. Furthermore, the invention relates to such a self-propelled soil compacting machine with a control device for carrying out the method.

Self-propelled soil compaction machines with pneumatic tires are used in road construction, for example as soil compaction machines. These usually include a machine frame, a driver's cab and driving devices, with at least one driving device having at least one wheel with pneumatic tires. Self-propelled soil compaction machines are not necessarily autonomous soil compaction machines, i.e. soil compaction machines that drive without a driver. Self-propelled within the meaning of the application refers to the fact that the soil compaction machines mentioned have a drive motor, for example an internal combustion engine, an electric motor or the like, which is part of a drive train for driving the driving devices in particular, and can therefore drive under their own power. Sensor devices for measuring operating parameters, such as driving speed or drive speed, of the soil compaction machine in driving operation are also usually present in self-propelled soil compaction machines, often for example for motor control and/or display of operating parameters, in particular driving parameters to the driver.

Generic soil compaction machines, in particular rubber-wheeled rollers or combination rollers, are used in road construction for compacting the ground and usually have at least one driving device with at least one rubber wheel. Combination rollers consist of a roller tire in combination with a set of rubber wheels, while rubber-wheeled rollers only have rubber wheels as both the front and rear driving devices. The compaction takes place when driving over the ground, in particular by the weight of the soil compacting machine, which weighs on the wheels and is transferred to the ground via the contact surface of the wheels. In order to increase this static compaction effect on the ground, it can be provided that, in addition to the empty weight of the soil compaction machine, it is weighed down with additional ballast before starting work in order to make it heavier and thus increase the machine weight-dependent static compaction effect on the ground. The selection of the extent of the ballasting can depend, for example, on the subsoil to be compacted or the subsoil layer to be compacted, for example the subsoil material, the layer thickness of the layer to be compacted, the temperature, etc. With such soil compaction machines it can be provided that the machine weight is Ballasting is increased by a multiple of the empty machine weight, so that depending on the amount of ballasting between empty weight and maximum ballasting, for example, a machine weight range of roughly approx. 5t to approx. 30t can be represented. The type of ballasting is also variable. For example, provision can be made for the machine to carry one or more liquid tanks, which can be filled with water, for example, to increase ballasting. In addition or as an alternative, it can be provided that bulk material or solid, for example plate-like, ballasting weights, for example made of metal or concrete, can be used for this purpose. In order to achieve the desired work result, it is now important on the one hand that the compacting and/or flexing effect on the subsoil produced by the at least one wheel is within the desired range. At the same time, it must be ensured that when driving over the soil, the compaction that has taken place does not damage the subsoil, such as the formation of furrows and/or lanes. Furrows can occur, for example, if the tire pressure of the wheels is too high and the weight of the roller rests on the ground over too small a contact area and presses it in too much when driven over. On the other hand, the tire pressure must not be too low either, otherwise the weight would be distributed over too large a contact surface, resulting in only a small compression effect, which significantly reduces the efficiency of the work process. Furthermore, the increased friction with insufficient tire pressure and too large a contact surface would result in higher fuel consumption and tire wear.

The tire pressure thus plays a central role in the operation of generic soil compaction machines. The tire pressure of the machine should be adjusted depending on the weight of the machine so that there is a high level of compaction. On the other hand, it should be ensured at the same time that no furrows are left in the ground by the soil compaction machine. Due to the fact that the ballasting of the machine can change between individual uses and/or throughout the work operation, for example due to increasing fuel and spray water consumption, or can be changed by the driver before and/or during use on a construction site , fluctuations in the optimal tire pressure can occur. With the change in the ballast, the machine weight changes, in some cases considerably, and with it the weight force acting on the at least one wheel. A further influencing factor with regard to a currently optimal tire pressure can also be the temperature, be it the temperature of the outside environment, the soil material to be compacted and/or the at least one wheel itself. The drivers of such soil compaction machines often roughly estimate the current machine weight and then, often based on this, estimate it based on subjective empirical values, the tire pressure.

From the prior art, for example from DE 11 2012 004 404 T5 , it is known to measure the machine weight directly by means of weight sensors additionally attached to the machine or to weigh the machine prior to operation. This method requires additional equipment. Alternatively, it is also possible to estimate the weight using level sensors in ballast tanks, as is the case, for example, in EP 1 493 599 A2 known for harvesting machines. This method is comparatively imprecise. These two methods are therefore only suitable to a limited extent for relieving the driver and for ensuring that optimal tire pressure is maintained throughout the work process, in order to avoid the formation of furrows in the soil to be compacted, for example.

It is therefore the object of the present invention to specify a possibility of improving the working result of a generic self-propelled soil compacting machine. However, this should not generate any additional work for the driver of the soil compaction machine.

The object is achieved with a method and a self-propelled soil compacting machine according to the independent claims. Preferred developments are specified in the dependent claims.

• - Ermitteln des Gewichtes der Bodenverdichtungsmaschine oder des Teilgewichtes, das auf mindestens einem mit einem Ist-Reifendruck aufweisenden Rad lastet, unter Berücksichtigung mindestens eines vom Gewicht der Bodenverdichtungsmaschine abhängigen und über einen Sensor erfassten Fahrbetriebsparameter der im Fahrbetrieb befindlichen Bodenverdichtungsmaschine;
• - Festlegen eines Sollreifendrucks anhand des ermittelten Gewichtes oder Teilgewichtes der Bodenverdichtungsmaschine;
• - Ermitteln des Ist-Reifendrucks mindestens einen Rades der Bodenverdichtungsmaschine;
• - Verändern des Ist-Reifendrucks des mindestens einen Rades, so dass sich der Ist-Reifendruck dem Sollreifendruck annähert.

Specifically, the method according to the invention includes the steps:

• - Determining the weight of the soil compaction machine or the partial weight that weighs on at least one wheel having an actual tire pressure, taking into account at least one driving operation parameter of the soil compaction machine in operation that is dependent on the weight of the soil compaction machine and is detected by a sensor;
• - Setting a target tire pressure based on the determined weight or partial weight of the soil compaction machine;
• - Determining the actual tire pressure of at least one wheel of the soil compaction machine;
• - Changing the actual tire pressure of the at least one wheel, so that the actual tire pressure approaches the target tire pressure.

The at least one wheel is thus filled with a gaseous fluid, in particular air. For this purpose, the at least one wheel comprises an enclosed cavity and at least one valve in a manner known per se. In particular, the at least one wheel is a rubber wheel. All wheels of the soil compaction machine can be identical.

The weight of the soil compacting machine or the partial weight that weighs on the at least one wheel is the physical mass or the weight force, since in practice it makes no difference which size is used. Furthermore, the mass of the soil compaction machine can be the total mass of the soil compaction machine including or without the wheels. Likewise, the weight of the soil compaction machine can include the total weight that weighs on the ground, i.e. including the wheels, or the weight that weighs on all wheels, i.e. without the wheels. Since the wheel weight (mass or weight force) is constant and known, it can easily be taken into account in the method when determining the weight of the soil compaction machine and determining the target tire pressure. The partial weight is the part of the weight or the weight of the soil compaction machine that bears on the at least one wheel. Conventionally, machine design attempts to distribute the weight of the soil compactor among all wheels of the soil compactor in substantially equal proportions to allow all wheels to engage the soil evenly. Thus, in practice, in the method according to the invention, the weight of the soil compaction machine and the number of wheels can also be used, at least approximately, to deduce the partial weight or the partial weight force acting on the at least one wheel. In the following, all constellations described in this paragraph should be taken into account when formulating weight or partial weight.

The core of the invention is the weight determination in the first step of the method. Here, the weight of the soil compaction machine or the partial weight that weighs on the at least one wheel over at least one travel bed friction parameters of the moving soil compaction machine are determined. The invention is thus based on the knowledge that driving operation parameters correlate with the current machine weight and therefore allow the current machine weight to be inferred. In other words: The invention makes use of the fact that the driving behavior of the machine changes depending on the weight. A driving operation parameter is now determined during driving operation and the machine weight is deduced from the current driving behavior. In the present case, driving operation parameters therefore refer to those operating parameters of the soil compacting machine that influence the driving operation of the soil compacting machine. Driving parameters are in particular those driving parameters that affect the driving speed of the soil compacting machine, in particular driving parameters correlating with an acceleration of the soil compacting machine. To this end, it is noted as a precaution that in the present case acceleration of the soil compacting machine from a standstill while driving is also included, as are acceleration processes from an initial speed to another speed. In particular, at least one acceleration, preferably several accelerations, should occur during driving operation, ie in particular the drive motor should be operated under towing load or in towing mode. The other way round: The relevant driving operation parameters in this case are driving operation parameters that are dependent on the machine weight or correlate with it. It is preferred here if the soil compacting machine is in driving operation over a defined period of time, ie over a time-defined measurement interval, so that the weight/partial weight can be determined in the manner according to the invention. The specific duration of the time interval depends on the practical application and results essentially from more metrological considerations, namely from when a sufficiently accurate result of the respective operating parameter is available. Driving operation also includes starting from a standstill. According to the invention, the at least one driving operation parameter is a parameter that is associated with the driving operation or can be measured during the driving operation and varies depending on the weight, ie behaves or develops differently depending on the current machine weight compared to another machine weight. Depending on the weight of the soil compacting machine, the at least one driving operation parameter changes under the given operating conditions. As a result, the weight of the soil compaction machine or the partial weight that weighs on the at least one wheel can also be determined indirectly based on the measurement of the at least one driving operation parameter.

Since the at least one driving operation parameter is detected by a sensor, it is preferred that it is a driving operation parameter that is usually already present in generic soil compaction machines or is already determined in conventional machine operation, but is (also) used in the present case to determine the weight . It is therefore not necessary, although in principle possible, to attach an additional sensor to the soil compacting machine in order specifically to carry out the method according to the invention. This advantageously saves both resources and effort. Of course, several operating parameters or other parameters and specifications that may be necessary for the specific determination of the machine weight and/or that improve the accuracy of the weight determination can also be taken into account and included in the determination of the machine weight. It is also possible for the driver to specify values/parameters in advance, in particular specifications that are essentially constant. This can be, for example, data on the wheel diameter, the number of wheels, data on rough ballast conditions, etc.

The at least one driving operation parameter can in particular be a driving drive parameter. A driving drive parameter designates a driving operation parameter from the drive train of the soil compacting machine. A traction drive parameter can be a torque parameter or torque value, in particular the torque currently applied to a part of the drive train, in particular the traction drive train, for example the torque of the drive, in particular specifically the crankshaft, and/or the wheel torque of the at least one wheel and/or the torque a drive torque-transmitting element, for example a shaft, a transmission, etc. The drive train designates that transmission section via which the drive torque generated by the drive is transmitted to the at least one wheel. If the drive of the soil compacting machine includes an electric motor, the at least one operating parameter can also be the voltage and/or current of the electric motor, for example. If the drive of the soil compacting machine includes a hydraulic motor, the at least one operating parameter can also be the fluid pressure or the fluid pressure drop or fluid pressure increase of the hydraulic fluid driving the hydraulic motor. The background to this development is the fact that the torque required for a given speed change depends on the weight of the soil compacting machine. The heavier the soil compactor due to the current ballast, the bigger is the torque to be applied for speed changes. It is possible to determine the torque directly or operating parameters correlating with the current torque, such as a voltage and/or current intensity or their drop at an electric motor, the hydraulic fluid pressure or pressure drop applied to a hydraulic motor. It is also possible to use an operating parameter that correlates with the current drive torque.

The determination of the acceleration of the soil compacting machine can also be a driving operation parameter to be taken into account, with positive accelerations being included here in particular, ie phases in which the drive motor is in traction operation. The heavier the soil compaction machine or the greater the weight of the soil compaction machine, the greater the energy expenditure required to accelerate the machine. It is thus possible to draw conclusions about the weight of the machine from a correlation between the acceleration of the soil compacting machine and the energy required for this change in speed or the drive torque. The advantage of this approach is that the machine weight can be derived from driving operation parameters, such as acceleration and a torque specification, for example a torque, from the driving operation of the soil compaction machine without an actual and comparatively complex direct measurement of the machine weight. In particular, this also allows the weight of the machine to be determined again while driving or working, so that adjustments to changes in the weight of the machine due to ongoing operation, for example due to the consumption of water and/or fuel, are possible without interrupting the ongoing work process. It goes without saying that, in addition to the direct determination of an acceleration, this can also be derived from the driving speed and/or change in driving speed over a time interval.

Depending on the design of the transmission train and/or the respective measuring point, the driving operation parameter can additionally or alternatively also be derived from a speed of a part of the drive train, for example the speed of a crankshaft or other rotating part of the drive train, and/or the wheel speed of the at least one wheel. For example, a transmission ratio from the wheel speed and the drive motor speed can also be included as a factor in the calculation of the machine weight.

In order to further improve the precision of the method according to the invention, it is possible to additionally or alternatively consider further operating parameters and/or operating factors. For example, it is possible to include information about the position of the soil compaction machine when determining the machine weight. For this purpose, it is generally known to use suitable position sensors, in this case in particular for determining the horizontal position of the soil compacting machine. In this way, inaccuracies in the weight determination caused by driving uphill and/or downhill and/or inclined positions of the soil compaction machine transversely to the longitudinal axis (i.e. transversely to the forward direction) can be eliminated. Operating factors, on the other hand, are static, machine-internal specifications that do not change in different operating states of the soil compaction machine. This can be the wheel diameter, the number of wheels, etc., for example.

Accordingly, the sensor by means of which the at least one driving operation parameter is recorded can be, for example, a torque sensor and/or a speed sensor and/or a speed sensor and/or an acceleration sensor and/or a voltmeter and/or a current meter and/or a Act fluid pressure measurement sensor. The torque sensor and speed sensor may be sensors attached to at least one wheel to sense wheel speed and wheel torque, respectively. The torque sensor and the speed sensor can also be sensors that are attached to the drive train in order to measure the speed or the torque of a part of the drive train. For this purpose, the sensors can be attached, for example, to the drive, in particular to a flywheel of the drive, to the drive shaft and/or to the transmission of the drive train. The fluid pressure measurement sensor for measuring the fluid pressure or the fluid pressure change of a hydraulic motor can be positioned in the hydraulic system, for example, in such a way that it determines the current fluid pressure at the pump inlet and/or at the pump outlet and/or at the hydraulic motor inlet and/or outlet and/or in the fluid line.

In principle, it is possible to connect the sensor(s) to the on-board network of the soil compaction machine to supply it with electrical energy. However, it is also possible to use an approach that is self-sufficient from the on-board network for the energy supply, for example with the help of suitable accumulators and/or generators that derive energy from movements of the soil compaction machine, such as a linear generator etc.

In principle, the method can be carried out with recourse to computer-aided processing of the determined operating parameters and factors. For this purpose, a determination algorithm can be provided, for example, which determines the current machine weight from the available operating parameter(s) based on the above-described correlation with the machine weight and possibly other specifications, and based on this determines the currently optimal target tire pressure. In addition or as an alternative, it can also be provided that one or more stored characteristic diagrams or the like are used for this purpose. In concrete terms, it can be provided that the target tire pressure is established, for example, by means of a predefined table of values from permissible tire pressures and the corresponding weights, as described above. In order to determine the desired tire pressure, the determined weight of the soil compacting machine or the partial weight that weighs on the at least one wheel can be compared with the specified weight values in the table or a characteristic diagram. The value from the table or characteristic curve that is the same or most similar to the determined weight/partial weight can be selected in order to determine the appropriate tire pressure according to the table or characteristic curve. This ascertained tire pressure is thus set as the target tire pressure.

The ascertained actual tire pressure of the at least one wheel is then changed so that it approaches the target tire pressure. According to a typical control process, the actual tire pressure of the at least one wheel is compared with the target tire pressure, for example. Here, for example, the difference between the actual tire pressure of the at least one wheel and the target tire pressure is determined and if this is not equal to 0, the actual tire pressure of the at least one wheel is changed so that it approaches the target tire pressure. This process can be carried out for at least one wheel and therefore also for all wheels. A tire pressure sensor, for example, can be used to measure the actual tire pressure of the at least one wheel. This tire pressure sensor can be attached to at least one wheel. Systems with which a tire pressure change can be achieved while driving in such soil compaction machines are, for example, from DE112012004404T5 known, to which reference is made in this context.

In a preferred embodiment, the weight of the soil compacting machine or the partial weight that is loaded on at least one wheel is determined, for example, at least approximately according to the following formula: m= _MA *k* _dx /a. Where m is the mass (or equivalently the weight according to the above statements), which is loaded on at least one wheel and/or the total weight of the machine, M _A is the torque of the drive of the soil compaction machine, k is a constant, the specified calculation variables, such as the radius of the wheel, and is, for example, its reciprocal. d _x denotes a speed or a speed ratio into which, for example, the speed of the drive or a part of the drive, for example the crankshaft, a transmission part transmitting drive torque or the like, the speed of the wheel etc. can flow into it. For example, this can be the transmission ratio of wheel speed and drive motor speed. a is the acceleration of the soil compaction machine, for example measured directly via an acceleration sensor or determined from the driving speed, for example using a speed sensor and/or a speed sensor and for example a timer etc. Thus, in the preferred exemplary embodiment, the torque M _A of the drive is recorded using a torque sensor. Furthermore, the acceleration a is preferably detected by means of an acceleration sensor. Alternatively, the driving speed v can be recorded using a speed sensor, the driving time t can be recorded using a time recording device (timer), and the acceleration can be calculated from the change in driving speed per unit of time t. Speeds of the at least one wheel or other elements can be detected using a speed sensor. According to a particularly preferred embodiment, the torque M _A of the drive engine and the engine speed are read out directly via the CAN bus of the electronically controlled diesel engine, which typically already determines these values and keeps them ready. In addition, when using a hydraulic travel drive, the wheel speed is preferably obtained directly from the speed sensor of the hydraulic motor, which is also already included as standard. In this way, all of the values to be determined are already available or can be determined from existing values, so that no additional sensor is required to implement the invention.

The acceleration of the soil compaction machine can be recorded within a specific measurement time window. Acceleration during start-up from a standstill or acceleration when the soil compaction machine is in motion can be recorded. Since the torque of the drive motor can typically only be determined in traction mode, positive accelerations are preferred in the present case. In the event that the torque of the drive motor also in driving conditions with nega tive acceleration can be determined, the invention can also be implemented with negative accelerations. In this case, the driving mode also includes braking of the soil compacting machine. Such situations would arise, for example, in the case of an electric motor with complete recuperation of braking energy.

Another variable to consider is temperature. Since the pressure inside the at least one wheel is also strongly temperature-dependent, it can be useful to include a temperature variable in the present method. For this purpose, it can be provided that the temperature of the ground, the temperature of the at least one wheel and/or the outside temperature is measured by means of a suitable temperature sensor in each case and that the target tire pressure is also determined as a function of the determined temperature(s). The temperature of the wheel can be the temperature of the wheel casing and/or the air inside the wheel.

Provision can also be made for the position of the machine to be determined and taken into account when determining the machine weight. For example, a longitudinal and/or a transverse inclination sensor can be provided. In this way, it is possible to determine whether the machine is currently moving on a horizontal surface or, for example, is driving uphill or downhill (which would ultimately affect the relationship between, for example, drive torque and acceleration, which can result in inaccuracies in determining the machine weight ). The control device can now be designed in such a way or the method according to the invention can be carried out in such a way that a weight determination either takes into account the horizontal position or current deviation from it when determining the machine weight or a weight determination is prevented, for example, until an at least adequate horizontal alignment of the machine is ensured . This can be signaled to the driver.

• - das ermittelte Gewicht der Bodenverdichtungsmaschine oder das ermittelte Teilgewicht, das auf dem mindestens einen Rad lastet;
• - der ermittelte Sollreifendruck;
• - der ermittelte Ist-Reifendruck des mindestens einen Rades;
• - die Differenz aus Ist-Reifendruck und Sollreifendruck;
• - die Veränderung des Ist-Reifendrucks zum Sollreifendruck;
• - ob das Verfahren aktiv ist.

In a further preferred exemplary embodiment, it is also provided that at least one of the following parameters is displayed to the driver in the driver's cab on a display device:

• - The determined weight of the soil compaction machine or the determined partial weight that weighs on the at least one wheel;
• - the determined target tire pressure;
• - The ascertained actual tire pressure of the at least one wheel;
• - the difference between the actual tire pressure and the target tire pressure;
• - the change of the actual tire pressure to the target tire pressure;
• - whether the procedure is active.

This serves to make operation easier for the driver or to make it easier for the driver to control the machine.

The method according to the invention can be triggered or initiated manually, for example by an operator or driver of the machine, or additionally or alternatively activated automatically. For example, the method can be activated automatically each time the soil compaction machine starts to move. Alternatively, the method can be activated while driving at predetermined time intervals and/or after specific distances covered and/or as a function of determined temperature differences or fluctuations. Furthermore, the method can also be activated after each ballasting or ballasting change and the subsequent initial start-up of the soil compacting machine.

The object is also achieved with a self-propelled soil compaction machine with pneumatic tires, preferably with a soil compaction machine, specifically a rubber-tyred roller or a combination wheel roller, which is designed to carry out the method according to the invention. A generic self-propelled soil compaction machine with at least partial pneumatic tires, in particular a rubber-tyred roller or a combination roller, comprises a machine frame, a driver's cab, front and rear driving devices, with at least one pneumatic-tired wheel being included in the driving devices, a drive motor, in particular a diesel internal combustion engine, especially as a part a hybrid drive system, a drive train that forwards the drive energy made available by the drive to the driving devices in a manner known per se, and at least one sensor device for measuring at least one driving operation parameter of the soil compaction machine that is in driving operation. All the features, effects and advantages described for the method according to the invention also apply in a figurative sense to the soil compacting machine according to the invention and vice versa. To avoid repetition, reference is made to the respective other versions.

The soil compaction machine also includes a tire pressure control system or at least tire pressure adjustment system with which the tire pressure of the at least one pneumatic wheel can be adjusted by the machine itself, ie without additional external devices not carried along with the machine. Such tire pressure control systems are known per se, for example from DE112012004404T5 and the EP1493599A2 . Tire pressure control systems of this type often include a control valve via which air can be supplied to and/or discharged from the wheel with pneumatic tires in order to increase or decrease the tire pressure. Furthermore, such a tire pressure system can have a compressor and/or a compressed air tank as the pressure source. It is also known to provide a pressure sensor, for example in a line and/or in the pneumatic wheel, in order to be able to determine the current pressure value of the pneumatic wheel. Furthermore, a suitable control device can be provided, which on the one hand receives the determined current pressure value (and is therefore in signal connection with the pressure sensor) and on the other hand is designed for manual and/or automatic control of the control valve, for example, in order to set the pressure value to a desired pressure value. The invention particularly relates to a rubber-tyred roller that has only pneumatic tires.

It is now essential that the soil compacting machine according to the invention comprises a control device which is designed to carry out the method according to the invention. The control device thus forms the interface between the determination of the at least one driving operation parameter and the control and/or regulation of the tire pressure. With regard to the individual method steps and preferred developments, reference is made to the above statements. In comparison to conventional systems, the control device according to the invention is therefore assigned a machine weight determination step, the weight determination taking place in the manner described above taking into account at least one driving operation parameter. The soil compaction machine is therefore not weighed, but the control device is used to draw conclusions about the machine weight based on at least one driving operation parameter, in particular, for example, the drive torque to be applied at a point in the drive system for a specific acceleration, or based on the current driving behavior of the machine the given operating conditions. In this way, the "weighing" of the machine can be circumvented in an elegant way and at the same time a sufficiently accurate statement can be made about the current machine weight for tire pressure control. Another major advantage is that the determination can be made while driving and can therefore also be carried out without delay or increased effort during ongoing work. Operational changes in weight, for example due to fuel and operating resource consumption, can thus be determined and taken into account without interrupting work operations.

The control device accordingly receives an input of recorded sensor data, in particular of the at least one driving operation parameter, the method according to the invention is carried out and, based on the machine weight thus determined, an output is generated by the control device, which in particular contains a target specification for the desired tire pressure. The input thus contains, for example, the at least one driving operation parameter of the soil compaction machine in driving operation required for (partial) weight determination and preferably also the actual tire pressure of the at least one wheel. Furthermore, the recorded temperature of the ground or the recorded temperature of the at least one wheel, for example the wheel casing or the air inside the wheel, can also be at least a supplementary input of the control device. In addition or as an alternative, other factors can also be taken into account, in particular those that are characteristic of the current operating state, specifically with regard to drive and driving operation. Based on the respectively suitable measuring sensors, which record the at least one driving operation parameter and possibly other parameters, such as the actual tire pressure and, for example, the temperature, the input is thus sent to the control device. Sensors are preferably used to measure the variables mentioned, which are already present in generic soil compacting machines, in particular for measuring the operating parameters of the soil compacting machine that is in driving operation. This can in particular be a torque sensor, for example, which determines a drive torque on the drive engine and/or in the drive train. Such a torque sensor is often already used for motor control, for example, and is therefore already available in many cases. With electronically controlled diesel engines, the drive torque is already determined, for example via the injection quantity. The engine speed is already determined and is available for electronic (data) processing via the CAN bus of the drive engine. The same applies to a speed and/or acceleration sensor. These are often already available to display the current driving behavior of the soil compaction machine to the driver and their measured values are often already used, for example, as part of the motor control and/or the energy management system of the machine. Alternatively, of course, separate, additional measuring sensors can also be provided, which specifically only in the scope of the method described above, in particular, for example, to measure the actual tire pressure and/or temperatures such as the external environment, tire and/or ground surface. In addition or as an alternative, one or more position sensors can also be included, which determine position information, in particular with regard to the longitudinal and/or transverse inclination of the machine, and transmit it to the control device. The output can therefore in particular be a control specification that the actual tire pressure is approximated to the specified setpoint tire pressure.

A tire pressure adjustment system or tire pressure control system can preferably be provided as part of the soil compaction machine, which is designed in such a way that it can be used to change the actual tire pressure of the at least one wheel. Accordingly, the tire pressure setting system contains the output that the control device generates in order to set the tire pressure of the at least one wheel. The control device thus controls the tire pressure adjustment system based on the method carried out for regulating the tire pressure. As already described above, such a tire pressure adjustment system usually includes at least one control valve and a compressed air source, such as a compressor. It goes without saying that the tire pressure adjustment system can be designed in such a way that individual tire pressure regulation of all existing pneumatic tires is possible.

Furthermore, the soil compacting machine preferably includes a switching device, by means of which the implementation of the method can be manually activated or initiated and/or deactivated. Here, the control device receives the input to start the method. It is also possible for the operator to use the switching device to give a signal that the machine has been reballasted. Based on this, the method can then be carried out at intervals as described above. It is also possible for the control device to be designed in such a way that the method according to the invention is initiated based on time and/or depending on the distance travelled.

The soil compacting machine is particularly preferably a rubber-wheeled roller with at least two, in particular at least three, front and rear pneumatic wheels. It is particularly optimal if the soil compaction machine only has pneumatic tires.

• 1 eine Seitenansicht einer Bodenverdichtungsmaschine zur Asphaltverdichtung, konkret eine Gummiradwalze;
• 2 eine Vorderansicht einer Bodenverdichtungsmaschine zur Asphaltverdichtung, konkret eine Gummiradwalze;
• 3 ein Verfahrensablaufdiagramm zum Regeln des Reifendrucks;
• 4 eine Detailansicht einer Steuervorrichtung;
• 5 ein Zeit-Geschwindigkeit-Beschleunigung-Antriebsdrehmoment-Diagramm;
• 6 ein Vergleichsdiagramm vom Beschleunigungsverhalten der Maschine bei verschiedenen Maschinengewichten bei gegebenen Antriebsdrehmomenten; und
• 7 Gewicht-Reifendruck-Diagramm.

The invention is described in more detail below with reference to the exemplary embodiments specified in the figures. They show schematically:

• 1 a side view of a soil compaction machine for asphalt compaction, specifically a rubber wheel roller;
• 2 a front view of a soil compaction machine for asphalt compaction, specifically a rubber wheel roller;
• 3 a process flow chart for controlling the tire pressure;
• 4 a detailed view of a control device;
• 5 a time-velocity-acceleration-driving torque diagram;
• 6 a comparison diagram of the acceleration behavior of the machine with different machine weights at given drive torques; and
• 7 Weight vs tire pressure chart.

Identical elements are provided with the same reference symbols in all figures. Repeating elements are sometimes not identified separately in each figure;

In 1 and 2 is a self-propelled soil compaction machine 1, specifically a rubber-tyred roller, with a machine frame 3, a control station 2, front and rear driving devices 5 and 6 with pneumatic wheels 8, and a drive motor 4. The drive motor 4 can be a diesel internal combustion engine or another motor for generating drive energy. It can also be designed as a hybrid system. is indicated in 1 furthermore, a drive train 10, which transmits the drive energy generated by the drive motor 4 to one or more of the existing wheels. This drive train can be designed mechanically, hydraulically, electrically or in combination. With the help of the drive train, drive energy generated by the drive motor 4 is ultimately converted into a rotational movement of the wheels and the machine advance is thereby achieved.

Furthermore, in 1 a control device 9 is shown. The control device 9 can, for example, have a signal connection to the drive motor 4, for example via a CAN bus, and receive suitable sensor data from it, for example data on driving parameters such as the drive torque, the speed, etc. One or more suitable sensors 11 can be present for this purpose. In addition or as an alternative, the control device can also obtain driving parameters from the drive train 10 using one or more of the sensors 12, such as torque, speed and/or acceleration data. Also add Finally or alternatively, the control device can also receive driving operation parameters from one or more sensors 13 from one or more of the wheels 8 and/or their bearings, such as torque, speed and/or acceleration data. In addition, temperature data, such as the temperature of the floor surface and/or one or more wheels 5, 6, can be recorded using a suitable temperature sensor 13 and transmitted to the control device 9. Furthermore, one or more pressure sensors 14 can be present, which measure the actual tire pressure of one or more of the air-filled wheels 5, 6 and transmit it to the control device. Furthermore, a tire pressure control system 15 can be provided, which allows the inflation pressure of one, several or all of the wheels 5, 6 to be changed. The construction and functioning of a tire pressure control system 15 are known per se. A suitable pressure source (for example a compressor) can thus be in air-conducting connection with the wheels. Furthermore, suitable control valves can be provided via which filling and/or deflation of air from one, several or all of the pneumatic wheels 5, 6 is possible. Provision can also be made for one or more position sensors 18 to be present and to have a signal connection to the control device 9 . For example, the longitudinal and/or transverse inclination of the machine relative to a horizontal reference surface can be determined with the aid of the position sensors 18 .

An input and/or display device 16 with a signal connection to the control device 9 can also be provided in the control station 3, via which data, for example, in particular constant data, such as a wheel diameter, setpoint values for the tire pressure, etc., ballast specifications, can be input and/or the implementation of the method described in more detail below can be initiated and/or a choice can be made between different operating modes of the control device 9 (for example between “time-dependent” or “distance-dependent”). Additionally or alternatively, information can be displayed to the driver in the driver's cab, such as the activity status of the control device 9, current measured values, current determination values, in particular weight values, ballasting information, filling levels, etc. With the help of specified ballasting specifications, for example rough filling levels of filled ballast chambers and/or the indication of recorded weighting elements, it is also possible, for example, to carry out a plausibility check on the weight values determined by the control device 9 and/or to design the control device 9 in such a way that it automatically carries out such a plausibility check. Specifically, it can be checked here, for example, whether there is a contradiction between the weight information entered by the driver and the weight information determined by the control device 9 (e.g. the machine weight is determined to be lighter than should actually be the case with the ballast specifications specified by the driver).

Rubber-tyred rollers of this type are typically provided for compacting in road construction, in particular for compacting asphalt mats, during which they travel over a ground 7 to be compacted. Before starting work, the soil compaction machine 1 can be loaded with ballast. The higher the ballasting of the machine, the greater the static compaction effect on the subsoil. Typical orders of magnitude of the ballasting of special rubber-tyred rollers can enable the machine to cover a weight range from approx. 5t (empty weight) to approx. 30t (maximum refueling and ballasting). The weight G1 or the mass of the soil compaction machine 1 rests on the wheels 8. Together with the own weight of the wheels, the total weight G is passed on to the ground via the wheels or they exert a corresponding vertically downward weight force on the ground. This weight transfer and a kneading and flexing effect emanating from the wheels 8 lead to a compaction of the soil material when driving over the soil 7 in and counter to the forward direction f. Usually, these machines are used reversing. In order to ensure a homogeneous compaction result, it is important to adjust the tire pressure of the wheels 8 depending on the weight G1/G of the soil compaction machine 1. The machine shown now makes it possible, with the aid of the control device 9, to determine the weight G1/G of the soil compaction machine while driving and, based on this determination of the weight, a tire pressure for the wheels 8 is set in such a way that a good compaction effect is achieved without irregularities such as Furrows appear in the ground.

3 illustrates details of the method according to the invention and preferred developments. The method is carried out in particular by the control device 9, in particular taking into account the at least one driving operation parameter and possibly further inputs or input signals (“input”). goal of the in 3 The method illustrated is to regulate the tire pressure as a function of the weight G of the soil compacting machine, the current machine weight being determined by the control device 9, in particular also taking into account the driving operation of the machine. on the ground Based on the determined machine weight (step s1), the control device 9 can define a target tire pressure value (step s2), for example by resorting to a corresponding machine weight/tire pressure characteristic diagram and/or target tire pressure values stored in some other way, and taking into account at least one current actual Tire pressure value (determining the same in step s3) generate control signals, in particular for a tire pressure control system, to approximate the current actual tire pressure value of the at least one pneumatic wheel to the target tire pressure (step s4). This can be done individually for at least one wheel with pneumatic tires, for several or all wheels with pneumatic tires individually or in groups, or for all wheels comprehensively.

If the soil compaction machine 1 accelerates from a standstill or while it is already being driven (both are referred to as "driving mode" in the present case), the at least one driving mode parameter of the machine that is in driving mode is detected via a sensor arranged for this purpose on the soil compacting machine (in 3 not shown) recorded and transmitted to the control device 9.

4 shows the control device 9, by means of which the above-mentioned method for regulating the tire pressure of the wheels 8 depending on the weight G/G1 of the soil compacting machine, is carried out in a greatly simplified form. The control device 9 receives input signals and sends out output signals or control signals. Both input signals and output signals can consist of several signals or of one signal each. The weight determination and control process 3 takes place within the control device 9, which controls a tire pressure adjustment system using the output generated by the control process. This tire pressure adjustment system adjusts the tire pressure of the wheels 8 based on the output of the control device 9 . The control device 9 can also be designed as part of the tire pressure control system. The input I1 consists, for example, of the detected operating parameters of method step s1, for example a torque signal from the drive train and/or an acceleration signal and/or a speed signal and/or a time signal. The input I2 consists, for example, of the actual tire pressure recorded in method step s3. Both input signals I1 and I2 are transmitted to the control device by their respective sensors or sensor devices. The output O1 is, for example, information about the extent to which the actual tire pressure is changed so that it approaches the target tire pressure.

5 FIG. 12 illustrates, for example, at which points in time or in which time windows operating parameters can be measured for the purpose of method step s1 and how these behave with a specific machine weight. The driving operation parameter of the acceleration of the vehicle is shown in the middle. Alternatively, for example, the speed or its change over a time interval of the acceleration a, for example the acceleration a or the speed v per time t within the time window t1 to t2, the start of the soil compaction machine, and/or t3 to t4, an acceleration while driving, and/or t5 to t6, when braking the machine with a negative acceleration, in particular, for example, via the engine brake. The behavior of the machine in these operating phases, for example, also depends to a large extent on the machine weight. A heavier machine with the same drive torque accelerates more slowly than a comparatively slower machine. Likewise, the braking deceleration or negative acceleration, for example when braking the machine via the engine brake, is lower in a heavier machine than in a lighter machine. It is also possible to determine the weight in phases with no acceleration, since a weight-dependent torque from the drive train is then also required to maintain a given driving speed. The use of phases of negative acceleration presupposes that the torque required for braking can also be determined in these phases. This is not determined with normal diesel engines, so that the phases of negative acceleration can only be used for the calculation in special cases, for example with an electric motor with full recuperation. For the sake of completeness, the phases of negative acceleration are nevertheless described here.

The triggering of the measurement intervals for determining the machine weight can be initiated manually by the driver and/or, for example, by the control device 9, for example triggered by the operating situation (e.g. "starting off") and/or time-controlled and/or distance-controlled, with the control device 9 then, for example, in such a way can be programmed so that it only determines the machine weight when the operating situation is optimally suited for this.

6 outlines the acceleration behavior for one and the same machine weight at ver different drive torques M1, M2 and M3. It goes without saying that the acceleration of the machine turns out to be greater, the higher the applied drive torque. A comparable relationship arises when different machine weights are considered. Then the acceleration at a given drive torque is smaller with increasing machine weight or increasing ballasting. This at least one driving operation parameter is subsequently used to determine the weight G of the soil compacting machine (s1). From the determined weight G, a target tire pressure corresponding to the weight G is established. For example, a table or characteristic curve of weight and tire pressure or the like previously stored in the control device is used to determine the desired tire pressure.

An exemplary characteristic curve from the weight G of the soil compaction machine and tire pressure p is shown in FIG 7 illustrated. Gmin and Gmax each indicate the minimum weight (empty weight of the machine) and the maximum weight (maximum ballasting and full operating resources and fuel tanks) that a soil compaction machine 1 may have after ballasting in order to be used in operation. Gmax thus limits the weight of the soil compacting machine 1 with regard to traffic safety and furrow formation. With a weight higher than Gmax, furrow formation can no longer be avoided despite tire pressure control. This can, for example, also be determined and recognized by the control device 9 and signaled to the driver, for example optically, acoustically and/or via an intervention in machine functions (for example active throttling of the driving speed, blocking of starting, etc.).

Regarding the in 3 Illustrated method, it can alternatively also be provided that when determining the target tire pressure, the temperature of the ground and/or the at least one wheel is determined (s5), which is then also taken into account when determining the target tire pressure (s2'). Thus, the tire pressure is adjusted not only depending on the weight G/G1 but also on the temperature of the ground and/or the wheels. For this purpose, a table or a characteristic map of weight, tire pressure and temperature can be stored in the control device. In order to control the tire pressure according to the target tire pressure, the actual tire pressure of the wheels 8 is first determined via a sensor (not shown) attached to the wheels 8, for example. The actual tire pressure is subsequently changed to such an extent that it approaches the target tire pressure. On the other hand, if the actual and target tire pressures are identical, the actual tire pressure is not changed. It is also possible to record and take into account location parameters, for example longitudinal and/or transverse inclination.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 112012004404 T5 [0005, 0020, 0029]
• EP 1493599 A2 [0005, 0029]

Claims (13)

Method for controlling the tire pressure of a self-propelled soil compacting machine (1) with pneumatic tires, in particular a rubber-tyred roller or a combination roller, comprising the following steps: - Determination of the weight (G, G1) of the soil compaction machine (1) or the partial weight that is loaded on at least one wheel (8) that is filled with an actual tire pressure, taking into account at least one of the weight (G, G1) of the soil compaction machine (1) dependent driving operation parameters detected by a sensor of the soil compacting machine (s1) in driving operation; - Defining a target tire pressure based on the determined weight (G, G1) of the soil compacting machine (1) or based on the partial weight that weighs on at least one wheel (8) (s2); - Determining the actual tire pressure of the at least one wheel (8) of the soil compaction machine (s3); - Changing the actual tire pressure of the at least one wheel (8) so that the actual tire pressure approaches the target tire pressure (s4). procedure according to claim 1 , characterized in that the determination of the weight (G, G1) of the soil compacting machine (1) and/or the partial weight that bears on at least one wheel by means of the formula $$\text{m}={\text{M}}_{\text{A}}*\text{k}*{\text{i.e}}_{\text{x}}\text{/a}$$

takes place, where m is the mass that weighs on at least one wheel (8), MA is the torque of a drive (4) of the soil compacting machine (1), k is a constant, d _x is a speed value or a speed ratio and a is the acceleration of the moving soil compacting machine ( 1) is. procedure according to claim 2 , characterized in that the determination of the weight (G, G1) and/or the partial weight that weighs on at least one wheel comprises at least one of the following steps: - detecting the torque M _A of the drive (4) by means of a torque sensor; - detecting the acceleration a by means of an acceleration sensor or calculating the acceleration from a driving speed v detected by means of a speed sensor per time t determined by means of a time recording device; - Detecting the speed d ₁ of the drive (4) by means of a speed sensor; - detecting the speed d ₂ of the at least one wheel (8) using a speed sensor or calculating the speed d ₂ of the at least one wheel (8) from a driving speed v detected using the speed sensor. Method according to one of the preceding claims, characterized in that the temperature of the floor (7) and/or the temperature of the at least one wheel (8) is measured using at least one temperature measuring device (s5) and that the specification of the target tire pressure is dependent on the temperature of the floor (7) and/or as a function of the temperature of the at least one wheel (8) (s2'). Method according to one of the preceding claims, characterized in that the method at least - after each ballasting and/or ballast change of the soil compacting machine (1); - and/or when driving is started; - and/or takes place at regular intervals during driving; - and/or activated manually by the driver. Method according to one of the preceding claims, characterized in that at least one of the following parameters is displayed on a display device: - the determined weight (G, G1) of the soil compaction machine (1) and/or the partial weight that is on at least one wheel (8) weighs,; - the determined target tire pressure; - the determined actual tire pressure; - the difference between the actual tire pressure and the target tire pressure; - the change of the actual tire pressure to the target tire pressure; - whether the procedure is active. Self-propelled soil compacting machine (1) with pneumatic tires, in particular a rubber-tyred roller or a combination roller, comprising - a machine frame (3), - an operator's platform (2), - front and rear driving devices (5, 6), the driving devices (5, 6) having at least have a wheel (8) with pneumatic tires, - a drive motor (4), - a drive train which transmits the drive energy made available by the drive motor to the driving devices (5, 6), and - at least one sensor device for measuring at least one operating parameter of the driving devices Soil compaction machine (1), characterized in that a control device (9) for carrying out the method of one of Claims 1 until 6 is provided. Self-propelled soil compaction machine (1) with pneumatic tires according to claim 7 , characterized in that at least one tempera Tower measuring device for measuring the temperature of the ground (7) and / or the at least one wheel (8) is provided and that the control device (7) carrying out the method according to claim 4 makes. Self-propelled soil compaction machine (1) with pneumatic tires according to one of Claims 7 or 8th , characterized in that the sensor device - a torque sensor for measuring the torque M _A of the drive (4); - And/or a torque sensor for measuring the torque of the at least one wheel (8); - And/or a speed sensor for measuring the speed d ₂ of the at least one wheel (8); - And / or a speed sensor for measuring the speed d ₁ of the drive (4); - And/or a speed sensor for measuring the driving speed v of the soil compacting machine (1); - and/or an acceleration sensor for measuring the acceleration a of the soil compacting machine (1). Self-propelled soil compaction machine (1) with pneumatic tires according to claim 9 , characterized in that the sensor device for measuring the torque M _A - on the drive (4), in particular on the flywheel of the drive (4), - on the drive shaft; - is arranged on the gearbox of the drive train and/or is positioned in such a way that torque values are derived from one of these devices. Self-propelled soil compaction machine (1) with pneumatic tires according to one of claims 9 or 10 , characterized in that the drive (4) consists of a hydraulic motor and that the sensor device comprises a sensor for measuring the fluid pressure and/or the fluid pressure change of the hydraulic fluid and is arranged at the pump inlet and/or at the pump outlet and/or in the fluid line. Self-propelled soil compaction machine (1) with pneumatic tires according to claim 9 , characterized in that the drive (4) comprises an electric motor and that the sensor device comprises a voltmeter and / or an ammeter for measuring the voltage and / or the current of the electric motor. Self-propelled soil compaction machine (1) with pneumatic tires according to one of Claims 7 until 12 , characterized in that a display device is designed to display at least one of the following parameters: - the determined weight (G, G1) of the soil compacting machine (1) and/or the partial weight that weighs on at least one wheel (8); - the determined target tire pressure; - the determined actual tire pressure; - the difference between the actual tire pressure and the target tire pressure; - the change of the actual tire pressure to the target tire pressure; - Whether a method, in particular the method according to one of Claims 1 until 6 , for tire pressure control is active.

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