SOIL PREPARATION MACHINE

Description

[0001] The present invention relates to a soil cultivation machine, such as a soil compactor, which can be used to compact the subsoil material, such as asphalt, soil or gravel.

[0002] An example of such a soil cultivation machine designed as a soil compactor is in Fig. 1 This soil cultivation machine 10, designed as a soil compactor, is constructed with a rear carriage 12 and a front carriage 14 pivotally connected to the rear carriage 12 about an approximately vertical steering axis. Drive wheels 16 are provided on the rear carriage 12, which can be driven to rotate the soil compactor 10 on the subsoil 18 to be compacted. A soil cultivation roller 20, designed as a compaction roller, is rotatably mounted on the front carriage 14. In the Fig. 1 In the illustrated configuration of a soil compactor, the soil cultivation roller 20 can, for example, be driven to rotate. Alternatively, the soil cultivation roller 20 can roll over the surface 18, propelled only by the drive wheels 16. For example, in a soil compactor where a compaction roller is also provided on the rear carriage 12, one or both compaction rollers could be driven to rotate in order to move the soil compactor over the surface 18.

[0003] The rear carriage 12 also includes an operator's platform 22, in which an operator can sit on an operator's seat 24 to operate the soil compactor. The operator's platform 22 also includes various actuating devices, which will be explained below, by means of which an operator seated on the operator's seat 24 in the operator's platform 22 can operate the soil compactor. Generally, such soil compactors have a drive unit designed as a diesel internal combustion engine on the rear carriage 12. It should be noted that, for the purposes of the present invention, the rear carriage 12 is considered the system area of ​​a soil compactor on which such a drive unit and / or the operator's platform 22 are located.In a soil compactor designed as a articulated tandem roller, in which a steering yoke, rotatably supporting a soil cultivation roller, is mounted on a frame area provided in the middle region of the soil compactor and generally supporting a drive unit and an operator's platform, in each of its two end regions, this centrally arranged area of ​​the soil compactor, which pivotably supports the two steering yokes, is to be regarded as the rear carriage in the sense of the present invention.

[0004] The drive unit powers one or more hydraulic pumps to supply pressurized fluid to various hydraulic circuits. For example, a travel hydraulic circuit can be provided, through which hydraulic motors assigned to the drive wheels 16 can be supplied with pressurized fluid to move the soil compactor over the ground 18. If such a soil compactor has one or more rotating compaction rollers or soil cultivation rollers 20, these can also be assigned hydraulic motors to drive their rotation. Another hydraulic circuit can be used to drive an unbalance system in the soil cultivation roller 20. Such an unbalance system, which can be designed to generate an oscillating and / or vibrating motion of the soil cultivation roller 20, can also include one or more hydraulic motors to drive the unbalanced masses to rotate.Another hydraulic circuit can be assigned to a steering system. The pressurized fluid present in such a steering hydraulic circuit can, via a hydraulic steering unit, direct hydraulic fluid to one or two steering piston / cylinder units 28, which act as steering elements 26, depending on a steering movement of a steering actuating device, for example, a steering wheel. By means of such steering piston / cylinder units 28, the front carriage 14 and the rear carriage 12 are pivoted relative to each other about the steering axis, thereby steering the soil compactor as it moves over the ground 18.

[0005] From WO 2020 / 200509 A1, a soil cultivation machine according to the preamble of claim 1 is known, in which a steering hydraulic pump driven by an electric motor is provided in association with a hydraulic steering system. A drive hydraulic pump driven by an electric motor is provided in association with a hydraulic drive system.

[0006] DE 10 2007 016 112 A1 discloses a method for controlling a hydraulic pump in a servo system associated with a steering system and a braking system. The speed of a hydraulic pump in the servo system is adjusted depending on a steering or braking request and also depending on the vehicle speed. DE 29 50 391 A1 discloses a hydrostatic transmission in a motor vehicle in which a pump driven by a drive unit generates the hydraulic pressure in a hydraulic circuit for operating a hydraulic pump associated with a drive system and the hydraulic pressure for a steering system. The object of the present invention is to provide a soil cultivation machine with which a hydraulic steering system and a hydraulic drive system can be operated with reduced energy consumption and adapted to the requirements.

[0007] According to the invention, this problem is solved by a soil cultivation machine, in particular a soil compactor, according to claim 1. The soil cultivation machine comprises a hydraulic steering system with at least one steering element actuated with pressure fluid and an electrohydraulic pressure fluid source with at least one steering hydraulic pump driven by at least one electric motor for feeding pressure fluid into a steering hydraulic circuit.

[0008] In a soil cultivation machine constructed according to the invention, the energy for operating the hydraulic steering system is provided by an electric motor powered by a battery or similar source. Compared to using a diesel engine, such an electric motor as a drive for a steering hydraulic pump has the advantage that the electric motor can be operated in accordance with the current energy or pressure fluid demand and, by spontaneously changing its speed, offers the possibility of adjusting the quantity of pressure fluid delivered to changing requirements. Such short-term changes are not possible with a diesel engine due to changes in its operating state.Nevertheless, the hydraulic steering system according to the invention offers the advantage, due to the inclusion of the steering hydraulic circuit, for example in comparison to purely electrically operated steering systems, that an emergency steering capability can be maintained, and that such a hydraulic steering system has a particularly high overload or shock resistance and provides an operator with mechanical feedback of the currently existing steering state or a steering movement.

[0009] The soil cultivation machine constructed according to the invention can comprise a rear carriage and a front carriage pivotable about a steering axis relative to the rear carriage, wherein at least one steering element acting between the front carriage and the rear carriage comprises a steering piston / cylinder unit. As already mentioned at the outset, it is advantageous to provide two steering elements, for example designed as steering piston / cylinder units, wherein one or both of these steering elements can be double-acting, i.e., acting in both directions of actuation.

[0010] In order to convert the actuation of a steering control device, such as a steering wheel, by an operator into a corresponding adjustment movement of a steering element, the hydraulic steering system can include a hydraulic steering unit, wherein the hydraulic steering unit is supplied with pressurized fluid from the steering hydraulic circuit and, depending on the actuation of a steering control device, supplies at least one steering element with pressurized fluid.

[0011] The hydraulic steering system comprises at least one steering sensor, wherein the steering sensor is configured to provide steering information representing a steering state. For example, such a steering sensor can detect the rotation of a steering shaft. The steering information represents a steering angle and / or a steering angle change rate. It should be noted that, within the meaning of the present invention, a steering angle change rate represents a change in the steering angle over time, for example, the change in the rotational position of a steering shaft over time or the change in the angle assumed between the front and rear sections of a tillage machine.

[0012] To support demand-based operation of the hydraulic steering system, the hydraulic steering system is designed to operate the electric motor of the electro-hydraulic steering pressure fluid source at a speed dependent on the steering information.

[0013] For this purpose, the hydraulic steering system is designed to operate the electric motor of the electro-hydraulic steering pressure fluid source with increasing speed as the steering angle increases, and / or to operate the electric motor with increasing speed as the steering angle change rate increases.

[0014] To enable demand-based and thus energy-saving operation of the steering system, it is further proposed that the hydraulic steering system be designed to operate the electric motor of the electro-hydraulic steering pressure fluid source at a speed dependent on the driving operating state of the tillage machine. It should be noted that, for the purposes of the present invention, such a driving operating state is characterized by states that are not directly related to a steering movement or that do not themselves represent the steering movement.

[0015] For example, the driving operating state of the soil cultivation machine can include the following states: a parking state, wherein in the parking state a driving control device is in a parking position and / or an operator seat is unoccupied, a driving preparation state, wherein in the driving preparation state the driving control device is in a driving preparation position, a driving state, wherein in the driving state the driving control device is in a driving position.

[0016] Taking into account these various states considered as driving operating conditions, the hydraulic steering system can be designed to to keep the electric motor of the electro-hydraulic steering pressure fluid source out of operation in the parked state, or / and to operate the electric motor of the electro-hydraulic steering pressure fluid source at a basic speed in the driving preparation state, or / and to operate the electric motor of the electro-hydraulic steering pressure fluid source at a working speed above the basic speed in the driving state.

[0017] In a design with simple construction and control technology, the hydraulic steering system can be configured to always operate the electric motor of the electro-hydraulic steering fluid source at its operating speed during operation. This means that whenever such a tillage machine is in operation, regardless of whether steering is taking place (i.e., regardless of any change in the steering state), this electric motor operates at its operating speed, which is higher than its base speed.

[0018] In an alternative variant, particularly advantageous with regard to efficient energy use, the hydraulic steering system can be designed to operate the electric motor of the electro-hydraulic steering fluid source at its operating speed when entering driving mode and / or during driving mode, specifically when the steering information indicates a change in the steering state. This means that increasing the speed of this electric motor can be limited to those phases during driving mode in which energy must be expended to change the steering state, i.e., to change the steering angle.In phases where this is not necessary, i.e., where no steering is taking place and therefore there is no change in the steering angle, for example when driving straight ahead or when cornering with an essentially constant curve radius, the electric motor can be operated at a lower speed, i.e., the basic speed, and therefore with less energy consumption.

[0019] Energy-saving operation, further adapted to the current requirements, can be supported by making the base speed dependent on the temperature of the hydraulic fluid in the steering hydraulic circuit and / or in a working hydraulic system supplied by the steering hydraulic circuit, and / or by making the base speed dependent on a load requirement in a working hydraulic system supplied by the steering hydraulic circuit.

[0020] In a soil cultivation machine constructed according to the invention, the operation of the hydraulic steering system is adapted to the energy demand or the demand for pressurized fluid by operating or controlling the electric motor for driving the steering hydraulic pump at a speed adapted to the existing demand. Structural modifications to the steering hydraulic pump that would allow its delivery rate to be adjusted to the existing demand are therefore not necessary, so that the steering hydraulic pump can be a constant-flow pump in which the change in the delivery rate of the hydraulic fluid is effected solely by changing the speed of the pump or the electric motor driving the pump.

[0021] The soil cultivation machine according to the invention is further equipped with a hydraulic drive system for moving it over the ground to be cultivated. This hydraulic drive system comprises an electro-hydraulic pressure fluid source with at least one electric motor and at least one hydraulic pump for supplying pressure fluid to a hydraulic circuit, and at least one hydraulic motor supplied with pressure fluid from the hydraulic circuit. The hydraulic drive system is thus also an electro-hydraulic system, which, like the electro-hydraulically operated steering system, offers the advantage that the operation of the electric motor of the hydraulic drive system can be quickly and spontaneously adapted to changes in the operating conditions or required changes in the operating conditions.

[0022] In the embodiment according to the invention, the hydraulic steering system and the hydraulic drive system comprise independently operable electric motors. This means that each of these hydraulic systems is assigned its own independent electric motor or several independently operating electric motors, and the electric motor of the hydraulic steering system is not intended to supply the drive hydraulic motor(s) with pressurized fluid, while the electric motor of the hydraulic drive system is not intended to supply a hydraulic steering unit or one or more steering elements with pressurized fluid. This makes it possible to operate each of these electro-hydraulic systems independently of the other system in a manner optimally adapted to the requirements of the respective system.

[0023] Regardless of the fact that the various hydraulic systems may have their own independent and separately operable electric motors, the hydraulic steering system can be designed to feed pressurized fluid into the driving hydraulic circuit via the steering hydraulic circuit. This makes it possible, for example, to compensate for a loss of pressurized fluid occurring in the driving hydraulic circuit or for a deliberate release of pressurized fluid from the steering hydraulic circuit into the driving hydraulic circuit.

[0024] The hydraulic steering system can be further designed to feed pressurized fluid back into a fluid reservoir via the steering hydraulic circuit. This means that the hydraulic steering system, or rather its steering hydraulic circuit, can fundamentally be an open circuit that allows the return of pressurized fluid to the fluid reservoir in order to prevent excessive heating of the pressurized fluid within it.

[0025] The present invention is described in detail below with reference to the accompanying figures. These show: Fig. 1 a side view of a soil cultivation machine designed as a soil compactor; Fig. 2 a schematic representation of a hydraulic steering system and a hydraulic drive system of a soil cultivation machine; Fig. 3 a relationship between a steering angle change rate and a rotational speed of an electric motor of an electro-hydraulic pressure fluid source of the hydraulic steering system of the Fig. 2 .

[0026] Before proceeding with reference to the Fig. 2 The detailed explanation of the design and function of a hydraulic steering system and a hydraulic drive system of a tillage machine should be noted, as follows, with reference to the Fig. 2 The systems described can be used, for example, in a soil cultivation machine 10 designed as a soil compactor, as shown in Fig. 1 is shown. However, it should be noted that the following refers to the Fig. 2 The systems described can also be used with differently designed soil cultivation machines, for example soil cultivation machines that have soil cultivation rollers on a front carriage and a rear carriage.

[0027] The Fig. 2 Figure 30 shows a hydraulic steering system, generally designated 30. The hydraulic steering system 30 comprises one or more steering elements 26 designed as double-acting steering piston / cylinder units 28, which are coupled to a steering hydraulic circuit 34 via a hydraulic steering unit 32. The hydraulic steering system 30 includes an electro-hydraulic pressure fluid source 36 with an electric motor 38 and a steering hydraulic pump 40 driven by the electric motor 38. The electric motor 38 of the hydraulic steering system 30 is controlled by a control unit 42 and is supplied with power from a voltage source, for example, a battery 44, to drive the steering hydraulic pump 40. The application of an electrical voltage to the electric motor 38 from the battery 44 can be carried out according to corresponding control commands from the control unit 42.

[0028] The Fig. 2 Figure 46 further shows a hydraulic drive system, generally designated 46. The hydraulic drive system 46 comprises a hydraulic pressure fluid source 48 with an electric motor 50 and a drive hydraulic pump 52 driven by the electric motor 50. The drive hydraulic pump 52 pumps a fluid, for example hydraulic oil, in a drive hydraulic circuit 54 and thus supplies two drive hydraulic motors 56, 58 integrated into the drive hydraulic circuit 54 with pressure fluid. For example, the two drive hydraulic motors 56, 58 can be assigned to two soil cultivation rollers provided on a soil compactor in order to drive each of these soil cultivation rollers to move the soil compactor. In the case of the Fig. 1 In the illustrated configuration of a soil cultivation machine, one of the two drive hydraulic motors 56, 58 could be assigned to one of the two drive wheels 16, and the other of the two drive hydraulic motors 56, 58 could be assigned to the other drive wheel 16. In a soil cultivation machine with a soil cultivation roller divided into, for example, two segments lying side by side in the direction of the roller's axis of rotation, each of the segments of such a divided soil cultivation roller could be assigned one of the drive hydraulic motors 56, 58.

[0029] The driving hydraulic circuit 46 further comprises a discharge valve arrangement 60, through which fluid from the driving hydraulic circuit 46 can be discharged to a fluid reservoir 62. From this fluid reservoir 62, the steering hydraulic pump 40 delivers fluid into the steering hydraulic circuit 34, which, as in Fig. 2 The diagram shows that the driving hydraulic circuit 54 is linked in such a way that fluid, for example hydraulic oil, supplied as pressure fluid by the steering hydraulic pump 40 into the steering hydraulic circuit 34 can be introduced into the driving hydraulic circuit 46. This makes it possible, for example, to keep the amount of fluid present in the driving hydraulic circuit 54 essentially constant by replenishing it with fluid from the steering hydraulic circuit 34 when fluid is discharged from the driving hydraulic circuit 46 into the fluid reservoir 62 via the discharge valve arrangement 60. Fluid leaks occurring in the driving hydraulic circuit 54 can also be compensated for in this way.

[0030] The steering hydraulic circuit 34 also includes a return valve 64, through which fluid or pressure fluid can be fed back from the steering hydraulic circuit 34 into the fluid reservoir 62. The return valve 64 can, for example, be pressure-controlled, so that when the fluid pressure in the steering hydraulic circuit 34 or also in the driving hydraulic circuit 54 exceeds a predetermined threshold pressure, fluid can be discharged to the fluid reservoir 62. The return valve 64 thus operates as a pressure relief valve.

[0031] The Fig. 2 The figure further shows that one or more working hydraulic systems 67 are coupled to the steering hydraulic circuit 34 in order to supply them with pressurized fluid from the steering hydraulic circuit 34 or via the steering hydraulic pump 40. Such working hydraulic systems 67 can be systems that, for example, can also be operated when the drive hydraulic circuit 54 is inactive. For example, a parking brake of the soil cultivation machine 10 can be such a working hydraulic system 67, as can an edge compactor found on soil compactors used for compacting asphalt material, which can be raised or lowered even when the soil compactor is stationary.

[0032] To use a soil cultivation machine, for example the one in Fig. 1 To steer the illustrated soil cultivation machine 10, a steering actuation element 66, generally designed as a steering wheel, is provided. An operator seated in the operator's platform 22 can steer the soil cultivation machine 10, which is moving over the subsoil 18 to be cultivated, by actuating the steering actuation element 66, i.e., by turning a steering wheel. The steering movement of the steering actuation element 66 is thereby converted in the hydraulic steering unit 32 into a corresponding supply of pressurized fluid into one chamber of each steering piston / cylinder unit 28 and a corresponding discharge of pressurized fluid from the other of the two chambers of each steering piston / cylinder unit 28.

[0033] The actuation of the steering actuator 66 is detected by a steering sensor 68. This sensor can, for example, detect the rotational movement of a steering shaft coupled to the steering actuator 66 for common rotation and output a signal to the control unit 42 containing information representing the steering state. This information can, for example, be information about the current rotational position of the steering actuator 66 or the steering shaft coupled to it, which represents a steering angle. A steering angle of zero can, for example, represent a steering state corresponding to driving straight ahead. An increasing steering angle can represent an increasing pitching of the front of the vehicle 14 relative to the rear of the vehicle 12, where, for example, the sign can represent the steering direction, i.e., the pitching direction.

[0034] A steering angle change rate can be determined from the temporal change of a signal representing the steering position. Alternatively, a signal representing the rotational speed and thus the steering angle change rate can be generated directly from the movement of, for example, the steering actuation element 66 or the steering shaft coupled to it.

[0035] It should also be noted that information representing the steering state can also be derived, for example, from the respective positioning state or movement state of a steering piston / cylinder unit 28, or can be provided directly by a sensor system acting or measuring between the front carriage 14 and the rear carriage 12.

[0036] The operator station 22 is equipped with additional controls by which an operator can operate such a soil cultivation machine 10. The operator can set the soil cultivation machine 10 in motion by means of a drive control lever 70, for example. This means that, for example, by pivoting the drive control lever 70, the electric motor 50 of the electro-hydraulic pressure fluid source 48 of the hydraulic drive system 46 is operated at a speed corresponding to the driving operating state specified by the operator. For example, the operator can move the drive control lever 70 to a park position. When the drive control lever 70 is in the park position, the soil cultivation machine 10 is generally stationary, and a parking brake can be activated, for example, to prevent it from rolling away.By pivoting from the park position to a drive-preparation position, a drive-preparation state is entered. In the drive-preparation state, the drive hydraulic motors 56, 58 remain inactive; that is, for example, the electric motor 50 is kept out of operation as in the park position, but the parking brake is released. When pivoting from the drive-preparation position corresponding to the drive-preparation state to a driving position corresponding to a driving state, a setpoint for the respective drive speed and direction, corresponding to the respective pivot position, is converted via the control unit 42 into a corresponding speed or...The direction of rotation of the electric motor 50 is converted so that it drives the drive hydraulic pump 52 in a direction of rotation corresponding to a respective driving direction and the two drive hydraulic motors 56, 58 are supplied with pressure fluid, thereby moving the soil cultivation machine 10 over the ground 18.

[0037] The operator seat 24 can be equipped with a seat occupancy sensor 74, which provides information on whether an operator is seated in the operator seat 24 or not. This information, as well as information on the respective operating position or operating state of the driving control element 72, can be fed into the control unit 42 in order to operate the electric motor 38 of the electro-hydraulic pressure fluid source 36 in the manner described below.

[0038] Taking into account the information representing the seat occupancy or the operating state of the drive control element 72, the control unit 42 can, for example, control the electric motor 38 such that when the drive control element 72 is in the park position, the electric motor 38 is deactivated or held in a deactivated state, which means that its control unit is deactivated. Alternatively or additionally, this can also occur if the information supplied by the seat occupancy sensor 74 indicates that no operator is sitting in the operator seat 24, which results in an optionally supplied parking brake being activated by no longer providing holding pressure for it. Furthermore, this also ensures, by design, that in the event of a failure of the control unit for the electric motor 38 and / or the electric motor 38 itself, the tillage machine comes to a safe standstill.

[0039] If the driving control element 72 is in the driving preparation position corresponding to the driving preparation state, which is generally the case when an operator is seated in the operator seat 24 and acting on the driving control element 72, the control unit 42 can operate the electric motor 38 of the electro-hydraulic pressure fluid source 36 such that it rotates at a base speed. This results in pressure being built up in the steering hydraulic circuit 34, which can also be used, for example, to operate one or more of the working hydraulic systems 67, such as releasing a parking brake. The base speed can be fixed, for example. However, it can also be variable depending on influencing factors, such as the temperature of the pressure fluid in the steering hydraulic circuit 34.in the area of ​​one or more of the working hydraulic systems 67, are adapted so that, for example, as the temperature of the pressure fluid increases, the basic speed is increased to ensure a faster exchange of the pressure fluid.

[0040] Depending on the load requirement in the working hydraulic system(s) 67, the base speed can also be adjusted or increased. For example, if it is detected that several such working hydraulic systems 67 are to be activated simultaneously, which corresponds to a high load requirement and is evident, for example, from the fact that one or more such working hydraulic systems 67 are operating at too low a speed when the base speed is present, the base speed can be increased accordingly.

[0041] When the driving control element 72 is moved into the driving position corresponding to the driving condition, the voltage applied to the electric motor 38 of the electro-hydraulic pressure fluid source 36 can be set under the control action of the control unit 42 so that the electric motor 38 is operated at a working speed above the basic speed, whereby the working speed can, for example, be fixed or, similar to the basic speed, can be adjusted depending on the temperature of the pressure fluid in the steering hydraulic circuit 34 and / or the load requirement in one or more of the working hydraulic systems 67.

[0042] Taking into account the steering information, i.e., for example, information about the steering angle to be provided according to an actuation of the steering actuation device 66 or a steering angle change rate, the control unit 42 adjusts the operating speed of the electric motor 38 of the electro-hydraulic pressure fluid source 36. This is described below with reference to the Fig. 3 Described using the steering angle change rate L as an example.

[0043] The Fig. 3 Figure 3 shows a relationship between the steering angle change rate L and the rotational speed n of the electric motor 38. The rotational speed n of the electric motor 38 is maintained at a substantially constant speed n0 until a lower threshold L0 is reached, which can, for example, correspond to the previously described operating speed. Upon exceeding an upper threshold L1 of the steering angle change rate L, the electric motor 38 is operated at a higher rotational speed n1. Between the lower threshold L0 and the upper threshold L1, the electric motor 38 is operated at a speed n that is, for example, linearly related to the steering angle change rate L. This means that between the thresholds L0 and L1, the electric motor 38 is controlled such that its rotational speed n changes proportionally to the steering angle change rate L.

[0044] It should be noted that other relationships between the rotational speed n of the electric motor 38 and the steering angle change rate L may also be provided. For example, a progressive or degressive increase of the rotational speed n with the steering angle change rate L may be provided, as well as a step-like increase.

[0045] By adjusting the speed of the electric motor 38 to the steering angle change rate L, it is possible to respond to a high load requirement in the hydraulic steering system 30 represented by a high steering angle change rate L and to ensure that sufficient pressurized fluid is provided in the steering hydraulic system 34 to effect a correspondingly rapid steering response. This is the case with the Fig. 2 The steering system 30 shown is therefore possible because the electric motor 38 reacts very quickly to a change in the voltage applied to it with a corresponding change in speed, so that an action on the steering actuator 66 can be reacted to essentially without time delay. For this purpose, it is not necessary to make any adjustments to the steering hydraulic pump 40 to adapt its delivery volume. The change in the delivery volume of the steering hydraulic pump 40 is achieved solely by changing its speed or the speed of the electric motor 38 driving it. The steering hydraulic pump 40 can therefore be a constant-flow pump, which ensures a simple design of the hydraulic steering system 30 as well as simple controllability of the system.

[0046] Alternatively or additionally to considering the steering angle change rate L when controlling the electric motor 38, the steering angle itself is used to adjust the speed of the electric motor 38. As the steering angle increases, the speed of the electric motor 38 is also increased, for example in one of the Fig. 3 corresponding, essentially linear relationship, a progressively or degressively increasing relationship, or a step-like relationship.

[0047] Upon entering or during driving mode, the speed of the electric motor 38 can generally be set or increased to the operating speed, which may need to be determined or adjusted as described above. Alternatively, the electric motor 38 can be operated at its operating speed only when entering or during driving mode if a change in the steering state occurs, for example, when transitioning from straight-ahead driving to cornering, from cornering to straight-ahead driving, or when changing the curve radius while cornering. If the steering state does not change, a soil cultivation machine, for example, remains stationary upon entering or during driving mode.During operation, if the steering system is already in a previously existing state (meaning the tillage machine is either traveling straight ahead or turning with a substantially constant radius), the speed of the electric motor 38 is not increased to the operating speed, as no additional force is required to change the steering state. If, during operation, the vehicle transitions from a state in which the steering state is changing to a state in which the steering state remains unchanged, the speed of the electric motor 38, which was initially operating at its operating speed, can be reduced back to its base speed. This results in efficient, energy-saving operation of the hydraulic steering system 30.

[0048] In a soil cultivation machine constructed according to the invention, the use of an electro-hydraulic pressure fluid source makes it possible to very quickly adapt its operation to the existing or required steering operation. This reduces energy consumption, since high power output from the electric motor of the electro-hydraulic pressure fluid source of the hydraulic steering system is only available or utilized when necessary. Nevertheless, such a system can be operated at the base speed to maintain basic functionality, for example, of the hydraulic steering system or of working hydraulic systems supplied by it. In the soil cultivation machine constructed according to the invention, the advantages of a hydraulic steering system are thus combined with the advantages of using an electric motor to operate a steering hydraulic pump with regard to efficient energy use.combined with energy savings and reduced noise emissions in phases where operation at a comparatively low speed is sufficient.

[0049] Finally, it should be noted that such a soil cultivation machine can, of course, be varied in many different aspects. For example, in the hydraulic steering system, the electro-hydraulic pressure fluid source can comprise several steering hydraulic pumps, which can be operated by a common or, if necessary, separate electric motors. Similarly, the hydraulic drive system can incorporate several drive hydraulic pumps, which can be driven by a common or, if necessary, separate electric motors. As already explained, a soil cultivation machine designed, for example, as a soil compactor, can, of course, be configured differently with regard to the use of soil cultivation rollers or drive wheels than described above. Fig. 1 depicted.

Claims

1. A soil processing machine, in particular a soil compactor, comprising : - a hydraulic steering system (30) with at least one steering element (26) actuated with pressurized fluid and an electrohydraulic pressurized fluid source (36) with at least one steering pressurized fluid pump (40) that can be driven by at least one electric motor (38) for feeding pressurized fluid into a steering pressurized fluid circuit (34), - a hydraulic drive system (46) wherein the hydraulic drive system (46) comprises an electrohydraulic pressurized fluid source (48) with at least one electric motor (50) and at least one hydraulic drive pump (52) for supplying pressurized fluid to a hydraulic drive circuit (54) and at least one hydraulic drive motor (56, 58) supplied with pressurized fluid from the hydraulic driving circuit (54), characterized in the hydraulic steering system (30) and the hydraulic drive system (46) comprise electric motors (38, 50) which can be operated independently of one another, that the hydraulic steering system (30) comprises at least one steering sensor (68), wherein the steering sensor (68) is designed to provide steering information representing a steering state, wherein the steering information represents a steering angle and / or a steering angle change rate (L), that the hydraulic steering system (30) is designed to operate the electric motor (38) of the electrohydraulic steering pressurized fluid source (36) at a speed (n) dependent on the steering information, that the hydraulic steering system (30) is designed to operate the electric motor (38) of the electrohydraulic steering pressure fluid source (36): - with increasing speed (n) as the steering angle increases, such that the electric motor (38) is operated at a substantially constant speed until a lower threshold of the steering angle is reached, and when the lower threshold of the steering angle is exceeded, the electric motor (38) is operated at a speed that increases with the steering angle, and / or - with increasing speed (n) as the steering angle change rate (L) increases, such that until a lower threshold (L0) of the steering angle change rate (L) is reached, the electric motor (38) is operated at a substantially constant speed (n0) until a lower threshold (L0) of the steering angle change rate is reached, and when the lower threshold (L0) of the steering angle change rate is exceeded, the electric motor (38) is operated at a speed (n) that increases with the steering angle (L).

2. The soil processing machine according to claim 1, characterized by a rear carriage (12) and a front carriage (14) which can be pivoted about a steering axis with respect to the rear carriage (12), wherein at least one steering element (26) acting between the front carriage (12) and the rear carriage (12) comprises a steering piston / cylinder unit (28).

3. The soil processing machine according to claim 1 or 2, characterized in that the hydraulic steering system (30) comprises a hydraulic steering unit (32), wherein the hydraulic steering unit (32) is supplied with pressurized fluid from the steering pressurized fluid circuit (34) and the at least one steering element (26) is exposed to pressurized fluid depending on an actuation of a steering actuator (66).

4. The soil processing machine according to any of claims 1-3, characterized in that the hydraulic steering system (30) is designed to operate the electric motor (38) of the electrohydraulic steering pressurized fluid source (36) at a speed (n) dependent on a driving operating state of the soil processing machine (10).

5. The soil processing machine according to claim 4, characterized in that the driving operating state of the soil processing machine (10) comprises the following states: - a parking state, wherein a driving actuator (72) is placed in a parking position and / or an operator's seat (24) is not occupied in the parking state; - a driving preparation state, wherein the driving actuator (72) is placed in a driving preparation position in the driving preparation state, - a driving state, wherein the driving actuator (72) is placed in a driving position in the driving state, wherein the hydraulic steering system (30) is designed - to keep the electric motor (38) of the electrohydraulic steering pressurized fluid source out of operation in the parking state, and / or to operate the electric motor (38) of the electrohydraulic steering pressurized fluid source (36) at a base speed in the driving preparation state, and / or - to operate the electric motor (38) of the electrohydraulic steering pressurized fluid source (36) at a working speed which is higher than the base speed in the driving state.

6. The soil processing machine according to claim 5, characterized in that the base speed depends on a temperature of the hydraulic fluid in the hydraulic steering circuit (34) and / or in a working hydraulic system (67) fed from the hydraulic steering circuit, and / or in that the base speed depends on a load requirement in a working hydraulic system (67) fed from the hydraulic steering circuit.

7. The soil processing machine according to claim 5 or 6, characterized in that the hydraulic steering system (30) is designed to operate the electric motor (38) of the electrohydraulic steering pressurized fluid source (36) always at the working speed in the driving state.

8. The soil processing machine according to claim 5 or 6, characterized in that the hydraulic steering system (30) is designed to operate the electric motor (38) of the electrohydraulic steering pressurized fluid source (36) at the working speed upon entering the driving state and / or in the driving state when the steering information indicates the presence of a change in the steering state.

9. The soil processing machine according to any of claims 1-8, characterized in that the hydraulic steering pump (46) is a constant delivery rate pump.

10. The soil processing machine according to claim 1-9, characterized in that the hydraulic steering system (30) is designed to replenish pressurized fluid to the hydraulic drive circuit (54) via the hydraulic steering circuit (34).

11. The soil processing machine according to any of claims 1-10, characterized in that the hydraulic steering system (30) is designed to return pressurized fluid to a fluid reservoir (62) via the hydraulic steering circuit (34).