Ground processing machine and method for operating a ground processing machine

Abstract

A ground working machine, particularly a ground compacting machine, includes a hydraulic travel drive system (46) comprising an electrically driven hydraulic pressurized fluid source (48) having at least one electric motor (50) and at least one travel hydraulic pump (52), a travel hydraulic circuit (54) supplied with pressurized fluid by the at least one travel hydraulic pump (52), at least one travel hydraulic motor (56, 58) supplied with pressurized fluid from the travel hydraulic circuit (54), and a drain valve assembly (60) outputting fluid from the travel hydraulic circuit (54) to a fluid reservoir (62). The hydraulic travel drive system (46) is configured to operate the drain valve assembly (60) to output fluid to the fluid reservoir (62) in dependence on at least one of the following parameters: a temperature of fluid in the travel hydraulic circuit (54), an ambient temperature, a viscosity of fluid in the travel hydraulic circuit (54), a degree of contamination of fluid in the travel hydraulic circuit (54), a duration since the hydraulic travel drive system (46) was last started, and a duration since fluid was last drained from the travel hydraulic circuit (54).

Description

TECHNICAL FIELD

[0001] The present application relates to a ground processing machine, for example a ground compactor, which can be used for compacting construction material of a ground base, for example asphalt, soil or gravel. The present application also relates to a method for operating such a ground processing machine. BACKGROUND

[0002] One example of a ground processing machine configured as a ground compactor is shown in Figure 1 The ground processing machine 10 configured as a ground compactor has a rear vehicle 12 and a front vehicle 14 which can be pivotably connected to the rear vehicle 12 about an approximately vertical steering axis. On the rear vehicle 12 there is provided a drive wheel 16 which can be driven in rotation in order to move the ground compactor 10 over a ground base 18 to be compacted. A ground processing roller 18 configured as a compaction roller is rotatably supported on the front vehicle 14. In Figure 1 In the configuration of the ground compactor shown, the ground processing roller 18 is not itself generally driven in rotation, but is rolled over the ground base 18 by the drive of the drive wheel 16. In ground compactors in which a compaction roller is also provided on the rear vehicle 12, one or both compaction rollers can be driven in rotation in order to move the ground compactor over the ground base 18.

[0003] On the rear vehicle 12 there is also provided an operator's station 22 in which an operator can sit on an operator's seat 24 in order to operate the ground compactor. Furthermore, in the operator's station 22 there are provided different operating mechanisms which will be described below, via which the operator sitting on the operator's seat 24 in the operator's station 22 can operate the ground compactor.

[0004] Generally, such a ground compacting machine has a drive aggregate configured as a diesel engine on the rear vehicle 12. This drive aggregate drives one or more hydraulic pumps to provide pressurized fluid in different hydraulic circuits. Thus, for example, a travel hydraulic circuit can be provided via which hydraulic motors assigned to the drive wheels 16 can be supplied with pressurized fluid to move the ground compacting machine on the ground 18. If such a ground compacting machine has one or more compacting or ground processing rollers 20 driven to rotate, these can also be assigned hydraulic motors to drive them to rotate. A further hydraulic circuit can be used to drive an unbalance system in the ground processing rollers 20. Such an unbalance system, which can be configured to generate an oscillating or / and a vibrating movement of the ground processing rollers 20, can comprise one or more hydraulic motors to drive an unbalance mass to rotate. A further hydraulic circuit can be assigned to a steering system. Pressurized fluid in such a steering hydraulic circuit can be actively directed to one or two steering piston / cylinder units 28 serving as steering mechanisms 26 via a hydraulic steering aggregate depending on a steering movement of a steering operating mechanism, for example a steering wheel. By means of such steering piston / cylinder units 28 the front vehicle 14 and the rear vehicle 12 are swung relative to each other about a steering axis, whereby the ground compacting machine can be steered when moving on the ground 18. SUMMARY

[0005] It is an object of the present application to provide a ground processing machine and a method for operating a ground processing machine, with the aid of which an efficient, energy-saving operation of a hydraulic travel drive system is achieved.

[0006] According to the application, this object is achieved by a ground processing machine, in particular a ground compacting machine, comprising a hydraulic travel drive system, wherein the hydraulic travel drive system comprises:

[0007] - an electrohydraulic pressurized fluid source having at least one electric motor and at least one travel hydraulic pump,

[0008] - a travel hydraulic circuit supplied with pressurized fluid by means of the at least one travel hydraulic pump,

[0009] - at least one travel hydraulic motor supplied with pressurized fluid from the travel hydraulic circuit,

[0010] - an outlet valve assembly (Ausspeiseventilanordnung) for outputting fluid from a travel hydraulic circuit into a fluid reservoir,

[0011] wherein the hydraulic travel drive system is configured to operate the outlet valve assembly to output fluid into the fluid reservoir depending on at least one of the following parameters:

[0012] - a temperature of the fluid in the travel hydraulic circuit,

[0013] - a temperature of the fluid in the fluid return to the fluid reservoir,

[0014] - an ambient temperature,

[0015] - a viscosity of the fluid in the travel hydraulic circuit,

[0016] - a degree of contamination of the fluid in the travel hydraulic circuit,

[0017] - a duration of time elapsed since a last start of operation (Inbetriebnahme) of the hydraulic travel drive system,

[0018] - a duration of time elapsed since a last fluid discharge (Fluidausspeisung) from the travel hydraulic circuit.

[0019] By discharging fluid from the travel hydraulic circuit of the hydraulic travel drive system it is possible to actually perform such a discharge only if it is necessary or if it can lead to an increase in efficiency or effect of the travel hydraulic circuit. Thus, the energy introduced into the travel hydraulic circuit via the at least one electric motor of the electrically driven hydraulic pressure fluid source can be used efficiently.

[0020] To enable the at least one travel hydraulic motor to be operated in different rotational directions in the travel hydraulic circuit it is proposed that the travel hydraulic circuit comprises a first connection line between a first connection interface of the at least one travel hydraulic pump and a first connection interface of the at least one travel hydraulic motor for conveying pressure fluid from the first connection interface of the at least one travel hydraulic pump to the first connection interface of the at least one travel hydraulic motor to operate the at least one travel hydraulic motor in a first rotational direction and a second connection line between a second connection interface of the at least one travel hydraulic pump and a second connection interface of the at least one travel hydraulic motor for conveying pressure fluid from the second connection interface of the at least one travel hydraulic pump to the second connection interface of the at least one travel hydraulic motor to operate the at least one travel hydraulic motor in a second rotational direction.

[0021] If the draining is implemented during a driving operation, it is particularly advantageous if the hydraulic drive system is configured such that, when the at least one travel hydraulic motor is supplied with pressurized fluid via the first connection line, the draining valve assembly is operated to drain fluid from the second connection line, or / and the hydraulic drive system is configured such that, when the at least one travel hydraulic motor is supplied with pressurized fluid via the second connection line, the draining valve assembly is operated to drain fluid from the first connection line. Thereby it is ensured that the draining of fluid does not affect the delivery of pressurized fluid to the at least one travel hydraulic motor.

[0022] The draining valve assembly can comprise a switching valve having a first input interface connected to the first connection line, a second input interface connected to the second connection line and an output interface connected to the fluid reservoir, wherein in a first valve position of the switching valve there is a connection between the first input interface and the output interface and no connection between the second input interface and the output interface, and in a second valve position of the switching valve there is a connection between the second input interface and the output interface and no connection between the first input interface and the output interface. It is thereby possible to output fluid from each connection line to the fluid reservoir.

[0023] In particular, in order to adjust the amount of drained fluid in a defined manner, it is possible to connect the output interface of the switching valve to the fluid reservoir via a shut-off valve, when the switching valve is initially set to provide a connection between the fluid reservoir and one of the fluid lines, wherein in an open position of the shut-off valve there is a connection between the output interface and the fluid reservoir and in a blocking position of the shut-off valve there is no connection between the output interface and the fluid reservoir.

[0024] In order to take the temperature of the fluid into account appropriately, it is proposed that the hydraulic drive system is configured such that, when the at least one travel hydraulic motor is supplied with pressurized fluid via the first connection line, the draining valve assembly is operated to output fluid to the fluid reservoir depending on the temperature of the fluid in the first connection line, and, when the at least one travel hydraulic motor is supplied with pressurized fluid via the second connection line, the draining valve assembly is operated to output fluid to the fluid reservoir depending on the temperature of the fluid in the second connection line.

[0025] The hydraulic drive system can be configured such that the draining valve assembly is operated to output fluid to the fluid reservoir when the temperature of the fluid in the travel hydraulic circuit is above a predetermined draining fluid threshold temperature or / and lies in a predetermined draining fluid temperature range. Thereby it is ensured that the fluid is first brought to an appropriate temperature and that fluid is only drained in this case and replaced, for example, by other, generally cooler fluid in the fluid reservoir.

[0026] It can be provided here that the amount of fluid to be output to the fluid reservoir and / or the fluid output rate is adjusted in dependence on the ambient temperature and / or the degree of contamination and / or the time elapsed since the last start of operation of the hydraulic drive system for travel and / or the time elapsed since the last discharge of fluid from the travel hydraulic circuit when the discharge valve assembly is operated to output fluid from the travel hydraulic circuit to the fluid reservoir. This makes it possible to take account more precisely of the operating state of the parameters influencing the hydraulic drive system for travel.

[0027] Furthermore, the hydraulic drive system for travel can be designed such that the discharge valve assembly is operated to output fluid to the fluid reservoir when the temperature of the fluid in the leakage line to the fluid reservoir and / or in the region of the fluid cooler to the fluid reservoir exceeds a predetermined discharge fluid threshold temperature and / or lies in a predetermined discharge fluid temperature range. Such a fluid leakage line, which for example conducts fluid leakage from one or more travel hydraulic cylinders to the fluid reservoir, or the fluid cooler, through which fluid flows back to the fluid reservoir, forms a system region of the fluid return line. The fluid temperature present therein can also be used as an indicator for triggering the discharge process.

[0028] Instead of or in addition to taking account of the temperature of the fluid in the travel hydraulic circuit, the hydraulic drive system for travel can be designed such that the discharge valve assembly is operated to output fluid to the fluid reservoir when the ambient temperature exceeds a predetermined discharge ambient threshold temperature and / or lies in a predetermined discharge ambient temperature range. A low ambient temperature generally indicates that the fluid in the travel hydraulic circuit also has a low temperature or can be cooled more rapidly, so that by taking account of the ambient temperature it is also possible to avoid a discharge which leads to lower efficiency.

[0029] Furthermore, the hydraulic drive system for travel can also be designed such that the discharge valve assembly is operated to output fluid to the fluid reservoir when the viscosity of the fluid in the travel hydraulic circuit is below a predetermined threshold viscosity and / or lies in a predetermined viscosity range. The viscosity of the fluid in the travel hydraulic circuit can for example be derived from the pressure drop between two pressure measurement points in the travel hydraulic circuit and is a parameter which is directly linked to the temperature of the fluid. It is also possible to take account of the viscosity of the fluid such that no fluid is discharged or for example only a small amount of fluid is discharged as long as the viscosity is sufficiently high, i.e. the fluid is relatively thick. Only after a sufficient duration of operation has elapsed for the viscosity to drop, fluid is discharged according to this aspect of the application in order to be able to keep the viscosity in a range which is optimal for efficient use of energy.

[0030] According to a further design it can be provided that the drain valve assembly is operated to output fluid to the fluid reservoir when the degree of contamination of the fluid in the travel hydraulic circuit is higher than a predetermined drain threshold degree of contamination or / and lies in a predetermined degree of contamination range. The degree of contamination of the fluid can be detected, for example, by an optical detector detecting a transmission or an absorption. If it is identified that the fluid circulating in the travel hydraulic circuit contains a too high content of contaminant particles, a portion of the fluid can be drained and, for example, guided through a particle filter when being conducted to the fluid reservoir, thus cleaning the fluid. Alternatively or additionally, the fluid newly supplied to the travel hydraulic circuit can be filtered when being conducted from the fluid reservoir.

[0031] According to a further aspect of the application, the hydraulic travel drive system can be configured to operate the drain valve assembly to output fluid to the fluid reservoir when a predetermined time has elapsed since the last start of operation of the hydraulic travel drive system or / and when a predetermined time has elapsed since the last draining of fluid from the travel hydraulic circuit.

[0032] In order to be able to provide sufficient fluid in the travel hydraulic circuit even when or after draining fluid therefrom, it is proposed that a steering hydraulic circuit (Lenk-Hydraulikkreislauf) is provided and configured to supply fluid to the travel hydraulic circuit.

[0033] The objects set out above are also achieved by a method for operating a ground processing machine, preferably a ground processing machine configured according to the application, comprising a hydraulic travel drive system, wherein the hydraulic travel drive system comprises:

[0034] - an electrically driven hydraulic pressurized fluid source having at least one electric motor and at least one travel hydraulic pump,

[0035] - a travel hydraulic circuit supplied with pressurized fluid by the at least one travel hydraulic pump,

[0036] - at least one travel hydraulic motor supplied with pressurized fluid from the travel hydraulic circuit,

[0037] - a drain valve assembly for outputting fluid from the travel hydraulic circuit to a fluid reservoir,

[0038] wherein the drain valve assembly is operated to output fluid to the fluid reservoir depending on at least one of the following parameters:

[0039] - the temperature of the fluid in the travel hydraulic circuit,

[0040] - the temperature of the fluid in the fluid return to the fluid reservoir,

[0041] - the ambient temperature,

[0042] - the viscosity of the fluid in the travel hydraulic circuit,

[0043] - the degree of contamination of the fluid in the travel hydraulic circuit,

[0044] - the duration of time since the last start of operation of the hydraulic travel drive system,

[0045] - the duration of time since the last discharge of fluid from the travel hydraulic circuit. BRIEF DESCRIPTION OF DRAWINGS

[0046] The application is described in detail below with reference to the accompanying drawings. Shown are:

[0047] Figure 1 a side view of a ground processing machine which is constructed as a ground compactor is shown;

[0048] Figure 2 a schematic diagram of the hydraulic steering system and the hydraulic travel drive system of a ground processing machine is shown. DETAILED DESCRIPTION

[0049] Before the structure and function of the hydraulic steering system and the hydraulic travel drive system of a ground processing machine are described in detail below, it is noted that the system described below can be applied, for example, in a ground processing machine 10 which is constructed as a ground compactor, as shown in Figure 2 Figure 2 Before the structure and function of the hydraulic steering system and the hydraulic travel drive system of a ground processing machine are described in detail below, it is noted that the system described below can be applied, for example, in a ground processing machine 10 which is constructed as a ground compactor, as shown in Figure 1 Figure 2

[0050] Figure 2 A hydraulic steering system is shown which is designated as a whole by 30. The hydraulic steering system 30 comprises a steering mechanism 26 which is constructed as one or more double-acting steering piston / cylinder units 28, which are coupled via a hydraulic steering group 32 to a steering pressurized fluid circuit 34. The hydraulic steering system 30 comprises an electrically driven hydraulic pressurized fluid source 36, which has an electric motor 38 and a steering pressurized fluid pump 40 which is driven by the electric motor 38. The electric motor 38 of the hydraulic steering system 30 is under the control of a control unit 42 and is supplied with electrical voltage from a voltage source, for example a battery 44, in order to drive the steering pressurized fluid pump 40. Depending on the corresponding control pre-given parameters in the control unit 42, electrical voltage can be applied to the electric motor 38 from the battery 44.

[0051] ​​​Figure 2 A hydraulic travel drive system is also shown generally at 46. The hydraulic travel drive system 46 includes a source of pressurized fluid 48 having an electric motor 50 and a travel hydraulic pump 52 driven by the electric motor 50. The travel hydraulic pump 52 delivers fluid (e.g., hydraulic oil) in a travel hydraulic circuit 54, thereby supplying pressurized fluid to two travel hydraulic motors 56, 58 integrated in the travel hydraulic circuit 54. For example, the two travel hydraulic motors 56, 58 can be assigned to two ground processing rollers provided on the ground compacting machine, so that each of these ground processing rollers can be driven to move the ground compacting machine. For example, the two travel hydraulic motors 56, 58 can be assigned to the two drive wheels 16, so that each of these drive wheels can be driven to move the ground compacting machine. Figure 1 For the construction of the ground processing machine shown, one of the two travel hydraulic motors 56, 58 can be assigned to one of the two drive wheels 16, and the other of the two travel hydraulic motors 56, 58 can be assigned to the other drive wheel 16.

[0052] The travel hydraulic circuit 46 further includes a drain valve assembly 60 via which fluid can be drained from the travel hydraulic circuit 46 to a fluid reservoir 62. The steering hydraulic pump 40 delivers fluid from the fluid reservoir 62 into the steering hydraulic circuit 34, which is connected to the travel hydraulic circuit 54 as shown in Figure 2 so that fluid (e.g., hydraulic oil) that is input from the steering hydraulic pump 40 into the steering hydraulic circuit 34 as pressurized fluid can be directed into the travel hydraulic circuit 46. Thereby, for example, the fluid in the travel hydraulic circuit 54 can be kept substantially constant by replenishing the fluid from the steering hydraulic circuit 34 when fluid is drained from the travel hydraulic circuit 46 via the drain valve assembly 60 into the fluid reservoir 62. In this way, fluid leaks occurring in the travel hydraulic circuit 54 can also be compensated.

[0053] The steering hydraulic circuit 34 further includes a return valve 64 via which fluid or pressurized fluid can be returned from the steering hydraulic circuit 34 to the fluid reservoir 62. The return valve 64 can be pressure controlled, for example, so that fluid can be output to the fluid reservoir 62 when the fluid pressure in the steering hydraulic circuit 34 or in the travel hydraulic circuit 54 exceeds a predetermined threshold pressure.

[0054] In order to move the ground processing machine (e.g., the ground compacting machine) in a desired direction, the two travel hydraulic motors 56, 58 can be driven in a coordinated manner. For example, the two travel hydraulic motors 56, 58 can be driven in a coordinated manner by the electric motor 50, so that the two drive wheels 16 are driven in a coordinated manner. Figure 1The ground processing machine 10 shown is steered by a steering control mechanism 66, which is generally configured as a steering wheel. An operator seated in the control panel 22 can steer the ground processing machine 10, which is moving on the foundation 18 to be processed, by manipulating this steering control mechanism 66 (i.e., by turning the steering wheel). Here, the steering motion of the steering control mechanism 66 in the hydraulic steering unit 32 is converted into the corresponding input of pressurized fluid into one chamber of each steering piston / cylinder unit 28 and the corresponding output of pressurized fluid from the other chamber of each steering piston / cylinder unit 28.

[0055] The steering sensor 68 detects the manipulation of the steering mechanism 66. The steering sensor 68, for example, can detect the rotational movement of the steering shaft coupled to the steering mechanism 66 and outputs a signal containing information representing the steering state to the control unit 42. This information may, for example, be information about the instantaneous steering position of the steering mechanism 66 or the steering shaft coupled thereto, representing the steering angle.

[0056] Other mechanisms are also provided in the control panel 22, through which the operator can operate the type of floor processing machine 10. The operator can move the floor processing machine 10 by means of, for example, a driving control mechanism 72 configured as a driving control lever 70. This means, for example, that swinging the driving control lever 70 causes the electric motor 50 of the electro-hydraulic pressurized fluid source 48 of the hydraulic driving drive system 46 to operate at a speed corresponding to a driving operation state preset by the operator. For example, the operator can bring the driving control lever 70 into the parking position. When the driving control lever 70 is in the parking position, the floor processing machine 10 is essentially stationary and, for example, the parking brake can be activated to prevent rollover. The driving preparation state is entered by swinging from the parking position to the driving preparation position. In the driving preparation state, the driving hydraulic motors 56, 58 remain inactive, that is, for example, the electric motor 50 remains inactive as in the parking position, but the parking brake is released. When swinging from a driving preparation position corresponding to a driving preparation state to a driving position corresponding to a driving state, for example, a voltage corresponding to the corresponding swing position is applied to an electric motor 50, causing the electric motor 50 to drive a driving hydraulic pump 52 in a rotation direction corresponding to the corresponding driving direction and supply pressurized fluid to two driving hydraulic motors 56, 58, thereby allowing the ground processing machine 10 to move on the foundation 18.

[0057] A seat occupancy sensor 74 can be assigned to the operator's seat 24, which provides information about whether an operator is seated on the operator's seat 24. This information can be introduced into the control unit 42, as is the case with the information about the respective steering position or steering state of the travel steering mechanism 72, in order to operate the electric motor 38 of the electrohydraulic pressure fluid source 36 in consideration of this information.

[0058] The control unit 42 can control the electric motor 38, for example, in consideration of information representative of the seat occupancy or the steering state of the travel steering mechanism 72, such that the electric motor 38 is deactivated or remains in a deactivated state when the travel steering mechanism 72 is in the parking position, which means that no voltage is applied to the electric motor. Alternatively or additionally, this can be done when the information provided by the seat occupancy sensor 74 indicates that no operator is seated on the operator's seat 24.

[0059] If the travel steering mechanism 72 is in the travel preparation position corresponding to the travel preparation state, which is generally the case when an operator acting on the travel steering mechanism 72 is seated on the operator's seat 24, the electric motor 38 of the electrohydraulic pressure fluid source 36 can be operated by the control unit 42 such that the electric motor rotates at a basic rotational speed. As a result, a pressure is generated in the steering hydraulic circuit 34.

[0060] If the travel steering mechanism 72 enters the travel position corresponding to the travel state, the voltage applied to the electric motor 38 of the electrohydraulic pressure fluid source 36 can be preset under the control action of the control unit 42 such that the electric motor 38 is operated at an operating rotational speed that is higher than the basic rotational speed, wherein the operating rotational speed can be preset, for example, to be constant. The control unit 42 can adjust the operating rotational speed of the electric motor 38 of the electrohydraulic pressure fluid source 36 in consideration of the steering information, i.e., information about the steering angle or the steering angle rate of change, for example, that is preset in accordance with the steering of the steering mechanism 66.

[0061] The travel hydraulic circuit 54 comprises a first connection line 76, which establishes a connection between a first connection interface 78 of the travel hydraulic pump 52 and respective first connection interfaces 80, 82 of the two travel hydraulic motors 56, 58. In addition, the travel hydraulic circuit 54 comprises a second connection line 84, which establishes a connection between a second connection interface 86 of the travel hydraulic pump 52 and respective second connection interfaces 88, 90 of the two travel hydraulic motors 56, 58.

[0062] Depending on the rotational direction in which the travel hydraulic pump 52 is driven by the electric motor 50 of the electrically hydraulic pressure fluid source 48, the fluid in the travel hydraulic circuit 54 is delivered as pressurized fluid to both travel hydraulic motors 56, 58 via the first connection line 76 or the second connection line 84. Depending on which of the two connection lines 76, 84 is loaded with pressurized fluid for the travel hydraulic motors 56, 58, the travel hydraulic motors are rotated in one of two possible rotational directions, whereby the ground processing machine can be moved in different movement directions, i.e. forwards or backwards.

[0063] The discharge valve assembly 60 comprises a switching valve 92 which is configured as a directional valve and which is under the control of a control unit 94 which also controls the electric motor 50, for example. The switching valve 92 has a first input connection 96 which is connected to the first connection line 76 and a second input connection 98 which is connected to the second connection line 84. The switching valve 92 also comprises an output connection 100 which is connected to the fluid reservoir 62 via a shut-off valve 102 which is configured as a proportional valve, for example, and is therefore under the control of the control unit 94.

[0064] In the discharge valve assembly 60, the switching valve 92 serves to establish a connection substantially between the two connection lines 76, 84 and the fluid reservoir 62. The switching valve 92 can also be brought into a neutral position in which the connection between each of the two connection lines 76, 84 and the fluid reservoir 62 is substantially interrupted, independently of which position the shut-off valve 102 is in. The shut-off valve 102 has the task of establishing or interrupting the connection to the fluid reservoir 62 by switching between the open position and the blocked position when the switching valve 92 connects the two connection lines 76, 84 or the assigned first or second input connection 96, 98 to the output connection 100, in order thereby to discharge fluid from one of the two connection lines 76, 84 to the reservoir 62 and to regulate the discharge quantity or discharge rate, in particular.

[0065] In the embodiment shown, two temperature sensors 104, 106 are also provided in correspondence with the travel hydraulic circuit 54. The temperature sensor 104 is positioned such that it detects the temperature of the fluid in the travel hydraulic circuit 54 in the region of the first connection line 76, not far before or in the vicinity of the first connection interfaces 80, 82 of the travel hydraulic motors 56, 58 and feeds the corresponding information into the control unit 94. The temperature sensor 106 is positioned such that it detects the temperature of the fluid in the travel hydraulic circuit 54 in the second connection line 84, not far before or in the vicinity of the second connection interfaces 88, 90 of the travel hydraulic motors 56, 58. The temperature information provided by the temperature sensor 106 is also fed into the control unit 94.

[0066] The control unit 94, in consideration of the temperature information provided by the temperature sensors 104, 106, controls the discharge valve assembly 60 in the manner described below, that is to say such that fluid is discharged from the travel hydraulic circuit 54 to the reservoir 62 at the appropriate time and in the appropriate amount. Here, in order to keep the amount of fluid present or circulating in the travel hydraulic circuit 54 substantially constant, the electrically driven hydraulic pressure fluid source 36 of the hydraulic steering system 30 can be operated at the same time, so that sufficient fluid is supplied to the travel hydraulic circuit 54 via the steering hydraulic circuit 34.

[0067] For example, it is assumed that the electrically driven motor 50 of the electrically driven hydraulic pressure fluid source 48 of the hydraulic travel drive system 46 is operated such that the travel hydraulic pump 52 directs pressure fluid to the two travel hydraulic motors 56, 58 via the first connection line 76 and thus rotates them in the first direction of rotation, for example to move the ground processing machine 10 forwards. In this state, for example, the shut-off valve 102 remains in its blocking position, the switching valve 92 can be switched to the valve position in which the second input interface 96 and the output interface 100 are connected to the second connection line 84. If the signal provided by the temperature sensor 104 indicates that the temperature of the fluid in a region not far upstream of the travel hydraulic motors 56, 58 to which fluid is to be supplied is below a predetermined discharge fluid threshold temperature, for example approximately 50°C, or is not in a predetermined discharge fluid temperature range, the shut-off valve 102 remains in its blocking position, so that no fluid is discharged from the travel hydraulic circuit 54.

[0068] If the temperature of the fluid in the region in the travel hydraulic circuit 54 not far upstream of the travel hydraulic motors 56, 58 exceeds the discharge fluid threshold temperature or reaches the discharge fluid temperature range, the shut-off valve 102 is operated by the operating unit 94 such that fluid is discharged from the travel hydraulic circuit 54 into the fluid reservoir 62. Here, for example, the respective discharge process can be set such that the amount of fluid defined by the respective operation of the shut-off valve 102 is discharged, for example, also at a defined rate, to ensure that sufficient fluid can be replenished via the steering hydraulic circuit 34.

[0069] If the travel hydraulic pump 52 is operated such that pressurized fluid is delivered to both travel hydraulic motors 56, 58 via the second connecting line 84, for example when the shut-off valve 102 is again held in its blocking position, the switching valve 92 can be brought into such a valve position in which a connection between the first input connection 96 and the output connection 100 and a connection between the first connecting line 76 and the output connection 100 can be established. If the temperature signal provided by the temperature sensor 106 not far before the region in which pressurized fluid is supplied to both travel hydraulic motors 56, 58 indicates that the temperature of the fluid in this region is above the discharge fluid threshold temperature or in the discharge fluid temperature range, the operating unit 94 operates the shut-off valve 102 such that fluid is discharged in a predetermined amount or / and at a predetermined output rate from the first connecting line 76 in the direction of the fluid reservoir 62.

[0070] By discharging fluid from the travel hydraulic circuit 54, it is ensured only when the fluid, for example, has a sufficiently high temperature that the discharge is initially suppressed and the fluid is brought quickly to a suitable operating temperature, for example, in the range of approximately 40°C to 65°C, for example, when the hydraulic travel drive 46 or the ground processing machine 10 is started. By suppressing the discharge, the duration until a sufficient temperature is reached is kept as short as possible when the temperature of the fluid is not yet sufficiently high, so that in this way the entry into a high-efficiency operating state in the hydraulic travel drive 46 on the basis of a sufficiently small fluid viscosity is as fast as possible. Only then is the fluid repeatedly discharged in successive discharge processes to keep the temperature of the fluid in the travel hydraulic circuit 54 in an optimum range. Alternatively, the fluid can also be continuously discharged at a relatively low rate in this operating state and replenished from the fluid reservoir 62 via the steering hydraulic circuit 34.

[0071] Furthermore, in the aforementioned processes, fluid is discharged from the travel hydraulic circuit 54 from the region in which pressurized fluid is not used to be delivered to the travel hydraulic motors 56, 58, respectively. This prevents a pressure drop due to the discharged fluid on the pressure side of the travel hydraulic motors 56, 58, i.e. in the region of the connecting lines 76, 84 for delivering pressurized fluid to the travel hydraulic motors 56, 58.

[0072] The temperatures of the fluid in the regions in the travel hydraulic circuit 54 upstream of the travel hydraulic motors 56, 58 supplied with pressurized fluid are taken into account, which makes it possible to take into account a fluid temperature that approximates an average temperature. In general, the fluid in the fluid reservoir 62 has the lowest temperature and the fluid in the regions downstream of the travel hydraulic motors 56, 58 supplied with pressurized fluid has the highest temperature. It is noted that it is naturally also possible to take into account the temperatures of the fluid at other regions of the travel hydraulic circuit 54 or of the hydraulic travel drive 46.

[0073] In Figure 2 As a system region for the fluid return of the fluid back into the fluid reservoir 62, the leakage line 108 and the fluid cooler 110 are shown. Via the leakage line 108, for example, it is possible to return fluid that occurs in the travel hydraulic motors 56, 58 into the fluid reservoir 62. Fluid that is drawn back from different system regions into the fluid reservoir can be guided through one or, if necessary, a plurality of fluid coolers 110 in order to output heat there. In such a fluid return region, i.e. for example in the region of the leakage line 108 or / and in the region of the fluid cooler 110, it is also possible to detect the temperature of the fluid and to use it as a basis for triggering the draining process.

[0074] The inventive principle, for which the fluid is drained from the travel hydraulic circuit 54 without affecting or increasing the efficiency of the hydraulic travel drive 46, can also be applied when other parameters are taken into account in addition to or instead of the temperature of the fluid in the travel hydraulic circuit 54. For example, the ambient temperature in the region of the ground processing machine 10 can be taken into account in the same way, since a low ambient temperature generally also results in the fluid in the travel hydraulic circuit 54 having a relatively low temperature. Furthermore, it is also possible to define a drain ambient threshold temperature or a drain ambient temperature range in relation to the ambient temperature, the exceeding or reaching of which leads to the triggering of the draining process. The viscosity of the fluid in the travel hydraulic circuit 54, which is directly related to the temperature of the fluid, can be taken into account as a parameter when the draining process is permitted or inhibited, as is the degree of contamination of the fluid in the travel hydraulic circuit 54. As a further parameter, the duration of time since the hydraulic travel drive 46 was started can be taken into account. If a predetermined duration of time is reached, it can be concluded from this that the fluid in the travel hydraulic circuit 54 has reached a sufficiently high temperature, so that the draining of the fluid does not affect the efficiency of the travel hydraulic circuit. Furthermore, the duration of time since the last execution of such a draining process can also be used as a criterion for the re-execution of the draining process.

[0075] It is also possible to associate a plurality of such parameters in such a way that one or more of these parameters essentially serve as a criterion for triggering the draining process, while one or more further parameters are used to determine the amount or rate of fluid to be drained. For example, the temperature of the fluid in the travel hydraulic circuit 54 can be used in the aforementioned manner as a criterion for triggering the draining process, while the ambient temperature can be used as a criterion for the amount of fluid to be drained or / and the draining rate, for example in such a way that the amount of fluid to be drained or / and the draining rate is gradually increased as the ambient temperature increases.

[0076] Finally, it should be noted that such a ground processing machine can naturally be varied in different design variants. Thus, in the hydraulic steering system, the electro-hydraulic pressurized fluid source can comprise a plurality of steering pressurized fluid pumps, which can be operated by means of a common electric motor of the electro-hydraulic pressurized fluid source or, if necessary, each by means of an individual electric motor. Furthermore, in the area of the hydraulic travel drive system, a plurality of travel hydraulic pumps can also be provided, which can be driven by means of a common electric motor or, if necessary, each by means of an individual electric motor. As mentioned, the ground processing machine itself, for example configured as a ground compactor, can naturally be designed differently in terms of the application of ground processing rollers or drive wheels than the aforementioned or Figure 1 in addition to the parameters listed above, influence variables which are important for the operation of the hydraulic travel drive system can also be taken into account for draining fluid from the travel hydraulic circuit or for inhibiting draining.

Claims

1. A ground processing machine, comprising a hydraulic drive system (46), wherein the hydraulic drive system (46) comprises: - A pressurized fluid source (48) having at least one driving hydraulic pump (52). - A travel hydraulic circuit (54), which is supplied with pressurized fluid via at least one of the travel hydraulic pumps (52), - At least one travel hydraulic motor (56, 58) is supplied with pressurized fluid from the travel hydraulic circuit (54), - A discharge valve assembly (60) for discharging fluid from the travel hydraulic circuit (54) to a fluid reservoir (62). The hydraulic drive system (46) is configured to operate the discharge valve assembly (60) to output fluid to the fluid reservoir (62) according to at least one of the following parameters: - The temperature of the fluid in the driving hydraulic circuit (54), - The temperature of the fluid during the fluid return journey to the fluid reservoir (62), - Ambient temperature, - The viscosity of the fluid in the driving hydraulic circuit (54), - The degree of contamination of the fluid in the driving hydraulic circuit (54), - The duration since the hydraulic drive system (46) last started operating, - The duration since the last fluid was discharged from the driving hydraulic circuit (54) The hydraulic driving system (46) is configured to cause the discharge valve assembly (60) to operate to output fluid to the fluid reservoir (62) when the temperature of the fluid in the driving hydraulic circuit (54) is higher than a predetermined discharge fluid threshold temperature and / or within a predetermined discharge fluid temperature range. Its features are, The pressurized fluid source (48) is an electro-hydraulic pressurized fluid source (48) having at least one electric motor (50), and When operating the discharge valve assembly (60) to output fluid from the travel hydraulic circuit (54) to the fluid reservoir (62), the amount of fluid to be output to the fluid reservoir (62) and / or the fluid output rate are adjusted according to at least one of the following parameters: - Ambient temperature, - Pollution level, - The time elapsed since the hydraulic drive system (46) last started operating, - The time elapsed since the last fluid was discharged from the driving hydraulic circuit (54).

2. The ground processing machine according to claim 1, characterized in that, The driving hydraulic circuit (54) includes: a first connecting line (76) between a first connecting port (78) of at least one driving hydraulic pump (52) and a first connecting port (80, 82) of at least one driving hydraulic motor (56, 58), for conveying pressurized fluid from the first connecting port (78) of at least one driving hydraulic pump (52) to the first connecting port (80, 82) of at least one driving hydraulic motor (56, 58) to cause at least one driving hydraulic motor (56, 58) to operate in a first rotational direction; and a second connecting line (84) between a second connecting port (86) of at least one driving hydraulic pump (52) and a second connecting port (88, 90) of at least one driving hydraulic motor (56, 58), for conveying pressurized fluid from the second connecting port (86) of at least one driving hydraulic pump (52) to the second connecting port (88, 90) of at least one driving hydraulic motor (56, 58) to cause at least one driving hydraulic motor (56, 58) to operate in a second rotational direction.

3. The ground processing machine according to claim 2, characterized in that, The hydraulic drive system (46) is configured to operate the discharge valve assembly (60) to discharge fluid from the second connection line (84) when pressurized fluid is supplied to at least one of the drive hydraulic motors (56, 58) via the first connection line (76), and / or the hydraulic drive system (46) is configured to operate the discharge valve assembly (60) to discharge fluid from the first connection line (76) when pressurized fluid is supplied to at least one of the drive hydraulic motors (56, 58) via the second connection line (84).

4. The ground processing machine according to claim 2 or 3, characterized in that, The discharge valve assembly (60) includes a switching valve (92) having a first input port (96) connected to the first connecting line (76), a second input port (98) connected to the second connecting line (84), and an output port (100) connected to the fluid reservoir (62), wherein, at a first valve position of the switching valve (92), there is a connection between the first input port (96) and the output port (100) and no connection between the second input port (98) and the output port (100), and at a second valve position of the switching valve (92), there is a connection between the second input port (98) and the output port (100) and no connection between the first input port (96) and the output port (100).

5. The ground processing machine according to claim 4, characterized in that, The output port (100) of the switching valve (92) is connected to the fluid reservoir (62) via a shut-off valve (102), wherein there is a connection between the output port (100) and the fluid reservoir (62) when the shut-off valve (102) is in the open position, and there is no connection between the output port (100) and the fluid reservoir (62) when the shut-off valve (102) is in the closed position.

6. The ground processing machine according to claim 2 or 3, characterized in that, The hydraulic drive system (46) is configured such that, when pressurized fluid is supplied to at least one of the driving hydraulic motors (56, 58) via the first connecting line (76), the discharge valve assembly (60) is operated according to the temperature of the fluid in the first connecting line (76) to output fluid to the fluid reservoir (62), and, when pressurized fluid is supplied to at least one of the driving hydraulic motors (56, 58) via the second connecting line (84), the discharge valve assembly (60) is operated according to the temperature of the fluid in the second connecting line (84) to output fluid to the fluid reservoir (62).

7. The ground processing machine according to any one of claims 1-3, characterized in that, The hydraulic driving system (46) can be configured to cause the discharge valve assembly (60) to operate to discharge fluid to the fluid reservoir (62) when the temperature of the fluid in the leakage line (108) leading to the fluid reservoir (62) or / and in the area leading to the fluid cooler (110) of the fluid reservoir (62) exceeds a predetermined discharge fluid threshold temperature or / and is within a predetermined discharge fluid temperature range.

8. The ground processing machine according to any one of claims 1-3, characterized in that, The hydraulic driving system (46) is configured to operate the discharge valve assembly (60) to output fluid to the fluid reservoir (62) when the ambient temperature exceeds a predetermined discharge ambient threshold temperature and / or is within a predetermined discharge ambient temperature range.

9. The ground processing machine according to any one of claims 1-3, characterized in that, The hydraulic driving system (46) is configured to operate the discharge valve assembly (60) to output fluid to the fluid reservoir (62) when the viscosity of the fluid in the driving hydraulic circuit (54) is below a predetermined threshold viscosity and / or within a predetermined viscosity range.

10. The ground processing machine according to any one of claims 1-3, characterized in that, The hydraulic driving system (46) is configured to cause the discharge valve assembly (60) to operate to output fluid to the fluid reservoir (62) when the contamination level of the fluid in the driving hydraulic circuit (54) is higher than a predetermined discharge threshold contamination level or / and within a predetermined contamination level range.

11. The ground processing machine according to any one of claims 1-3, characterized in that, The hydraulic driving system (46) is configured to operate the discharge valve assembly (60) to output fluid to the fluid reservoir (62) when a predetermined time has elapsed since the last start of operation of the hydraulic driving system (46) or / and when a predetermined time has elapsed since the last discharge of fluid from the driving hydraulic circuit (54).

12. The ground processing machine according to any one of claims 1-3, characterized in that, A steering hydraulic circuit (34) is provided, and the steering hydraulic circuit (34) is configured to supply fluid to the driving hydraulic circuit (54).

13. The ground processing machine according to any one of claims 1-3, characterized in that, The ground processing machine is a ground compactor.

14. A method for operating a ground processing machine (10), the ground processing machine (10) comprising a hydraulic drive system (46), wherein the hydraulic drive system (46) comprises: - An electro-hydraulic pressurized fluid source (48) having at least one electric motor (50) and at least one travel hydraulic pump (52). - A travel hydraulic circuit (54), which is supplied with pressurized fluid via at least one of the travel hydraulic pumps (52), - At least one travel hydraulic motor (56, 58) is supplied with pressurized fluid from the travel hydraulic circuit (54), - A discharge valve assembly (60) for discharging fluid from the travel hydraulic circuit (54) to a fluid reservoir (62). The discharge valve assembly (60) is operated to output fluid to the fluid reservoir (62) according to at least one of the following parameters: - The temperature of the fluid in the driving hydraulic circuit (54), - The temperature of the fluid during the fluid return journey to the fluid reservoir (62), - Ambient temperature, - The viscosity of the fluid in the driving hydraulic circuit (54), - The degree of contamination of the fluid in the driving hydraulic circuit (54), - The duration since the hydraulic drive system (46) last started operating, - The duration since the last fluid was discharged from the driving hydraulic circuit (54) When the temperature of the fluid in the driving hydraulic circuit (54) is higher than a predetermined discharge fluid threshold temperature and / or within a predetermined discharge fluid temperature range, the discharge valve assembly (60) is operated to output fluid to the fluid reservoir (62). When operating the discharge valve assembly (60) to output fluid from the travel hydraulic circuit (54) to the fluid reservoir (62), the amount of fluid to be output to the fluid reservoir (62) and / or the fluid output rate are adjusted according to at least one of the following parameters: - Ambient temperature, - Pollution level, - The time elapsed since the hydraulic drive system (46) last started operating, - The time elapsed since the last fluid was discharged from the driving hydraulic circuit (54).

15. The method according to claim 14, characterized in that, The method is used to operate the ground processing machine (10) according to any one of claims 1-13.

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