Method for operating self-propelled road-building machine, in particular road-compacting drive-type machine, and self-propelled road-building machine, in particular road-compacting drive-type machine

Abstract

The invention relates to a method for operating a self-propelled road-building machine, in particular a road-compacting driving machine, and to a self-propelled road-building machine, in particular a road-compacting driving machine.

Description

Field of the Invention

[0001] The present invention relates to a method for operating a self-propelled road construction machine, in particular a ride-on road compactor, and to a self-propelled road construction machine, in particular a ride-on road compactor. Background Art

[0002] Road construction machines of this type are, for example, road milling machines, in particular cold milling machines, and road compactors, such as, in particular, rollers, for example so-called tandem rollers, rubber-tyred rollers or road rollers. Road compactors with a cab enclosing the driver's platform are known. Alternatively, these machines, in particular relatively small road compactors, can be equipped with an open driver's platform, which, however, sometimes includes at least one driver's platform roof. Finally, hand-guided road compactors are known, in which the operator of the machine accompanies the machine during its operation. Machines in which the operator travels along with the machine on the driver's platform are also referred to as ride-on road compactors. The present invention relates to self-propelled road construction machines in which the operator sits or stands on the machine and travels along with it during travel and work operations.

[0003] Road construction machines are generally used for creating and / or renovating roads, streets, runways and / or squares. Road compactors are used in the construction of streets and roads for compacting the subgrade or the road surface, such as an asphalt layer or a soil surface. For this purpose, road compactors typically have at least one or more compaction belts, which are, for example, constructed as rolling belts (Walzbandagen) with a hollow cylindrical base body, and with which the road compactor moves on the road surface. Such compaction belts can likewise be vibrated, for example, by a vibration exciter, usually an unbalanced exciter, in order to thus influence the compaction and achieve a dynamic compaction that goes beyond pure static compaction. It is also possible for the compaction belts to be used in combination with wheels, in particular rubber-tyred wheels or other travel devices. In addition, road compactors are known which have only wheels, such as so-called rubber-tyred soil compactors, which are likewise used in road construction.

[0004] Such road construction machinery is usually constructed as self-propelled and includes a drive motor. This drive motor is often an internal combustion engine, such as a diesel internal combustion engine. For a common drive concept for such a road compactor, the drive motor drives one or more hydraulic pumps of a hydraulic system, which in turn apply hydraulic drive energy to hydraulic loads, such as travel motors and / or working unit motors, which drive, for example, one or more vibration exciters, edge trimming devices (Kantenschneidgerät), spreaders, milling rollers (Fräswalze), fans of dust collectors, etc. In addition, the hydraulic system includes well-known suitable pipeline connections. The hydraulic pump responsible for the travel drive hydraulic circuit is also referred to as the travel pump. In addition, such road construction machinery can have a hydraulically driven steering device, especially in the case of so-called articulated steering road construction machinery, as is known in particular for road rollers themselves. The hydraulic pump responsible for the steering hydraulic circuit is also referred to as the steering hydraulic pump.

[0005] Taking into account the increasingly strict emission regulations for users and manufacturers of such road construction machinery, such road construction machinery is increasingly also equipped with one or more electric motors, up to a complete replacement of the hitherto common internal combustion engine by one or more electric motors. Thus, in particular, the primary drive unit, i.e., the main drive source of the road construction machinery, can also be an electric motor. Such road construction machinery can always include a hydraulic system and thus an electro-hydraulic drive architecture.

[0006] The hydraulically operated system has been proven as well as possible and has several advantages. In particular, at the start of operation, if the hydraulic fluid of the hydraulic system is still relatively cold, the increased viscosity associated with the low temperature of the hydraulic fluid can, however, be disadvantageous. On the one hand, increased wear on the components of the hydraulic system can result from this. On the other hand, the operation of the individual operating elements can be sluggish, for example, the steering movement of a hydraulic steering system is implemented via the steering wheel. In the case of road construction machinery with an internal combustion engine, it is therefore customary for the road construction machinery to run for a period in no-load operation at the start of operation and thereby heat the hydraulic fluid. Such no-load operation is naturally not only harmful from an environmental perspective but also not equally possible in the case of using one or more electric motors, since electric motors generally do not have the possibility of no-load operation corresponding to that of an internal combustion engine. In addition, users of such road construction machinery find it uncomfortable that they have to be present in the driver's cab during this heating phase, because for reasons of operational safety, the drive motor of the road construction machinery can only be put into operation when the operator is present in the driver's cab. This can be detected by means of a so-called operator detection device, such as a driver's seat switch, which is actuated when the driver is sitting on the driver's seat. Summary of the Invention

[0007] Based on this, the object of the present invention is therefore to improve the operating comfort of road construction machinery.

[0008] The solution to this object is achieved by means of a method for operating a self-propelled road construction machine, in particular a ride-on road compactor, according to the independent claims and a self-propelled road construction machine, in particular a ride-on road compactor. Preferred refinements are proposed in the dependent claims.

[0009] In a first aspect, the invention thus relates to a method for operating a self-propelled road construction machine (in particular a ride-on road compactor). A road construction machine of this type includes an electrohydraulic drive system which includes an electric motor as a drive unit. The drive system can, for example, drive one or more travel devices, in particular one or more wheels and / or a roller belt and / or a chain drive (Kettenlaufwerke) and / or one or more working units. Such a working unit can be, for example, a vibration exciter, a steering device, a unit adjustable by a linear actuator, such as, for example, a trimming device or a stroke cylinder, a conveyor belt drive or the like. The electric motor, for example a synchronous or asynchronous motor, is connected to an energy storage device, in particular a battery, configured for storing electrical energy. The energy storage device can include a plurality of sub-parts. In addition, a converter can be present. The electric motor can thus obtain electrical energy from the energy storage device and be driven by this electrical energy. The electric motor can be the primary drive unit of the road construction machine. The road construction machine can be configured without an internal combustion engine, so that all the energy required for operating the road construction machine is mainly provided by one or more electric motors.

[0010] In addition, a road construction machine of this type includes at least one hydraulic pump drivable by an electric motor, which, in a state driven by the electric motor, sucks hydraulic fluid from a hydraulic fluid container through a hydraulic system and conveys it into the hydraulic fluid container. The hydraulic pump can be a fixed-displacement pump or a variable-displacement pump with a variable delivery volume per revolution and / or per unit of time. The hydraulic system can in particular be an open hydraulic circuit, where the hydraulic pump sucks hydraulic fluid from the hydraulic fluid container at at least one extraction location and conveys this hydraulic fluid in some cases also at another location, at at least one outlet location, back into the hydraulic fluid container. The hydraulic circuit can also be a closed hydraulic circuit, where in this case, for example, in order to compensate for leakage losses, leakage oil is collected in the hydraulic fluid container and hydraulic fluid is fed from the hydraulic fluid container into the closed hydraulic circuit. The conveyance of hydraulic fluid between the extraction location and the outlet location takes place through at least a part of the hydraulic system. The hydraulic system can include suitable pipes and / or hose lines for this purpose. The hydraulic fluid container can be a hydraulic fluid tank.

[0011] Furthermore, a part of this type of road construction machinery is a controllable throttle valve within the hydraulic system. By "within" here is meant that the hydraulic fluid conveyed by the hydraulic pump is pumped through a section of pipeline, the cross-section of which, i.e., the flow cross-section, can be changed by this throttle valve. The throttle valve thus represents a device by means of which at least transiently a flow obstruction can be generated for the hydraulic fluid within the hydraulic system. Furthermore, the throttle valve can be configured, for example, such that it at least transiently narrows the flow or pipeline cross-section available for the hydraulic fluid within the hydraulic system with respect to the flow cross-section or pipeline cross-section at the throttle valve along and against the flow direction of the hydraulic fluid through the throttle valve. It is essential that the throttle valve is adjustable at least between a passive state and at least one heated state. The throttle valve can thus change the flow cross-section or pipeline cross-section defined by it between at least two cross-sectional areas of different sizes with respect to the cross-sectional area of flow (in the sense of being transverse to, i.e., perpendicular to the main flow direction), where such a state - in which the throttle valve has a larger cross-sectional area of flow - is called the passive state, and such a state - in which the throttle valve has a relatively smaller cross-sectional area of flow - is called the heated state. The passive state can be configured with respect to the cross-sectional area of flow available in this state of the throttle valve such that no flow obstruction is provided at all by the throttle valve itself in the passive state, i.e., the cross-sectional area of flow is at least equal to or even larger than the cross-sectional area of flow of the flow cross-section or pipeline cross-section at the throttle valve along and against the flow direction of the hydraulic fluid through the throttle valve. It is feasible that the throttle valve can be adjusted such that it can only be reciprocally adjusted between two end positions, the "passive state" and the "heated state". Naturally, it can also be set that the throttle valve can in particular occupy more than one heated state or is adjustable within the range of the heated state.

[0012] Furthermore, according to the invention, it is provided that the road construction machinery includes a control device that controls the adjustment of the throttle valve between the passive state and at least one heated state. The control device can be, for example, part of the machine controller of the road construction machinery. This can be, for example, a computer device.

[0013] The road construction machine configured to implement the method according to the invention further includes a machine activation device, which can be adjusted by the operator of the road construction machine in order to adjust the road construction machine between an activated state and a deactivated state. In the deactivated state, all drive units required for the driving and working operation of the road construction machine are deactivated, especially without current or without energy. Thus, in this state, especially the at least one hydraulic pump may not deliver hydraulic fluid. The deactivated state typically exists when the road construction machine is to be transported and / or is not required for a relatively long time interval, such as often overnight and / or during a long pause time. The deactivated state can especially be an operating state in which the supply of electrical energy to one or more components of the road construction machine is separated from the accumulator during the normal operation of the road construction machine. For this purpose, for example, a physically acting, especially also manually operable battery disconnect switch can be provided. Naturally, there can also be separation electronics supplemented or alternatively, by which this separation is at least functionally achieved. In the activated state, in contrast, the road construction machine can be put into operation by the operator, even though it can be set that for this purpose, additional conditions, such as for example the position or orientation determined by the operator on the road construction machine, releasing the parking brake, etc., must be partially satisfied. In the activated state, naturally, compared to the deactivated state, there is already a more comprehensive possible power supply to one or more loads from the electrical energy obtained from the accumulator. In the activated state, for example, one or more lighting devices, display displays, and / or touchscreen functions can already be realized, which are without current or deactivated in the deactivated state. In addition, the activated and / or deactivated state can be related to the respective functions considered. For "driving", for example, what may be required for transitioning to the activated state is that the driver is seated and the joystick is removed from the brake catch (Bremsraste). For "working functions", such as for example operating the trimming device and / or activating the vibration function / unbalance exciter, it can be set that the transition from the deactivated state to the activated state is only feasible when the joystick is positioned in the brake catch.

[0014] Supplemented, the road construction machine configured to run the method according to the invention includes a parking brake device adjustable between a braking position and a releasing position. In the braking position, the parking brake device directly or indirectly exerts a braking effect on at least one of the running gears, thereby hindering the road construction machine from driving or rolling. This can be achieved, for example, by means of suitable form-fitting and / or friction-locking. The parking brake device can be configured, for example, as a claw brake or a multi-disc brake.

[0015] Furthermore, it is provided that the road construction machine has a braking state detection device configured to detect at least the activated braking position and / or the activated release position of the parking brake device. By means of the braking state detection device, it is thus possible to detect and monitor, for example by means of one or more suitable sensors, which of the two positions the parking brake device is exactly in. Such a sensor can be, for example, a contact switch or the like. The signal detected by the braking state detection device can be transmitted to the control device.

[0016] Based on the above basic structure of a road construction machine according to the method of the present invention, the core aspect of the present invention lies in a method for heating a hydraulic fluid. With this method, on the one hand, it is possible to heat the hydraulic fluid without the operator having to be present at a certain operating position in the driver's cab for this purpose. On the other hand, at the same time, it is possible to ensure compliance with the current requirements for the operating safety of such a road construction machine. The operating position here means the position of the operator inside or on the road construction machine, which the operator should occupy during the driving and working operation of the road construction machine as a matter of course. This can often be, for example, the sitting position in the driver's seat included in the road construction machine. However, this does not mean that the operation of particularly partial functions of the road construction machine is in principle only achievable from the said operating position, especially in the scope of non-conventional operation of the road construction machine.

[0017] In order to heat the hydraulic fluid outside the driving and working operation, based on the road construction machine being in a deactivated state, in step a), it is first set that the operator of the road construction machine realizes the adjustment of the machine activation device from the deactivated state to the activated state. This can be achieved directly by the operator, for example, by manually operating an operating element on the road construction machine. Additionally or alternatively, it can also be set that the control device of the road construction machine has a timing function, whereby the operator can pre-determine a future moment at which the machine controller will then place the road construction machine from the deactivated state into the activated state. The timing function can be provided by the control device. Furthermore, additionally or alternatively, the adjustment can also be achieved by the operator via a wireless signal connection using a mobile phone, where then a suitable communication device is included, through which the operator transmits a signal for adjusting the road construction machine from the deactivated state to the activated state from their mobile phone, such as a smartphone, to the road construction machine. The method thus also includes, in this case, transmitting a switching signal from the deactivated state to the activated state from the mobile phone to the road construction machine.

[0018] If the road construction machine is in the activated state, then the road construction machine alone is not yet fully ready for use based on this. Instead, it is now first implemented in step b): The parking brake device is detected by means of a brake state detection device as to whether it is in the braking position or the released position and transmitted to the control device. In the braking position, the parking brake device is in particular in a position - in which it exerts the parking brake function - in particular such that the road construction machine can neither be actively moved by its own drive nor be passively moved from the outside. The detection of the current position of the parking brake device is achieved by means of a brake state detection device and can on the one hand include only one actual detection of the presence of the braking position. If it is thus currently detected that: the braking position does not exist, then it can be assumed that the parking brake device is in the released position. Alternatively, conversely, it is also possible to set the actual detection of only the presence of the released position, so that if the released position is not detected, then it is assumed to be in the braking position. Preferably, the presence of both the released position and the braking position is actively detected. Specifically, the brake state detection device can for this purpose have one or more suitable sensors, such as for example one or more position sensors, contact switches, non-contact, in particular inductive proximity switches, etc. In one embodiment, for example, it can be set that there is a separate adjusting element, such as a lever, only for the activation / deactivation of the parking brake device, the adjustment position of which is detected. Alternatively, there can also be a multi-functional adjusting element, which can implement at least one additional function in addition to the activation / deactivation of the parking brake device. In particular, it is possible to have a joystick, which on the one hand can implement the control of the driving speed and / or the driving direction (forward - backward). This can be achieved, for example, by offsetting the joystick along or opposite to the forward direction. At the same time, it can be set that the joystick, in particular from a defined zero position - in which no driving movement is predetermined - can be adjusted to a position that activates the parking brake device, which is oriented on the joystick, in particular transversely to the driving direction and / or the driving speed control direction. The detection of the activation and / or deactivation of the parking brake device can then be achieved, for example, by detecting the adjustment position of the joystick. Additionally or alternatively, it is also possible to detect one or more relative positions of the actually mechanically interacting brake elements of the parking brake device by means of suitable sensors, such as for example the relative position of the claws of a claw brake and / or the occupation of a defined position, etc.

[0019] Based on the typical start-up situation of a road construction machine that has been inactive for a relatively long period of time - where the hydraulic fluid is cooled, for example, to the external ambient temperature and is thus significantly below the normal operating temperature of the hydraulic fluid - targeted heating of the hydraulic fluid can now be achieved in step c) without the operator having to be physically present on the road construction machine. For this purpose, in the parking heating mode, the control device is made to control the position of the throttle valve between a passive position and a heating position. This is naturally only feasible if the road construction machine is in an active state, which can be queried separately by the control device, for example, if the control device is also powered on in the deactivated state of the road construction machine and implements one or more monitoring functions, such as a timing function. For the case where the control device is also currentless and thus inactive in the deactivated state, it is not necessary to separately query the control device for the actual presence of the active state. In addition, the control of the throttle valve in the parking heating mode is achieved based on the detection signal of the braking state detection device. The control device thus also queries the current state of the parking brake device in this mode or detects whether the parking brake device is currently in the braking position or in the released position. When, in particular only when, the parking brake device is in the activated braking position, the control device activates in the parking heating mode the conveyance of hydraulic fluid by a hydraulic pump driven by an electric motor and adjusts the throttle valve to at least one heating position. At least part, preferably completely, of the conveyed hydraulic fluid flows through the throttle valve. By the throttle valve being in the heating position and thus in a position representing a flow blockage for the hydraulic fluid flow, the hydraulic fluid is heated when passing through the throttle valve by converting mechanical or hydraulic energy into heat energy. The heated oil can be fed into the travel hydraulic circuit. At the same time, the parking brake device in the braking position ensures that the conveyed hydraulic fluid flow reliably keeps the road construction machine from being put in motion as long as the heating of the hydraulic fluid is desired during parking operation. Overall, the parking heating mode can thus be ended without the operator having to be permanently present on the road construction machine for safety reasons. If the operator subsequently puts the road construction machine into operation at a later time, i.e., if the hydraulic fluid has been heated at least ideally by a notable part, then for the operator, full operating comfort is available immediately in an ideal situation and at the same time wear phenomena at the hydraulic components can be reduced.

[0020] The parking heating mode can be configured in such a way that it is only variable between the activated and deactivated operating states. In other words, the parking heating mode can be simply controlled between the on and off states. This can naturally result in that the parking heating mode also pumps the hydraulic fluid through the throttle valve in the heating position during such phases where the temperature of the hydraulic fluid is already high enough. If the parking heating mode continues to be maintained during these phases, this correspondingly reduces the energy efficiency of the road construction machine. Therefore, it is preferred that the activation of the hydraulic pump by the control device, especially in the pre-activated warm-up mode by the operator, is only achieved if the state parameter affecting the current viscosity of the hydraulic fluid and / or the operating parameter related to the current viscosity of the hydraulic fluid is outside a defined range. The state parameter affecting the current viscosity of the hydraulic fluid is especially the temperature of the hydraulic fluid. The lower the temperature of the hydraulic fluid, the higher its viscosity. Therefore, it can be set that the temperature of the hydraulic fluid is determined by means of a suitable sensor, for example by means of a temperature sensor and transmitted to the control device. Temperature limit values can be defined, which should be exceeded in order to obtain a low enough viscosity. Only during the phases of the parking heating mode where the current temperature of the hydraulic fluid is below this temperature limit value does the control device activate at least one hydraulic pump and / or the throttle valve. The operating parameter related to the current viscosity of the hydraulic fluid can be, for example, the pumping resistance and / or the pumping torque to be applied and / or the adjustment torque to be applied for adjustment movements, for example for one or more hydraulically actuated components, especially for the adjustment movement of the hydraulic steering device, and / or the pressure in at least one area of the hydraulic system. These operating parameters can also be detected, monitored and / or transmitted to the control device by means of suitable sensors, especially load sensors and are decisive for the activation of the hydraulic pump in the parking heating mode. And for this purpose, one or more limit values can also be defined, exceeding or falling below which indicates that the current viscosity is still too high and thus the current temperature of the hydraulic fluid is still too low and / or vice versa. As a supplement or alternative, if the state parameter affecting the current viscosity of the hydraulic fluid and / or the operating parameter related to the current viscosity of the hydraulic fluid is within a defined range, especially the temperature of the hydraulic fluid is above the temperature limit value or an alternative state parameter exceeds a defined limit, then the control device can deactivate the activated hydraulic pump. Whether the control device takes into account the limit values to be below and / or above and / or the value ranges to be used for the activation and / or deactivation of the hydraulic pump and / or the throttle valve results in all variants in that the hydraulic fluid is only pumped through the throttle valve in the parking heating mode if it is required to obtain optimized operating conditions. Thus, there can also be operating phases in the parking heating mode where, if not required, the hydraulic fluid is not pumped through the throttle valve, so that the energy balance of the road construction machine can be increased again overall.Alternatively or additionally, it can also be provided that at least one or more individual properties of the hydraulic fluid used are stored and / or input by the operator and the above-described process is also implemented based on these one or more properties. This can also be the input of a hydraulic fluid of a certain type or the like.

[0021] In principle, it is feasible that the throttle valve is adjustable between exactly one passive position and exactly one heating position. It can naturally be advantageous if the throttle valve is adjustable in at least two mutually different heating positions in addition to the passive position within a variable adjustment range, where one heating position has a higher throttling effect or a mutually different pipeline cross-section relative to the other heating position. This enables a further optimization of the operation of the road construction machine in the parking heating mode, such as the current charge state of the accumulator, the heating of the hydraulic fluid, especially quickly or alternatively especially energy-efficiently. The throttle valve can be configured, for example, as an adjustable throttle valve. Functionally, it is advantageous if the functions connected downstream of the throttle valve in the hydraulic fluid circuit are not considered in terms of performance.

[0022] As will be further described below, the use of the throttle valve does not have to be limited to the heating of the hydraulic fluid in the parking heating mode, but can also be extended to heating purposes and / or other tasks during the continuous driving and working operation of the road construction machine in each case, for example for braking. For this case, it is preferably provided that when at least the parking brake device is in the activated braking position, the control device can set and sets at least one heating position having a higher throttling effect relative to the other heating position. On the one hand, this enables the highest heating effect to be obtained solely by the throttle valve in the parking heating mode. On the other hand, this ensures that the throttling reserve is available during the operating phases outside the parking heating mode, especially during the driving and working operation of the road construction machine, and can be used, for example, for braking purposes or the like if required.

[0023] In addition to the above-described parking heating mode, which is only available if the parking brake is in the braking position and thus the road construction machine is stopped, it can be set that the control device can operate in an operating heating mode. The operating heating mode is characterized compared to the parking heating mode in that if the road construction machine is in a driving and working operation, then this operating heating mode can be adopted, in particular, for further heating of the hydraulic fluid in some cases. This assumes that in this case the road construction machine is not only in an activated state, but also the parking brake is in the released position. In this case, it can be set that the control device adjusts the position of the throttle valve to the at least one heating position state to generate a braking torque and / or to heat the hydraulic fluid in at least a part of the hydraulic system. Thus, it can be set that, in particular for the purpose of additionally and / or more rapidly heating the hydraulic fluid, the throttle valve is adjusted to the heating position state by the control device during this operating phase. This can in particular also be achieved according to the states and / or operating parameters previously elucidated for the parking heating mode. The use of the throttle valve for the supplementation or replacement for generating a braking torque is particularly meaningful in the case where the road construction machine has an electro-hydraulic travel drive system. Different from the case of a conventional road construction machine with an internal combustion engine, such as a diesel engine, for travel drive, in the electro-hydraulic drive solution, it is no longer easily feasible to use the support torque originating from the internal combustion engine for braking the road construction machine. In the case of braking or during downhill travel, for example, the hydraulic travel motor of the road construction machine acts as a pump, so that the torque applied to the travel motor is transmitted to at least one travel pump, which then acts as a motor. The support torque of the internal combustion engine can be used in such a road construction machine to support the torque applied to at least one travel pump, whereby the road construction machine can be braked overall (this effect is generally also referred to as "motor braking"). In contrast, an electric motor is not suitable for reliably establishing a support torque or a braking torque that can be used for braking the road construction machine. Thus, for example, a reduced support torque can be generated according to the state of charge of the battery or according to the power reduction of the electric motor and / or the converter. The throttle valve can now naturally be used in the electro-hydraulic drive solution for: increasing the resistance in the hydraulic system at least locally for braking purposes. The throttle valve can thus be used for a dual function in the method according to the invention. On the one hand, for heating the hydraulic fluid purposefully, in particular also selectively, especially also in the case where the road construction machine is stopped, and on the other hand, as a braking device for purposefully generating a braking torque during the driving and / or working operation of the road construction machine, if required. To achieve this functionality, in particular, it can be set that the travel drive hydraulic pump, the working or operating hydraulic pump, in particular the steering hydraulic pump, and the electric motor are mechanically coupled to each other, for example, jointly driven by the electric motor in a series arrangement structure.

[0024] It can be set that the control device controls the throttling effect of the throttle valve such that the throttling effect is greater in the parking heating mode than in the operating heating mode. This can be advantageous, for example, in this context compared to the fact that in the parking heating mode, the power reserve of the electric motor does not actually have to be made available, and the throttling effect of the throttle valve is actually only available for heating the hydraulic fluid during this operating phase. In the operating heating mode, in contrast, one or more hydraulic loads can be active or activated, such as the travel drive hydraulic motor and / or the work unit drive hydraulic motor. Therefore, it is important that the available hydraulic drive can be consumed by the throttle valve for heating purposes only to such an extent that the reliable and situation-appropriate operation of the travel drive hydraulic motor and / or the work unit drive hydraulic motor is always ensured.

[0025] In another preferred implementation variant of the method according to the invention, it can be set that the control device controls at least one safety function of at least one hydraulically actuable functional unit of the road construction machine in the operating heating mode and with the throttle valve in the heating position, and furthermore starts a position adjustment of the throttle valve in order to increase the throttling effect of the throttle valve when a higher throttling effect is required for obtaining the safety function compared to the operating heating mode. If the throttling effect of the throttle valve is used for multiple functions, especially during the operating heating mode, then the control device and / or the throttle valve obtain, in some cases, mutually different requirements. In this case, it is set that the control device establishes priorities for these requirements in order to always ensure at least a sufficient throttling effect of the throttle valve.

[0026] Specifically, for example, it can be set that the control device prioritizes a request signal for generating a braking torque - which ultimately represents a safety function - and a request signal for generating heating power in the operating heating mode. In other words, the control device weighs the control signal for generating the braking torque against the control signal for heating the hydraulic fluid. Here, it can be set that the control signal originating from the safety function is always prioritized over the signal originating from the heating purpose. In particular, for the case where the throttling effect currently generated by the throttle valve in the heating position is already above the throttling effect currently required by the safety function, it can preferably be set that the control device then maintains the existing throttling effect or the current position of the throttle valve in the heating position and thus does not reduce it to only the throttling effect currently required by the safety function. Once the throttling effect currently required by the safety function naturally rises above the currently existing throttling effect, then the control device will increase the throttling effect of the throttle valve by adapting the heating position. Therefore, it can be particularly set here that the control device controls the position of the throttle valve between the passive position and the heating position based on the detection signal of the braking state detection device or the service brake device that can be controlled separately from the parking brake device. Supplementary (or alternatively), the heat input into the hydraulic circuit can also be achieved by an electrical heating unit at at least one position in the pipeline routing.

[0027] A road construction machine may have a cab, and an operator can control the driving and working operations of the road construction machine from the cab. The cab may include, for example, a driver's seat and / or one or more operating elements that can be manually operated by the operator in the cab. The following road construction machines are known, and their operation safety schemes are provided with an operator detection device included in the cab, which is configured to detect the presence and / or absence of the operator in the operating position in the cab. By means of such an operator detection device, it is especially ensured that the road construction machine can only achieve driving and working operations or even be put into operation in principle when the operator actually stays in the cab for this purpose. A typical operator detection device may be, for example, a seat contact switch, which is only activated when the operator sits on the driver's seat. By means of the operator detection device, it is thus possible to detect whether the operator is in the cab in the operating position and transmit it to the control device. Typically, the control device and / or the operator detection device are configured such that in fact as long as the operator detection device does not confirm the presence of the operator in the cab, all drive components of the road construction machine are deactivated, partially or even without current. Moreover, this safety function may also have a timing function during the running operation, so that the deactivation of the running driving and / or working operations of the road construction machine is only achieved when the operator detection device does not detect the presence of the operator for a period exceeding a defined period. In order to now be able to achieve the operation of the road construction machine in the parking heating mode even so with respect to the usually existing safety scheme, it can be set that the throttle valve is also implemented by the control device in the parking heating mode and / or the running heating mode according to whether the operator detection device detects the operator in the operating position. If, for example, the parking heating mode is activated, then for the following situations, that is, when the parking brake device is adjusted to the release position and / or the operator detection device records the presence of the operator, which in both cases on the one hand indicates that the parking heating mode may be about to end and, if necessary, a transition to the running heating mode and on the other hand the possible imminent start of the driving and / or working operations of the road construction machine, it can be set that the control device prophylactically changes the position of the throttle valve in the first heating state such that the pressure drop caused by the throttle valve or the throttling effect of the throttle valve is increased to the passive state or at least adjusted to a second heating state with a throttling effect reduced relative to the first heating state. Additionally or alternatively, for example, in the case of the existence of a running heating mode and a throttle valve in the heating state, it can be set that if the parking brake device moves from the release position to the braking position and / or the operator detection device no longer detects the previously detected presence of the operator, for example because the operator has left the cab or at least its operating position, then the control device adjusts the throttle valve to the passive state or - if necessary - transitions to a matching parking heating mode with the necessary state of the throttle valve as required.

[0028] In the case where the road construction machine includes a hydraulically actuated steering device, a likewise preferred design of the method according to the invention is feasible. Different design options are known to exist in principle for the design of the hydraulic steering device. In addition to the servo steering device, a particularly proven arrangement includes a steering hydraulic pump that conveys hydraulic fluid through a hydraulic steering regulator (Lenkorbitrol) in the steering hydraulic circuit. The steering hydraulic pump can in particular be operated as a fixed-displacement pump and / or almost self-sufficiently by the rest of the hydraulic system. In the case of using a hydraulically actuated steering device, in particular as a hydraulic system for heating the hydraulic fluid, as described above, it can now be set that the control device controls the road construction machine in the parking heating mode such that: in variant a), when the operator detection device does not detect the presence of an operator in the operating position, the rotational speed of the electric motor is reduced when the steering device is activated, in particular according to the current heating position of the throttle valve, or the rotational speed of the electric motor is limited to the maximum allowable steering operating speed. This can also achieve, on the one hand, the hydraulic steering of the road construction machine in situations outside the operating position set in the case of operating the road construction machine according to the conventional operation in the parking heating mode. More specifically, especially in the case of a so-called "ride-on road construction machine", i.e., in particular, for example, a road construction machine with a total dead weight of up to no more than 5 tons, an operator standing next to the road construction machine can adjust the steering operating elements, such as the steering wheel and / or the steering lever, located in the driver's cab at least for steering purposes, which can be advantageous, for example, when the road construction machine is facing a transport vehicle for transport purposes. At the same time, the previous measures ensure that: the hydraulic power available for steering is relatively small, thereby significantly reducing the accident risk in situations outside the operating position and especially when operated outside the road construction machine. As a supplement or alternative, it can be set that in variant b), if the operator detection device detects the presence of an operator in the operating position, the electric motor is operated at a rotational speed that is increased relative to at least one of the rotational speeds from variant a), in particular also as long as the parking brake device is still in its braking position. This enables more powerful steering, which is acceptable for the case where the operator is in the conventionally set operating position.

[0029] For the case where the hydraulic pump is a steering hydraulic pump and the hydraulic system includes a travel drive hydraulic pump, it can be set that in the parking heating mode, the hydraulic fluid conveyed from the hydraulic fluid container by the steering hydraulic pump passes through at least a part of the steering hydraulic circuit in the hydraulic system and from there through at least a part of the travel drive hydraulic pump and from there is conveyed into the hydraulic fluid container. In particular, the hydraulic fluid conveyed by the steering hydraulic pump can also be utilized and fed for "lateral flushing" and / or for leakage compensation of the travel drive hydraulic circuit set for the travel drive hydraulic circuit during normal operation. In addition, an additional bypass line can also be provided, which in particular switches the hydraulic fluid from the steering hydraulic circuit to the travel drive hydraulic pump and / or the travel drive hydraulic circuit only in the activated parking heating mode and / or the operating heating mode by means of a suitable hydraulic valve. However, as long as the road construction machine is in the parking heating mode, it is advantageous that the conveyance of the hydraulic fluid is effected such that no travel drive power is generated on one or more hydraulic motors driven by the travel drive hydraulic pump. This can be achieved, for example, by means of a suitable valve controller, which for this state causes the hydraulic fluid to pass by the hydraulic motor and / or - if the hydraulic motor is configured as an adjustable motor - by means of a full swing-out (Ausschwenken) of the adjustment device of the adjustable motor, so that the hydraulic fluid flowing through the adjustable motor does not drive the motor movement of the adjustable motor.

[0030] The road construction machine can include specific working devices, in particular also hydraulically driven working devices. For a road milling machine, for example, it can be set that the rotational movement of the hydraulically driven milling drum is effected. For a road compactor, it can be set that it has one or more so-called vibration exciters. The hydraulic pump can thus also be a vibration exciter drive hydraulic pump, and the hydraulic system can include a vibration hydraulic system, which includes a vibration drive motor driven by the vibration exciter drive hydraulic pump. For this specific design of the hydraulic system, it can be advantageous that a controllable throttle valve - for example in the form of a pressure limiting valve - is provided in the bypass line to the vibration drive motor, wherein in the parking heating mode or the operating heating mode, at least a part of the hydraulic fluid conveyed from the hydraulic fluid container by the vibration exciter drive hydraulic pump passes through the controllable throttle valve bypassing the vibration drive motor and from there is conveyed into the hydraulic fluid container. In this way, it is also possible for the vibration exciter hydraulic circuit to be used for heating the hydraulic fluid. If the vibration drive motor is an adjustable motor, the bypass line can be dispensed with. Usually, a fixed displacement motor is naturally used here, so that each of the hydraulic motors has a driving effect on the vibration arrangement. In particular, for the parking heating mode, it is naturally advantageous to ensure that no vibration is generated on the vibration arrangement.

[0031] Precisely in the case of such road construction machinery, whose primary drive is implemented by an electric motor or in other words does not have an internal combustion engine, the overall energy management of the road construction machinery is particularly important, because the charging cycles required for charging the accumulator are usually still relatively time-intensive. For this reason, it is preferred that the control device only allows the parking heating mode when the charge state of the accumulator is above the charge state boundary value. In this way, it is avoided that the accumulator is discharged in the parking heating mode solely based on the operation of the road construction machinery and then can no longer be used by its own drive to move the road construction machinery. As a supplement or alternative, it can be set that the control device controls the heating position of the throttle valve according to the current charge state of the accumulator. If the charge state of the accumulator is still relatively high, then compared to the situation where it only has a relatively low charge state, an energy-intensive parking heating mode or the positioning of a throttle valve with a relatively high throttling effect can rather be accepted.

[0032] Another aspect of the invention relates to a self-propelled road construction machine, in particular a ride-on road surface compactor. Regarding the device features included by this type of road construction machine, in order to avoid repeated reference to the previous disclosure of the method according to the invention. According to the invention, the road construction machine is configured to implement the method according to the invention as described above.

[0033] Preferably, the self-propelled road construction machine, in particular a ride-on road surface compactor, includes a machine activation device having an operating device that can be operated outside the driver's cab of the road construction machine. The operating device can be a mobile phone, in particular a smart phone, where the road construction machine is then configured for wireless communication, for example via a wireless local area network, NFC, etc., so that signals can be received by the mobile phone, in particular signals can be exchanged with it. As a supplement or alternative, however, the operating device can also include manually operable operating elements, such as switches and / or buttons, in particular also a key switch or a keyboard area. Without having to board the driver's cab or in other words only from outside the road construction machine, the operator can in this case operate the machine activation device and thereby, for example, adjust the road construction machine from the deactivated state to the activated state and / or activate the parking heating mode. Description of the Drawings

[0034] In the following, the invention will be explained in detail based on the exemplary embodiments schematically shown in the drawings, supplementing the previous description. The drawings show:

[0035] Figure 1a shows a side view of a road construction machine of the ride-on road surface compactor type;

[0036] Figure 1b shows a side view of a road construction machine of the compact milling machine type;

[0037] Figure 2 A schematic diagram of a hydraulic system showing a first exemplary embodiment;

[0038] Figure 3Schematic diagram of a hydraulic system showing a second embodiment;

[0039] Figure 4 Schematic diagram of a hydraulic system showing a third embodiment;

[0040] Figure 5 Showing a control device and additional components, in particular for controlling the embodiments shown in Figures 2 to 4 ;

[0041] Figure 6 Showing the operating state of a road construction machine in the parking heating mode;

[0042] Figure 7 Showing the operating state of a road construction machine also in the running heating mode; and

[0043] Figure 8 Showing a method flow chart for operating a road construction machine. DETAILED DESCRIPTION

[0044] Elements that are identical in structure and / or function and are repeated in the drawings do not have to be shown in each drawing.

[0045] Figure 1A and 1B Exemplarily shown are two road construction machines 1 of this relevant type in two specific design configurations. In Figure 1A a road construction machine of the type of a ride-on road roller is shown; while in Figure 1B a road construction machine of the type of a compact milling machine is shown. These two road construction machines include an electro-hydraulic drive system, which includes an electric motor 2 as a drive unit, and the drive unit is connected to an accumulator 3 configured to store electrical energy, in particular a storage battery. The electric motor 2 can thus obtain electrical drive energy from the accumulator 3. The electric motor 2 drives at least one hydraulic pump 4 and can be connected thereto directly, for example, to the electric motor 2 or be in a drive connection via a suitable, in particular mechanical, drive transmission. The hydraulic pump 4 driven by the electric motor 2 conveys hydraulic fluid in the hydraulic system 5 to a hydraulic fluid container 6, in particular a hydraulic fluid tank, in the driven state. In addition, a part of the hydraulic system 5 is a throttle valve 15, which will be further described below, and which can be adjusted between a passive state and at least one heating state. The adjustment of the throttle valve can be controlled by a control device 14.

[0046] In addition, the two road construction machines 1 shown in Figure 1A and 1B have a machine frame 7 as a basic load-bearing structure, wherein in Figure 1AThe machine frame of the illustrated embodiment is a hinged machine frame 7, which includes a hinge joint connecting the front frame and the rear frame of the machine frame 7, in particular a folding swivel steering joint (Knickpendellenkgelenk). Figure 1B In contrast, it has a rigid frame with a running gear 8 that is at least partially steerable relative to the machine frame 7. The running gear 8 can be wheels ( Figure 1B ), or a chain drive. Alternatively, the running gear can also be a rolling belt ( Figure 1A ). In addition, the road construction machine has a driver's cab 9, which has a respective driver's seat 10 and operating elements 11, such as the steering wheel of the steering device 12, for example. If the operator sits in the driver's seat 10 in the driver's cab 9, then he is in the conventional operating position. Figure 1A and 1B It has been clarified that it is also possible to reach the individual operating elements from outside the respective road construction machine 1, for example from a position standing next to the road construction machine 1. This position does not represent the conventional operating position of the respective road construction machine 1.

[0047] The driver's cab 9 can have an operator detection device 13, by means of which it is possible to monitor whether the operator is in the operating position in the driver's cab 9. This can be, for example, a seat contact switch. The operator detection device 13 can be signal-connected to a control device 14, in particular a machine controller, which controls the operation of the electric motor 2 in particular.

[0048] In addition, a part of the road construction machine 1 is a parking brake device 16 each. This parking brake device can be adjustable between a braking position - in which the running gear 8 is locked - and a release position, in which the running gear 8 can rotate about its respective axis of rotation (freely or driven). The parking brake device 16 can include one or more mechanically acting brake elements, which directly or indirectly cause the locking of the respective running gear 8 in the braking position by frictional engagement and / or form-locking. In addition, the road construction machine includes a brake state detection device 17, which is configured such that it determines whether the parking brake device 16 is currently in the braking position and / or the release position. The brake state detection device is signal-connected to the control device 14.

[0049] In addition, the road construction machine 1 can have a service brake device (not further shown in the drawing) in addition to the parking brake device 16, by means of which the road construction machine can be braked during running operation.

[0050] Finally, Figure 1A and 1BBoth of the road construction machines have a machine activation device 18, which is provided with an operating device 21. The machine activation device is configured to adjust the road construction machine 1 between an activation mode and a deactivation mode. The machine activation device or its operating device 21 can be particularly arranged at a position on the road construction machine 1 that is accessible from outside the road construction machine 1, in particular at least from outside the driver's cab 9. The machine activation device 18 can be configured as, for example, a button or other manually operable element on the road construction machine 1, and can also be configured as a numeric keypad for entering an authorization code, for example. As a supplement or alternative, it is also feasible that the machine activation device 18 has a mobile phone 19, such as a smartphone, as an operating element. The machine activation device can be in a signal transmission connection with the road construction machine 1, and for this purpose, the road construction machine has a suitable receiving device 20, which can also be configured for two-way communication. The machine activation device 18 can be in a signal connection with the control device 14.

[0051] Figure 1A and 1B The difference between the two road construction machines lies especially in the type of working devices present and thus their tasks. According to Figure 1A The road construction machine 1 can especially include a hydraulically driven vibration exciter 22, especially an unbalanced exciter, and is used for compacting the road surface foundation, in addition to a traveling device configured as a rolling belt. According to Figure 1B In contrast, the basic working device of the road construction machine 1 is especially a hydraulically driven milling roller (covered by a milling roller box 23 in Figure 1B ), so that the subgrade can be milled with a milling depth.

[0052] Figure 2 、 3 And 4 will now illustrate additional details of different embodiments of the present invention according to the respective hydraulic systems 5 shown.

[0053] In Figure 2 the hydraulic system 5 includes a traveling drive hydraulic pump 24. The traveling drive hydraulic pump can be configured as a regulating pump with a delivery volume variable per revolution or as a fixed-displacement pump with a constant delivery volume per revolution. The traveling drive hydraulic pump conveys hydraulic fluid from a hydraulic fluid container 6 into a traveling drive hydraulic circuit 25, and through this traveling drive hydraulic circuit, for example, it can especially drive, by means of a suitable hydraulic motor, in Figure 1A and 1BThe indicated travel device 8 is provided to enable the self-propelled operation of the road construction machine 1. In addition, there is a steering hydraulic circuit 26 which, for example, can include a hydraulic steering regulator 27 and a hydraulically adjustable steering actuator 28. The hydraulic pump 4, which is thus a steering hydraulic pump in this case, is driven by the electric motor 2. In addition, in the present embodiment, there is a through-drive 29 by means of which the drive of the travel drive hydraulic pump 24 is also effected. The pumps 4 and 24 are thus positioned in a series arrangement and are jointly driven by the electric motor. Irrespective of the specific embodiment, in particular in the drive train from the electric motor 2, in particular to the travel drive hydraulic pump 24, an intermediate clutch element or the like (not shown) can be provided so that the drive train from the electric motor 2 to at least the travel drive hydraulic pump 24 can also be mechanically interrupted at least transitively. In particular, the drive of the hydraulic pump 4 is thus also effected by the electric motor 2, so that overall there is an electro-hydraulic drive system, here for steering and travel drive. Figure 2 an intermediate clutch element or the like, not shown, can be provided in the drive train from the electric motor 2, in particular to the travel drive hydraulic pump 24, so that the drive train from the electric motor 2 to at least the travel drive hydraulic pump 24 can also be mechanically interrupted at least transitively. In particular, the drive of the hydraulic pump 4 is thus also effected by the electric motor 2, so that overall there is an electro-hydraulic drive system, here for steering and travel drive.

[0054] Figure 2 It is explained that the throttle valve 15 is positioned in the hydraulic system 5 such that the hydraulic fluid conveyed by the hydraulic pump 4 first passes through the throttle valve 15 and in the present embodiment is conveyed back to the hydraulic fluid reservoir 6 via the hydraulic steering regulator 27. The throttle valve 15 can be adjusted by the control device 14 between a passive position and at least one heating position. In the passive position, the hydraulic fluid passes through the throttle valve in the direction towards the hydraulic steering regulator 27 with virtually no additional flow resistance generated by the throttle valve 15. In the heating position, the throttle valve relatively reduces the flow cross-section compared to the flow cross-section released by the throttle valve 15 in the passive position. Thereby, a throttling effect is generated by the throttle valve within the hydraulic circuit 26, and by means of this throttling effect, the heating of the hydraulic fluid flowing through the throttle valve is finally achieved. This effect is used not only for heating the hydraulic fluid itself, but also for heating the individual hydraulic components themselves by means of heat convection by guiding the heated hydraulic fluid downstream of the throttle valve 15 through the hydraulic steering regulator and then guiding the hydraulic fluid transversely to the travel drive hydraulic circuit 25 through the travel drive hydraulic pump 24 (i.e., without a pump drive acting on the travel drive hydraulic circuit 25 and without any significant feed into the travel drive hydraulic circuit 25 for drive purposes).

[0055] Different from the embodiment shown in Figure 2 the embodiment according to Figure 3 is characterized in that there is a switching valve 29. This switching valve can be arranged, for example, downstream of the hydraulic steering regulator 27. Depending on the switching position, the hydraulic fluid can be directly guided back to the hydraulic fluid reservoir 6 and / or Figure 2guided in the manner described to the travel drive hydraulic pump 24. This variant has the advantage that, for example, a specific area of the overall hydraulic system of the road construction machine 1 and / or the targeted heating of the overall volume of the hydraulic fluid can be influenced in a targeted manner, wherein, for example, heating losses through heat transfer from the heated hydraulic fluid to one or more components of the hydraulic system 5 are avoided. Moreover, the valve 29 can be in signal connection with the control device 14.

[0056] According to Figure 4 the embodiment of Figure 2 and 3 the embodiment of is characterized in that, instead of the steering hydraulic circuit, the working unit hydraulic circuit is recycled, here, for example, the drive hydraulic circuit of the vibration exciter 22, in particular comprising at least one or more so-called unbalanced exciters. In the case of the road construction machine 1 configured as a road milling machine, in particular a compact milling machine, this can be, for example, the milling drum or the milling drum drive. It is advisable not to operate this working device during the heating operating mode, which will be further described below. To ensure this, in particular, there is a shut-off valve 31 which is selectively adjustable, in particular by the control device 14, between at least one shut-off position and a release position upstream of the hydraulic drive motor 32 of the vibration exciter 22 (or the drive of the corresponding working device). In the shut-off position, the shut-off valve prevents any hydraulic fluid flow towards the drive motor 32, so that the drive motor is not driven. In the release position, the hydraulic fluid conveyed by the hydraulic pump 4 can flow relatively to the drive motor 32 and thus drive it. If the shut-off valve 31 is in the shut-off position, then in the present embodiment the hydraulic fluid is guided through a bypass line 33 - the hydraulic fluid passes through this bypass line around the drive motor 32, in particular at least with respect to the driving action (previously for Figure 2 and 3 the type of "lateral flushing" described can also be set for the drive motor 32) - to and through a throttle valve 15, which is therefore arranged in the bypass line 33 in this case. Similarly, the steering hydraulic circuit 26 or another hydraulic circuit can be bypassed additionally or alternatively, as indicated by the dashed line in Figure 4 In place of the shut-off valve 31, it can also be provided that the drive motor 32 is configured as a regulating motor which has a variable displacement per revolution (Schluckvolumen).

[0057] Figure 5 Clarify the details of the possible connections of the control device 14 for implementing the method according to the invention.

[0058] It can be set that the control device obtains a plurality of status signals, and the status signals are transmitted to the control device 14 by respective suitable sensors through suitable signal lines. For example, the machine activation device 18 can be in signal connection with the control device 14 directly or through a sensor and transmit: whether the machine activation device 18 is in an activated state and / or a deactivated state and / or undergoes a transformation from one state to another. In addition, the braking state detection device 17 can include a status sensor 34, which determines and monitors whether the parking brake device 16 is in a braking position and / or a released position and / or undergoes a transformation between these positions. There can also be a service brake sensor (not further shown in the drawings), which determines the operating state and / or braking request of the service brake and transmits it to the control device 14. In addition, there can be a temperature sensor 35 (and / or a sensor that supplements or replaces the temperature and determines the status parameter that affects the current viscosity of the hydraulic fluid), which determines the current temperature of the hydraulic fluid at one or more suitable positions in the hydraulic system 5. As a supplement or alternative to this, a sensor 36 can also be included, which determines operating parameters related to the current viscosity of the hydraulic fluid, such as, for example, the torque required for the conveyance of the hydraulic fluid, or a load sensor or the like. There can also be a sensor 37, which, as part of the operator detection device 13, determines whether the operator is exactly in the operating position. In addition, as a supplement or alternative, there can be a travel speed sensor 38, through which the current travel speed of the road construction machine 1 can be determined. A pump sensor 39 can also be included, which determines the operating state of the hydraulic pump 4. The current charge state of the accumulator 3 can be determined by means of a charge state sensor 40 and transmitted to the control device 14.

[0059] Taking into account and based on the above and the sensor information available in a single case, the control device 14 open-loop controls or closed-loop controls the throttle valve 15 or adjusts it between a passive state and one or more heating states. This can be limited to the parking heating mode or, alternatively, also in the operating heating mode. In addition, it can be set that the control device also open-loop controls and / or closed-loop controls the operation of at least the hydraulic pump 4.

[0060] If one or more shut-off valves 31 are included in the road construction machine 1 in the above manner, the control device 14 can also control the position or state of the shut-off valve 31.

[0061] Not only the throttle valve 15 but also one or more shut-off valves can be adjustable either only between their respective two positions or, in particular, within a range with respect to the heating state or the shut-off state. Therefore, it can be set for both the throttle valve 15 and one or more shut-off valves 31 that there is a valve sensor each, which is configured to determine the current state of the respective valve.

[0062] Finally, the control device 14 can also control the electric motor 2. Additionally, an operating state sensor 42 can be provided, by means of which at least one operating parameter of the electric motor 2, such as its rotational speed, and / or at least one operating state of the electric motor 2, such as whether the electric motor is receiving electrical energy exactly, can be determined and monitored.

[0063] Moreover, a clutch present in certain cases can also be controlled by the control device 14 and monitored with respect to its current engaged or disengaged state by means of a suitable sensor.

[0064] Figure 6 and 7 Now, different operating processes are exemplarily illustrated, which describe possible open-loop control and / or closed-loop control situations of the control device 14, in particular with respect to the control device being exemplarily integrated into the road construction machine 1 as shown in Figure 5 Herein. Figure 6 Basically, it relates to the parking heating mode, Figure 7 The operating phase is also shown, in which the road construction machine is in the operating heating mode. The curves of the respective control functions and operating and state parameters over time t are shown. This is a schematic view and it goes without saying that the shown curve trends can vary in practice, particularly with a partially curved trend.

[0065] In Figure 6 and 7 In a), the current state of the machine activation device 18 between the deactivated state D and the activated state A is indicated. In b), the current state of the operator detection device 13 is shown. The time - at which the presence of the operator in the operating position is detected - is indicated by +. The time - at which the absence of the operator in the operating position is detected - is indicated by -. In c), the current state of the parking brake device 16 is shown, including the stage C - if the parking brake device is in the braking position - and the stage O, if the parking brake device is in the released position. Figure d) indicates the current temperature (or the average value of multiple measurement positions) of the hydraulic fluid at a defined measurement position within the hydraulic system, such as within a pipeline section and / or in the hydraulic fluid container 6. The temperature limit value TG is also indicated in d). It is determined here that the viscosity of the hydraulic fluid within the temperature range above this temperature limit value TG is low enough or the temperature of the hydraulic fluid is high enough so that the desired operating comfort can be provided to the operator and / or the wear phenomenon of the hydraulic components due to the too high viscosity of the hydraulic fluid is sufficiently reduced. e) shows the curve of the rotational speed (in revolutions per minute) of the hydraulic pump 4, where in this embodiment, the hydraulic pump 4 is a fixed-displacement pump with a constant displacement per revolution. This means that in this embodiment, the volume flow rate of the pump is correlated with the rotational speed of the pump. f) Finally, the pressure drop Δp of the hydraulic fluid across the throttle valve 15 is indicated and thus the current throttling effect compared to the passive state.

[0066] InFigure 6 The starting point of the operating process elucidated in Figure 6 is the time t0, at which the road construction machine 1 is in the deactivated state D and the parking brake device 16 is in the braking position C. If there is an optional operator detection device, then this operator detection device detects that there is currently no operator in the operating position. Correspondingly, the hydraulic pump 4 also stops, so that no hydraulic fluid is conveyed in the hydraulic system. The road construction machine can, for example, maintain the overall state described while it is being transported on a transport vehicle or parked at a construction site and is not being used at the moment.

[0067] At time t1, the operator adjusts the road construction machine from the deactivated state D to the activated state A. This can be achieved, for example, by operating the operating device 21 or by means of the mobile phone 19 or triggered thereby, i.e., when the timing function programmed by the operator previously reaches the time set for this switchover in terms of time, so that in this case the manual predetermination by the operator and the actual switchover are staggered in terms of time. This can be implemented by the control device 14. With the switchover to the activated state A, the control device 14 at least queries the current position of the parking brake device 16, which is in the braking position C here. Optionally, the state of the operator detection device 13 can also be queried, which determines at time t1 that there is no operator in the operating position. In this embodiment, the control device 14 thus first activates the hydraulic pump 4 at time t1, which accelerates up to the rated speed R1 determined for the parking heating mode according to e) and thereby conveys hydraulic fluid, for example, in one of the hydraulic systems as described in Figures 2 to 4 one of the hydraulic systems described in

[0068] At time t2, the hydraulic pump 4 reaches its rated speed R1 and the control device 13 adjusts the position of the throttle valve 15 from the passive state to the heating state. Thereby, a pressure drop Δp is generated by the throttle valve 15, which reaches its maximum value at time t3. The hydraulic energy is converted into heat energy by the generated throttling effect, whereby the hydraulic fluid is heated. Correspondingly, the temperature rises in the time period t3 to t4.

[0069] At time t4, the temperature T reaches the temperature boundary value TG. The hydraulic fluid has now reached a sufficiently high temperature. To save electrical energy, the hydraulic pump is now switched off, so that the rotational speed of the hydraulic pump and correspondingly also the pressure drop across the throttle valve 15 drop back to zero from t4 to t5. It can also be set here to maintain a type of cyclic state, in which, for example, only the current rotational speed of the pump is reduced but remains greater than zero, in order to, for example, efficiently contain the re-cooling of the hydraulic fluid in terms of energy.

[0070] At time t6, the operator occupies the operating position. This means that until time t6, no operator was present at the operating position and this was also not required. By occupying the operating position, the operator now naturally knows that they may want the road construction machine 1 to enter the driving and / or working operation. Additionally or alternatively, this can also be achieved by releasing the parking brake device at time t7 or by adjusting the parking brake device 16 from the braking position C to the release position O and, for example, displayed to the control device 14 in the above-mentioned manner.

[0071] First, at time t7, the road construction machine can be operated normally by the operator in the operating position, and the parking heating mode ends (and if necessary, switches to the operating heating mode). At time t8, the operator's driving command is input. Accordingly, the control device controls the increase in the rotational speed of the hydraulic pump according to e), whereby finally the current temperature of the hydraulic fluid can also continue to rise (from t8 to t9). Since in this case the current temperature of the hydraulic fluid naturally remains above the temperature boundary value TG as before, in Figure 6 the case shown at time t8, additional heating of the hydraulic fluid by the throttle valve 15 is not required.

[0072] Figure 7 Similarly based on the road construction machine in the deactivated state as already Figure 6 explained. The process is the same until time t3 and the machine is in the parking heating mode. Different from what was Figure 6 stated, the operator now naturally occupies their operating position at time t4 and the parking brake device 13 is released or adjusted to the release position at time t5. At time t5, the hydraulic fluid has naturally not yet exceeded the temperature boundary value TG and thus has not yet reached its rated temperature. The control device 14 therefore switches from the parking heating mode to the operating heating mode. Specifically, for this purpose, for example, the throttle valve is adjusted from the heating position at time t4 - at which time a pressure drop Δp2 occurs at the provided reference rotational speed of the hydraulic pump - to another heating position in which a smaller pressure drop Δp1 occurs relative to this. This is the case between t5 and t6. The flow cross-section still released by the throttle valve 15 at position Δp2 is therefore smaller than in the case of position Δp1. At the same time, the driver performs the driving and working operation of the road construction machine, for which the rotational speed of the hydraulic pump is further increased between t5 and t6.

[0073] At time t6, the hydraulic fluid reaches the threshold marked by TB, so that no further heating of the hydraulic fluid is required during the current operation of the road construction machine in the operating heating mode. The control device 14 adjusts the throttle valve to the passive position (Δp0) and reduces the rotational speed of the hydraulic pump by a value of hydraulic power, which is required to convey the hydraulic fluid through the throttle valve that was previously in the heating position Δp1. Through the driving and working operation of the road construction machine, the hydraulic fluid can also continue to increase above the temperature boundary value independently of the throttling effect of the throttle valve, as is clearly visible, for example, during the period between time t6 and t7.

[0074] At time t7, a characteristic now appears. A request signal for generating an additional braking torque is transmitted to the control device 14, for example, a service brake device not further shown in the figure. This causes the control device to adjust the throttle valve to another position with a throttling effect (variable and increased from Δp2 to Δp3), even though the temperature of the hydraulic fluid is above TG at this moment. Naturally, the control device 14 prioritizes the required braking torque over the temperature management of the hydraulic fluid in this case.

[0075] Figure 7 Explanation: The throttle valve can be adjusted to more than one heating position and is especially not only used for heating purposes but can also be equipped with multiple functions. In particular, the throttle valve or its heating position can be variable and adjustable within the adjustment range.

[0076] Figure 8 Finally, the exemplary different feasible processes of the method according to the invention according to the flow chart are explained, especially for operating the embodiment presented in the previous figures.

[0077] The method includes, in step 43: the operator of the road roller adjusts the machine activation device from the deactivated state to the activated state. In step 44, it is then realized to detect by means of the brake state detection device 17 whether the parking brake device 16 is in the braking position or the released position and transmit it to the control device 14. In the parking heating mode, now in step 45, if the road construction machine 1 is in the activated state, then according to the detection signal of the brake state detection device, the control device 14 controls the position of the throttle valve 15 between the passive position and the heating position, wherein the control device activates at least the conveyance of the hydraulic fluid by the hydraulic pump driven by the electric motor and adjusts the throttle valve to at least one heating position at least when the parking brake device is in the activated braking position. Therefore, at least it is required that the machine is in the activated state and at the same time the parking brake device 16 is in the braking position in order to operate the hydraulic pump 4 for heating purposes.

[0078] Step 45, i.e., activating the hydraulic pump by the control device, can be selectively implemented only if the state parameter affecting the current viscosity of the hydraulic fluid and / or the operating parameter related to the current viscosity of the hydraulic fluid is outside a defined range, in particular if the temperature of the hydraulic fluid is below the temperature boundary value. Accordingly, in step 46, it is also possible to monitor one or more state and / or operating parameters and adjust step 45.

[0079] Step 45 can also supplement or replace heating the hydraulic fluid for additional functions, in particular for generating braking torque during the driving and working operation of a road construction machine, for example. If such additional braking torque is required, it can be set that the control device for controlling the position of the throttle valve 15 establishes a priority between "heating requirement" and "braking requirement" and sets the position of the throttle valve according to this priority in step 47.

[0080] It can be set that, in order to control the position of the throttle valve, it is also considered in step 48 whether the operator detection device determines the presence and / or absence of the operator in the operating position.

[0081] The method can also include, in step 49, switching one or more bypass valves, for example for bypassing the hydraulically driven working devices, such as a vibration exciter or a milling roller drive, in the parking heating mode.

Claims

1. A method (40) for operating a self-propelled road construction machine (1), in particular a ride-on road compactor, I.) The road construction machine (1) comprises: - An electro-hydraulic drive system including an electric motor (2) as a drive unit, the electric motor being connected to an accumulator (3) configured to store electrical energy, - A hydraulic pump (4) drivable by the electric motor (2), the hydraulic pump delivering hydraulic fluid into a hydraulic fluid container (6) via a hydraulic system (5) in a state driven by the electric motor (2), - A throttle valve (15) controllable within the hydraulic system, the throttle valve (15) being adjustable between a passive state and at least one heating state, - A control device (14) that controls the adjustment of the throttle valve (15) between the passive state and the at least one heating state, - A machine activation device (18) that can be adjusted by an operator of the road construction machine (1) to adjust the road construction machine (1) between an activated and a deactivated state, - A parking brake device (16) adjustable between a braking position and a release position and a braking state detection device (17), the braking state detection device being configured to detect at least the activated braking position and / or the activated release position of the parking brake device (16), II.) The method for heating the hydraulic fluid comprises the following steps: a) The operator of the road construction machine adjusts the machine activation device (18) from the deactivated state to the activated state; b) The braking state detection device (17) detects whether the parking brake device (16) is in the braking position or the release position and transmits it to the control device (14); c) In the parking heating mode, if the road construction machine (1) is in the activated state, then the position of the throttle valve (15) between the passive state and the heating state is controlled by the control device (14) according to the detection signal of the braking state detection device (17), wherein the control device (14) activates the delivery of hydraulic fluid by the hydraulic pump (4) driven by the electric motor and adjusts the throttle valve (15) to the at least one heating state at least when the parking brake device (16) is in the activated braking position.

2. The method according to claim 1, characterized in that The activation of the hydraulic pump (4) by the control device (14) is carried out only when state parameters affecting the current viscosity of the hydraulic fluid and / or operating parameters related to the current viscosity of the hydraulic fluid are outside a defined range, in particular when the temperature of the hydraulic fluid is below a temperature boundary value; and / or the deactivation of the activated hydraulic pump by the control device (14) is carried out when state parameters affecting the current viscosity of the hydraulic fluid and / or operating parameters related to the current viscosity of the hydraulic fluid are within a defined range, in particular when the temperature of the hydraulic fluid is above a temperature boundary value.

3. The method according to one of the above claims, characterized in that, The throttle valve (15) can be adjusted to at least two mutually different heating states within a variable adjustment range, one heating state having a higher throttling effect relative to the other heating state.

4. The method according to claim 3, characterized in that, At least one heating state with a higher throttling effect relative to another heating state is set by the control device (14) only when at least the parking brake device (16) is in the activated braking position.

5. The method according to one of the above claims, characterized in that, During operation of the heating mode, when the road construction machine (1) is in the activated state and the parking brake device (16) is in the released position, the control device (14) adjusts the position of the throttle valve (15) to the at least one heating state for generating braking torque and / or for heating the hydraulic fluid in at least a part of the hydraulic system (5).

6. The method according to claim 5, wherein The control device (14) controls the throttling effect of the throttle valve (15) such that the throttling effect in the parking heating mode is greater than that in the operation heating mode.

7. The method according to claim 5 or 6, characterized in that, During operation of the heating mode and in the case of the throttle valve (15) in the heating state, the control device (14) controls at least one safety function of at least one hydraulically actuable functional unit of the road construction machine, and in addition, when a higher throttling effect relative to the operation heating mode is required to obtain the safety function, it starts to adjust the position of the throttle valve (15) to increase the throttling effect of the throttle valve (15).

8. The method according to any one of claims 5 to 7, characterized in that During operation of the heating mode, the control device (14) sets priorities for the request signal for generating braking torque and the request signal for generating heating power relative to each other.

9. The method according to one of the above claims, characterized in that The road construction machine (1) has a driver's cab (9) by which an operator can control the driving and working operation of the road construction machine (1). The driver's cab (9) has an operator detection device (13) configured to detect the presence and / or absence of the operator in the operating position in the driver's cab. By means of the operator detection device (13), it is detected whether the operator is in the operating position in the driver's cab (9) and transmitted to the control device (14), and the throttle valve (15) is also controlled by the control device (14) in the parking heating mode and / or the operation heating mode according to whether the operator detection device (13) detects the operator in the operating position.

10. The method according to claim 9, wherein The road construction machine (1) includes a hydraulically actuable steering device (12), and during the parking heating mode, the control device (14) controls the road construction machine (1) such that: a) When the operator detection device (13) detects that no operator is present in the operating position, in the case of the activated steering device (12): - Reduce the rotational speed of the electric motor (2), in particular according to the current heating state of the throttle valve (15), or - Limit the rotational speed of the electric motor (2) to the maximum allowable steering operating speed, and / or b) When the operator detection device (13) detects that an operator is present in the operating position, operate the electric motor (2) at no-load speed, which is increased relative to at least one of the rotational speeds from a).

11. The method according to any one of the preceding claims, characterized in that The hydraulic pump (4) is a steering hydraulic pump. The hydraulic system (5) includes a travel drive hydraulic pump (24). In the parking heating mode, the hydraulic fluid delivered from the hydraulic fluid container (6) by the steering hydraulic pump passes through at least a part of the steering hydraulic circuit (26) in the hydraulic system (5), and from there through at least a part of the travel drive hydraulic pump (24), and from there is delivered into the hydraulic fluid container (6).

12. The method according to any one of the preceding claims, characterized in that The hydraulic pump (4) is a vibration-excitation-driven hydraulic pump. The hydraulic system (5) includes a vibration hydraulic system. The vibration hydraulic system includes a vibration drive motor driven by the vibration-excitation-driven hydraulic pump. A controllable throttle valve (15) is provided in a bypass line (33) leading to the vibration drive motor. In the parking heating mode or the operating heating mode, at least a part of the hydraulic fluid delivered from the hydraulic fluid container by the vibration-excitation-driven hydraulic pump passes through the controllable throttle valve (15) bypassing the vibration drive motor, and from there is delivered into the hydraulic fluid container.

13. The method according to one of the above claims, characterized in that, The control device (14) permits the parking heating mode only when the charge state of the accumulator (3) is above a charge state boundary value and / or the control device controls the heating position of the throttle valve (15) according to the current charge state of the accumulator (3).

14. Self-propelled road construction machines (1), in particular ride-on road rollers, characterized in that, The self-propelled road construction machine is configured to carry out the method according to one of the preceding claims.

15. Self-propelled road construction machinery (1), especially a ride-on road roller, characterized in that, The machine activation device (18) has an operating device that can be actuated from outside the driver's cab (9) of the road construction machine (1).

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