HYDRAULIC WORK VEHICLE WITH A VEHICLE FRAME AND A WORK TOOL

Description

[0001] The invention relates to a hydraulic work vehicle, in particular an excavator, wheel loader, tractor, telescopic loader or the like, wherein a hydraulic unit is provided for actuating and / or pressurizing a tool holding device and / or a working tool and / or a drive element, according to the preamble of claim 1. State of the art

[0002] Mobile machinery, such as excavators, dump trucks, wheel loaders, telescopic wheel loaders, compact loaders, or similar equipment, which have at least one hydraulic drive unit, typically also have at least one rotary-driven fluid displacement unit, usually powered by a drive motor. These pumps are either fixed-displacement pumps and / or variable-displacement pumps and are usually driven by at least one internal combustion engine or an electric motor. Depending on the speed and displacement volume of the pump(s), a flow rate is established, which is then directed to the connected actuators either via a distribution unit, e.g., valve(s), or directly as required.

[0003] Depending on the pump design, a minimum speed is required before the pumps can be subjected to significant operating pressures. Therefore, these pumps require the ability to start without a load. Due to their design, there are also pumps and motors that can start under load, but these are considerably more expensive compared to positive displacement units, which are used, among other things, in hydraulic systems.

[0004] In positive displacement pumps that have a minimum flow rate depending on their rotational speed, i.e., especially in constant and variable displacement pumps, a load-free start-up up to a maximum permissible starting pressure must be ensured due to system requirements. Up to now, a bypass has been used in such systems. This bypass does not direct the flow rate generated as the rotational speed increases to the actuator, but instead returns it at virtually no pressure. This bypass can be integrated into the valve system itself or installed separately.

[0005] A similar principle is used in positive displacement pumps, which, despite their rotary motion, do not necessarily deliver a flow rate. These pumps are designed so that the displacement unit only swings out once a minimum required rotational speed is reached. While a bypass approach would be conceivable here as well, it would entail additional component complexity and power loss due to unused flow.

[0006] Up to now, the standard method for starting machines without a load has typically involved a safety switch. In one position, the machine can be started but not controlled, and in the other position, it can be controlled but not started. Such a safety switch must be actively operated by the operator. This approach can also be used for machines with positive displacement units that do not generate a flow rate despite being rotated.

[0007] There are exceptions to these approaches. Especially with very small and / or cost-driven machines that have purely mechanical controls, start-up protection is not always implemented, as it is technically very complex to implement. Therefore, the operator is responsible for not activating the protection.

[0008] It is evident that, until now, the machine, or one or more drive motors, have operated at least at a minimum speed after startup before the actuators are ready for use. However, this contradicts the use of start-stop systems, which are increasingly employed for energy-saving / efficiency reasons. These systems switch off the corresponding pumps / motors when individual or all drive trains are not in use and restart them automatically when activated again. As previously explained, the drive units may only start when the safety switch is activated to prevent power supply to the actuators. Either the operator must initiate the start manually using a start routine, e.g., by actuating the safety switch, with protection ensured either by the previously described system safeguards for the components, or the responsibility is left to the operator.This is very complex and cumbersome, as well as prone to errors, especially if only individual axes are switched off and the machine is still being used.

[0009] Especially with electric machines, drive trains that are not currently in use are often switched off to further reduce energy consumption. However, these problems also occur with internal combustion engines equipped with automated start-stop functions. Therefore, internal combustion engines often do not use start-stop systems, but rather so-called auto-idle systems, where the minimum required displacement speeds are not undershot, or an auto-stop function is used that forces the operator to perform a normal starting procedure upon restarting. An excavator with an auto-idle mode is described, for example, in document US 2022 / 145590 A1. Purpose and advantages of the invention

[0010] In contrast, the object of the invention is to propose a hydraulic work vehicle that at least partially improves the disadvantages of the prior art.

[0011] This problem is solved, starting from a hydraulic work vehicle of the type mentioned in the introduction, by the features of claim 1. Advantageous embodiments and further developments of the invention are possible by the measures mentioned in the dependent claims.

[0012] Accordingly, a hydraulic work vehicle according to the invention is characterized in that at least one sensor is provided for detecting an actual operating parameter of the pressure generating device or the control element or the hydraulic unit, and that a comparison unit is provided for comparing the actual operating parameter with a rest / target operating parameter of a rest state of the pressure generating device or the control element or the hydraulic unit, wherein a start-up time is provided between the rest state and the operating state of the pressure generating device for starting up the pressure generating device up to a start-up speed of the rotary axis, and that the control unit is designed as a control unit for generating an inactive waiting state of the tool holding device or the working tool or the drive element during the start-up time.

[0013] The invention leads, firstly, to improved user behavior in connection with lower energy consumption, since unused drive trains can be switched off, and secondly, to the fact that no further measures, in particular no manual intervention or action by the driver, are required to restart the drive trains when a volume flow or pressure is requested.

[0014] Accordingly, a fully automated operating mode can be advantageously implemented, eliminating the need for further operation. From a user perspective, this results in virtually identical machine behavior with regard to flow rate and pressure delivery, regardless of whether the drive systems are currently running or still need to start up. The minimal time lag, i.e., the relatively short start-up time according to the invention, until the flow rate request is met after prior start-up, is practically imperceptible to the operator, especially with electrically driven motors or pumps. This achieves excellent system dynamics and energy efficiency.

[0015] Preferably, the sensor is designed as a speed sensor for detecting the rotational speed of the axis of rotation of the pressure generating device and / or the motor shaft of the pump motor and / or the pump shaft of the hydraulic pump, such that the actual operating parameter is the actual rotational speed. Advantageously, the quiescent setpoint operating parameter is a quiescent speed, i.e., a standstill or a speed of zero revolutions per minute.

[0016] In a preferred embodiment of the invention, the sensor is configured as a pressure sensor for detecting the pressure of the hydraulic oil / fluid and / or the hydraulic line and / or the hydraulic unit, and / or as a volumetric flow sensor for detecting the volumetric flow rate of the hydraulic oil / fluid and / or the hydraulic line and / or the hydraulic unit, such that the actual operating parameter is an actual pressure and / or a volumetric flow rate. Advantageously, the quiescent setpoint operating parameter is a quiescent pressure and / or a quiescent volumetric flow rate, i.e., no flow or pressure of nearly zero bar and / or a flow velocity / quantity of zero liters per minute.

[0017] In an advantageous embodiment of the invention, the sensor is designed as a position sensor for detecting a position, in particular a rest and / or an operating position, of the control element and / or an actuator or the tool holding device and / or the working tool and / or the drive element, such that the actual operating parameter is an actual position. Advantageously, the rest target operating parameter is a rest position and / or a state of non-movement, i.e., a rest end position and / or a standstill, or a movement speed of the actuator, such as a hydraulic cylinder and / or a hydraulic motor, in particular a linear motor, of zero centimeters per minute.

[0018] The aforementioned advantageous variants of the invention can be used individually or in combination. For example, at least one speed sensor and / or at least one pressure sensor and / or at least one position sensor can be provided. This improves the operational reliability and accuracy of the control system for the work vehicle according to the invention. The system according to the invention can, for example, firstly, detect the rotary motion, especially of the pressure generating device(s) or the displacement unit(s), i.e., in particular their shafts or their drive units / electric motors, or detect or verify the current flow rates or pressures, and secondly, detect or process the flow rate or pressure demand, the latter optionally being performed either by the operator or by the machine itself. Furthermore, a control system is advantageous that, according to the invention, determines the operating states and executes the corresponding actions.

[0019] Advantageously, the start-up time is designed such that the starting speed of the rotary axis and / or the actual rotational speed is a predetermined minimum speed of the rotary axis. This allows for a flexible or variable start-up time, which depends in particular on the current operating situation and / or any load, e.g., a full or empty excavator bucket, a retracted or extended telescopic arm of a telehandler, etc.

[0020] In a particular embodiment of the invention, the start-up time is a fixed, predetermined duration. Here, a precisely defined duration is established and used as the start-up time according to the invention. This duration is typically not variable or flexible and does not depend on the current operating situation of the work vehicle.

[0021] This duration is based on empirical data or preliminary tests, whereby a sufficiently long duration is used as a precaution to give the pressure generating device or displacement unit time to reliably reach its respective minimum speed.

[0022] According to the invention, the control unit is designed as an electronic control unit for electrically / electronically controlling the pressure generating device and / or the pump motor and / or the pump electric motor and / or the hydraulic pump. Preferably, the control unit is designed as an electronic control unit for electrically / electronically controlling the hydraulic unit and / or the hydraulic control element and / or the directional control valve and / or the tool holding device and / or the working tool and / or the drive element. For example, an electronic control unit can advantageously process or utilize electrical sensor signals and use them for advantageous control according to the invention. The electronic control unit can also advantageously control electrically controllable actuators and / or electrical actuators. In principle, advantageous software or...Programming and / or processor and / or electrical storage are provided, which allows the most diverse actual and / or target parameters, sensor signals, operating states, functionalities, characteristic curves, etc. to be stored / deposited, interact with each other or be processed.

[0023] In a preferred embodiment of the invention, the control unit is designed as a start-stop control unit for the automated implementation of a start-stop function of the pressure generating device and / or the pump motor and / or the pump electric motor and / or the hydraulic pump. This improves the operation and, in particular, the energy efficiency of the entire system or the work vehicle.

[0024] According to the invention, it can generally be ensured that an advantageous, load-free start-up or restart, e.g., with a start-stop function of the pressure generation device(s) or the displacement unit(s), can be guaranteed. This is particularly relevant after these pressure generation devices or displacement units have not been used for a certain period of time and have been in standby mode to save energy, and are then to be / can be operated again. According to the invention, the advantageous control unit prevents, for example, control signals and / or the control supplies to valves or actuators of the pressure generation device(s) or displacement units from being activated or from being pressurized with hydraulic fluid / oil.

[0025] In an advantageous embodiment of the invention, if the control signal is advantageously absent, the actuator or hydraulic unit will not react. For example, if the power supply is interrupted, the actuator or hydraulic unit cannot / will not react because it is not supplied with power. To utilize one or both of these advantageous start-up protection options, the actual rotational speeds are preferably compared with the target / setpoint speed, at least until load application is possible, at least when, for example, at least one actuator control signal from a deactivated drive train is present.

[0026] If the speed requirements are not met, no power is supplied to the actuators by interrupting the control signal and / or the control supply, thus enabling a load-free start-up. By implementing speed checks using logic or control units, including suitable software, the operator has no task or (manual) action required to restart the drive trains properly, for example, if the machine has already started operating. This is independent of whether the operator or the machine itself requests a flow rate for the actuators.

[0027] This advantageous approach of comparing rotational speeds and suppressing control signals or control supply for valves and / or actuating systems of displacement units or pressure generating devices can be used both during regular machine start-up and during restart of drive units or actuators.

[0028] Accordingly, the invention can be used regardless of whether the machine is being restarted or whether the entire machine or individual drives need to be restarted, e.g., after a start-stop scenario. This advantageously prevents the flow rate request, e.g., from the actuator's requirements, from being suppressed until the required minimum speeds are reached. For example, if the operator or one or more system components request a flow rate or hydraulic energy, this is only made available once the required minimum operating speed is reached, according to the invention, preferably by suppressing control signals and / or control supplies. The same applies, for example, if there is no flow rate request, but rather a pressure request to the system supply.

[0029] According to an advantageous embodiment of the invention, it is helpful, for example, to detect or record the movement of the pump(s) or their delivery volume flow rate or pump pressure, and, secondly, to transmit the volume flow rate or pressure requirement preferably only in a safe operating state, especially to the displacement units and / or, if present, to the respective valve system of the drive train or to a valve block or the like. Depending on the design, e.g., of the actuating elements of displacement units and / or valve systems, either the electrical signal or the hydraulic or electrical control, as well as the supply to the components themselves, can be suppressed according to the invention until the safe operating state or the starting speed is reached. Therefore, at least one advantageous logic unit or control unit or controller, including software, is also helpful, wherein, for example, the control system or controller does not forward or process internal and / or external control commands and / or does not forward the control commands to the components and / or prevents the supply of the actuators for the components themselves, whereby the supply could be electrical or hydraulic, until a safe operating state is reached in an advantageous manner.

[0030] Alternatively or in combination with this, it is also possible, for example, not to monitor the rotational speed for "signal transmission," but rather to monitor whether at least one signal transmitter is activated or not. If no activation is currently present, the control signals or the supply to the valve / hydraulic system or valve block, etc., are withheld for a defined period of time or during the start-up time according to the invention, until, for example, the motor(s) / pump(s) have reached the sufficient minimum rotational speed and only then are the (electrical and / or hydraulic) signals for activation passed through or the supply to the valve / hydraulic system or valve block, etc., is released so that the valves or valve spools can be actuated / deflected. Example of implementation

[0031] An embodiment of the invention is shown in the drawing and is explained in more detail below with reference to the single figure.

[0032] Figure 1 shows a schematic hydraulic circuit diagram of a hydraulic control system of a hydraulic work vehicle according to the invention.

[0033] In Figure 1 A schematic electro-hydraulic circuit diagram for a mobile work vehicle according to the invention is shown. Five optional sub-circuits / subsystems I to V are shown as examples, some in dashed lines, i.e., optional representations. Accordingly, hydraulic cylinders 1, hydraulic motors 2 or so-called hydrostatics 2, as well as electric motors 3, can be used as actuators. A work vehicle according to the invention can have only a single subsystem I, or several or all subsystems I to V, e.g., to lift a wheel loader's boom and to move or tilt its bucket.

[0034] Subsystems I to V typically include a hydraulic pump 4 or a pressure generator 4, in particular with a pump shaft 5 and / or motor shaft 6. This allows subsystems I to V to be pressurized or hydraulic oil to be pumped or transported. Various electric pump motors 9 are controlled and operated via inverters (INVs) 10.

[0035] Furthermore, hydraulic actuators or valve blocks 7 and / or valves 8 are provided. A central electrical / electronic control unit (ECU) 11 with an electronic comparator unit 12 controls the electro-hydraulic system or subsystems I to V, or the valves 8 and valve blocks 7, as well as the motors 9, 3 and inverter 10. An electrical and / or electronic data storage device is provided, in particular as part of the control unit (ECU) 11, without further detail.

[0036] Furthermore, various sensors for detecting a wide range of operating parameters or actual parameters are provided according to the invention, without further description, e.g. pressure sensors for detecting hydraulic pressure, speed sensors for detecting the speed of a motor 3, 9 or hydrostatic unit 2, volume flow sensors for detecting the volume flow within the hydraulic system or subsystems I to V, position sensors for detecting the position of the actuators or hydraulic cylinders 1, hydrostatic units 2, valves 8, valve blocks 7 or their internal actuators / valves, etc.

[0037] The sensors advantageously generate electrical sensor signals that can be transmitted to and evaluated by the control unit (ECU) 11, as illustrated by the dotted lines in the diagram. Figure 1The control unit (ECU) 11 processes or compares the sensor signals with stored parameters, in particular idle parameters or idle setpoint parameters, in accordance with the invention.

[0038] During a standstill or idle phase of subsystems I to V, or their motors 3, 9 or pumps 4, the control unit (ECU) 11 can generate an inactive standby state according to the invention for starting and / or restarting these systems. In this state, the motors 3, 9 or pumps 4 begin to start up or accelerate to their minimum speed, while simultaneously the transmission of hydraulic oil and / or electrical control signals to the valve blocks 7, valves 8, or actuators 1, 2, etc., is interrupted. This inactive standby time corresponds to the start-up time according to the invention and can be configured as a fixed duration or as a flexible / variable duration. The latter is preferable if the speed, flow rate, or pressure of the pumps 4 or motors 9 are detected and evaluated.

[0039] Alternatively or in combination with this, the position of a control element 13 or joystick and / or a foot pedal (not shown) can also be detected and evaluated by a sensor. According to the invention, this can also be used to determine whether one of the subsystems I to V is in a rest state or an active state.

[0040] According to the invention, the aforementioned diverse options and components ensure that the pumps 4 can start up without load and without manual intervention from the driver or operator. This very short inactive waiting time or start-up period will be barely perceptible to the driver. Thus, according to the invention, a fully automatic and / or safe start-up phase with a high level of comfort for the driver or operator is achievable.

Claims

1. Hydraulic work vehicle, in particular excavator, wheel loader, tractor, telehandler or the like, with a vehicle frame, with an in particular releasably connectable attachment, in particular a load fork, a grab arm, a bucket, a push blade or a platform, and with a drive unit for driving at least one drive element, e.g. a drive wheel and / or crawler track unit, wherein at least one tool holding device, in particular lifting arm, telescopic arm, lifting unit or the like, is provided for holding the attachment, wherein an at least one pressure generating device (4), in particular hydraulic pump (4), for pressurizing a hydraulic unit comprising a hydraulic oil / fluid and at least one hydraulic line for actuating and / or pressurizing the tool holding device and / or the attachment and / or the drive element is provided, wherein the pressure generating device (4) comprises at least one motor shaft (5, 6), which can be rotated about a rotation axis, of a pump motor (9), in particular a pump electric motor (9), and / or pump shaft (5, 6) of the hydraulic pump (4), wherein at least one electric and / or electronic and / or hydraulic control unit (11) has at least one controllable hydraulic control element (7, 8), in particular a directional control valve, for hydraulically controlling the tool holding device and / or the attachment and / or the drive element and at least one operator control element (13), in particular a foot pedal and / or so-called joystick (13), for manual operation / actuation by an operator, wherein the control unit (11) receives control signals from the operator control element (13) and / or passes on control signals to the tool holding device and / or the attachment and / or the drive element, characterized in that at least one sensor is provided for detecting an actual operating parameter of the pressure generating device (4) or the operator control element (13) or the hydraulic unit, and in that a comparison unit (12) is provided for comparing the actual operating parameter with a standby target operating parameter of a standby state of the pressure generating device (4) or the operator control element (13) or the hydraulic unit, wherein, between the standby state and the operating state of the pressure generating device (4), a start-up period for starting up the pressure generating device (4) to a start-up rotational speed of the rotation axis is provided, in that the control unit (11) is designed as a control unit (11) for generating an inactive waiting state of the tool holding device or the attachment or the drive element during the start-up period, and in that the control unit (11) is designed as an electronic control unit (11) for electrically / electronically controlling / activating the pressure generating device (4) and / or the pump motor (9) and / or the pump electric motor (9) and / or the hydraulic pump (4).

2. Work vehicle according to Claim 1, characterized in that the sensor is designed as a rotational speed sensor for detecting a rotational speed of the rotation axis (5, 6) of the pressure generating device (4) and / or the motor shaft (5, 6) of the pump motor (9) and / or the pump shaft (5, 6) of the hydraulic pump (4), so that the actual operating parameter is an actual rotational speed.

3. Work vehicle according to either of the preceding claims, characterized in that the sensor is designed as a pressure sensor for detecting a pressure of the hydraulic oil / fluid and / or the hydraulic line and / or the hydraulic unit and / or as a volume flow sensor for detecting a volume flow of the hydraulic oil / fluid and / or the hydraulic line and / or the hydraulic unit, so that the actual operating parameter is an actual pressure and / or a volume flow.

4. Work vehicle according to any of the preceding claims, characterized in that the sensor is designed as a position sensor for detecting a position, in particular a standby and / or an operating position, of the operator control element (13), so that the actual operating parameter is an actual position.

5. Work vehicle according to any of the preceding claims, characterized in that the start-up period is designed in such a way that the start-up rotational speed of the rotation axis (5, 6) and / or the actual rotational speed is a specified minimum rotational speed of the rotation axis (5, 6).

6. Work vehicle according to any of the preceding claims, characterized in that the start-up period is a fixedly specified period.

7. Work vehicle according to any of the preceding claims, characterized in that the control unit (11) is designed as an electronic control unit (11) for electrically / electronically controlling / activating the hydraulic unit and / or the hydraulic control element (7, 8) and / or the directional control valve (8) and / or the tool holding device and / or the attachment and / or the drive element.

8. Work vehicle according to any of the preceding claims, characterized in that the control unit (11) is designed as a start / stop control unit (11) for the automated implementation of a start / stop function of the pressure generating device (4) and / or the pump motor (9) and / or the pump electric motor (9) and / or the hydraulic pump (4).

9. Work vehicle according to any of the preceding claims, characterized in that the hydraulic unit and / or the tool holding device and / or the attachment and / or the drive unit comprises at least one hydraulic cylinder (1) and / or a hydraulic motor (2).

10. Method for operating a hydraulic work vehicle, characterized in that a work vehicle according to any of the preceding claims is provided and used.