EP4321693A1 - Hydraulic work vehicle comprising a vehicle frame and a work tool - Google Patents

Abstract

There is a hydraulic work vehicle with a work tool, with at least one tool holding device being provided for holding the work tool, with a hydraulic unit comprising at least one pressure generating device being provided for actuating and/or pressurizing the tool holding device and/or the work tool and/or the drive element, wherein at least one control unit (11) has at least one controllable hydraulic control element (7, 8) and at least one operating element (13) for manual operation/actuation by an operator, which at least partially improves the disadvantages of the prior art. This is achieved according to the invention in that at least one sensor is provided for detecting an actual operating parameter of the pressure generating device and/or the operating element and/or the hydraulic unit and that a comparison unit is provided for comparing the actual operating parameter with a resting target operating parameter of a resting state of the Pressure generating device (4) and/or the operating element (13) and/or the hydraulic unit is provided, with a start-up period for starting up the pressure generating device (4) up to a starting speed of the axis of rotation being provided between the idle state and the operating state of the pressure generating device (4), and that the control unit (11) is designed as a control unit (11) for generating an inactive waiting state of the tool holding device and/or the work tool and/or the drive element during the start-up period.

Description

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

State of the art

Mobile work machines, such as excavators, dumpers, wheel or telescopic, telescopic wheel, compact loaders or the like, which have at least one hydraulic drive unit, usually also have at least one rotary-driven fluid displacement unit, which is usually driven by a drive motor with mechanical energy is supplied. These pump(s) are designed either as fixed displacement pumps and/or as 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 volume flow is established which is passed on either by means of a distribution unit, e.g. valve(s), or directly to the connected actuator system as required.

Depending on the pump design, a minimum speed is required from which the pumps can be subjected to significant operating pressures. Therefore, these pumps require the possibility of starting without load. Due to their design, there are also pumps and motors that are allowed to start under load, but this is clearly the case are more expensive compared to displacement units, which are used in work hydraulics, among other things.

For positive displacement units that have a minimum delivery rate depending on their speed, i.e. especially for fixed and variable displacement pumps, load-free starting up to a maximum permitted starting pressure must be ensured due to the system. To date, a bypass has been used in such systems, which does not forward the delivery volume flow that arises at the onset of speed to the actuator, but rather returns it almost without pressure. This bypass can be installed in the valve system itself or separately.

A similar principle is used in displacement units, which do not necessarily provide a delivery volume flow despite rotational movement. With these pumps, the system ensures that the displacement unit only swings out from a minimum required speed. Here too, the approach using a bypass would be conceivable, but would mean additional component costs and power loss due to unused volume flow.

So far, when starting machines as standard, load-free starting has usually been implemented in such a way that the machines have a safety switch and in one position the machine can be started but cannot be controlled and in the other position it can be controlled but cannot be started can. Such a safety switch must be actively activated by the operator. This approach can also be used on machines with displacement units that do not produce a delivery volume flow despite the speed being applied. There are also exceptions to these approaches. Especially in very small and/or cost-driven machines that have purely mechanical control, start-up protection is not always implemented because it is technically very complex to implement. Failure to act is therefore the responsibility of the operator.

It can be seen that until now the machine or one or more drive motors have been operated at least at a basic speed (minimum speed) after starting before the actuators are ready for use. However, this contradicts the use of automatic start-stop systems, which are increasingly used for reasons of energy saving/efficiency, which switch off the corresponding pumps/motors when individual or all drive trains are not in use and start them again automatically when they are activated again, as explained above The drive units may only start when the safety switch is changed in order to prevent supply to the actuators. Either the operator must carry out the start himself using a start routine, e.g. actuating the safety switch, whereby either protection of the components is ensured by means of the previously described system protection of the components, or the responsibility is left to the operator. This is very complex and complicated as well as prone to errors, especially when only individual axes are switched off and the machine is still being used.

Especially with electrical machines, drive trains that are not currently in use are often switched off in order to further reduce energy requirements. But these problems also occur in internal combustion engines with automated start-stop functions. For this reason, start-stop systems have often not been used in internal combustion engines. but only so-called auto-idle systems are used, whereby the minimum required displacement speeds are not exceeded, or only an auto-stop function is used, which forces the operator to return to the normal start routine when restarting.

Task and advantages of the invention

The object of the invention is, in contrast, to propose a hydraulic work vehicle that at least partially improves the disadvantages of the prior art.

This task is based on a hydraulic work vehicle of the type mentioned in the introduction, solved by the features of claim 1. The measures mentioned in the subclaims make advantageous embodiments and developments of the invention possible.

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 and/or the operating element and/or the hydraulic unit and that a comparison unit is provided for comparing the actual operating parameter with a rest target -Operating parameters of a rest state of the pressure generating device and/or the control element and/or the hydraulic unit are provided, wherein between the rest state and the operating state of the pressure generating device there is a start-up time period for starting up the pressure generating device up to a starting speed of the axis of rotation, and that the control unit acts as a control unit for Generating an inactive waiting state of the tool holding device and/or the work tool and/or of the drive element is formed during the start-up period.

The invention leads, on the one hand, to better operating behavior in connection with lower energy requirements, since unused drive trains can be switched off, and, on the other hand, to the fact that no further measures, in particular no manual intervention or action by the driver, are required when volume flow or pressure is required to restart the drive trains.

Accordingly, a completely automated mode of operation can advantageously be realized and therefore no further operation is required. As a result, from a usage perspective, the machine behavior in terms of volume flow or pressure provision is almost identical, regardless of whether drive systems are currently in operation or have yet to start up. The minimum time delay, i.e. the relatively short start-up time according to the invention, until the volume flow requirement is implemented during the previous start-up, is almost not noticeable to the operator, especially with electrically operated motors or pumps. This results in very good system dynamics and energy efficiency.

Preferably, the sensor is designed as a speed sensor for detecting a speed of the rotation axis of the pressure generating device and/or the motor shaft of the pump motor and/or the pump shaft of the hydraulic pump, so that the actual operating parameter is an actual speed. Here, the rest target operating parameter is advantageously one Resting speed, ie a standstill or speed of zero revolutions per minute.

In a preferred embodiment of the invention, the sensor is used 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 or the hydraulic line and/or the hydraulic unit, so that the actual operating parameter is an actual pressure and/or a volume flow. Here, the rest target operating parameter is advantageously a rest pressure and/or a rest volume flow, i.e. a non-flow or pressure of almost zero bar and/or a flow rate/quantity of zero liters per minute.

In an advantageous variant 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 operating element and/or an actuator or the tool holding device and/or the work tool and/or the drive element, so that the actual operating parameter is an actual position. Here, the rest target operating parameter is advantageously a rest position and/or non-moving, i.e. a rest end position and/or standing still or a movement speed of the actuator such as a hydraulic cylinder and/or a hydraulic motor, especially linear motors, from zero centimeters per minute.

The aforementioned advantageous variants of the invention can be used individually or in combination with one another. So 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 a control or regulation of the work vehicle according to the invention. The system according to the invention can, for example, on the one hand detect the rotational movement, especially of the pressure generating device/s or the displacement unit/s, ie in particular its shafts or its drive units/electric motors or the detection or checking of the current volume flows or pressures, and on the other hand the volume flow - Use or process pressure requirement recording, whereby the latter can be done either by the operator or the machine itself. In addition, a controller is advantageous which, according to the invention, determines the operating states and carries out the corresponding actions.

The start-up period is advantageously designed such that the start-up speed of the axis of rotation and/or the actual speed is a predetermined minimum speed of the axis of rotation. This makes it possible to achieve a flexible or variable start-up time, which is particularly dependent on the current operating situation or, if applicable, load application, e.g. full or empty excavator bucket, retracted or extended telescopic arm of a telescopic loader, etc.

In a special development of the invention, the start-up time is a fixed time period. Here, a firmly defined period of time is set and used as the start-up period according to the invention. This period of time is usually not variable or flexible and does not depend on the current operating situation of the work vehicle. Rather, this period of time is based on empirical values or preliminary tests, whereby, for safety reasons, a sufficiently long period of time is used to give the pressure generating device or displacement unit time to safely reach its respective minimum speed.

Preferably, the control unit is designed as an electronic control unit for electrical/electronic control/activation of the pressure generating device and/or the pump motor and/or the pump electric motor and/or the hydraulic pump and/or the control unit is as an electronic control unit for electrical/electronic control/activation the hydraulic unit and/or the hydraulic control element and/or the directional control valve and/or the tool holding device and/or the work 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/control electrically controllable actuators and/or electrical actuators. In principle, advantageous software or programming and/or processor and/or electrical memory can be provided, with which the most diverse actual and/or target parameters, sensor signals, operating states, functionalities, characteristic curves, etc. are stored/stored, interact with one another, or are processed can be.

In a preferred variant of the invention, the control unit is used as a start-stop control unit for automated Implementing 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 especially the energy efficiency of the entire system or the work vehicle.

According to the invention, it can fundamentally be ensured that an advantageous, load-free start or restart can be guaranteed, for example with/with a start-stop function of the pressure generating device/s or the displacer unit/s. Especially after this pressure generating device/s or the displacement unit/s have not been used for a certain time and have been in the idle state in order to save energy and then should/can be operated again or now. According to the invention, the advantageous control unit prevents, for example, control signals and/or the control supplies to valves or actuating systems of pressure generating devices or displacement units from being put into operation or from being subjected to pressure/hydraulic fluid/oil.

In an advantageous embodiment of the invention, if the control signal advantageously fails to occur, the actuating system or the hydraulic unit will not react. For example, if the supply is stopped, the actuating system or the hydraulic unit cannot/will not react because it is not supplied. In order to use one or both advantageous options for starting protection, the actual speeds are preferably compared with the target/specified speed, at least until load application is possible, at least if, for example, at least one actuator control signal of a deactive drive train is present.

If the speed requirements are not met, there is no supply to the actuator system by preventing the control and/or the control supply, and thus a load-free start-up is possible. By mapping the speed tests using logic or control device(s) or control unit(s) including advantageous software, the operator has no task or no (manual) action to restart drive trains properly if, for example, the machine has already started working . For example, it is independent of whether the operator or the machine itself requests a volume flow for actuators.

This advantageous approach of speed comparison and the suppression of control signals or control supply of valves and/or actuating systems of displacement units or pressure generating devices can be used both during regular machine starts and when restarting drive units or actuators.

Accordingly, the invention can be used regardless of whether the machine is restarted or the entire machine as well as partial drives must/should be restarted, for example from a start-stop scenario. This advantageously prevents the volume flow requirement, which arises, for example, from the needs of the actuator system, from being suppressed until the required minimum speeds are present. For example, if the operator or one or more system components requests a volume flow or hydraulic energy, this is only made available from the required minimum operating speed according to the invention, preferably by control signals and / or Control supplies are prevented. The same applies, for example, if there is not a volume flow requirement, but rather if a pressure requirement is placed on the system supply.

• die Steuerung bzw. der Controller interne und/oder externe Steuerbefehle nicht weiterleitet bzw. verarbeitet und/oder
• die Ansteuerungsbefehle zu den Komponenten hin nicht weiterleitet und/oder
• die Versorgung der Stellsysteme für die Komponenten selbst unterbindet, wobei hier die Versorgung elektrisch oder hydraulisch sein könnte,
  bis in vorteilhafter Weise der sichere Betriebszustand erreicht ist.

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 or pump pressure and, on the other hand, the volume flow or pressure requirement, preferably only in the safe operating state, in particular Displacer units and/or, if applicable, to the respective valve system of the drive train or to a valve block or the like. Depending on the design, for example, of the actuating instances of displacement units and/or valve systems, either the electrical signal or the hydraulic or electrical activation/control as well as the supply of the components themselves can be prevented according to the invention until the safe operating state or the starting speed is reached is. As a result, at least one advantageous logic unit or control or controller including software is helpful, for example

• the control 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 actuating systems for the components themselves, whereby the supply could be electrical or hydraulic,
  until the safe operating state is advantageously reached.

Alternatively or in combination with this, it is also possible, for example, not to monitor the speed for "signal switching", but to monitor whether at least one signal transmitter is controlled or not. If there is currently no control, the control signal(s) or the supply to the valve/hydraulic system or valve block etc. is withheld for a defined time range or during the start-up period according to the invention until, for example, the motor(s)/pumps are sufficient Minimum speed has been reached and only then are the (electrical and/or hydraulic) signals for control passed through or the supply to the valve/hydraulic system or valve block etc. is released so that the valves or valve slides are actuated/deflected can be.

Example embodiment

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

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

In Figure 1 an electro-hydraulic circuit diagram for a mobile work vehicle according to the invention is shown schematically. For example, five partial circles/subsystems I. to V. that can be optionally provided or combined are shown, some in dashed lines, ie optional representation. Accordingly, hydraulic cylinders 1, hydraulic motors 2 or so-called hydrostats 2 as well as electric motors 3 can be present as actuators. A work vehicle according to the invention can only have a single subsystem I. or several or all subsystems I.
to V., for example to raise a lifting arm of a wheel loader and to move or tilt its bucket.

The subsystems I. to V. usually have a hydraulic pump 4 or a pressure generator 4, in particular with a pump shaft 5 and / or motor shaft 6. This allows the subsystems I. to V. to be pressurized or hydraulic oil can be pumped around or be promoted. Various pump electric motors 9 are controlled or controlled/operated via inverter (INV) 10.

Furthermore, hydraulic actuators or valve blocks 7 and/or valves 8 are provided. A central,
Electrical/electronic control unit (ECU) 11 with an electronic comparison unit 12 controls the electro-hydraulic system or the subsystems I. to V. or the valves 8 and valve blocks 7 as well as the motors 9, 3 and inverters 10 . Without further representation, an electrical and/or electronic data/memory is provided, in particular as part of the control unit (ECU) 11.

In addition, without further representation, various sensors are provided for detecting a wide variety of operating parameters or actual parameters according to the invention, for example pressure sensors for detecting a hydraulic pressure, speed sensors for detecting a speed of a motor 3, 9 or hydrostat 2, volume flow sensors for detecting a volume flow within of the hydraulic system or the subsystems I. to V., position sensors for detecting a position of the actuators or hydraulic cylinders 1, hydrostats 2, valves 8, valve blocks 7 or their internal actuators/valves, not shown, etc..

The sensors advantageously generate electrical sensor signals which can be passed to the control unit (ECU) 11 and used/evaluated, which is exemplified and not completely shown as dotted lines in Figure 1 is shown. In the sense of the invention, the control unit (ECU) 11 processes or compares the sensor signals with stored or stored parameters, in particular rest parameters or target rest parameters.

When the subsystems I. to V. or their motors 3, 9 or pumps 4 are at a standstill or in a rest phase, the control unit (ECU) 11 can then enter an inactive waiting state for starting up and/or restarting generate, whereby the motors 3, 9 or pumps 4 begin to start up or rev up, i.e. to reach the minimum speed, and at the same time the forwarding of the hydraulic oil and / or the electrical control signals to the valve blocks 7, valves 8 or actuators 1, 2 etc. to prevent. This inactive waiting time corresponds to the start-up period according to the invention and can be designed as a fixed period of time or as a flexible/variable period of time. The latter preferably in the event that the speed or flow speed or the pressure of the pumps 4 or motors 9 are recorded and evaluated.

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 correspondingly detected and evaluated/used with a sensor. According to the invention, this can also be used to determine whether one of the subsystems I. to V. is in a resting state or in an active state. With the various options and components mentioned above, it can be ensured according to the invention that the pumps 4 can start without load without the driver or operator having to intervene manually. This very short inactive waiting time or start-up time will hardly be noticeable to the driver. According to the invention, a fully automatic and/or safe starting phase with a high level of comfort for the driver or operator can be achieved.

Claims (11)

Hydraulic work vehicle, in particular an excavator, wheel loader, tractor, telehandler or the like, with a vehicle frame, with a particularly releasably connectable work tool, in particular a load fork, a gripper arm, a shovel, a clearing blade or a platform, and with a drive unit for driving at least a drive element, for example a drive wheel and/or crawler chassis, with at least one tool holding device, in particular a lifting arm, telescopic arm, lifting unit or the like, being provided for holding the work tool, with at least one pressure generating device (4), in particular a hydraulic pump (4), for applying pressure 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 work tool and/or the drive element is provided, the pressure generating device (4) having at least one motor shaft (5) rotatable about an axis of rotation , 6) of a pump motor (9), in particular a pump electric motor (9), and/or a pump shaft (5, 6) of the hydraulic pump (4), wherein at least one electrical and/or electronic and/or hydraulic control unit (11) 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 work tool and/or the drive element and at least one operating element (13), in particular a foot pedal and/or a so-called joystick ( 13), for manual operation/actuation by an operator, the control unit (11) in particular receiving control signals from the operating element (13) and/or forwarding them to the tool holding device and/or the work tool and/or the drive element, characterized in that at least a sensor to detect an actual operating parameter of the pressure generating device (4) and/or the control element (13) and/or the hydraulic unit is provided and that a comparison unit (12) for comparing the actual operating parameter with a resting target operating parameter of a resting state of the pressure generating device (4 ) and/or the operating element (13) and/or the hydraulic unit is provided, wherein between the idle state and the operating state of the pressure generating device (4) there is a start-up period for starting up the pressure generating device (4) up to a starting speed of the axis of rotation, and that the Control unit (11) is designed as a control unit (11) for generating an inactive waiting state of the tool holding device and / or the work tool and / or the drive element during the start-up period. Work vehicle according to claim 1, characterized in that the sensor is used as a speed sensor for detecting a 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) is designed so that the actual operating parameter is an actual speed. Work vehicle according to one of the preceding claims, characterized in that the sensor is used 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/ -fluid and/or the hydraulic line and/or the hydraulic unit is formed, so that the actual operating parameter is an actual pressure and/or a volume flow. Work vehicle according to one of the preceding claims, characterized in that 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 (13), so that the actual operating parameter is an actual position . Work vehicle according to one of the preceding claims, characterized in that the start-up period is designed such that the start-up speed of the axis of rotation (5, 6) and/or the actual speed is a predetermined minimum speed of the axis of rotation (5, 6). Work vehicle according to one of the preceding claims, characterized in that the start-up period is a fixed period of time. Work vehicle according to one of the preceding claims, characterized in that the control unit (11) is designed as an electronic control unit (11) for electrically/electronic 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). Work vehicle according to one of the preceding claims, characterized in that the control unit (11) is designed as an electronic control unit (11) for electrical/electronic control of 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 work tool and / or the drive element is formed. Work vehicle according to one of the preceding claims, characterized in that the control unit (11) acts as a start-stop control unit (11) for automatically implementing 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) is formed. Work vehicle according to one of the preceding claims, characterized in that the hydraulic unit and/or the tool holding device and/or the work tool and/or the drive unit comprises at least one hydraulic cylinder (1) and/or a hydraulic motor (2). Method for operating a hydraulic work vehicle, characterized in that a work vehicle according to one of the preceding claims is used.

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