EP1897846B1 - Charging device - Google Patents

Description

The invention relates to a charger with a hydraulically actuated boom, a sensor for monitoring the load condition on the charger and a hydraulic arrangement for actuating the boom and / or attached to the boom tool, wherein the hydraulic arrangement at least one hydraulic cylinder, at least one hydraulically controllable control unit for Controlling the at least one hydraulic cylinder, a hydromechanical actuator for generating hydraulic control pressure signals for the at least one control unit, a hydraulic source, a hydraulic tank and an electronic control unit, wherein at least one control pressure line extending between the actuator and the control unit control pressure varying means are connected, with which, as a function of a sensor signal supplied by the sensor, the control pressure generated by the actuating device can be varied.

In the field of chargers, such as loaders or telehandlers and the like, systems are known which protect the vehicle from getting into an insecure state of charge. Uncertain states of charge occur, for example, when the vehicle overturns due to a shift of emphasis forward over the front axle away. In these systems, the hydraulic functions are slowed down and stopped as soon as a sensor detects that the vehicle is about to tip over. After the hydraulic actuators have been stopped, only the functions can be operated, which bring the vehicle back to a safe state, such. B. raise boom, tilt tool or load and retract boom.

In such systems, it makes sense not abruptly prevent the movements of a boom, as this may still lead to a tipping over of the vehicle due to the inertia of the load and the boom. It makes sense to increasingly slow down the functions as they approach a critical operating state or load state.

The WO 2004/007339 A1 discloses such a system. Here, a tilting moment acting on the vehicle is detected by sensors and fed to an electronic control. Furthermore, several hydraulic cylinders for lifting, lowering and telescoping a telescopic boom and an electro-hydraulic control of the hydraulic cylinder are provided. The system provides that, when approaching a predetermined threshold for the stalling torque, the hydraulic functions to operate the hydraulic cylinders are slowed down before the complete stoppage of the hydraulic cylinders occurs. In this case, for example, the load signal is further processed electronically and the operating possibilities are reduced by the operator or the actuation is prevented. The more mature the technique is, for. B. by electronic control units, the easier is the intervention by the electronics.

The JP 05 202535 A discloses a system for monitoring a load condition of a work machine with a boom. It is provided that a control pressure for a control device for actuating the arm can be influenced by the control pressure introduced by an actuating device being variable as a function of a sensor signal in conjunction with an electronic control unit and thereby controllable means.

For hydromechanical systems are those in the WO 2004/007339 A1 and JP 05 202535 A disclosed teachings not applicable because you can not interfere in a hydraulically piloted system in such a simple way in the functions, as a suitable electronics is missing.

The object underlying the invention is seen to provide a charger of the type mentioned, by which the aforementioned disadvantages are overcome.

The object is achieved by the teaching of claim 1. Further advantageous embodiments and modifications of the invention will become apparent from the dependent claims.

According to the invention, a charger of the type mentioned above is formed such that the control pressure varying means comprise at least one controllable by the electronic control unit electro-hydraulic pressure relief valve or electro-hydraulic pressure reducing valve. About the control pressure varying means the operability of the hydraulically controlled control device is influenced such that the pressure in the control pressure line is reduced, so that the manipulated variable is reduced at the control unit and thus controlled via the control unit volume flow of hydraulic fluid for the hydraulic cylinder. The control pressure in the control pressure line is thereby reduced more, the closer one approaches a critical value for the load state, which is predetermined by the electronic control unit. In order to prevent an operator from being able to bring the vehicle into an unsafe condition, which could ultimately result in the vehicle tipping over, the functions of the hydraulic cylinder are first slowed down and then finally completely stopped. The control pressure varying means may comprise at least one controllable by the electronic control unit electro-hydraulic pressure relief valve. The electrohydraulic pressure relief valve can be increasingly opened depending on the load signal or overload signal supplied by the sensor. The further you approach the preset threshold, the greater the risk that the vehicle tilts, and the lower the pressure relief valves are set. Due to the resulting lower control pressure, the valve spool of the control unit is deflected less, whereby the control units send less flow to the hydraulic cylinder, which then slows down to a standstill. In the opposite direction of movement, the control unit can be operated as usual. It is of course conceivable that a plurality of hydraulic cylinders are arranged in the hydraulic arrangement and thus a plurality of control devices can be hydraulically adjustable for controlling the hydraulic cylinder can be used. In the event that several control devices or a plurality of hydraulic cylinders are used, a plurality of electro-hydraulic pressure relief valves can be used correspondingly, which are adjusted by the electronic control unit in dependence of the sensor signal. In an alternative embodiment, the control pressure varying means may comprise at least one controllable by the electronic control unit electro-hydraulic pressure reducing valve, which is arranged directly in a control pressure line for the valve spool of the control unit. The electrohydraulic pressure reducing valve can be controlled as a function of the load signal or overload signal supplied by the sensor. The further you go to the preset threshold approaches, the greater the risk that the vehicle tilts, and the higher the control pressure for the valve spool is throttled or reduced by the pressure reducing valve. Due to the resulting lower control pressure, the valve spool of the control unit is deflected less, whereby the control units send less flow to the hydraulic cylinder, which then slows down to a standstill. In the opposite direction of movement, the control unit can be operated as usual. It is of course conceivable that a plurality of hydraulic cylinders are arranged in the hydraulic arrangement and thus a plurality of control devices can be hydraulically adjustable for controlling the hydraulic cylinder can be used. In the event that several control devices or a plurality of hydraulic cylinders are used, a plurality of electro-hydraulic pressure reducing valves can be used correspondingly, which are adjusted by the electronic control unit in dependence of the sensor signal.

It is thus possible to limit the boom movements so that the vehicle can not get into a dangerous operating condition, the operator will also notice in addition to the already occurring in the cab of the charger warning signals that despite its adjustment of the boom to standstill slower becomes.

Preferably, the hydromechanical actuator is designed as a joystick. In this case, valves are actuated by appropriate mechanical deflection of a control lever, which are connected to the hydraulic source and the control pressure line and generate a control pressure for the control unit of the hydraulic cylinder.

The charger is preferably designed as a telescopic loader, wherein the boom via a first hydraulic cylinder in its angle of attack and a second hydraulic cylinder in its length is variable and wherein a third hydraulic cylinder may be provided with the on Outrigger arranged tool is pivotable. Thus, for example, the tipping of a loading bucket filled with load can weaken a critical state of charge without the boom being moved. In any case, arranged in the control pressure lines of the control valves overpressure valves or pressure reducing valves ensure a slow implementation of the operator specified movements, so that no disturbing inertial mass effects of the load or the boom occur, which then trigger a tipping over of the charger in the vicinity of the threshold range can.

In another embodiment, the charger comprises a front loader, wherein the boom is designed as a rocker of a front loader, which is variable in its angle of attack via a first or a first and a second hydraulic cylinder. A third hydraulic cylinder may be provided, with which a tool provided on the boom, for example a loading shovel or a loading fork, can be pivoted.

Of course, all other conventional charging tools can also be used for the telescopic loader as well as for the charger equipped with the front loader, such as bucket, bale puller, etc.

Preferably, the sensor is designed and arranged such that a critical load condition on the charger can be detected. The sensor may be arranged, for example, on an axle of the vehicle and signal a critical state of charge with a correspondingly high, one-sided load. In this case, for example, strain gauges or force sensors can be used. It is also conceivable the sensor at one position other suitable location and define, for example, the inclination of a vehicle frame relative to the vehicle axle as a critical state of charge state.

Reference to the drawing, which shows embodiments of the invention, the invention and further advantages and advantageous developments and refinements of the invention are described and explained in more detail below.

Fig. 1

eine schematische Seitenansicht eines als Teleskoplader ausgebildeten Ladegeräts mit einer hydraulischen Anordnung,

Fig. 2

einen schematischen Schaltplan einer hydraulischen Anordnung,

Fig. 2a

einen schematischen Schaltplan einer alternativen Ausführungsform der hydraulischen Anordnung aus Figur 2 und

Fig. 3

eine schematische Seitenansicht eines einen Frontlader aufweisenden Ladegeräts mit einer hydraulischen Anordnung.

It shows:

Fig. 1

a schematic side view of a designed as a telescopic loader charger with a hydraulic arrangement,

Fig. 2

a schematic circuit diagram of a hydraulic arrangement,

Fig. 2a

a schematic circuit diagram of an alternative embodiment of the hydraulic arrangement FIG. 2 and

Fig. 3

a schematic side view of a front loader having charger with a hydraulic arrangement.

In FIG. 1 a charger 10 is shown in the form of a telescopic loader. The telescopic loader has a frame 12, on which a boom 14 is articulated. The frame is supported by a front axle 16 and a rear axle 18 with respective front and rear wheels 20, 22.

The boom 14 is formed as a telescopic boom and is articulated via a hydraulic cylinder 24 in its angle relative to the frame 12 adjustable. A second hydraulic cylinder is arranged inside the boom 14 (not shown) and allows the extension and retraction (telescoping) of the boom. A third hydraulic cylinder is disposed at the free end of the boom 14 in the interior and allows the pivoting or tilting of a loading tool 26th

The charger 10 has a hydraulic source 28 and a hydraulic tank 30, which are arranged below the vehicle body and serve to supply the hydraulic components.

An operating device 34 arranged in a cab 32, in the form of a hydromechanical joystick, serves to control the hydraulic components. The hydraulic components are essentially in FIG. 2 shown.

In FIG. 2 a provided for the charger 10 hydraulic arrangement 36 is shown. The hydraulic arrangement 36 comprises the hydraulic cylinder 24, and optionally the hydraulic cylinder (not shown) for telescoping the boom and tilting the loading tool. The hydraulic cylinder 24 is connected via a first and second hydraulic supply line 38, 40 with a hydraulically controllable control unit 42, via which the connection of the supply lines 38, 40 with the hydraulic pump 28 and the hydraulic tank 30 can be produced. In the hubseitigen chamber of the hydraulic cylinder 24 associated supply line 40, a load-holding valve 44 is arranged. The load-holding valve includes an in the direction of Control unit 42 openable pressure limiting valve 46 which is arranged in the supply line 40 and via control pressure lines 48, 50 which are connected to two supply lines 38, 40 can be opened, and arranged in a bypass line and in the direction of the hydraulic cylinder 24 opening check valve 52. The load-holding valve 44 serves to ensure that in the event of a pipe break on the lifting side of the hydraulic cylinder 24, no hydraulic fluid can escape and the hydraulic cylinder 24 maintains its position.

The control unit 42 comprises three slide positions, one for lifting, one for lowering and another for holding the hydraulic cylinder. The control unit 42 is designed as a hydraulically controllable proportional valve and can be hydraulically controlled or adjusted via corresponding control pressure lines 54, 56. The control pressure is generated by the hydromechanical control device 34, which is designed as a joystick.

The operating device 34 has mechanically actuatable valves 58, 60, for example by moving the joystick, which establish a connection or disconnection of the hydraulic pump 28 with the control pressure lines 54, 56. The mechanically operable valves 58, 60 are preferably designed as pressure reducing valves. For example, a joystick or operating lever located on the operating device 34 is pushed forward, whereby the actuation of the valve 58 takes place. Subsequently, the control pressure line 56 is acted upon by a hydraulic pressure generated by the hydraulic pump 28, whereupon the control unit 42 is moved to its lifting position and the hydraulic cylinder 24 on the lift side is filled with hydraulic fluid, so it is extended. A corresponding opposite actuation of the actuating lever would cause actuation of the valve 60, whereupon the control pressure line 54 filled with hydraulic fluid and the control pressure valve 42 is moved to the lowering position, so the hydraulic cylinder 24 would be drained.

In the in FIG. 2 illustrated embodiment, the control pressure line 54 is connected to a connected to the hydraulic tank 30 electro-hydraulic pressure relief valve 62. The pressure relief valve 62 causes the pressure prevailing in the control pressure line 54 control pressure is reduced. If a preset limit pressure is reached or exceeded by the control pressure, the pressure relief valve 62 opens increasingly, so that more and more hydraulic fluid flows into the hydraulic tank 30, resulting in that the adjustment of the control unit 42 is reduced by the control pressure line 54 and thus the actuation the hydraulic cylinder 24, in this case the lowering of the hydraulic cylinder 24, is slowed down. Of course, the other control pressure line 56 may be connected to such a pressure relief valve 62. In this case, then the lifting of the hydraulic cylinder 24 would be slowed down.

The control of the pressure relief valve 62 is performed by the electronic control unit 64, which in turn receives control signals from a load sensor 66. Depending on the load condition, the sensor 66 signals a more or less critical load condition. If one approaches the critical load state, the control signal emitted by the electronic control unit 64 also amplifies to adjust the overpressure valve 62, which is then increasingly opened, so that hydraulic fluid from the control pressure line 54 is increasingly drained and the control pressure decreases. The adjustment or the gain of the control signal is preferably proportional to the signal supplied by the sensor.

The sensor is preferably arranged on the rear axle 18 of the charger 10. For example, the sensor 66 is designed as a strain gauge and registers or detects the deflection of the rear axle 18. From the signal values for the deflection can then be closed to the loading or unloading of the rear axle 18. If the load on the rear axle 18 decreases progressively, this may indicate a critical load condition, namely at the latest when no load on the rear axle 18 is detected or signaled. In this case, the charger 10 begins to tip over. The same is also conceivable for the front axle 16.

This in FIG. 2 illustrated embodiment shows the arrangement of only one hydraulic cylinder 24. As mentioned above, further hydraulic cylinders (not shown) are used in parallel, which are actuated in the same manner by an actuator 34 and also in a hydraulic arrangement 36, as shown in FIG. 2 is shown, are involved. Furthermore, it is not only possible to limit the retraction or lowering of the hydraulic cylinder 24 or slow down. Of course, it is also conceivable to limit the extension or slow down, as would be necessary, for example, to avoid extension of the boom 14 in order to prevent tipping over of the telescopic loader. In this case, the control pressure line 56, with the lifting position of the controller 42 and thus the Lifting of the hydraulic cylinder 24 can be controlled, provided with an electro-hydraulic pressure relief valve 62 and connected.

FIG. 2a shows an alternative embodiment of the hydraulic arrangement, wherein the control pressure line 54 is provided with an electro-hydraulic pressure reducing valve 62 ', wherein the connection line to the hydraulic tank 30, which in the embodiment of FIG. 2 is provided, deleted. The pressure reducing valve 62 'also causes here that the pressure prevailing in the control pressure line 54 control pressure is reduced or throttled. Should a preset limit pressure be reached or exceeded by the control pressure, the pressure reducing valve 62 'closes, so that the control pressure in the control pressure line 54 decreases, resulting in that the adjustment of the control unit 42 is reduced by the control pressure line 54 and thus the actuation of the Hydraulic cylinder 24, in this case the lowering of the hydraulic cylinder 24, is slowed down. Of course, the other control pressure line 56 may be connected to such a pressure reducing valve 62 '. In this case, then the lifting of the hydraulic cylinder 24 would be slowed down.

The control of the pressure reducing valve is also carried out here by the electronic control unit 64, which in turn receives control signals from a load sensor 66. Depending on the load condition, the sensor 66 signals a more or less critical load condition. If one approaches the critical load state, the control signal emitted by the electronic control unit 64 also amplifies to adjust the pressure reducing valve 62 ', which is then increasingly closed, so that the control pressure decreases. The Adjustment or the gain of the control signal is preferably proportional to the signal supplied by the sensor.

The sensor is also preferably arranged on the rear axle 18 of the charger 10 and is analogous to the in FIG. 2 illustrated embodiment formed.

This in FIG. 2a Represented embodiment also shows the arrangement of only one hydraulic cylinder 24. Again, other hydraulic cylinders (not shown) are used in parallel, which are actuated in the same manner by an actuator 34 and also in a hydraulic arrangement 36, as shown in FIG. 2a is shown, are involved. Furthermore, it is not only possible to limit the retraction or lowering of the hydraulic cylinder 24 or slow down. Of course, it is also conceivable to limit the extension or slow down, as would be necessary, for example, to avoid extension of the boom 14 in order to prevent tipping over of the telescopic loader. In this case, the control pressure line 56, with which the lifting position of the control unit 42 and thus the lifting of the hydraulic cylinder 24 can be controlled, would also be provided or connected to an electrohydraulic pressure reducing valve 62 '.

FIG. 3 shows as a further embodiment, a charger 10 in the form of a tractor 68 with front loader 70, wherein the same reference numerals apply to the same components of the charger 10, such as frame 12, front axle 16, rear axle 16, wheels 20, 22, loading tool 26 and cabin 32. Here, the rockers 70, which are arranged on both sides of the tractor 68, a boom, by the actuation in certain situations and overcharging critical load conditions of the charger 10 can be caused. The hydraulic cylinders 74 arranged to actuate the rockers 70 and the hydraulic cylinders 76 arranged to actuate the loading tool 26 are analogous to those in FIG FIG. 2 operated hydraulic arrangement 36 operated.

Although the invention has been described by way of example only, in light of the foregoing description and the drawings, those skilled in the art will recognize many different alternatives, modifications and variations which are within the scope of the present invention.

Claims (6)

1. Loader with a hydraulically operated extension arm (14, 72), a sensor (66) for monitoring the load condition on the loader (10) and a hydraulic arrangement (36) for actuation of the extension arm (14, 72) and/or an implement (26) attached to the extension arm (14, 72), the hydraulic arrangement (36) exhibiting at least one hydraulic cylinder (24), at least one hydraulically actuatable control device (42) for controlling the at least one hydraulic cylinder (24), a hydromechanical actuating device (34) for generating hydraulic control pressure signals for the at least one control device (42), a hydraulic source (28), a hydraulic tank (30) and an electronic control unit (64), wherein means (62, 62') for varying the control pressure are connected to at least one control pressure line (54, 56) extending between the actuating device (34) and the control device (42), the control pressure generated by the actuating device (34) being variable by said means (62, 62') depending on a sensor signal supplied by the sensor (66), characterized in that the means (62, 62') for varying the control pressure consist of at least one electrohydraulic overpressure valve or electrohydraulic pressure-reducing valve capable of actuation by the electronic control unit (64).
2. Loader according to Claim 1, characterized in that the hydromechanical actuating device (34) is configured as a joystick or actuating lever.
3. Loader according to Claim 1 or 2, characterized in that the loader (10) is configured as a telescopic loader and the extension arm (14) is capable of being varied via a first hydraulic cylinder (24) in respect of its angle of attack and via a second hydraulic cylinder in respect of its length, in conjunction with which a third hydraulic cylinder may be provided, with which an implement (26) arranged on the extension arm (14) is capable of being caused to pivot.
4. Loader according to one of Claims 1 to 3, characterized in that the loader (10) consists of a front loader (70) and the extension arm is configured as a load arm (72) of a front loader (70), which is capable of being varied via a first or a first and a second hydraulic cylinder (24) in respect of its angle of attack, in conjunction with which a third hydraulic cylinder (24) can be provided, by means of which an implement (26) provided on the load arm (72) is capable of being caused to pivot.
5. Loader according to one of Claims 1 to 4, characterized in that the sensor (66) is configured and arranged in such a way that a critical load condition on the loader (10) is detectable.
6. Loader according to one of Claims 1 to 5, characterized in that the sensor (66) is arranged on a vehicle axle (16, 18) of the loader (10).

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