POWER MACHINE WITH A FRAME AND A SWIVELING BOOM

Description

[0001] The invention relates to a power machine, in particular a motor vehicle, with a frame and a boom pivotable about a first pivot axis with respect to the frame according to the preamble of claim 1. State of the art

[0002] Telescopic handlers have been used for years in various sectors, including civil engineering, recycling and waste management, landscaping, and agriculture. In addition to standard attachments and tools such as buckets and forks, other tools like lifting hooks, concrete buckets, sweepers, work platforms, winches, and grapples can also be used. Quick-change plates allow for rapid tool changes.

[0003] The loading systems of telescopic handlers typically feature a lifting arm with at least one extension stage, which is usually mounted on a pivot at the rear of the vehicle. The lifting movement is performed by a lifting cylinder, which is controlled and actuated by the operator via a directional control valve. A sealed load-holding valve is installed directly on the lifting cylinder and prevents the load from lowering uncontrollably due to leaks at the directional control valve or a line rupture. During a controlled lowering movement, the load-holding valve is controlled by pressure build-up.

[0004] A tilting cylinder is used to vary the inclination of the tool carrier or load-bearing device. Like the lifting cylinder, the tilting cylinder is also operated by the driver or supplied with hydraulic energy via a directional control valve, and the load is secured by a load-holding valve.

[0005] During the lifting motion, the tool holder pivots in a circular path around the lifting arm's pivot point. To compensate for the resulting change in the tool's angular orientation, a compensation cylinder is mounted on the lifting arm. This cylinder is extended during the lifting motion. The displaced oil is supplied to the tilting cylinder, thus maintaining its spatial orientation, and consequently that of the tool, at a nearly constant level.

[0006] A disadvantage of this design, however, is that the mechanical coupling of the lifting cylinder and the compensating cylinder via the lifting arm means that, for example, if the tool carrier tilts, the lifting cylinder or the other hydraulic circuit can be affected, or the pressure conditions of the lifting cylinder can be altered. Under certain circumstances, this could even lead to the lifting arm being raised uncontrollably, which poses a safety risk. Furthermore, if the lifting arm is pivoted by means of the lifting cylinder, the compensating cylinder or the pressure conditions of the circuit with the tilting cylinder and compensating cylinder can be affected or altered.

[0007] For safety and hydraulic reasons in particular, an overridable differential pressure control valve is arranged between the directional control valve for actuating the tilting cylinder and the compensation cylinder in order to eliminate corresponding risks.

[0008] Furthermore, various variants for hydraulic controls of the lifting arm of various construction vehicles have become known from the documents US 2014 / 365 081 A1, which discloses the preamble of claim 1, WO 2018 / 044871 A1 and EP 1 600 419 A1. Purpose and advantages of the invention

[0009] In contrast, the object of the invention is to propose a power machine, in particular a motor vehicle, which, compared to the prior art, achieves an improved or more efficient mode of operation, in particular an improved pressurization or energy utilization of the hydraulic system.

[0010] This problem is solved, starting from a power machine, in particular a motor 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.

[0011] Accordingly, a power machine according to the invention, in particular a motor vehicle, is characterized in that at least one second load-holding unit for holding a load or a second load-holding valve for holding a load is arranged between the tilting actuation unit and the tilting cylinder or the compensating cylinder or the first controllable actuator or the second controllable actuator, and that the second load-holding unit is designed as a locking valve arrangement for hydraulic locking and / or comprises at least two second load-holding valves. This ensures that a preload is achieved in the tilting or tilting cylinder circuit. Due to this preload, the load-holding unit or the load-holding valve is held in its open switching position. Thus, the transmission of the load pressure from the piston side of the tilting or tilting cylinder is not hindered by the load-holding valve before the start of the stroke movement of the pivoting cylinder.This ensures safe operation.

[0012] In the power machine according to the invention, it is also achieved that, in addition to the (passive) mechanical coupling of the hydraulic tilt compensation system with the hydraulic lifting system by means of the lifting arm, an (active) separate control or actuation of the hydraulic tilt compensation system is also possible. Thus, under certain conditions or operating conditions, the hydraulic tilt compensation system can be advantageously influenced or...

[0013] Continued on the original page 4can be controlled / monitored. For example, the first actuator and / or the first connecting line can be opened directly via the second control line and / or via the second, controllable actuator, in addition to the existing control options, or the flow of the hydraulic fluid / oil can be enabled. This effectively prevents or limits adverse pressure changes or pressure increases in the hydraulic lifting system or the lifting cylinder circuit.

[0014] Accordingly, the invention opens up a wide range of control options, enabling more flexible and optimized operation of the power unit or the boom / lifting arm. This allows for the fulfillment of high safety requirements and also improves the hydraulic system(s). For example, according to the invention, the first connecting line or the first actuator can be opened / activated or actuated / controlled before or at the start of the lifting cylinder operation, thus preventing adverse pressure conditions in the hydraulic tilt compensation system and / or hydraulic lifting system.

[0015] According to the invention, an advantageous increase in payload can be achieved because pressure losses or pressure-reducing effects of previous control systems can be reduced or avoided. For example, the first connecting line can be "switched on" before or simultaneously with the application of hydraulic pressure to the lifting cylinder, so that under certain operating conditions the compensating cylinder is no longer adjusted by the lifting cylinder as before, but is free-running or even hydraulically pressurized itself, thus supporting the lifting movement of the boom. Initial tests have shown that the invention can increase the payload by 10 to 15%.

[0016] Advantageously, the second control line is arranged between the rotary actuator and the first actuator. This ensures that the first actuator is controlled or actuated in a favorable manner immediately upon operation of the rotary actuator or the lift valve by the operator. This is not only easily implemented in terms of design and circuitry, but also offers a high degree of operational reliability.

[0017] Alternatively, or in combination with the variant using a second control line, it is advantageous to arrange the second controllable actuator hydraulically in parallel to the first controllable actuator, with the first and second controllable actuators positioned between a first branch point and a second branch point of the first connecting line. This allows the second controllable actuator to be operated / controlled separately or independently / in addition to the first controllable actuator, thus advantageously opening or disconnecting the first connecting line. This also allows the first connecting line to be "disconnected" before or simultaneously with the actuation of the lifting cylinder.

[0018] Advantageously, an (electrical and / or electronic) actuation sensor is provided to detect the actuation / adjustment of the lifting cylinder and / or the swivel actuation unit / valve and / or the boom. Preferably, the actuation sensor is arranged on the swivel actuation unit and / or on the lifting cylinder and / or on the boom. This allows an advantageous (electrical) (control) signal to be generated, which is transmitted, for example, by means of an electrical cable or wirelessly via a transmitter and receiver to / for the first / second actuator. Consequently, opening or disconnecting the first connecting line according to the invention can also be advantageously achieved in this way.

[0019] According to the invention, the first connecting line comprises at least one first load-holding unit and / or one first load-holding valve, with preferably at least one third control line being provided between the second connecting line and the first load-holding unit and / or the first load-holding valve. This ensures that the (double-acting) lifting cylinder(s) used are protected against uncontrolled and impermissible pressures. It also prevents the fluid flow or oil column from breaking down. Furthermore, it prevents the load from lowering impermissibly in the holding position. The check valves in the load-holding valves incorporate a pipe rupture protection device. This prevents the load from lowering if a hose or hydraulic pipe bursts or ruptures. These components or valves must therefore be installed directly on the lifting cylinder.The load-holding valve opens proportionally via the provided control line until the pressure conditions are balanced.

[0020] According to the invention, the first controllable actuator is designed as a first differential pressure control unit and / or first differential pressure control valve and / or first pressure limiting unit and / or first pressure limiting valve and / or pressure reducing valve. This advantageously reduces the pressure that builds up at the connection of the tilting actuation unit to a value low enough that the unloaded loading system cannot be lifted solely by the compensating stroke cylinder. When the compensating stroke cylinder is pulled apart by an active lifting movement of the tilting stroke cylinder, hydraulic fluid / oil is displaced via the rod side of the compensating stroke cylinder. The pressure that builds up from the cylinder connection actuates both the load-holding valve and the differential pressure control valve.During an active lifting movement, starting from the loading system, an unimpeded volume compensation between the tilting lifting cylinder and the compensating lifting cylinder is thus enabled according to the invention. Continued on the original page 8

[0021] Advantageously, at least a third load-holding unit and / or a third load-holding valve is arranged between the swivel actuator and the swivel cylinder. This also advantageously protects the swivel cylinder against impermissible lowering in the event of damage or a line break in the swivel cylinder circuit. Example of implementation

[0022] An embodiment of the invention is shown in the drawing and will be explained in more detail below with reference to the figures.

[0023] In detail: Figure 1 shows a first, schematic hydraulic circuit diagram of a telescopic loader and Figure 2 shows a second, schematic hydraulic circuit diagram of a telescopic loader.

[0024] The figures schematically depict two different hydraulic systems according to the invention for a telescopic loader 1. The telescopic loader 1 comprises, among other things, a boom 1.1 or a telescopic lifting arm 1.1, which is adjustable / pivotable about a first pivot axis 1.8 with the aid of a pivot cylinder 2.1 or lifting cylinder 2.1 relative to a vehicle frame 1.6. This allows the height of the boom arm 1.1 to be adjusted. The length adjustment can be implemented in a known single-stage or multi-stage manner and is not shown or described in detail here.

[0025] The telescopic loader 1 also features a driver's cab 1.7 in a known manner, in which one or two or more control elements for driving and for operating the hydraulic system are advantageously provided. Furthermore, wheels are provided in a known manner, which are preferably all driven by a drive motor and / or steerable by the driver.

[0026] A load-bearing device 1.3 or tool carrier 1.3 is pivotably arranged on the boom 1.1 or telescopic boom arm 1.1 about a second pivot axis 1.9. A load 1.4 or a tool 1.4 is arranged at one arm end 1.5, wherein the tool carrier 1.3 can be adjusted / pivoted relative to the arm end 1.5 by means of a tilting cylinder 3.1 or tilting cylinder 3.1.

[0027] The tilting cylinder 3.1 is hydraulically connected to a compensation cylinder 4.1 via a first connecting line I and a second connecting line II, meaning that hydraulic fluid / oil can be exchanged via the two connecting lines I and II or that they are integrated in a common hydraulic circuit.

[0028] With regard to the present invention, it is of particular interest that when the tilting cylinder is extended without a load to its mechanical end position, the maximum possible working pressure is applied starting from port 3.2 / B of an actuating valve 3.2 or directional control valve 3.2. Without a differential pressure regulating valve 6.1, this pressure would also be present at port 4.1 / K of the compensation cylinder 4.1, and a Continued on the original page 10

[0029] A force is exerted on the lifting arm 1.1 that is sufficient to fully lift the entire loading system without a load. If the lifting movement is not actuated, i.e., if neither a swivel control valve 2.2 nor a lifting / directional control valve 2.2 is actuated, the lifting cylinder 2.1 opposes this movement, and the loading system would be subjected to stress by the resulting forces. This situation would become dangerous if the directional control valve 2.2 of the lifting cylinder 2.1 were slightly actuated in the lifting direction or if other advantageous valves 5.1 and 5.2 of a lifting arm damping system 5.5 were switched. The actuation of valve 5.2 is particularly critical. Since the lifting cylinder 2.1 can no longer counteract the force of the compensating cylinder 4.1, the loading system would be lifted uncontrollably, creating a vacuum on the piston side K of the lifting cylinder 2.1.

[0030] To prevent this potential hazard, an overridable differential pressure control valve 6.1 is advantageously arranged between the directional control valve 3.2 and the compensation cylinder 4.1, according to the invention. This valve 6.1 reduces the pressure that builds up at port 3.2 / B of the directional control valve 3.2 to a value low enough that the unloaded loading system can no longer be lifted solely by the compensation cylinder 4.1. The same protective function can also be achieved by an overridable pressure relief valve 6.1. The pressure relief valve 6.1 has a first control line III or first pilot line III for its control or actuation.

[0031] When the compensating cylinder 4.1 is pulled apart by an active lifting movement of the lifting cylinder 2.1, oil is displaced via the rod side S of the compensating cylinder 4.1. The pressure that builds up from port 4.1 / S of the cylinder 4.1 actuates both the load-holding valve 3.3 and the differential pressure control valve 6.1. During an active lifting movement originating from the loading system, this allows for unimpeded volume equalization between the tilting cylinder 3.1 and the compensating cylinder 4.1. Free movement of the lifting arm is also enabled with active lifting arm damping.

[0032] According to the invention, a valve unit 6 or valve block 6 comprises, in addition to the differential pressure control valve 6.1, further valves 6.2, 6.3, 6.4 and / or 6.5. To selectively override the pressure-reducing effect of the differential pressure control valve 6.1 according to the invention, a second control line IV or a second, so-called pilot signal is made available at port 6 / X1 of the valve unit 6 via a branch 6.2 or an advantageous changeover valve 6.2. Port 6 / X1 is advantageously connected to the pressure / working line from port 2.2 / B of the lift or directional control valve 2.2 to port 2.3 / A of the load-holding valve 2.3 on the lift cylinder 2.1. This ensures that a signal pressure is built up at 6 / X1 of the valve unit 6 or of the valve 6.1 precisely when the machine operator initiates a lift movement via the directional control valve 2.2. In this case, a force effect from the compensation cylinder 4.1 is desired or advantageous.

[0033] To ensure that the load pressure is transmitted from the tilting cylinder 3.1, it is also advantageous for the load-holding valve 3.3 to remain in its opened switching state as long as there is no line break. According to the invention, this is achieved by pre-pressurizing the line circuit to the tilting cylinder 3.1 by means of a check valve arrangement 6.3 or a block valve assembly 6.3. The pre-pressurization pressure results from the fact that the (two) check valves or load-holding valves are opened by the pressure in the respective opposite working line and should advantageously be higher than the required opening pressure of the load-holding valve 3.3.

[0034] In the event of a failure of the safety-critical line I between the connections 6 / A1 and 3.3 / A of the load-holding valve 3.3 on the tilting cylinder 3.1, the pre-tension of the circuit cannot be maintained, so that the load-holding valve 3.3 closes immediately and holds the load on the tilting cylinder 3.1 in a seat-tight manner.

[0035] To ensure that the preload of the tilting cylinder circuit is reliably maintained even after the cylinder has been operated, an additional differential pressure control valve 6.4 is advantageous. This valve prevents line II between 3.1 / S of the tilting cylinder 3.1 and 6 / B1 from being completely relieved of pressure via the directional control valve 3.2 to the tank T during tilting movements of the tool carrier 1.3. The load-holding valve 3.3 of the locking function is actuated by a fourth control line V during these movements, which is why it cannot maintain the preload.

[0036] The present invention differs from the prior art primarily in the following ways: The check valve arrangement 6.3 and the differential pressure control valve 6.4 achieve an advantageous preload in the tilting cylinder circuit. This preload keeps the load-holding valve 3.3 in its open position. This prevents the load-holding valve 3.3 from obstructing the transmission of the load pressure from the piston side K of the tilting cylinder 3.1 before the start of the lifting movement. To actuate the differential pressure control valve 6.1, no prior extension movement of the compensation cylinder 4.1 is necessary, and therefore no energy exchange from the lifting section to the piston side K of the compensation cylinder 4.1 is required. The differential pressure control valve 6.1 is actuated by an additional pressure signal, i.e., the signal from the second control line IV at port X1 of the valve block 6. The lifting-supporting force of the compensation cylinder 4.1, utilizing the force on the piston side K of the tilting cylinder 3.1, is then applied.The lifting support function is advantageously available through the two features described above, even before a lifting movement of the lifting arm 1.1 takes place. The lifting support function becomes effective from a load pressure on the piston side K of the lifting cylinder 2.1 that is advantageously high enough to actuate the differential pressure control valve 6.1. Depending on the actuation ratio of the differential pressure control valve 6.1, this pressure is low enough that the lifting support function of the circuit is effective across the entire payload range of the machine. Thus, according to the invention, in addition to an advantageous increase in the maximum lifting force, the energy efficiency of lifting movements can be optimized across the entire payload range of a machine.

[0037] The circuit configurations shown as examples are fundamentally functional even without the additional differential pressure control valve 6.4. However, reliable operation under all load conditions is ensured with this valve 6.4.

[0038] In addition to the variant according to the invention Figure 1 , i.e., with the overridable differential pressure control valve 6.1, which receives the additional pressure signal via 6 / X1 of the valve block 6, alternatively also a separate control according to a second variant according to the invention as in Figure 2to implement as shown. For example, a further valve 6.5, in particular a directional control valve 6.5, can be connected in parallel to valve 6.1. This valve 6.5 can be electronically controlled, for example, by an (electro-)magnetic force. Electronic signals, e.g., from an advantageous sensor, can control / actuate the valve 6.5. Preferably, the valve 6.5 is actuated / controlled based on the stroke movement of the directional control valve 2.2; e.g., a magnet on the valve 6.5 is activated / switched on or off by means of the aforementioned sensor signal, so that the valve 6.5 opens / closes. The differential pressure control function can either be overridden directly by actuating the valve 6.5 itself or bypassed by the valve 6.5 or 2 / 2-way valve 6.2 connected in parallel to the differential pressure control valve 6.1 (see Figure 2). Figure 2 ).

[0039] The two embodiments essentially share the principle of disabling the pressure-reducing functions of the valves in the line between ports 3.1 / K of the tilting cylinder 3.1 and 4.1 / K of the compensation cylinder 4.1 in a controlled manner, without impairing the safety-relevant functions of the valves. Advantageous features of the invention include overriding the differential pressure control valve 6.1 by an additional signal at the moment of an active lifting movement of the loading system and holding the load-holding valve 3.3 in its opened switching position by pre-tensioning the tilting cylinder circuit.

[0040] By eliminating the pressure-reducing effect, an additional force component is available at the compensation cylinder 4.1 for lifting the load. This increases the maximum possible lifting force of the telescopic handler 1. Furthermore, regardless of the load size, the force that the lifting cylinder 2.1 has to overcome, and thus the required operating pressure for the lifting process, is reduced. Compared to the prior art, this leads to a general increase in energy efficiency during lifting operations.

[0041] The system according to the invention requires less energy to lift the same load compared to previous hydraulic systems. This means that less work is required to lift the lifting arm 1.1. This is because the pressure required in the lifting cylinder 2.1 to lift a defined load is lower than in previous systems. One reason for this is that, according to the invention, the load pressure of the tilting cylinder 3.1 is fully available on the bottom side of the compensating cylinder 4.1 during lifting, thus supporting the lifting cylinder 2.1.

Claims

1. Power machine (1), in particular a motor vehicle (1), having a frame (1.6) and having a boom (1.1) which is pivotable about a first pivot axis (1.8) in relation to the frame (1.6), wherein provision is made of a pivoting lifting cylinder (2.1) for pivoting, in particular raising and lowering, the boom (1.1) in relation to the frame (1.6), wherein the boom (1.1) comprises a load-receiving device (1.3) for receiving / fixing a load-receiving means (1.4) such as a tool or the like, in particular a load fork, a gripper arm, a bucket or a platform, wherein provision is made of a tipping lifting cylinder (3.1) for tipping / pivoting the load-receiving device (1.3) in relation to the boom (1.1) such that the load-receiving device (1.3) is adjustable / pivotable about a second pivot axis (1.9) in relation to the boom (1.1), wherein a compensation lifting cylinder (4.1) is arranged between the boom (1.1) and the frame (1.6) such that the compensation lifting cylinder (4.1) or a piston of the compensation lifting cylinder (4.1) is adjustable in relation to a cylinder of the compensation lifting cylinder (4.1) when the boom (1.1) is pivoted about the first pivot axis (1.8), wherein provision is made of at least one hydraulic unit comprising a hydraulic oil / fluid for actuating and / or pressurizing the lifting cylinders (2.1, 3.1, 4.1), wherein provision is made of at least one tipping actuating unit (3.2), in particular a tipping valve (3.2), for actuating and pressurizing the tipping lifting cylinder (3.1), wherein provision is made of at least one pivoting actuating unit (2.2), in particular a pivoting valve (2.2), for actuating and / or pressurizing the pivoting lifting cylinder (2.1), wherein provision is made of a first connecting line (I) and a second connecting line (II) between the tipping lifting cylinder (3.1) and the compensation lifting cylinder (4.1) for hydraulic connection to one another such that they are integrated in a common hydraulic circuit, wherein the first connecting line (I) comprises at least one first controllable actuating member (6, 6.1), wherein provision is made of at least one first control line (III) for controlling / actuating the first controllable actuating member (6, 6.1) between the first actuating member (6, 6.1) and the second connecting line (II), wherein provision is made of at least one second control line (IV) for controlling / actuating the first actuating member (6, 6.1), or wherein at least the first connecting line (I) comprises at least one second controllable actuating member (6.5), characterized in that the first controllable actuating member (6, 6.1) is designed as a first differential-pressure-regulating unit for regulating a differential pressure or as a first differential-pressure-regulating valve for regulating a differential pressure, and in that the first connecting line (I) comprises at least one first load-holding unit (6) for holding a load or first load-holding valve for holding a load, or in that the second connecting line comprises at least one second differential-pressure-regulating unit for regulating a differential pressure or second differential-pressure-regulating valve for regulating a differential pressure, and in that at least one second load-holding unit (6.3) for holding a load or second load-holding valve (6.3) for holding a load is arranged between the tipping actuating unit (3.2) and the tipping lifting cylinder (3.1) or the compensation lifting cylinder (4.1) or the first controllable actuating member (6.1) or the second controllable actuating member (6.5), and in that the second load-holding unit (6.3) is designed as a shut-off-valve arrangement (6.3) for hydraulic shut-off and / or comprises at least two second load-holding valves.

2. Power machine according to Claim 1, characterized in that the second control line (IV) is arranged between the pivoting actuating unit (2.2) and the first actuating member (6, 6.1).

3. Power machine according to either of the preceding claims, characterized in that the second controllable actuating member (6.5) is arranged hydraulically parallel to the first controllable actuating member (6.1), wherein the first controllable actuating member (6.1) and the second controllable actuating member (6.5) are arranged between a first branching point (31) and a second branching point (32) of the first connecting line (I).

4. Power machine according to one of the preceding claims, characterized in that the first controllable actuating member (6, 6.1) is designed as a pressure-limiting unit for limiting a pressure or as a first pressure-limiting valve for limiting a pressure or as a pressure-reducing valve for reducing a pressure.

5. Power machine according to one of the preceding claims, characterized in that provision is made of at least one third control line (III) between the second connecting line (II) and the first load-holding unit and / or first load-holding valve.

6. Power machine according to one of the preceding claims, characterized in that at least one third load-holding unit (2.3) for holding a load or third load-holding valve (2.3) for holding a load is arranged between the pivoting actuating unit (2.2) and the pivoting lifting cylinder (2.1).