EP2049802B1 - Actuating device - Google Patents

Abstract

The invention relates to an actuating device for the activation of a hydraulic load (10), such as a working cylinder, by means of a fluid supply flow. As a result of the fluid supply flow for the load (10) being activated by means of an activating unit (48) in such a way as to obtain a damped actuation with a soft starting behaviour, soft accelerations fundamentally occur for a hydraulic load, which soft accelerations are perceived by an operator to be comfortable with regard to the continuous speed behaviour.

Description

The invention relates to an actuating device for controlling at least one hydraulic consumer, such as a working cylinder, by means of a fluid supply current, wherein by means of a drive unit, the fluid supply current for the consumer is controlled such that a damped operation is achieved with a gentle starting behavior, wherein the drive unit is a proportional -Ventil which acts as a throttle whose throttling action is at least partially adjustable via a control input with a constant fluid volume flow, wherein for obtaining a constant fluid volume flow on the control input side at least one shutter is connected, the output side is connected to the input of a pressure relief valve, and wherein between the output of a diaphragm and input of the pressure relief valve, a further orifice is connected in the control input for the proportional valve.

These actuating devices are known in a variety of different embodiments and freely available on the market. The known actuators are used to control work machines, such as excavators, tractors, harvesters and cranes, but are also used for hydraulic lifts, forklifts, elevators, etc. and for various types of hydraulically operated machines, including machine tools, plastic injection molding machines etc .. A variety of other applications, such as power plant technology, off-shore technology, wind farms, aerospace engineering, also use such actuators for triggering movement and work processes. For triggering pertinent work and actuation processes actuators are regularly required as hydraulic consumers, for example in the form of pumps, hydraulic motors or working cylinders. The enumeration is only an example and not exhaustive.

However, when approaching pertinent actuating devices for triggering operations and movements, it often already occurs the incompressibility of the fluid supply flow to pressure surges and jerky movements in a direct pressurization, which is disadvantageous insofar as the overall hydraulic system can be overloaded, especially a gentle operation is not possible and unpleasant pressure surges it comes to jerky movements of the driven consumer, which the Operation and even lead to security problems. If, for example, pertinent actuators for cabin adjustment on excavators or loading machines, such as cranes, used in which the operator's cab is to move from an initial state to the operator to provide improved insight into the respective handling situation, such as loading and unloading of ships , It comes to jerky movements in the cabin and to the operator uncomfortable perceived acceleration behavior, which can be correspondingly aggravated by multiple occurrences during a workday routine lead to incorrect operation, due to the poor ease of use and the associated lack of ergonomics, which may even be massive health problems among the operators.

Although it has been tried in the past to provide pertinent actuators with a corresponding hydraulic technology, such as proportional 4/3-way slide valves, possibly with the additional use of load-holding valves, such as unlockable check valves or lowering brake valves and the like; But in order to be reasonably successful here, very expensive electrical controls and measures to maintain the high oil quality required for the proportional technology are necessary. Although the alternative or additional installation of hydraulic accumulators for the provision of energy in the connection lines of the respective hydraulic consumer leads to a corresponding damping effect conditional through the biased gas side of the hydraulic accumulator; only the hereby achievable damping effect is considered to be low and until the overall system, consisting of hydraulic accumulator and hydraulic consumer, has adjusted to a common pressure level, it comes to corresponding compensatory movements of the fluid supply current, which leads to the known phenomenon of "hydraulic rocking", ie the component to be moved with the hydraulic actuator, for example in the form of a driver's cab, starts to rock violently, which is perceived more unpleasantly by the respective operator.

An actuator of the type mentioned is out EP 1 353 076 A2 known. The known actuator is used in an adjustable by the user in a desired position chair. In a system for hydraulic actuation and fluid control, at least two fluid operated cylinders and a bi-directional motor are arranged. The fluid control system includes several elements to achieve smooth cylinder movement at start, stop and intermediate positions, including piston type accumulators, automatic fluid flow control valves and buffer valves. In this case, it comes in principle for the hydraulic consumer to gentle accelerations that are perceived by the operator to be pleasant in Hin look at the steady speed behavior and any hydraulic or hydraulic devices connected to the mechanical or hydraulic actuators are spared in the context of the respective work and actuation process and the entire hydraulic system relieved of undesired pressure surges.

Based on this prior art, the invention has the object to further improve the known solutions to the effect that the disadvantages described above do not occur, in particular improved Ease of use and Ergonomieansprüchen is taken into account.

A related object solves an actuator with the features of claim 1 in its entirety. According to the characterizing part of claim 1, the two apertures of the drive unit on different aperture diameters. By the orifices, the pressure relief valve and the acting spring force on the compression spring on the oppositely acting control input side is determined by reference to the geometry of the piston of the proportional valve, the opening characteristic for the throttle and thus the damping effect for the entire system. Preferably, one aperture has a larger diameter than the other aperture in the control input of the proportional valve.

Thus, the actuating device according to the invention with drive unit for the fluid supply flow, that when moving a control cabin of an excavator or a crane in each displacement position, the acceleration for the cabin is smooth, which in addition to an increased ease of use also contributes to operator safety. The drive unit used can be chosen so that existing machine complexes can be retrofitted and that the actuator according to the invention with the oil purities on the ground comes home, even if they should be of poor quality. Since the drive unit represents a substantially pure hydraulic solution, no changes to the electronics or electrical system are necessary in a retrofit of existing units, which helps to save costs. Overall, the actuator according to the invention can be designed more cost-effective than the known use of a variety of costly proportional directional spool valves with expensive control electronics used.

Further advantageous embodiments of the actuating device according to the invention are the subject of the dependent claims.

Fig.1

in der Art eines Schaltplanes eine erste Ausführungsform der erfindungsgemäßen Betätigungsvorrichtung;

Fig.2 und 3

gegenüber der Fig.1 geänderte Ausführungsformen und

Fig.4

im Längsschnitt ein für die hydraulische Betätigungsvorrich- tung einsetzbares Proportional-Ventil als Drossel.

In the following the actuating device according to the invention will be explained in more detail with reference to various embodiments according to the drawing. This show in principle and not to scale representation of the

Fig.1

in the form of a circuit diagram, a first embodiment of the actuating device according to the invention;

Fig.2 and 3

opposite the Fig.1 modified embodiments and

Figure 4

in longitudinal section, a proportional valve which can be used for the hydraulic actuating device as throttle.

In the manner of a hydraulic circuit diagram after the Fig.1 shown actuating device serves to control at least one hydraulic consumer 10 in the form of a hydraulic differential cylinder. Instead of a pertinent differential cylinder could also occur a Gleichgangzylinder or a hydraulic motor and comparable consumers who want to help to a smooth starting behavior. The hydraulic consumer 10 in the form of the working cylinder has a piston rod unit 12 which separates two hydraulic working spaces 14,16 from each other. The construction of this working cylinder or actuators is common, so that will not be discussed in more detail here at this point.

The working space 14, also called piston working space, is connected via a connection A with the actual hydraulic circuit and the working space 16, which is also called bar working space, with the corresponding junction B. The terminals S1 and S2 shown in the upper part of the hydraulic circuit seen serve the connection of corresponding sensors, for example for pressure value detection in the corresponding hydraulic lines, each open at the connection points A, B to the outside, wherein the actuating device is preferably designed in the manner of a hydraulic modular control block. Furthermore, the actuating device in addition to the Nutzanschlüssen A, B nor a hydraulic supply port P and a drain T, which preferably opens at ambient pressure in a corresponding supply tank. The hydraulic supply at port P can be done via a corresponding hydraulic pump.

Unless in the in Fig.1 The numerals 1, 2, 3 and 4 occur in the hydraulic circuit diagram shown, these each number the hydraulic inputs and outputs for the respective hydraulic valve or other control component. If reference is made in the following to certain inputs and outputs of a pertinent hydraulic component, the cited paragraphs will be consulted for the more detailed determination. In addition to the two mentioned sensor connections S1, S2 is in the direction of the Fig.1 seen below the Nutzanschlüsse A, B in a corresponding arrangement each have an adjustable throttle 18 is present and in the secondary branch in the direction of Nutzanschlüsse opening check valve 20. Arranged in the hydraulic supply line for the Nutzanschlüsse A and B, two mutually releasable check valves 22 are connected. The pertinent hydraulic supply structure for the Nutzanschlüsse A, B is common, so that will not be discussed in more detail here at this point.

To the supply port P, a proportional valve 24 is connected, which forms a kind of throttle or throttle valve. Proportional valves are continuously adjustable pressure, flow and directional valves that can convert a variable input signal into a proportional hydraulic output signal. Between the input 3 of the proportional valve 24 and the supply port P, a diaphragm 26 is connected, which throttles the fluid supply flow coming from the supply pump so far. Furthermore, the proportional valve 24 has two control inputs 28,30, wherein at the control input 28, the fluid pressure at the point 1 of the proportional valve 24 is present and at the control input 30 of the set pressure of a compression spring 32 (see. Figure 4 ). The working space of the compression spring 32 is connected via the terminal 4 of the proportional valve 24 and thus via a leakage oil connection 34 with the tank T. In the secondary branch between the connection points 2 and 3 of the proportional valve 24, in turn, a diaphragm 36 is connected.

To the valve outlet 2 of the proportional valve 24, a slide valve 38 is connected to the input 3, which is in the manner of a 4/3-way slide valve is formed with a further connection point 1, which is connected to the tank connection T and to the leakage oil connection 34. The pertinent slide valve 38 is spring-centered on both sides held in the initial position shown and can be controlled via appropriate actuation or switching magnets in a known manner. The output 4 of the slide valve 38 opens in the direction of the Fig.1 Seen on the right side in the line for the Nutzanschluß B, via the input 1 of the pilot-operated check valve 22. On the left opposite terminal side, the output 4 of the spool valve 38 opens onto the input side 1 of a shuttle valve 40 of known type. The other input 3 of the shuttle valve 40 opens to the other output 2 of the slide valve 38. For the mutual unlocking of the two check valves 22 open the control lines on the Input side 3 of the check valves 22 each in the opposite feed line for the Nutzanschlüsse A, B.

The output 2 of the shuttle valve 40 in turn opens via an aperture 42 to the input side 1 with the control input 28, in turn, another aperture 44 is connected. Between orifice 42 and tank port T and in the direction of the Fig.1 seen in the junction of the other aperture 44 in the connecting line, a pressure relief valve 46 is connected, which is formed in the present case as a spring-loaded check valve with opening direction in the direction of the tank port T. If in the application apertures and aperture cross-sections are addressed, their function can also be optionally achieve comparably not shown chokes and their cross sections.

The drive unit designated as a whole by 48 consists essentially of the pressure relief valve 46 and of the orifices 42 and 44. The pertinent control unit 48 controls the fluid supply flow for the consumer 10 such that a damped operation is achieved with a gentle starting behavior for the hydraulic consumer 10 in the form of the working cylinder. The system pressure prevailing in the region of the shuttle valve 40, which supplies the useful ports A, B, can assume a wide range of pressure values within a certain range of variation and depending on the load acting on the hydraulic cylinder 10, different volume flows occur, in particular with respect to the diaphragm 42 between the shuttle valve 40 and pressure relief valve 46. By the pressure bias across the pressure relief valve 46 can be kept constant using the further orifice 44 of the thus pending volume flow with the result that the setting speed for the proportional throttle 24 is also constant. The latter, however, is a mandatory requirement in order to be able to ensure the damped gentle starting process for the hydraulic consumer.

To generate the damped travel movement, the slide valve 38 is first to be activated, which can take place via a suitable actuation or control device triggered by an operator. The extent the slide valve 38 upstream throttle in the form of the proportional valve 24 is partially open and, moreover, also finds a minimized hydraulic primary supply from the supply port P coming via the aperture 36 in addition to the free opening cross-section of the throttle 24 in the initial state. If the slide valve 38 in the direction of the Fig.1 seen in a switching position, which corresponds to the right circuit diagram of the valve 38, the throttle 24 is opened due to the oil flow via the shuttle valve 40 via the working or control input 28 noticeably. Through the apertures 42 and 44, the pressure relief valve 46 and the acting spring force on the compression spring 32 on the oppositely acting control input side 30 is taking into account the geometry of the piston 50 of the proportional valve 24 (see. Figure 4 ) determines the opening characteristic for the throttle 24 and thus the damping effect for the entire system.

The over the terminal 1 of the proportional valve 24 increasingly tapered control oil flow moves the piston 50 visibly further, whereby the opening cross-section is steadily increased. However, this also increases the fluid supply flow for the hydraulic consumer 10, the opening behavior of the throttle in the form of the proportional valve 24 being independent of the load pressure at the consumer 10 due to the pressure limiting valve 46. Due to such a steady increase of the fluid flow to the hydraulic consumer 10, this drives smoothly and continuously until it reaches the maximum speed. The displaced in the rod working space 16 fluid in the pertinent extension movement of the piston rod unit 12 is pushed over the Nutzanschluß B and the terminal 4 of the spool valve 38 in the direction of the tank port T in the tank. Due to the upcoming fluid flow at the entrance 3 of the shuttle valve 40 is in the direction of the Fig. 1 seen right unlockable check valve 22 is open and the voltage applied to the input 1 of the left-hand check valve pressure level controls the left check valve 22 for the fluid supply via the Nutzanschluß A of the piston working chamber 14. If the slide valve 38 in the direction of the Fig.1 seen moved to its left shift position, the processes run in reverse and the piston rod unit 12 moves accordingly. Furthermore, the closing element of the shuttle valve 40 is opposite to the representation of the Fig.1 brought into the upper position, which faces in the direction of the input 3 of the shuttle valve 40, so that the input 1 is fluidly connected to the output 2 of the shuttle valve 40 and in turn via the proportional valve 24 in a throttled manner and thus gently the retraction movement of the piston rod unit 12 can be done. It is preferably provided that the aperture 42 has the same aperture diameter as the aperture 36 and that the further aperture 44 has a smaller aperture diameter than the aperture 42 and 36, wherein the pump inlet-side arranged aperture 26 should have the smallest aperture diameter. The shuttle valve 40 operates in the manner of a tapping point, wherein a pertinent tapping point (not shown) via other hydraulic means would be realized, but this is associated with a correspondingly increased circuit complexity. The combination of an initial throttling via the proportional valve 24 with the inlet panel 36 ensures that pressurized fluid is present on the input side of the actuating or sliding valve 38 even in the non-switched state for the gentle starting process of the consumer. Such a delay-free starting is possible and the indicated hydraulic switching unit can basically be used for each hydraulic consumer, even if the requirements for the initial volume flow are different. Will a modified solution as shown in the Figure 3 used, in which the aperture 36 has been omitted, one would have to use basically a changing proportional valve 24 with a calculated throttled basic supply with changing requirements on the initial volume flow, which would lead to increased costs for the hydraulic circuit.

According to another modified embodiment of the Fig.2 can be closed at the existing aperture 36, the proportional valve in the illustrated switched position, in which case the entire adjustment has to be made via the aperture 36, which optionally also limits the adjustment options for the hydraulic circuit. In the Fig.1 shown combination of initial throttling on the proportional valve 24 with inserted aperture 36 with permanent aperture cross-section makes sense especially from a cost point of view, if the proportional valve 24 is designed for the smallest occurring volume flow and the larger volume flows is realized by the parallel connection of the diaphragm 36 to the proportional valve 24. Also results from the pertinent arrangement, an increased dynamic behavior during soft damped startup of the hydraulic load 10. If the embodiments according to the Fig.2 and 3 towards the solution after the Fig.1 are changed, only the major changes have been explained above and otherwise the same reference numerals are used for the same components, as in Fig. 1 specified.

The constructive solution of the proportional valve 24 is in Figure 4 demonstrated. In addition to the block-like valve housing with the corresponding connection points 1,2,3 and 4, a further housing part 54 is screwed on the upper side of the housing 52, which receives the compression spring 32 substantially, with its one free end on the inside of the other housing part 54th supported and at its other end to the displacement or control piston 50, which in the Fig.1 shown throttling between the terminals 2 and 3 of the proportional valve 24 performs. If the solution after Fig.1 be realized, the piston 50 each has a basic position occupy, in which still a minimal throttled fluid flow between the terminals 2 and 3 is reached. In an embodiment according to the illustration of the Fig.2 the piston 50 would then completely block the pertinent fluid path, so that the compensation can take place via the diaphragm 36. For a corresponding throttling of the fluid flow of the piston 50 is provided between two piston parts 56,58 with a reduced diameter control or annular groove 60 and the pressure applied to the control input 1 or 28 relative to the constant volume flow is then permanently at the bottom of the piston part 58 on. Towards the top, the spring chamber above the piston 50 opens into the leakage oil connection 34, which opens out to the tank side T.

The actuating device according to the invention is preferably used there in which operating cabins of excavators or cranes have to move several meters forwards or upwards; Adjusting movements of the cabin, as they are necessary to make a timely unloading of ships od. Like. To make, where the operator needs an extended field of view. Thanks to the smooth start-up and stop movements with linear speed and acceleration behavior, the otherwise unpleasant rocking movements of the car which otherwise occur are counteracted, which, in addition to increasing the ease of operation, also meets increased safety requirements.

As the above explanations make clear, the proportional valve 24 is designed in the manner of a continuous valve. In the form of a continuous valve, the proportional valve 24 can be used for poor oil cleanliness classes, which otherwise make the use of conventional proportional valves impossible, provided that they are provided with electrically operable switching or actuating magnet. So far as in the present application of a proportional valve is mentioned, this means a continuous valve without the use of a switching or actuating magnet. Furthermore, all throttles and / or diaphragms used can be protected by sieves against contamination.

Claims (7)

1. An actuating device for controlling a hydraulic consumer (10), such as an operating cylinder, by means of a fluid supply flow,

   - the fluid supply flow for the consumer (10) being controlled by means of a control unit (48) such that damped actuation is obtained with gentle start-up characteristics,

   - the control unit (48) having a proportional valve (24) which acts as a restrictor, the restricting effect of which can be at least partially set by means of a control input (28) with constant fluid volume flow,

   - in order to obtain a constant fluid volume flow on the one control input side (28) at least one aperture (42) being connected which is connected on the output side to the input of a pressure limiting valve (46), and

   - there being connected between the output of the one aperture (42) and the input (1) of the pressure limiting valve (46) a further aperture (44) into the control input (28) for the proportional valve (24),

   - characterised in that the two apertures (42, 44) of the control unit (48) have different aperture diameters.
2. The actuating device according to Claim 1, characterised in that the one aperture (42) has a larger diameter than the other aperture (44) in the control input (28) of the proportional valve (24).
3. The actuating device according to either of Claims 1 to 2, characterised in that the other control input (30) for the proportional valve (24) has a pressure spring (32).
4. The actuating device according to any of Claims 1 to 3, characterised in that there is connected between the hydraulic consumer (10) and the control unit (48) a slide valve (38), in particular a 4/3-way slide valve.
5. The actuating device according to Claim 4, characterised in that there is connected between the slide valve (38) and the hydraulic consumer (10) a two-way valve (40) with its two inputs (1, 3) that is connected with its output (2) on the input side to the one aperture (42).
6. The actuating device according to any of the preceding claims, characterised in that there is connected in a sub-branch between the in- and output (3, 2) of the proportional valve (24) a further third aperture (36).
7. The actuating device according to any of the preceding claims, characterised in that the proportional valve (24) is provided in an non-actuated initial position with basic restriction.

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