WO2008017359A1

WO2008017359A1 - Actuating device

Info

Publication number: WO2008017359A1
Application number: PCT/EP2007/006179
Authority: WO
Inventors: Hermann Albert; Harald BÄR
Original assignee: Hydac Fluidtechnik Gmbh
Priority date: 2006-08-10
Filing date: 2007-07-12
Publication date: 2008-02-14
Also published as: EP2049802B1; WO2008017359A8; EP2049802A2; ATE523698T1; DE102006037631A1

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

actuator

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 stream.

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 employ such actuators to initiate motion and work operations. 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 actuating these actuators for triggering operations and movements, it often already occurs. Due to 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 shocks it comes to jerky movements of the driven consumers, which impaired 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 at the machine operators can lead.

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 Senkbremsventilen 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. The alternative or additional installation of hydraulic accumulators for energy provision position in the leads of each hydraulic consumer leads to a corresponding damping effect conditional through the biased gas side of the hydraulic accumulator; but the damping effect that can be achieved hereby is considered to be low and until the entire system, consisting of hydraulic accumulator and hydraulic consumer, has adjusted to a common pressure level, corresponding compensatory movements of the fluid supply flow occur, which leads to the known phenomenon of "hydraulic rocking" That is, the component to be moved with the hydraulic actuator, for example in the form of a driver's cab, violently rocking, which is perceived by the operator more than unpleasant.

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 account is taken.

A related object solves an actuator with the features of claim 1 in its entirety. Characterized in that according to the characterizing part of claim 1 by means of a drive unit, the fluid supply current is controlled for the consumer so that a muted operation is achieved with a gentle starting behavior, it comes basically for the hydraulic consumer to gentle accelerations, with respect to the steady Speed behavior of the operator are perceived as pleasant and any hydraulic or hydraulic actuators connected to the mechanical or hydraulic actuators are protected in the context of the respective work and actuation process and the entire hydraulic system relieved of undesired pressure surges. 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 cost-intensive proportional directional spool valves with expensive control electronics used.

Further advantageous embodiments of the actuating device according to the invention are the subject matter of the subclaims.

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

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

Figures 2 and 3 with respect to the Fig.1 modified embodiments and

4 shows a longitudinal section for a usable for the hydraulic actuator proportional valve as a throttle. The actuating device shown in the manner of a hydraulic circuit diagram according to Figure 1 is used 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.

If the numbers 1, 2, 3 and 4 appear in the hydraulic circuit diagram shown in FIG. 1, they each indicate the hydraulic inputs and outputs for the respective hydraulic valve or other control components. te. 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 SI, S2, as viewed in FIG. 1, an adjustable throttle 18 is provided below the useful connections A, B in a corresponding arrangement and a non-return valve 20 opens in the auxiliary branch in the direction of the utility connections Supply line for the Nutzanschlüsse A and B two mutually releasable check valves 22 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 FIG. 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 is connected to the input 3, a slide valve 38 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 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 via appropriate actuation or switching solenoids in a known manner. The output 4 of the spool 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 opens the output 4 of the spool valve 38th on the input side 1 of a shuttle valve 40 of known type. The further input 3 of the change venti Is 40 opens on the input side 1 of the left-handed check valve 22. Furthermore, the further input 3 of the shuttle valve 40 opens to the other output 2 of the slide valve 38. For the mutual EntSperrung the two check valves 22 open the control lines on the input side 3 of the check valves 22 in each case in the opposite supply 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 the aperture 42 and tank connection T and in the direction of 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 the application diaphragms and diaphragm cross-sections are addressed, their function can also be achieved if necessary via chokes not shown in detail and their cross-sections comparable.

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 in such a way that a damped actuation with a gentle starting behavior for the hydraulic consumer 10 in the form of the working cylinder is achieved. 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 fluctuation range and depending on the load acting in the system 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 must first be actuated, 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 incidentally also 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 is moved in the direction of the Fig.1 in a switching position corresponding to the right circuit diagram of the valve 38, the throttle 24 is opened due to the oil inflow 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 Fig.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 chamber 16 fluid in the pertinent Ausfahrbewe- movement of the piston rod unit 12 is pushed through 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 inlet 3 of the shuttle valve 40 seen in the direction of FIG. 1 right unlockable check valve 22 is open and the pressure applied to the input 1 of the left-open check valve pressure level controls the left check valve 22 for the fluid supply via the Nutzanschluß A of the piston Workroom 14 on. If the slide valve 38 is moved into its left switching position as viewed in the direction of FIG. 1, the processes proceed in the opposite direction and the piston rod unit 12 retracts accordingly. 1, the closing element of the shuttle valve 40 is brought into the upper position, which points in the direction of the input 3 of the shuttle valve 40, so that the input 1 to the output 2 of the shuttle valve 40 is fluidly connected 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 take place. 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 aperture 26 arranged on the pump inlet side 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 inlet 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. If a modified solution according to the illustration according to FIG. 3 is used in which the orifice 36 has been omitted, a changed proportional valve 24 with a calculated throttled basic supply would basically have to be used each time changing requirements for the initial volumetric flow occur , which would lead to increased costs for the hydraulic circuit.

According to a further modified embodiment according to FIG. 2, if the orifice 36 is present, the proportional valve may also be closed in the switched position shown, in which case the entire adaptation via the orifice 36 must take place, which may also be the adaptation possibilities for the hydraulic circuit limited. The combination of initial throttling shown in FIG. 1 via the proportional valve 24 with inserted diaphragm 36 with permanent diaphragm cross-section makes sense, in particular from a cost-technical 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 in the soft damped startup of the hydraulic load 10. If the embodiments of Figures 2 and 3 compared to the solution according to Fig.1 are changed, only the essential changes have been explained and otherwise, the same reference numerals are used for the same components, as indicated in Fig. 1.

The constructive solution of the proportional valve 24 is shown in Figure 4. 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 in on the upper side of the housing 52, essentially accommodating the compression spring 32, which with its one free end adjoins the inside of the other Housing part 54 is supported and at its other end to the displacement or control piston 50, which performs the throttling shown in Figure 1 between the terminals 2 and 3 of the proportional valve 24. If the solution according to FIG. 1 is to be realized, the piston 50 has in each case to assume a basic position, in which there is still a minimum of throttling

Fluid flow between the terminals 2 and 3 is reached. In an embodiment according to the illustration according to FIG. 2, the piston 50 would then have to 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, the piston 50 is equipped with a diameter-reduced control or annular groove 60 between two piston parts 56, 58 and the pressure prevailing at the control input 1 or 28 relative to the constant volume flow is then permanently at the bottom of the piston part 58. 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; Adjustment 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 velocity and acceleration behavior, the unpleasant rocking movements of the cabin, which otherwise occur, have been met, which, in addition to increasing operating convenience, 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 training as 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 actuated 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

Patent claims

1. Actuating device for controlling a hydraulic consumer (10), such as a working cylinder, by means of a Fluidversor- supply current, characterized in that by means of a drive unit (48) of the fluid supply current for the consumer (10) is driven such that a damped operation with a gentle starting behavior is achieved.

2. Actuating device according to claim 1, characterized in that the drive unit (48) has a proportional valve (24) which acts as a throttle whose throttle effect is at least partially adjustable via a control input (28) with a constant fluid volume flow.

3. Actuator according to claim 2, characterized in that for obtaining a constant fluid volume flow on the one control input side (28) at least one diaphragm (42) is connected, which is connected on the output side to the input of a pressure relief valve (46).

4. Actuator according to claim 3, characterized in that between the output of a diaphragm (42) and input (1) of the pressure relief valve (46), a further diaphragm (44) in the control input (28) for the proportional valve (24) connected is.

5. Actuating device according to one of claims 2 to 4, characterized in that the other control input (30) for the proportional valve (24) has a compression spring (32).

6. Actuating device according to one of claims 1 to 5, characterized in that between hydraulic consumer (10) and Control unit (48) a slide valve (38), in particular 4/3-way slide valve, is connected.

7. Actuator according to claim 6, characterized in that between slide valve (38) and hydraulic consumer (10) a

Shuttle valve (40) with its two inputs (1,3) is connected, which is connected with its output (2) on the input side to the one aperture (42).

8. Actuating device according to one of claims 2 to 7, characterized in that in a side branch between the input and output (3,2) of the proportional valve (24), a further third aperture (36) is connected.

9. Actuating device according to one of claims 2 to 8, characterized in that the proportional valve (24) is provided in an unactuated initial position with a basic throttling.

10. Actuating device according to one of claims 4 to 9, characterized in that the two diaphragms (42, 44) of the drive unit (48) have different diaphragm diameters, in particular one diaphragm (42) has a larger diameter than the other diaphragm ( 44) in the control input (28) of the proportional valve (24).