EP2452078A1

EP2452078A1 - Arrangement for providing a variable throttle cross-section for a fluid flow

Info

Publication number: EP2452078A1
Application number: EP09775737A
Authority: EP
Inventors: Eneko Goenechea; Josef ZÜRCHER; Silvan Thuerlemann
Original assignee: Bucher Hydraulics AG
Current assignee: Bucher Hydraulics AG
Priority date: 2009-07-06
Filing date: 2009-07-06
Publication date: 2012-05-16
Anticipated expiration: 2029-07-06
Also published as: WO2011003210A1; EP2452078B1; CN102483077A; CN102483077B; US20120125190A1; US9032861B2

Abstract

The invention relates to an arrangement for providing a throttle cross-section (1) for a fluid flow. The throttle cross-section (1) can be varied depending on a pressure difference present across said throttle cross-section. The arrangement is designed in such a way that the polarity of the pressure difference, by means of which the throttle cross-section can be varied, can be changed. It is thereby possible to use the arrangement according to the invention for fluid flows that alternate in the flow direction thereof.

Description

Arrangement for providing a variable throttle cross section for a fluid flow

TECHNICAL AREA

The invention relates to an arrangement for providing a variable throttle cross section for a fluid flow, a lift control valve with the arrangement, a hydraulic lift system with the lift control valve and a method for operating the lift according to the preambles of the independent claims.

STATE OF THE ART

In the case of hydraulic and pneumatic systems, various arrangements are currently used today to provide variable throttle cross-sections for fluid flows guided therein, both for regulating pressures and / or volume flows and for detecting them. The change in the throttle cross-section is carried out either by external control engagement by means of mechanical, hydraulic, pneumatic or electric actuators, eg control valves, or by the pressure, a pressure difference and / or a flow force of the guided in the arrangement fluid, such as pressure relief valves or check valves. The latter arrangements have the advantage that a high operational reliability is achieved due to the relatively simple hydraulic / pneumatic coupling and the independence of auxiliary power. The disadvantage here, however, that these arrangements are typically used only in a flow direction. This is a problem in devices in which depending on the operating situation in their flow direction changing fluid flows occur, such as in lift control valves for hydraulic lifts, which is a problem today Use of several such arrangements and a complex interconnection thereof is solved. However, this is associated with a considerable financial and technical equipment and also often leads to not inconsiderable maintenance costs.

PRESENTATION OF THE INVENTION

It is therefore the object to provide an arrangement for providing a variable throttle cross-section for a fluid flow to make available, in which the throttle cross-section by the pressure, a pressure difference and / or a current force of the guided in the arrangement fluid is variable and which previously mentioned disadvantages of the prior art does not have or at least partially avoids.

This task is gemassen by the arrangement

Claim 1 dissolved.

Accordingly, the arrangement for providing a variable throttle cross section for a fluid flow, preferably for a fluid flow, e.g. a stream of hydraulic oil, a throttle assembly and a drive assembly. The throttle arrangement forms a throttle cross-section variable by movement of a throttle body. The drive arrangement has a drive element arranged movably in a housing, which drive element is connected to the throttle body

Throttling arrangement is coupled such that the throttle cross-section of the throttle arrangement is variable by changing the relative position of the drive element in the housing. Preferably, the coupling between Drosselkorper and drive element takes place in a hydraulic or mechanical manner, advantageously by common in particular emstuckige training of throttle body and drive element.

In this case, the arrangement is designed such that the drive element is permanently acted upon by a spring force (the claim-compliant first spring force) or, for example, by supplying auxiliary power, can be acted upon with such a spring force. The spring force acts in a claim according to the first direction on the drive element, in which this is movable in the housing. For this it is conceivable, for example, that a

Spring element or a pressurized compressible medium in a suitable direction exerts a compressive force directly on the drive element and / or on the throttle body coupled to the drive element. The spring force acts ^¬ , that the drive element is positioned in a basic position in the housing in the absence of at least equal, acting in a direction opposite to the first direction opposite claims the second direction on the drive element.

Further, the arrangement being such trained det, that the drive element as a result of fluid pressures in a first fluid chamber of the arrangement, which communicates with a first side of the throttle cross-section continuously in fluidic contact with or engageable with said first side in flui ^¬ sized contact, and a second Fluid space of the arrangement, which is permanently in fluidic contact with the other, second side of the throttle cross-section or can be brought into fluid contact with this second side, can be acted upon by a second and a third force, both of which act in the second direction as claimed, so contrary to

Spring force.

Also, the arrangement is designed such that due to a fluid pressure in a third fluid space of the arrangement, the drive element is acted upon by acting in the claim first direction fourth force, ie with a fourth force acting in the direction of the spring force.

This configuration results in that the drive element acts on it in the event that no further forces act on it in the first and the second direction according to the claims, and that results from the second, third and fourth force, a total force in the spring force ent ^¬ against set according to the claims second direction and the spring force exceeds in the basic position, is moved from the basic position out until a balance of forces between the in the respective relative position acting on the drive element spring force and acting from the second, the third and the fourth force in the direction opposite to the spring force resulting force occurs or a maximum movement position of the drive element is reached.

Furthermore, the arrangement according to the invention comprises a switching arrangement, e.g. a hydraulically actuatable 3/2-way valve, by means of which either either the first and the third fluid space of the arrangement or the second and the third fluid space of the arrangement are fluidically connectable to each other. When the first side of the throttle section is in fluid communication with the first fluid space and the second side of the throttle section is fluidically in communication with the second fluid space, the drive element is dependent on the switching state, i. depending on whether the third fluid space is connected to the first or the second fluid chamber, either on the occurrence of a positive or negative pressure difference between the first side and the second side of the throttle gap from the home position movable to open or enlarge the throttle cross-section.

The invention provides for the first time an arrangement for providing a throttle cross-section for a fluid flow, in which the throttle cross-section is variable as a function of an existing pressure difference across this and apparently in which the polarity of the pressure difference, by means of which the throttle cross-section variable or apparently, is switchable. This makes it possible to inventive arrangement for devices with changing in their flow direction fluid streams to use.

In a preferred embodiment, the arrangement is designed such that the throttle cross-section is completely closed when arranged in the basic position drive element, so the two sides of the throttle cross-section are separated, so that in this position, the first fluid space is separated from the second fluid space. This separation is preferably carried out such that there is a leak-free separation at the intended pressures and the intended fluids. This can be achieved, for example, in that the throttle arrangement is designed as a seat valve ^' . ¹ Such embodiments of the erfindüngsgemässen arrangement for example may be used as switchable non-return valves, which is a preferred use thereof.

In a further preferred embodiment, the arrangement has means for determining the opening of the throttle cross-section of the throttle arrangement, the relative position of the drive element in the housing and / or the relative position of the throttle body of the throttle arrangement, ie means with which a size representing the respective throttle cross section are determined can. Preferably, these means comprise sensors with which the relative positions of the drive element and / or the throttle body can be converted into electrical signals, so that an electronic evaluation of the determined measured values is possible. Such embodiments of the erfindüngsgemässen arrangement can be used for example as a flow meter with switchable flow direction, which represents a further preferred use of the erfindüngsgemässen arrangement. Especially with non-compressible fluids such as water or with only very low compressible fluids such as mineral oil, there is the advantage that, with known characteristics of the erfindüngsgemässen arrangement and known Viscosity of the fluid all other required for the determination of the volumetric flow, these are the throttle cross-section, the hydraulic ratio of the inventive arrangement in this throttle cross-section and the given viscosity of the fluid and the pressure difference between the first and the second side of the

Throttle cross-section, with good accuracy from the determined, the throttle cross section representing size result.

Particularly preferred are embodiments which combine the features of the two aforementioned embodiments with each other. These can be used as combined reversible flow and check valve units. These functionalities ^■ •> ^■ are required for example in lift control valves where they are deployed today in a complex manner by combining several individual arrangements.

In yet another preferred embodiment, the arrangement is such that the second force and the third force at identical fluid pressures in the first and second fluid spaces are about the same size, e.g. It can be achieved by directly applying force without over- or reduction mechanisms, the effective areas used to generate the respective force are made the same size.

In this way it can be achieved that the operating behavior of the arrangement in both switching states, i. both when the first and third fluid spaces are interconnected via the switching arrangement and when the second and third fluid spaces are interconnected via the changeover arrangement, apart from the reverse polarity, the pressure differential required to actuate the drive element is substantially identical.

In yet another preferred embodiment, the arrangement is designed such that at identical fluid pressures in the first, second and third fluid space cancel the second, third and fourth forces substantially each other. This can be achieved, for example, that in direct Kraf ^'teinleitung be formed as large as the effective area used for generating the fourth force without over- or under-reduction mechanisms, the active areas used to produce the second and third force in the sum. In this way, a particularly sensitive response of the arrangement can be achieved, such that even slight pressure differences between the first and the second side of the throttle cross section lead to an opening or enlargement of the throttle cross section.

If the drive element has axial surfaces which are used to generate the second; third and fourth force respectively with the first, the second and the third

Fluid space fluidly connected, which is preferred, so there is a direct and loss-free introduction of force in the drive element.

Advantageously, the drive element of the drive arrangement and the throttle body of the throttle arrangement are formed by one and the same one-piece or multi-piece component. This allows a simple and compact design with a lossless coupling between the drive element and throttle body realize.

A second aspect of the invention relates to a lift control valve with the inventive arrangement. The lift control valve has a first connection for a supply line for hydraulic fluid coming from a hydraulic pump, a second connection for a return of hydraulic fluid into a tank and a third connection for a hydraulic line leading to a hydraulic drive of a lift system. Furthermore, the lift control valve has a control arrangement with which the first side of the throttle cross section and the first fluid space of the arrangement according to the invention can be fluidically connected either to the first port or to the second port, depending on whether the Lift control valve is to be brought into a position in which it is intended to allow the passage of hydraulic fluid from a hydraulic pump to a hydraulic drive a lift system (UP-drive operation) or the return of hydraulic fluid from a hydraulic drive a lift system in a tank (AB ride operation). Furthermore, the lift control valve is designed in such a way that the second side of the throttle cross section and the second fluid chamber of the arrangement according to the invention are connected to the third connection or can be connected thereto.

In this way, the inventive arrival '■ sort out the precautionary _measures' is of the same main line flowed through ON-drive mode and AB-drive operation of the lift control valve in changing direction of the hydraulic fluid involved and can appropriate configuration as described previously, for example, tasks perceive as a reversible check valve and / or as a reversible flow meter, which is preferred. It is particularly preferred if the arrangement according to the invention, as stated at the outset, is designed in such a way that it forms a combined flow measuring and check valve unit which can be switched over with respect to the flow direction, ie can simultaneously perform the two aforementioned tasks. As a result, the system engineering effort compared to previous lift control valves can be significantly reduced with the same functionality and save corresponding provisioning and maintenance costs.

In this case, in a preferred embodiment, the lift control valve is designed in such a way that, when the first side of the throttle cross section and the first fluid chamber with the first connection are connected as intended, the second fluid chamber also connects to the third fluid chamber through the switchover arrangement and that a binding the first side of the throttle cross-section and the first fluid space with the second connection inevitably leads to the first fluid space is connected by the switching arrangement with the third fluid space. This ensures that the inventive arrangement in a switchover of the control arrangement of the lift control valve from ON-drive operation on AB-drive operation and vice versa each also switched and is thereby adapted to the respective flow direction.

Advantageously, as a control arrangement for enabling the optional connection of the first side of the throttle cross section with either the first or the second connection of the lift control valve, a preferably continuously acting, preferably hydraulically operable main valve is used, which is preferably designed as a piston slide design. Such control arrangements are proven, reliable and low maintenance.

Further, in embodiments in which the control arrangement of the lift control valve is a hydraulically operable main valve, it is advantageous that the lift control valve has a valve with which the fluid supply to the hydraulic drive of the main valve upon reaching or exceeding a certain pressure at the first port is fluidically connected to the second port, so with the connection, for a

Return of hydraulic fluid is provided in a tank. This makes it possible to permit certain positions of the main valve and thus certain operating states or operating state changes of the lift control valve only if no appreciable fluid pressure is present at the connection for the supply of hydraulic fluid from a hydraulic pump (demanding first connection), eg if the switched off there hydraulic pump or the Hydraulikflüssig- keitsstrom is deactivated. It is also in embodiments in which the control arrangement of the lift control valve has a hydraulically actuated main valve, preferably, when the lift control valve has an electrically operable Vorsteuerven ^¬ til for the hydraulically actuated main valve, by means of which the hydraulic drive of the main valve fluidly with the second side of the throttle cross-section or connected to the third port or can be disconnected. In this way, when the lift control valve is used as intended, the fluid pressure generated by the weight of a lift operated therewith can be used in the line leading to the lift drive to actuate the main valve, which results in the advantage that a controlled DOWN drive is possible even in the event of a failure the hydraulic pump is possible.

It is further preferred that the sized ^¬ flui communication between the pilot valve and the hydraulic drive of the main valve ie to the tank port having a second port, leading throttle point. This throttle point advantageously has a variable depending on the valve position of the main valve throttle cross-section. When executed in piston valve design main valve, it is preferred that the throttle cross section is variable depending on the position of the spool, which is advantageously realized such that the throttle cross section between the spool and a stationary component of the main valve is formed. As a result, a pressure relief of the connecting line between the pilot valve and the main valve is ensured with closed pilot valve. In versions with variable throttle cross section, it is also possible to specifically influence the response of the main valve.

In a further preferred embodiment, the lift control valve is designed in such a way that when hydraulic fluid is present under pressure at the first connection. It is not possible to connect the first side of the throttle cross section of the throttle arrangement to the second connection. In this way it can be ensured that an AB drive operation of a system formed with this lift control valve is possible only when the hydraulic pump or the hydraulic fluid flow is switched off.

In yet another preferred embodiment of the lift control valve, the change-over device of the inventive arrangement in a hydraulically betätig ^¬ bares switching valve that is switchable during normal operation by opening or closing a pressure relief opening. The Steueranord ^¬ tion of the lift control valve is designed such that it opens when connecting the first side of the throttle cross-section of the throttle arrangement with the second port (Tankan- conclusion), the pressure relief opening of the changeover valve. As a result, a coupling of the control arrangement and switching arrangement is possible in a simple and reliable manner.

In general, it is preferred that the lift control valve is designed in such a way that the actuating energy required for the actuation of hydraulically actuatable valves contained in it can be removed from the hydraulic fluid guided in the lift control valve during operation. In this way can be dispensed with further supply and discharge lines for hydraulic fluid and there is a lift control valve unit with a minimum of interfaces.

A third aspect of the invention relates to a hydraulic lift system with a lift control valve according to the second aspect of the invention. The lift system has a hydraulic pump connected or connectable to the first port of the lift control valve, a hydraulic fluid tank connected or connectable to the second port of the lift control valve, and a hydraulic drive connected or connectable to the third port of the lift control valve, to which one Lift the lift system can be driven. The hydraulic drive is preferably designed as a linear drive in the form of a hydraulic cylinder, but it can also be designed differently, for example as a rotary hydraulic motor. The formation of such a lift system represents a proper use of the lift control valve according to the second aspect of the invention.

In a preferred embodiment, the elevator system to a lift control valve with a Inventions according assembly which is provided with means for determining the opening of the Drosselguerschnitts the throttling arrangement, the relative position of the drive element and / or the Re ^¬ lativposition of the throttle body of the throttle assembly. Furthermore, this embodiment of the lift system comprises a control for the driving operation of the lift, which is so connected to the aforementioned means and is configured to provide information about the opening of the Drosselguerschnitts, the relative position of the drive element and / or the relative position of the throttle body can receive and this can take into account in the control or regulation of the driving operation of a lift of the lift system, and preferably as a parameter, which represent the hydraulic fluid flow, which flows through the throttle cross-section of the inventive arrangement, and in particular the associated

Travel speed of the lift. With such hydraulic lifts it is possible to realize a very precise regulation of the travel speed of the lift with little system outlay.

A fourth aspect of the invention relates to

Method for operating a lift system according to the third aspect of the invention. The method comprises the following steps:

Lifting a lift of the lift system by conveying a volume flow of hydraulic fluid from the hydraulic pump to the hydraulic drive of the lift, wherein the hydraulic fluid flows through the throttle cross section of the throttle arrangement of the arrangement according to the invention from the first side of the throttle cross section to the second side of the throttle cross section and the second fluid space and the third fluid space of the arrangement are fluidically connected to one another via the switching arrangement and are also fluidically connected to the second side of the throttle cross section, while the first side of the throttle cross-section is fluidly connected to the first fluid space or

Lowering a lift of the lift by

Conveying a volume flow of hydraulic fluid from the hydraulic drive of the lift into the tank, wherein the hydraulic fluid is the throttle cross section of the throttle arrangement of the inventive arrangement from the second side of the throttle cross section to the first side of the

Throttle cross-section flows through and the first fluid space and the third fluid space of the arrangement are fluidly interconnected via the switching arrangement and are also fluidly connected to the first side of the throttle cross section, while the second side of the throttle cross-section is fluidly connected to the second fluid space;

Determining the opening of the throttle cross section of the throttle arrangement, the relative position of the drive element of the drive arrangement and / or the relative position of the throttle body of the throttle arrangement of the inventive arrangement during the promotion of the volume flow of hydraulic fluid through the throttle cross section;

Comparing the determined opening of the throttle cross-section, relative position of the drive element, the relative position of the throttle body of the throttle arrangement and / or a value calculated from one or more of these determined values with a desired value; and Changing the volume flow through the

Throttle cross-section funded hydraulic fluid upon detection of a deviation from the desired value such that the opening of the throttle cross-section, the relative position of the drive element, the relative position of the throttle body and / or the calculated value approaches the target value.

It is preferred that the volume flow of hydraulic fluid conveyed through the throttle cross-section of the throttle arrangement is ascertained by means of an algorithm exclusively from the determined opening of the throttle cross section, the determined relative position of the drive element and / or the determined relative position of the throttle body of the throttle arrangement additional consideration of an additionally determined temperature value of the hydraulic fluid.

This makes it possible, the lift system according to the third aspect of the invention in the ON-drive operation and AB-drive operation precisely with respect

Travel speed of the lift to regulate without requiring the determination of system pressures is required, so that a cost-effective and very safe operation is possible.

In a preferred embodiment of the method, when the lift is lifted, the volume flow of hydraulic fluid delivered through the throttle cross section of the throttle arrangement is changed by controlling a larger or smaller part of the volume flow conveyed by the hydraulic pump into the tank with the control unit of the lift control valve , In this way, the use of low-constant pumps is possible and the entire regulation via the lift control valve. BRIEF DESCRIPTION OF THE DRAWINGS

Further embodiments, advantages and applications of the invention will become apparent from the dependent claims and from the following description with reference to FIGS. Showing:

1 shows a section through an inventive

Lift control valve in a first operating situation;

FIG. 2 shows a section through the lift control valve according to FIG. 1 in a second operating situation; FIG. and

Fig. 3 is a hydraulic diagram of a lift system with the lift control valve according to the preceding figures.

WAYS OF CARRYING OUT THE INVENTION ^■ - ¹

1 shows a section through a lift control valve according to the invention in an idle state of rest of the lift control valve. As can be seen, the lift control valve on a solid metal housing 3, within which by inserting various functional units from the outside a hydraulically actuated 3/4-way main valve 14, an electrically operable

Pilot valve 15 for the main valve 14, a pressure relief valve 18, a releasable check valve 22 and a switching valve 8 are formed for the check valve 22. The check valve 22, together with the switching valve 8, is a claimed arrangement for providing a variable throttle cross section for a hydraulic fluid flow to be controlled by the lift control valve for a hydraulic lift drive.

The main valve 14 is as a continuous acting

Slide valve formed with a piston slide 17 which limits a control oil space 25 at its left end and forms at this end together with a control edge of the housing 3 a variable depending on the Kolbenschieberstel- ment throttle 16. At its right end the piston slide 17 delimits a spring raum 27, in which a return spring 26 is arranged, which pushes the spool 17 at unpressurized control oil space 25 to the left in a basic position. The spring chamber 27 is limited over a part of its axial extent and at its end facing away from the spool 17 of a Drosselhulse 28, which relieves pressure on this space 27 via a throttle point formed by them to the second port 12 (tank connection). Within the piston slide 17, a central bore 30 is further arranged with a check valve 31, via which oil from a radial groove 32 on the circumference of the spool 17 in the spring chamber 27 can be passed.

The pilot valve 15 for controlling the main valve 14 is designed as a steadily acting poppet valve which forms a check valve in the illustrated currentless state in the direction of its intended flow direction.

The main valve 14 and the associated pilot valve 15 form the claimed mass control unit of the lift control valve.

The unlockable check valve 22 is formed in a seated construction, with a in the housing 3 against the force of a spring 23 (the claimed first force) displaceable Drosselkorper 2 and a fixedly arranged in the housing 3 valve seat body 9. The Drosselkorper 2 and valve seat body 9 formed throttle cross section 1 in a basic position with non-deflected throttle body 2 closed in a fluid-tight manner and can be changed by deflection of the throttle body 2 from the basic position as a function of the position of the throttle body 2.

The Drosselkorper 2 forms in the present case at the same time the claim moderate drive element 4 by having axial surfaces, which are in direct contact with a claimed first fluid chamber 5, a claimed second fluid chamber 6 and a claimed third fluid chamber 7, so that 5 following fluid pressures in these fluid spaces 5, 6, 7 corresponding claim-compliant second, third and fourth forces in and against the direction of force of the spring 23 can be exerted on the throttle body 2. If the sum of these second, third and fourth forces exceeds the

10 force of the spring 23 in the opposite direction, the throttle body 2 is lifted from the valve seat body 9 and the throttle section 1 is opened so far that a balance between the spring force and the sum of the second, third and fourth forces in the opposite direction

15 of the spring force is present. In the present arrangement, the ratios of the axial faces of the Drosselkör ^¬ pers 2, 4 so chosen that the second, third ^{■ •} .. -.- and the fourth force at identischeπv fluid pressure in the first, second and third fluid space 5 , 6, 7 each other

20 pick up. As can also be seen, the throttle body 2 is coupled at its right end with a position sensor 10, with which its position in the housing 3 in the form of electrical signals can be determined to determine the in operation by the throttle cross-section. 1

25 of the throttle valve 22 flowing volume flow of

Hydraulic fluid.

The switching valve 8, which serves as a claim switching arrangement for switching the check valve 22 is as a switching 3/2-way valve in

Shutter construction is formed and is in the situation shown in Fig. 1 in a position in which it fluidly connects the second fluid chamber 6 and the third fluid chamber 7 and separates them from the first fluid chamber 5. This allows the throttle cross-

35 cut 1 of the check valve 22 only open when in the first fluid chamber 5 a fluid pressure is generated, which exceeds the fluid pressure in the second 6 and the third fluid chamber 7 and also additionally large enough to overcome the force of the spring 23 in the home position ,

40 As can be seen, the piston valve of the change-over valve 8 is loaded by a spring in this way, so that it is held in the position shown in the absence of larger forces acting in the direction opposite to the spring force. This spring is arranged in a spring chamber 24, which communicates fluidically via a throttle point in the piston slide with the second 6 and third fluid chamber 7. Next, the spring chamber 24 is fluidly in contact with the end face of the throttle sleeve 28 of the main valve 14, to which a central pressure relief opening 19 for depressurizing the spring chamber 24 is located, which is fluid-tightly sealed in the operating situation shown in Fig. 1 by a spring-loaded ball , so that the spring chamber 24 is not depressurized in this operating situation. The spool 17 of the main valve 14 has at its right end to an actuating pin 29, by means of which he in a fully controlled position the

Pressure relief opening 19 can open by lifting the spring-loaded ball from its seat and thereby fluidly connect the spring chamber 24 of the switching valve 8 with the spring chamber 27 of the main valve 14.

As further in particular in conjunction with

3, which shows the hydraulic diagram of a hydraulic lift system formed with this lift control valve, the first fluid chamber 5, which is arranged on the claimed first side of the throttle cross-section 1 of the check valve 22, via the main valve 14 optionally with a first port 11 for a coming from a hydraulic pump 33 supply line for hydraulic fluid and with a second port 12 for a return of hydraulic fluid in a tank 34 connectable. The second fluid chamber 6, which is arranged on the claimed second side of the throttle cross-section 1 of the check valve 22, is permanently connected to a third connection 13 for a hydraulic line leading to a hydraulic drive 35 of a lift system and draulic side with the inlet side of the pilot valve 15. In the illustrated basic position is the throttle gap 1 is completely closed, so that the first 5 and the second fluid chamber 6 are fluidly separated from each other via this.

The pressure relief valve 18 is located in the feed from the pilot valve 15 for the control oil to the control oil chamber 25 of the main valve 14 and is designed such that when exceeding a certain fluid pressure at the first port 11, this feed is connected to the second port 12 for the tank and thereby the control oil pressure collapses.

Now, as shown in Fig. 3, starting from the illustrated in Fig. 1 switching situation of the lift control valve, the first port 11 by means of a hydraulic pump '--- 33- fed' with hydraulic oil and the second port connected to a hydraulic oil tank 34, from which conveys the hydraulic pump 33, the oil is passed through the hollow main spool 17 of the main valve 14 to the second port 12 and back to the tank 34, wherein in the interior of the slide 17 sets a circulation pressure. This circulating pressure penetrates via columns into the first fluid space 5. By connected to the third terminal 13 of the lift control valve hydraulic drive 35 a lift system on which the weight of the lift loads, the fluid pressure in the second 6 and in the third

Fluid space 7 greater than the circulation pressure, so that the throttle cross-section 1 of the valve 22 remains closed.

Is now by opening the pilot valve 15 at the third port 13 and in the second

Fluid chamber 6 present pressure at least partially guided in the control oil chamber 25 of the main valve 14 and this driven, so the main spool 17 of the

Valve 14 shifted to the right, whereby the outlet closed to the tank and the first port 11 is connected to the first fluid chamber 5. At the same time, with increasing deflection of the main slide 17, the throttle cross-section of the variable throttle point 16 is enlarged, via which a part of the control oil flow for the Main valve 14 to the second port 12 and into the tank 34 is passed. As a result, the pilot valve 15 must be opened disproportionately for an increasing off ^¬ steering of the spool 17 of the main valve 14, so that a sensitive adjustability of the Hauptven- tils 14 results.

As soon as the pressure in the first fluid chamber 5 has exceeded the fluid pressure in the second fluid chamber 6 and, in addition, has also neutralized the force of the spring 23, the throttle body 2 is deflected to the right. The throttle cross section 1 opens and hydraulic oil under pressure flows from the first port 11 to the third port 13 and from there to the hydraulic lifting actuator 35, in the case ahead ^¬ a unilaterally acting hydraulic cylinder. This condition corresponds to the OPEN drive operation of the lift control valve. In this case, the position of the throttle body 2 via the sensor 10 as an electrical position signal for an electronic control (not shown) can be tapped and is available for a determination of the flowing through the throttle cross-section volume flow of hydraulic oil, without this being a determination of

Pressure values required.

The changeover valve 8 remains in its ON position during the OPEN-OPERATION operation, since the spring chamber 24 on the right-hand side of its piston valve, which is not relieved of pressure in this operating situation, is fluidically connected to the second 6 and third fluid chamber 7 via a throttle point in the piston valve and whose spring compensates for the slight overpressure in the first fluid space 5 with respect to the pressures in the second 6 and third fluid space 7 or in the spring space 24.

If the pilot valve 15 is closed again, the pressure in the control oil chamber 25 of the main valve 14 breaks down via the throttle point 16 and the slide 17 of the main valve 14 is pushed back by the spring 26 into the initial position shown in FIG. For a conversion of the lift control valve in the situation shown in Fig. 2, which shows the lift control ^¬ valve in AB-drive operation, the slider 17 of the main valve 14, as can be seen, be brought into a fully deflected position to the right.

However, this is only possible if the first port 11 is depressurized, so this is not connected to a running hydraulic pump 33, otherwise at the latest at a Kolbenschieberprosition in which the circumferential groove 32 with the annulus, in which the first port 11 opens, in Overlap device, the spring chamber 27 of the main valve 14 is pressurized Would ^¬ de and thus further deflection to the right of the spool 17 would be hydraulically prevented.

If the pilot control valve 15 is now completely opened when the first connection 11 is depressurized and the third connection 13 is under pressure, the control oil pressure can displace the piston slide 17 of the main valve 14 to the right up to the position shown in FIG. 2, this being the spring-loaded ball the discharge opening 19 closes fluid-tight, lifts with its actuating pin 29 from its seat. As a result, the first fluid chamber 5 is connected directly via the main valve 14 and the spring chamber 24 of the changeover valve 8 indirectly via the discharge opening 19 and the throttle sleeve 28 to the second port 12 and the tank 34 and thereby relieved of pressure. As a result, the fluid pressure in the second fluid space 6 in conjunction with the axial surfaces of the spool valve of the changeover valve 8, to which it acts, is sufficient to deflect this spool valve counter to the spring force to the right. In this case, increases after lifting the piston valve of the switching valve 8 from its seat, the pressure in the first fluid chamber 5, which acts on the front side of the spool 'and then additionally helps to deflect it completely to the right in the position shown. As a result, the first fluid space 5 is connected to the third fluid space 7, while the second fluid space 6 is separated therefrom. By connecting the third fluid space 7 with the first fluid space 5, the fluid pressure in the second fluid space 6, which acts axially only on an annular surface of the throttle body 2, in conjunction with the fluid pressure in the first fluid space 5, which extends to the end face of the Drosselkorpers 2 acts, to move the throttle body 2 from the basic position to the right and thereby open the throttle section 1. As a result, the hydraulic fluid flows from the second fluid chamber 6 via the throttle section 1 in the first fluid chamber 5 and from there via the main valve 14 and the second port 12 in the tank 34. This state corresponds to the AB-drive operation of the lift control valve, said Here, too, as already described in the above drive-ON operation, the position of the Drosselkorpers 2 via the sensor 10 as an electrical position signal for an electronic control (not shown) can be tapped and so for a determination of the now in the reverse direction through the throttle section. 1 flow volume of hydraulic oil is available, again without the need for a determination of system pressures.

If the pilot control valve 15 is closed again, the pressure in the control oil space 25 of the main valve 14 breaks down via the throttle point 16 and the slide 17 of the main valve 14 is pushed back by the spring 26 into the initial position shown in FIG. As a result, the discharge opening 19 is again closed by the spring-loaded ball and it builds up in the spring chamber 24 of the switching valve 8, a fluid pressure which causes the spool of the switching valve 8 is printed to the left back to the position shown in Fig. 1 in that it connects the second 6 and the third fluid space 7 with one another and separates the first fluid space 5 from them. This leads to the fact that the pressure in the spring chamber 7 of the check valve 22 increases and the throttle body 2 to the left in the normal position shifts, in which this fluid-tight against the valve seat body 9 and the lift control valve again completely has the rest state shown in Fig. 1. In this state, in the lift system shown in FIG. 3, the piston of the lift drive 35 rests hydraulically on the check valve 22, the pilot control valve 15 and the changeover valve 8.

While preferred embodiments of the invention are described in the present application, it should be clearly understood that the invention is not limited to these and may be practiced otherwise within the scope of the following claims.

Claims

1. Arrangement for providing a variable throttle cross-section for a fluid flow, in particular for a liquid flow, comprising

a throttle assembly (20) with a through

Movement of a throttle body (2) changeable

Throttle section (1),

a drive assembly (21) having a

movably arranged in a housing (3)

Drive element (4) which is coupled to the throttle body (2) of the throttle arrangement for changing the throttle cross-section (1) in dependence on it

Relative position in the 'housing (3), wherein the arrangement is designed such

in that the drive element (4) is permanently loaded with a first spring force or is acted upon by a first spring force acting on the drive element (4) in a first direction of its mobility and the drive element (4) in the absence of at least the same size, in one second, opposite to the first direction direction on the drive element (4) acting forces in a basic position in the housing (3)

positioned

in that, as a result of a pressure of a fluid in a first fluid space (5) of the arrangement, which is fluidically connected or connectable to a first side of the throttle cross section, the drive element (4) can be acted on by a second force acting in the second direction,

in that, as a result of a pressure of a fluid in a second fluid space (6) of the arrangement, which is fluidically connected or connectable to the second side of the throttle cross-section, the drive element (4) can be acted on by a third force acting in the second direction, in that, as a result of a pressure of a fluid in a third fluid space (7) of the arrangement, the drive element (4) can be acted on by a fourth force acting in the first direction,

such that the drive element (4) acts on the drive element (4) in the event that no further forces in the first or the second direction act and the sum of the second, the third and the fourth force is a resultant force, which in the second direction acts and in the basic position on the

Drive element (4) exceeds in the first direction acting first spring force, is moved out of the basic position until an equilibrium of forces between in the respective relative position of the drive element (4) acting on this first spring force and the resulting force occurs or a maximum movement position is reached,

and further comprising a switching arrangement (8) by means of which selectively either the first fluid space (5) and the third fluid space (7) are fluidically connectable to one another or the second fluid space (6) and the third fluid space (7).

2. Arrangement according to claim 1, wherein the throttle cross-section (1) of the throttle arrangement is completely closed in the basic position arranged drive element (4).

3. Arrangement according to one of the preceding claims, wherein the arrangement comprises means for determining the opening of the throttle cross section (1) of the throttle arrangement, the relative position of the drive element (4) in the housing (3) and / or the relative position of the throttle body (2) of the throttle assembly , In particular, sensors (10), with which the relative positions of the drive element (4) and / or the throttle body (2) are convertible into electrical signals.

4. Arrangement according to one of the preceding claims, wherein the arrangement is designed such that the second and the third force at identical fluid pressures in the first fluid space (5) and in the second

Fluid space (6) are substantially equal.

5. Arrangement according to one of the preceding claims, wherein the arrangement is designed such that at identical fluid pressures in the first, second and third fluid space (5, 6, 7) cancel the second, third and fourth forces substantially each other.

6. Arrangement according to one of the preceding claims, wherein the drive element (4) has axial surfaces which for generating the second, third and fourth force respectively with the first, the second and the third fluid space (5, 6, 7) fluidly in communication stand.

7. Arrangement according to one of the preceding claims, wherein the throttle arrangement is designed as a seat valve.

8. Arrangement according to one of the preceding claims, wherein the drive element (4) of the Antriebsanord ^¬ tion and the throttle body (2) of the throttle assembly are formed by a common component.

9. A lift control valve with an arrangement according to one of the preceding claims, wherein the lift control valve, a first connection (11) coming from a hydraulic pump supply line for Hydraulikflüssig- speed, a second connection (12) for a return of hydraulic fluid in a tank and a third A control arrangement (14, 15), which is designed such that the first fluid space (5) of the arrangement and the first side of the throttle cross-section (1) fluidly with either the first connection (11) or with the second connection (12) are connectable, and wherein the second fluid space (6) of the arrangement and the second side of the throttle cross-section (1) with the third terminal (13) are connected or connectable.

10. Lift control valve according to claim 9, wherein the lift control valve is designed such that in the normal operation when connecting the first fluid space (5) and the first side of the throttle cross section with the first port (11) automatically connecting the second fluid chamber (6) the third fluid space (7) through the switching arrangement (8) and at a connecting the first fluid space (5) and the first side of the throttle cross-section with the second port (12) automatically connecting the first fluid space (5) with the third Fluid space (7) through the switching arrangement (8).

11. Lift control valve according to one of the claims

9 to 10, wherein the control assembly (14) for enabling the selective connection of the first side of the

Throttling cross-section (1) with the first port (11) or with the second port (12) has a particular continuously acting, in particular hydraulically actuated main valve (14) which in particular in

Piston spool design is executed.

12. Lift control valve according to one of the claims

10 to 11, wherein a valve (18) is present, which connects the fluid supply to the hydraulic drive of the main valve (14) on reaching a certain pressure at the first port (11) with the second port (12).

13. Lift control valve according to one of claims 10 to 12, wherein the lift control valve comprises an electrically actuable pilot valve (15) for the hydraulically actuated main valve (14), by means of which the hydraulic drive of the main valve (14) optionally with the second side of the throttle cross-section (1 ) and / or with the second fluid space (6) is fluidically connectable or fluidly separable from these, for actuating the main valve (14).

14. Lift control valve according to claim 13, wherein the fluidic connection between the pilot valve (15) and the hydraulic drive of the main valve (14) has a second port (12) leading to throttle point (16).

15. Lift control valve according to claim 14, wherein the throttle point (16) has a throttle cross section which can be varied as a function of the valve position of the main valve (14), in particular when the main valve (14) is designed as a piston slide design, as a function of the position of the piston slide (17). which, in particular in the case of the main valve (14) designed as a piston slide design, is formed between the piston slide (17) of the main valve (14) and a stationary component of the main valve (14).

16. Lift control valve according to one of claims 9 to 15, wherein the control arrangement (14, 15) is designed such that at the first port (11) under pressure pending hydraulic fluid connecting the first side of the throttle cross-section (1) of the throttle assembly and / or of the first fluid space (5) with the second port (12) is not possible.

17. Lift control valve according to one of the claims

9 to 16, wherein the switching arrangement (8) has a hydraulically actuated ümschaltventil (8), which in normal operation by opening or

Closing a pressure relief opening (19) is switchable and wherein the control arrangement (14, 15) is designed such that when connecting the first side of the throttle cross section (1) of the throttle arrangement and / or the first fluid space (5) with the second terminal (12 ) opens the pressure relief opening (19) of the changeover valve (8).

18. Lift control valve according to one of claims 9 to 17, wherein the lift control valve is designed such that for the actuation of the hydraulically actuated valves (8, 14) required Betätigungsenergie- of the guided in operation in the lift control valve hydraulic fluid can be removed.

19. Hydraulic lift system with a lift control valve according to one of claims 9 to 18, wherein the lift system connected to the first port (11) of the lift control valve or connectable hydraulic pump (33), one with the second terminal (12) of the

Lift control valve connected or connectable tank (34) and connected to the third port (13) of the lift control valve or connectable hydraulic drive (35), in particular hydraulic cylinder, with which a lift of the lift system is driven, has.

20. Lift system according to claim 19, wherein the

Lift control valve with an arrangement according to claim 9 with means (10) for determining the opening of the throttle cross-section (1) of the throttle arrangement, the relative position of the drive element (4) and / or the relative position of the throttle body (2) of the throttle arrangement is formed, and wherein the lift system further comprises a control for the driving operation of the lift, which in such a way with these means (10) is connected and configured, that in operation via these means (10) information about the opening of the throttle cross-section (1), the relative position of the drive element (4) and / or can receive the relative position of the throttle body (2) and can take this into account in the control or regulation of the driving operation of a lift of the lift system, in particular as a parameter, which measures the hydraulic fluid flow which flows through the throttle cross section (1) of the throttle arrangement, and in particular represents the associated travel speed of the lift.

21. A method for operating a lift system according to any one of claims 19 to 20, comprising

steps

Lifting a lift of the lift system by promoting a volume flow of hydraulic fluid from the hydraulic pump (33) to the hydraulic drive (35) of the lift, wherein the hydraulic fluid

Throttle cross-section (1) of the throttle assembly of the flows through the first side of the throttle cross section (1) to the second side of the throttle cross section (1) and the second fluid chamber (6) and the third fluid chamber (7) fluidly with each other and with the second side of the

Throttle cross-section (1) are connected, while the first side of the throttle cross-section (1) is fluidly connected to the first fluid space (5)

or

Lowering a lift of the lift system by promoting a volume flow of hydraulic fluid from the hydraulic drive (33) of the lift in the tank (34), wherein the hydraulic fluid is the throttle cross section (1) of the throttle assembly from the second side of the

Throttle cross section (1) to the first side of

Throttle cross-section (1) flows through and the first

Fluid space (5) and the third fluid space (7) fluidly with each other and with the first side of the

Throttling cross-section (1) are connected, while the second side of the throttle cross section (1) is fluidly connected to the second fluid chamber (6);

Determining the opening of the throttle cross section

(1) the throttle arrangement, the relative position of the drive element (4) of the drive arrangement and / or the relative position of the throttle body (2) of the throttle arrangement during the promotion of the volume flow of hydraulic fluid through the throttle cross-section;

Comparing the determined opening of the throttle cross-section (1), the determined relative position of the drive element (4), the determined relative position of the throttle body (2) of the throttle arrangement and / or a calculated from one or more of these determined values with a set value; and

Changing the volume flow of the through the throttle cross-section (1) promoted hydraulic fluid upon detection of a deviation from the desired value such that the opening of the throttle cross-section (1), the relative position of the drive element (4) Relative position of the throttle body (2) and / or the calculated value approaches the target value.

22. The method according to claim 21, wherein upon lifting of the lift, the volume flow of hydraulic fluid conveyed through the throttle cross section of the throttle arrangement is changed by the control unit (14, 15) of the lift control valve being replaced by a larger or smaller part of the lift control valve Hydraulic pump (33) subsidized volume flow in the tank (34) is controlled.

23. The method according to any one of claims 21 to

22, wherein the through the throttle cross-section (1) funded volume flow of hydraulic fluid by means of an algorithm exclusively from the determined opening of the throttle cross-section (1), the determined relative position of the drive element (4) and / or the determined relative position of the throttle body (2) of the throttle assembly, if necessary, with additional consideration of a likewise determined temperature value of the hydraulic fluid, is determined.