DE102007027567B4 - Control arrangement with pipe rupture function - Google Patents

Abstract

Control arrangement (1, 50) for controlling a consumer (12) with an adjustable flow control valve (24) arranged in the return from the consumer (12) for pipe burst protection, comprising a directional control valve (26) with metering orifice and associated pressure compensator (32) and with a adjustable hydraulic machine (4) via which in bypassing the flow control valve (24) pressure medium to the consumer (12) is conveyed and which can be driven by the pressure flowing from the consumer pressure medium, the metering orifice and the hydraulic machine (4) are each set so that by the hydraulic machine (4) predetermined volume flow is approximately equal to or smaller than the volume flow to which the flow control valve (24) is set.

Description

The invention relates to a control arrangement with pipe rupture function to control a consumer.

For the pipe rupture protection pipe rupture valves are used in the prior art, which are normally controlled from the outside with the same control signal as a consumer associated directional control valve. Pipe-break safety valves are usually arranged directly on the consumer and have the task of preventing a uncontrolled drop in the load during a pipe break. Such pipe rupture valves are used in particular in mobile machines, such as construction machinery, for use. The lowering speed of the load must not exceed twice the lowering speed before the pipe break.

The EP 0 669 281 B1 shows a hydraulic control arrangement for controlling a consumer with an adjustable hydraulic machine, in which an effective in the direction of depressions Druckmittelströmungspfad a hydraulic pressure limiter is arranged on which drops in certain operating points, the entire hydraulic pressure, so that the hydraulic pressure limiter takes over the load.

In the EP 1 188 934 A2 a control arrangement is shown in which a pressure-reducing valve is arranged between the consumer and the hydraulic machine so that it reduces the pressure applied to the hydraulic machine when lowering the load.

From the RD leaflet 64623 / 03.99 the Rexroth Bosch AG is a pipe rupture protection with a proportional control valve via a control pressure known. Parallel to the directional valve, a secondary pressure relief valve is connected, which allows a flow of pressure medium to the load and limits the maximum load pressure and allows a leak oil-free support of the load.

From the publication DE 10 2004 005 402 B4 is a valve assembly for raising and lowering a lifting cylinder is known in which in return from the lifting cylinder, a flow control valve with metering orifice and upstream pressure compensator is provided, through which a certain flow cross section of the metering orifice certain load-independent lowering speed of the lift cylinder is made possible.

From the publication DE 4425455 A1 goes out a hydraulic control device for a lifting cylinder with a pump in the flow and a flow control valve in the return. To the flow control valve opening in the feed direction to the lift cylinder check valve is connected in parallel, via which the lifting cylinder is rapidly extendable.

In the prior art, there is the problem of relatively high pressure losses over the metering orifice, resulting in energy losses.

The object of the present invention is to provide a control arrangement with pipe rupture function in which a low pressure loss occurs.

This object is achieved by the control arrangement according to claim 1.

It is provided a control arrangement for controlling a consumer, which has a return valve arranged by the consumer flow control valve consisting of a directional control valve with metering and associated pressure compensator and an adjustable hydraulic machine, via the bypass valve when the flow control valve pressure medium is conveyed to the consumer and from can be driven by the pressure fluid flowing away from the consumer, wherein the metering orifice and the variable displacement are adjusted so that the pressure medium flow rates through the metering orifice and the hydraulic machine are about the same or that the volume flow of the hydraulic machine is smaller than that of the metering orifice. Thus, with a pipe break, the flow control valve can prevent a substantial increase in the lowering speed. The power supplied to the hydraulic machine can be used to drive other consumers.

According to one embodiment of the invention, the speed of the hydraulic machine is taken into account when setting the metering orifice and the hydraulic machine, whereby an optimized with respect to the energy recovery specification of the control signal can take place.

Furthermore, it is preferable to provide a bypass line with check valve which bypasses the flow control valve, whereby the flow control valve can be bypassed when a hydraulic cylinder, which is the consumer, is extending. During normal operation, the pressure compensator of the flow control valve is wide open, with the hydromachine limiting the lowering speed.

Preferably, the flow control valve is arranged on the consumer, which has the shape of a hydraulic cylinder. Due to this close arrangement, the risk of a pipe break between hydraulic cylinder and flow control valve can be minimized.

Furthermore, it is preferred if a hydraulic accumulator is provided by the hydraulic machine is rechargeable. This can save energy.

Furthermore, the metering orifice can be a seat slide, whereby a load holding function can be implemented.

The flow control valve may be associated with a pressure limiting valve, whereby the system pressure can be limited to a predetermined maximum pressure.

The pressure compensator may be upstream or downstream of the directional control valve of the flow control valve.

In a further development, the hydraulic machine is connected to a pump, so that the potential energy of the load can be made available to a drive train of the pump.

Inventive developments are the subject of the dependent claims.

The invention will be described in detail with reference to the accompanying drawings. Show it:

1 1 is a circuit diagram of a control arrangement with pipe rupture function according to the first embodiment,

2 a circuit diagram of a pipe rupture valve and a working cylinder for a control arrangement according to the second embodiment,

3 a seat slide for use as a metering orifice in a control arrangement according to the first and second embodiments, and

4 a memory usable in the control arrangements according to the first and second embodiments.

The circuit diagram of 1 shows a control arrangement 1 according to the first embodiment with a lifting cylinder 12 , In the lifting cylinder 12 there is a piston 16 with a piston rod 17 putting the cylinder in a bottom pressure chamber 18 and a rod-side pressure chamber 19 divided. An adjustable hydraulic machine 4 that have a control line 5 can be controlled electrically or hydraulically, supplies the bottom-side pressure chamber 18 the lifting cylinder 12 via a valve arrangement 10 with pipe rupture function with pressure medium to the lifting cylinder 12 extend. When retracting the lifting cylinder 12 flows pressure medium over the valve assembly 10 and about the hydraulic machine 4 to the tank 2 , The return from the lifting cylinder 12 to the hydraulic machine 2 via a flow control valve 24 the valve assembly 10 and the flow via a bypass line bypassing the flow control valve 38 the valve assembly 10 ,

The hydraulic machine 4 is in the operating mode pump via a motor 6 driven. Further, on the drive train between engine 6 and hydraulic machine 4 also a pump 8th provided via the other consumers pressure medium can be supplied.

About the in 1 bottom connection of the hydraulic machine 4 is in the pump operating mode of the hydraulic machine 4 Pressure medium from a tank 2 sucked in and flows in the operating mode hydraulic motor pressure fluid to the tank 2 from.

The in 1 overhead connection of the hydraulic machine 4 is with a supply line 22 the valve assembly 10 connected with pipe rupture function. The bottom pressure chamber 18 the lifting cylinder 12 is via a supply line 20 with the valve assembly 10 connected. This is directly to the lifting cylinder 12 grown. In this respect, the advance performance 20 only one channel in a housing.

In the control arrangement according to the first embodiment is a pump-controlled linear drive, in which the load acts pulling or pushing, so that at the bottom pressure chamber 18 adjusts a corresponding load pressure to hold the load. In the case of construction machinery, it may happen that a static holding pressure of, for example, 150 bar in the pressure chamber occurs under a pressing load 18 is present.

Between the supply line 20 and with the in 1 overhead connection of the hydraulic machine 4 related supply line 22 is in the valve assembly 10 a flow control valve 24 provided, which consists of a metering orifice and a pressure compensator. The metering orifice in the flow control valve 24 is provided by a proportionally adjustable 2/2-way valve 26 Made like the hydraulic machine 4 over the control line 5 is controllable. The piston 28 of the directional valve 26 is spring-loaded. The pressure compensator piston 30 the pressure balance 32 is in the opening direction by the force of a biasing spring 31 and, when viewed in the direction of lowering the lift cylinder 12 , from the pressure downstream of the directional control valve 26 pressurized and in the direction of throttling from the pressure upstream of the directional control valve 26 acted upon in relation to the lowering of the lifting cylinder. About the pressure balance 32 the pressure difference across the metering orifice is kept constant independent of the load. Parallel to the directional valve 26 and to the pressure balance 32 is in the bypass performance 38 in the direction of lifting the lift cylinder 12 opening check valve 34 intended. Further, the pressure in the flow line 20 via a pressure relief valve 36 limited.

The operation of the control arrangement according to the invention will be described below.

To extend the lift cylinder 12 the hydraulic machine works 4 as a pump and delivers pressure medium via the supply line 22 , the open check valve 34 and the supply line 20 in the pressure room 18 , In the pressure room 18 pressure builds up. Upon reaching the load pressure given by the load, the piston starts 16 to move and the lift cylinder 12 is extended. The system pressure is via the pressure relief valve 36 limited to a predetermined pressure. Because the actuating signal for the hydraulic machine 4 also at the directional valve 26 is applied, this also opens a flow cross-section. But that's not necessarily necessary.

Although it is preferred that the hydraulic machine 4 tending to a smaller volume flow than the metering orifice in the directional control valve 26 is set, but the theoretical volume flows at the metering orifice of the control valve and the hydraulic machine can be the same, but in practice can not be implemented exactly. Therefore, the slightly smaller volume flow on the hydraulic machine is preferred.

You can use the control line for the way valve 26 also from the control line for the hydraulic machine 4 separate. The directional control valve would then not be activated when lifting. If a pipe breaks with an applied lifting signal, the cylinder would then stop.

For retracting the lifting cylinder 12 the measuring orifice will be at the directional control valve 26 set via appropriate control signals to a slightly larger theoretical volume flow than the hydraulic machine. The pressure balance 32 opens due to the force acting on the control piston spring and the low pressure difference of, for example, 3 bar on the control piston of the pressure compensator 32 essentially complete and thus without function. The pump 8th is about the hydraulic machine 4 driven, wherein the sinking speed of the lifting cylinder 12 due to the swivel angle and the displacement of the hydraulic machine 4 is given. The pressure difference across the directional valve 26 should be as small as possible to maximize the proportion of potential energy through the hydromachine 4 to be able to use.

If a pipe break occurs, the pressure compensator throttles 32 the volume flow to such a value that over the orifice a the pressure equivalent of the Vorspannfelder 31 corresponding pressure difference occurs. Because of the slightly larger volume flow to which the orifice plate is set in comparison to the hydraulic machine, the lowering speed of the cylinder increases 12 only a little and remains within the demands made.

A control arrangement 50 according to the in 2 shown second embodiment differs from the in 1 shown control arrangement only in that the pressure compensator 32 the directional valve 26 in the direction of lowering the lift cylinder 12 upstream. The function of the flow control valve 54 of the second embodiment corresponds to that of the flow control valve 24 in the first embodiment.

In the illustration accordingly 2 are only the valve assembly 52 and the lifting cylinder 12 shown, the tank 38 , the hydraulic machine 6 and the pump 8th as well as the tank 2 have been omitted for the sake of clarity and comparability of the arrangement with the first embodiment.

At the directional valve 26 According to the first and second embodiments, the valve designed as a slide valve 26 closed in the spring-biased initial position a, with a leak is present. For leak-free support of the load can accordingly 3 be selected for the directional control valve, a design in which the piston in the spring-biased initial position has a load-holding function, ie that a seat slide 56 is provided.

In the control arrangement according to the first and second embodiments, the potential energy when lowering the load instead of the pump 8th about one in 4 shown memory 62 be used. In one variant is the tank 2 through the store 62 replaced. However, it is preferred if the tank 2 about to in to 1 bottom connection of the hydraulic machine 4 opening check valve is connected to the hydraulic machine and the in 1 bottom connection of the hydraulic machine 4 with the memory 62 about to the store 62 opening check valve is connected.

In the first and second embodiments of the present invention, a pressure relief valve 36 not necessarily required.

Thus, with the present invention, a control arrangement with pipe rupture protection functions can be implemented for use in pump-controlled cylinder drives. The potential energy when lowering the load can be used in the drive train or to charge a hydraulic accumulator. Only with the pipe rupture protection of the present invention, a pump-controlled cylinder drive is also interesting for construction equipment, since the energy recovery possibilities improve significantly.

It is a control arrangement with pipe rupture function to control the consumer provided which has an adjustable, usable as a pump and motor hydromachine and a flow control valve with metering orifice, the hydraulic machine and metering orifice control signals can be supplied by the hydraulic machine to a smaller flow than the metering orifice or a substantially equal volume flow as the metering orifice is adjusted. Thus, there is a backup of the cylinder when lowering against burst pipe at low pressure loss during normal operation.

LIST OF REFERENCE NUMBERS

1

hydraulic arrangement

2

tank

4

hydromachine

5

control line

6

engine

8th

pump

10

valve assembly

12

lifting cylinder

14

floor area

16

piston

17

piston rod

18

bottom pressure chamber

19

rod-side pressure chamber

20

supply line

22

supply line

24

Flow control valve

26

way valve

28

piston

30

Pressure regulator piston

31

biasing spring

32

pressure compensator

34

check valve

36

Pressure relief valve

38

bypass line

50

Hydraulic valve arrangement

52

valve assembly

54

Flow control valve

56

seat slide

62

Storage

Claims (9)

Control arrangement ( 1 . 50 ) for controlling a consumer ( 12 ) with a return from the consumer ( 12 ) arranged for pipe rupture protection, adjustable flow control valve ( 24 ), consisting of a directional control valve ( 26 ) with metering orifice and associated pressure compensator ( 32 ) and with an adjustable hydraulic machine ( 4 ), when bypassing the flow control valve ( 24 ) Pressure medium to the consumer ( 12 ) is drivable and which is drivable by the pressure flowing away from the consumer pressure medium, wherein the metering orifice and the hydraulic machine ( 4 ) are each set so that by the hydraulic machine ( 4 ) predetermined volume flow is approximately equal to or smaller than the volume flow to which the flow control valve ( 24 ) is set. Control arrangement according to claim 1, wherein in the adjustment of the metering orifice and the hydraulic machine ( 4 ) the speed of the hydraulic machine ( 4 ) is taken into account. A control arrangement according to claim 1 or 2, further comprising a flow control valve ( 24 ) bypass line ( 38 ) with check valve ( 34 ) having. Control arrangement according to one of the preceding claims, wherein the consumer is a hydraulic cylinder ( 12 ) and the flow control valve ( 24 ) is arranged on the hydraulic cylinder. Control arrangement according to one of the preceding claims with a hydraulic accumulator ( 62 ), of the hydraulic machine ( 4 ) is rechargeable. Control arrangement according to one of the preceding claims, wherein the metering orifice a seat slide ( 56 ). Control arrangement according to one of the preceding claims, wherein the flow control valve ( 24 ) a pressure relief valve ( 36 ) is assigned to limit the system pressure. Control arrangement according to one of the preceding claims, wherein the pressure compensator ( 32 ) the directional control valve ( 26 ) of the flow control valve ( 24 ) upstream or downstream. Control arrangement according to one of the preceding claims, wherein the hydraulic machine ( 4 ) with a pump ( 8th ) connected is.

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