NO325086B1 - Method and apparatus for maneuvering actuators - Google Patents

Abstract

Method and device for maneuvering at least a first double-acting activator (1) and a second activator (2) by means of a first tube (16) and a second tube (18), the two tubes (16, 18) being common to both actuators (1, 2) and wherein both pipes (16, 18) in the unloaded state are drained, and wherein the working means (4) of the first activator (1) are caused to be displaced in a first direction by pressurizing the first pipe (16) with a relatively high first pressure, and that the working means (4) is caused to be displaced in a second direction by pressurizing the second pipe (18) with a relatively low second pressure after the first pipe (16) is relieved, and where it the working means (10) of second actuators (2) are caused to be displaced in a first direction by pressurizing the second pipe (18) with a relatively high third pressure.

Description

METHOD AND DEVICE FOR MANEUVERING ACTUATORS

This invention relates to a method for maneuvering actuators. More specifically, it concerns a method for maneuvering at least one first double-acting actuator and a second actuator using a first pipe and a second pipe where the two pipes are common to both actuators and where both pipes are drained in the unloaded state. The working member of the first actuator is caused to be displaced in a first direction by pressurizing the first pipe with a relatively high first pressure. The working member is caused to be displaced in a second direction by pressurizing the second pipe with a relatively low second pressure, the second actuator's working member being caused to be displaced in a first direction by pressurizing the second pipe with a relatively high third pressure. The invention also includes a device for carrying out the method.

Individual maneuvering of double-acting hydraulic actuators is often carried out using two pipe runs for each actuator, where one pipe run is pressurized to cause the actuator's maneuvering member to be displaced in a first direction, while the other pipe run is pressurized when the actuator's maneuvering member is to be moved in the opposite direction.

In this context, displacement means both linear and rotational displacement.

In the case of relatively large distances between maneuvering valves and actuators, pipe connections of this nature can be expensive, while the available space can be limited. Several solutions are thus known where there are fewer than two pipe connections to each actuator in a group of actuators.

US patent 6516888 describes a solution where seven double-acting actuators are individually maneuvered using four pipe connections. According to this document, both pipes are pressurized to an actuator to activate corresponding valves, whereby the displacement force of the actuator is dependent on the pressure difference between the pipe connections.

NO-patent 306033 deals with mutually independent control of regulation devices for regulation of downhole well flow. Several regulating devices are arranged in series, and each regulating device includes a flow regulator with a movable regulating element/regulating body as well as a hydraulic actuator with two ports which activates the flow regulator via lines and control valves. The control valves control the flow of hydraulic fluid between the actuator and the hydraulic line.

The purpose of the invention is to remedy or reduce at least one of the disadvantages of known technology.

The purpose is achieved according to the invention by the features indicated in the description below and in the subsequent patent claims.

A method for maneuvering at least one first double-acting actuator and a second actuator by means of a first pipe and a second pipe where the two pipes are common to both actuators and where both pipes are drained in an unloaded state is characterized in accordance with the invention by that the

the working member of the first actuator is caused to be displaced in a first direction by pressurizing the first tube with a relative

tively high first pressure, and that the working member, after the first pipe is relieved, is caused to be displaced in a second direction by pressurizing the second pipe with a relatively low second pressure, and where the working member of the second actuator is caused to be displaced in a first direction by pressurizing the second pipe with a relatively high third pressure.

In this context, working organ means the organ which, by being exposed to a fluid pressure, performs work. The working body can be made up, for example, of a piston or an actuator wing.

In a preferred method, this is carried out more precisely by causing the working member of the first actuator to be displaced in a first direction by pressurizing the first pipe which communicates with the first port of the first actuator via a first controlled non-return valve, with a first pressure that is higher than the opening pressure of the first controlled check valve. The working member is caused to be displaced in a second direction by pressurizing the second pipe communicating with the second port of the first actuator with a second pressure less than the opening pressure of a second controlled check valve connected between the second pipe and the first actuator gate.

Furthermore, the working member of the second actuator is caused to be displaced in a first direction by pressurizing the second pipe with a third pressure that is higher than the opening pressure of the second controlled check valve, the working member of the second actuator being caused to be displaced in a second direction by pressurizing the first pipe communicating with the second actuator's second port after the second pipe is relieved, at a fourth pressure less than the opening pressure of the first controlled check valve.

A first double-acting actuator and a second actuator are. as mentioned connected to a first pipe and a second pipe where the two pipes are common to both actuators and where both pipes are drained in the unloaded state.

A first check valve which is controlled by the pressure in it

first pipe, is connected between the first pipe and the first actuator's first port. A second check valve which is controlled by the pressure in the second pipe is connected between the second pipe and the first port of the second actuator. The first actuator's second

port communicates with the second pipe, while the second actuator's second port communicates with the first pipe. The controlled check valves are normally closed in the direction from their respective pipes and to their respective actuators.

The controlled check valves are arranged to switch at a relatively high first or third pressure.

Control of the various pressures from a hydraulic aggregate into the first and second pipes, as well as pressure relief from these, is carried out using directional and diverter valves in accordance with per se known technology and is described in more detail in the special part of the description.

In a practical design, a pressure that is described as a relatively high pressure can be in the order of several hundred bars, while a pressure that is described as a relatively low pressure can be in the order of less than several hundred bars.

It has given good results to use a high pressure of between 300 and 500 bar and a low pressure of between 100 and 200 bar.

A method and device according to the invention provides a hydraulic circuit where two double-acting actuators can be remotely operated essentially independently of each other by means of two hydraulic pipe connections. The hydraulic circuit makes it possible that the actuator does not have to work against a back pressure during maneuvering and that a relatively modest number of valves are used at the actuator, which indicates a relatively high operational reliability in the plant.

In what follows, a non-limiting example of a preferred method and embodiment is described which is illustrated in the accompanying drawings, where: Fig. 1 shows a connection diagram of a hydraulic circuit according to the invention; Fig. 2 shows the connection diagram in fig. 1 where fluid is supplied to the first port of the first actuator; Fig. 3 shows the connection diagram in fig. 1 where fluid is supplied to the second port of the first actuator; Fig. 4 shows the connection diagram in fig. 1 where the second actuator's first port is supplied with fluid; and Fig. 5 shows the connection diagram in fig. 1 where the second actuator's second port is supplied with fluid.

In the drawings, the reference number 1 denotes a first actuator and the reference number 2 a second actuator. The first actuator 1 is provided with a working member 4, a first port 6 and a second port 8 for hydraulic fluid. Supply of fluid via the first port 6 causes the working member 4 to be displaced in a first direction, while supply of fluid via the second port 8 causes the working member 4 to be displaced in an opposite second direction.

Correspondingly, the second actuator 2 is provided with a working member 10, a first port 12 and a second port 14.

Actuators 1 and 2 supply and return hydraulic fluid

via a first pipe 16 and a second pipe 18.

A controlled first non-return valve 20 is connected between the first pipe 16 and the first port 6 of the first actuator 1 via a first connecting pipe 22. The first non-return valve 20 is normally closed in the direction from the first pipe 16 to the first port 6, but is open in the opposite direction. The first check valve 20's control port 24 communicates with the first pipe 16 via a first control pipe 26, while a first drainage pipe 28 runs between the first check valve 20 and the second pipe 18.

Correspondingly, a controlled second non-return valve 30 is connected between the second pipe 18 and the first port 12 of the second actuator 2 via a second connecting pipe 32. The second non-return valve 30 is normally closed in the direction from the second pipe 18 and to the first port 12, but is open in the opposite direction. The control port 34 of the second check valve 30 communicates with the second pipe 18 via a second control pipe 36, while a second drainage pipe 38 runs between the second check valve 30 and the first pipe 16.

The second port 8 of the first actuator 1 communicates with the second pipe 18 via a third connecting pipe 42, while the second port 14 of the second actuator communicates with the first pipe via a fourth connecting pipe 44.

A hydraulic unit (not shown) supplies liquid under relatively high pressure via a high-pressure pipe H, liquid under relatively low pressure via a low-pressure pipe L, the liquid being drained to the hydraulic unit (not shown) via a return pipe R.

A first directional valve's 50 inlet port communicates with the high-pressure pipe H while its outlet port communicates with a first diverter valve 52, the first directional valve's 50 return port communicating with the return pipe R.

A second directional valve 54's inlet port communicates with the low pressure pipe L while its outlet port communicates with the first diverter valve 52, the second directional valve 54's return port communicating with the return pipe R.

The first diverter valve 52's third port is connected to the first pipe 16. The diverter valve 52 is normally open for flow in both directions between the first pipe 16 and the second directional valve 54.

A third directional valve 56's inlet port communicates with the high-pressure pipe H while its outlet port communicates with a second diverter valve 58, the third directional valve's 56 return port communicating with the return pipe R.

A fourth directional valve's 60 inlet port communicates with the low-pressure pipe L while its outlet port communicates with the second diverter valve 58, the fourth directional valve's 60 return port communicating with the return pipe R.

The second diverter valve 58's third port is connected to the second pipe 18. The diverter valve 58 is normally open for flow in both directions between the second pipe 18 and the fourth directional valve 60.

The directional valves 50, 54, 56 and 60 are controlled electrically in a manner known per se from a control system not shown which is connected to the coils of the valves 50, 54, 56 and 60. The connection is indicated in the drawings with dashed lines designated El.

In an initial state, the inlet ports of all directional valves 50, 54, 56 and 60 are closed and the valves are drained to the return pipe R, see fig. 1.

When the working member 4 of the first actuator 1 is to be displaced in the first direction, the first directional valve 50 is brought to alternate, see fig. 2. Fluid from the high-pressure pipe H can now flow through the directional valve 50 and to the first diverter valve 52, which alternates so that fluid cannot flow into the second directional valve 54 from the first diverter valve 52. The high-pressure fluid thereby flows via the first pipe 16 and to the second actuator 2's second port 14 via the fourth connecting pipe 44. If the second actuator's 2 working member 10 had not already been displaced in its second direction, the working member 10 would have been displaced in its other direction.

At the same time, fluid flows to the first non-return valve 20 which, until the necessary pressure has built up in the control port 24 via the first control pipe 26, shuts off fluid from the first pipe 16. When sufficient pressure is present in the control port 24, the first non-return valve 20 switches, whereby fluid can flow from the first pipe 16, via the first non-return valve 20, the first connecting pipe 22 and to the first port 6 of the first actuator 1.

While the working member 4 is displaced in its first direction, liquid is drained from the first actuator 1 via the second port 8, the third connecting pipe 42, the second pipe 18, the second changeover valve 58, the fourth directional valve 60 and to the return pipe R. The first directional valve 50 then switches to its initial position, which causes the first diverter valve to also be relieved and switches to its initial position. The first pipe 16 is thereby relieved via the first changeover valve 52 and the second directional valve 54 to the return pipe R. The first check valve 20 thereby also changes back to its initial position.

When the working member 4 of the first actuator 1 is to be displaced in its second direction, the fourth directional valve 60 switches, see fig. 3. Liquid can thereby flow through the fourth directional valve 60, the second diverter valve 58, the second pipe 18, the third connecting pipe 42 and to the second port of the first actuator 1. While the working member 4 is displaced in its second direction, liquid flows from the second port 6 via the first connecting pipe 22, the first check valve 20, the first pipe 16, the first changeover valve 52, the second directional valve 54 and to the return pipe R.

Note that the pressure in the second pipe 18 is not sufficiently great to be able to open the second non-return valve 30. The fourth directional valve 60 then switches to its initial position.

When the second actuator's 2 working body 10 is to be displaced i

its first direction, the third directional valve 56 alternates, see fig. 4, whereby the second changeover valve 58 and the second check valve 30 are brought to change. High-pressure fluid thereby flows in a similar manner as described for the first actuator 1 above, to the first port 12 of the second actuator 2.

The working member 10 of the second actuator 2 is displaced in its second direction by the second directional valve 54 switching, see fig. 5. Other flow to and from the second actuator 2 corresponds to what is described above for the first actuator 1, and is therefore not explained further.

It will be clear to a person skilled in the art that what is referred to as pipe in the description can be made up of many forms of hollow element, for example hoses, channels, bores or the like.

Although the directional valves 50, 54, 56 and 60 as well as the changeover valves 52 and 58 are shown as separate standardized units, it is understood that the functions of these valves can also be taken care of by other suitable for the purpose valve assemblies not shown.

Claims (6)

1. Method for maneuvering at least one first double-acting actuator (1) and a second actuator (2) using a first pipe (16) and a second pipe (18), where the two pipes (16, 18) are common to both actuators (1, 2) and where both pipes (16, 18) are drained in the unloaded state, characterized in that the working member (4) of the first actuator (1) is caused to be displaced in a first direction by pressurizing the first pipe (16 ) with a relatively high first pressure, and that the working member (4) is caused to be displaced in a second direction by pressurizing the second pipe (18) with a relatively low second pressure after the first pipe (16) has been relieved, and where the working member (10) of the second actuator (2) is caused to be displaced in a first direction by pressurizing the second pipe (18) with a relatively high third pressure. 2. Method according to claim 1, characterized in that the working member (4) of the first actuator (1) is caused to be displaced in a first direction by pressurizing the first pipe (16) which communicates with the first port of the first actuator (1) (6) via a controlled first non-return valve (20), with a first pressure that is higher than the opening pressure of the controlled first non-return valve (20), and that the working member (4) is caused to be displaced in a second direction by pressurizing the second pipe (18) which communicates with the second port (8) of the first actuator (1), with a second pressure less than the opening pressure of a controlled second check valve (30) which is connected between the second pipe (18) and the second actuator ( 2) first port (12) . 3. Method according to claim 2, characterized in that the working member (10) of the second actuator (2) is caused to be displaced in a first direction by pressurizing the second pipe (18) with a third pressure that is higher than the opening pressure for the controlled second check valve (30), and that the working member (10) is caused to be displaced in a second direction by pressurizing the first pipe (16) which communicates with the second port (14) of the second actuator (2), with a fourth pressure which is less than the opening pressure for the controlled first non-return valve (20). 4. Device for maneuvering at least one first double-acting actuator (1) and a second actuator (2) by means of a first pipe (16) and a second pipe (18), where the two pipes (16, 18) are common to both actuators (1, 2) and where both pipes (16, 18) are drained in the unloaded state, characterized in that a first check valve (20) which is controlled by the pressure in the first pipe (16) is connected between the first pipe (16) ) and the first port (6) of the first actuator (1), and that a second check valve (30) which is controlled by the pressure in the second pipe (18) is connected between the second pipe (18) and the second actuator (2) first port (12), and where the second port (8) of the first actuator (1) communicates with the second pipe (18), and the second port (14) of the second actuator (2) communicates with the first pipe (16), the controlled check valves (20, 30) normally close to flow in the direction from their respective pipes (16, 18) and to their respective actuators (1, 2). 5. Device according to claim 4, characterized in that the controlled non-return valves (20, 30) alternate at a relatively high first or third pressure. 6. Device according to claim 4, characterized in that the pipes (16, 18) communicate with a high-pressure pipe (H), a low-pressure pipe (L) and a return pipe (R) via directional valves (50, 54, 56, 60) .