GB2498725A - An improved hydraulic intensifier circuit for use in the actuation of a double-acting hydraulically powered tool - Google Patents

Abstract

A hydraulic intensifier circuit 1 is provided for use in the actuation of a double-acting hydraulically powered tool 3. The circuit 1 comprises: first and second input/output ports 7, 8 for connection respectively to a control valve 4 linked to the supply 5 and to the tool 3 for operating the tool 3; and third and fourth input/output ports 9, 10 adapted for connection respectively to the control valve 4 and to the tool 3 for operating the tool 3. A hydraulic intensifier 12 has a pressurizing port 13 connected to the first input/output port 7, a high pressure port 15 connected to the second input/output port 8 and a tank port 17 connected via a non-return valve 18 to a first line 11 connecting the third and fourth input/output ports 9, 10 to one another. A spool valve 19 is connected between the tank port 17 of the hydraulic intensifier 12 on one side and said first and third input/output ports 7, 9 on its other side. The spool valve 19 is biased into a first position whereby once a pressurizing flow of hydraulic fluid to the circuit 1 has ceased pressurized hydraulic fluid can drain from the tool 3 and the circuit 1 to the supply 5 through the third input/out port 9 from the first line 11 and from the tank port 17 through the spool valve 19 and the non-return valve 18, and also through the first input/pout port 7 via a backflow of hydraulic fluid from the pressurizing port 13 directly to the first input/output port 7.

Description

IMPROVEMENTS TO HYDRAULIC INTENSIFIER CIRCUITS

The present invention relates to an hydraulic intensifier circuit in particular but not exclusively to such a circuit for use underwater, for example in submarine conditions for the supply of high pressure hydraulic fluid to a hydraulically powered tool for remote operation via a remotely operated vehicle (Roy).

Underwater hydraulically powered tools are designed for gripping, lifting and cutting lines such as submarine wire ropes, armoured telecommunication and power cables, and hoses. Conventionally, such tools are attached to an arm of a remotely operated vehicle (ROV) and are hydraulically powered. Some of these tools, for example cutting tools, require hydraulic fluid to be supplied at a high pressure in order to operate, for example to force a culling blade through an item to be cut. An hydraulic intensifier circuit is therefore used to supply hydraulic fluid to the tool in order to transform the hydraulic power supplied by the ROV at its normal pressure into a reduced volume supply at a significantly higher pressure sufficient to power the tool. The circuit comprises hydraulic components, including an hydraulic intensifier, that can be linked to the tool and to a control valve carried by the ROV which is connected to a tanked supply of hydraulic fluid and a pump. Usually, therefore, such an intensifier circuit is mounted on a panel that is itself adapted for attachment to the ROVso that it can be connected between the control valve and the tool when required.

Conventionally, hydraulic intensifier circuits have two input/output ports that link to two input/output ports of the control valve and two input/output ports that link to the tool for the supply and return of the hydraulic fluid. These tools are typically double-acting tools that have two modes of operation, for example in the case of a cutting tool these modes are a "blade down" mode (cutting mode) and a "blade up" mode (blade retraction mode). In the "blade down" mode the hydraulic pressure is amplified by the intensifier to power the cutting blade. In the "blade up" mode the pressure is not amplified as retracting the blade does not require a great force. However, in most conventional hydraulic intensifier panels, at the end of a "blade down" mode of operation when the input pressure on the cutting blade is removed, a non-return valve prevents the pressure in a ram, which forms part of the tool and which is used to operate the blade, from being released. To release this pressure, the "blade up" mode must selected, which opens the "blade down" line and allows the hydraulic fluid to return to the tank located on the ROy. If an operator forgets to select the "blade up" mode after a cut, then the tool may be brought back to a surface vessel with a potentially dangerous hydraulic pressure inside. For example, common operating pressures of submarine culling tools may be 690 bar (io,ooo psi) or above.

The aforementioned problem is compounded by the external sea pressure. If a 690 bar submarine culling tool is used at a depth of 3000 m, then when it is brought back to the surface, the internal pressure will increase to 990 bar, Furthermore, the surface temperate is usually significantly higher than the submarine temperature at depths of around 3000 m, which is typically around 3°C. If such a tool is left on deck in the sun, its internal temperature can rise to 40°C and its internal pressure may rise by a further 400 bar. Potentially, therefore a 690 bar rated cutting tool may sit on the deck of a surface vessel containing hydraulic fluid at a pressure of around 1390 bar (over 20,000 psi). Such pressures can damage the tool and are also potentially highly dangerous to persons on board the surface vessel.

One way of overcoming the aforementioned problem is to use an hydraulic intensifier circuit that does not include a non-return valve but such a circuit requires an additional hose to vent the pressurized hydraulic fluid back to the tank. However, this arrangement complicates matters for ROV operators, who prefer to keep the operation of double-acting hydraulic tools relatively simple by having only two input/output ports and associated hoses connecting the tool being used with the ROy. Requiring a third hose is non-standard and tends to result in further problems.

The object of the present invention is to provide an hydraulic intensifier circuit that overcomes or substantially mitigates the aforementioned problem without requiring a third hose connection to an ROy.

According to the present invention there is provided an hydraulic intensifier circuit for use in the actuation of a double-acting hydraulically powered tool, the circuit comprising: first and second input/output ports adapted for connection respectively to a control valve linked to a supply of hydraulic fluid and to the tool for operating the tool in a first mode of operation; third and fourth input/output ports adapted for connection respectively to the control valve and to the tool for operating the tool in a second mode of operation; an hydraulic intensifier having a pressurizing port connected to the first input/output port, a high pressure port connected to the second input/output port and a tank port connected via a non-return valve to a first line connecting the third and fourth input/output ports to one another; and a spool valve connected between the tank port of the hydraulic intensifier on one side and said first and third input/output ports on its other side, the spool valve being actuated (i) into a first position via a pressurizing flow of hydraulic fluid from the first input/output port to the pressurizing port of the intensifier to operate the tool in the first mode wherein the spool valve connects the tank port of the intensifier to the third input/output port via the non-return valve, and (ii) into a second position via a pressurized flow of hydraulic fluid along the first line from the third to the fourth input/output port to operate the tool in the second mode wherein the spool valve connects the tank port of the intensifier to the first input/output port, the spool valve being biased into its first position whereby once a pressurizing flow of hydraulic fluid to the circuit has ceased pressurized hydraulic fluid can drain from the tool and the circuit to the supply (a) through the third input/output port from said first line and from the tank port through the spool valve and the non-return valve, and (b) through the first input/output port via a backflow of hydraulic fluid from the pressurizing port directly to the first input/output port.

Preferably, a pressure relief valve is connected between the high pressure port of the intensifier and said first line connecting the third and fourth input/output ports to one another Preferably also, the pressure relief valve is adapted to operate at a predetermined hydraulic pressure that is at or above the operating pressure required by the tool in its first mode of operation.

Preferably also, an output pressure gauge is included in the circuit between the high pressure port of the intensifier and the second input/output port.

Preferably also, an input pressure gauge is included in the circuit between the first input/output port and the pressurizing port of the intensifier.

Preferably also, the circuit is mounted on a panel.

Other preferred but non-essential features of the invention are described in the dependent claims.

An example of the present invention will now be described by way of example with reference to the accompanying drawings in which;-Fig. 1 is a circuit diagram of an hydraulic intensifier circuit in accordance with the present invention when connected between a cutting tool and a control valve, which is shown in a neutral position; Fig. 2 is a diagram similar to Fig. ibut showing the circuit when in a first mode of operation; Fig. 3 is a diagram similar to Fig. ibut showing the circuit when in a second mode of operation; and Fig. 4 is a diagram similar to Fig. 1 but showing the circuit when in a pressure relief mode of operation.

An hydraulic intensifier circuit 1 in accordance with the invention is shown in the drawings mounted on a panel 2 that is connected between a tool 3 and a control valve 4 which is linked to a tanked supply 5 of hydraulic fluid and a pump 6. It will be appreciated that neither the tool 3 nor the control valve 4, supply 5 and pump 6 form part of the circuit 1, the panel 2 being adapted for connection between them when required. In this example the tool 3 is shown as a double-acting hydraulically powered cutting tool but it could comprise any double-acting tool that has two modes of operation, one of which requires a high pressure hydraulic supply.

The circuit 1 comprises first and second input/output ports, 7 and 8 respectively, that are adapted for respective connection to the control valve 4 and the tool 3 in order to operate the tool in a first mode of operation. In this example, this first mode of operation is shown as a "blade down" cutting mode. The circuit also comprises third and fourth input/output ports, 9 and respectively, that are adapted for respective connection to the control valve 4 and to the tool 3 in order to operate the tool in a second mode of operation. In this example, this second mode of operation is shown as a "blade up" cutting blade retraction mode. The third and fourth input/output ports 9 and 10 are linked via a first hydraulic line ii.

In order to generate the high hydraulic pressure required for the cutting mode of the tool 3, an hydraulic intensifier 12 forms part of the circuit 1. This is preferably a G-Type intensifier wherein the output pressure is proportional to the input pressure so that the former is controllable by varying the latter. In the present example an output pressure of four times the input pressure would be appropriate. The intensifier 12 may be of conventional construction and comprises a pressurizing port 13, which is connected to the first input/output port 7 by a second line 14, a high pressure port 15, which is connected to the second input/output port 8 by a third line 16, and a tank port 17, which is connected via a non-return valve i8 to the first line ii that connects the third and fourth input/output ports 9 and 10 to one another.

A spool valve 19 is connected between the tank port 17 of the hydraulic intensifier 12 on one input/output side and the first and third input/output ports 7 and 9 on its other input/output side. The connection to the first input/output port 7 is via the line 14 and immediately upstream of the connection of the line 14 to the pressurizing port 13. The connection to the third input/output port 9 is via the line 11 and is between the non-return valve i8 and the tank port 17.

The spool valve 19 is actuated by pressure inputs along lines 20 and 21 between first and second positions respectively as shown in Figs. 2 and 3.

The line 20 connects one side of the spool valve 19 to the second line 14 adjacent its connection to the pressurizing port 13. The line 21 connects the other side of the spool valve 19 to the first line 11. In addition, the spool valve 19 is biased by a biasing means such as a spring 22 into its first position so that when not actuated by any pressurizing flow along either of the lines 20 and 21 it normally adopts its first position, as shown in Fig. 1.

In the first position of the spool valve 19 as shown in Figs. 1 and 2, it connects the tank port 17 of the intensifier 12 to the third input/output port 9 via the non-return valve iS. In this position of the spooi valve 19, there is no flow along a line 23 that connects the spool valve 19 to the second line 14 as the port 24 at the termination of the line 23 at the spooi valve end is closed.

In contrast, in the second position of the spool valve 19 as shown in Fig. 3, it connects the tank port 17 of the intensifier 12 to line 23 and thence to the first input/output port 7. In this position of the spool valve 19 there is no flow along a line 25 that connects the spool valve 19 to the first line ii via the non-return valve iS as the port 26 at the termination of the line 25 at the spool valve end is closed.

As a safety measure, a pressure relief valve 27 is connected between the high pressure port 15 of the intensifier 12 and the first line ii. The pressure relief valve 27 is adapted to operate at a predetermined hydraulic pressure that is at or slightly above the operating pressure required by the tool 3 in its first mode of operation. The relief valve 27 is biased so that it is normally closed. Once opened against the force of the bias by the high pressure fluid it receives from the line 16 achieving reaching the predetermined pressure, it allows high pressure fluid to by-pass the tool 3 and flow directly from the line i6 to the line ii. However, as the tool 3 is still connected to the high pressure supply, it remains pressurized at this high pressure and in its first more of operation. Further operation of the pressure relief valve 27 is described in more detail below.

In order that the hydraulic pressures within the circuit can be monitored, an input pressure gauge 28 is included in the circuit 1 between the first input/output port 7 and the pressurizing port 13 of the intensifier 12 and an output pressure gauge 29 is included in the circuit 1 between the high pressure port 15 of the intensifier 12 and the second input/output port 8.

The flow of hydraulic fluid through the circuit 1 is also controlled by three one-way flow restrictors 30, 31, 32. A first 30 of these restrictors is located in the line ii connecting the third and fourth input/output ports 9 and 10 to one another in order to control hydraulic flow in a direction from the fourth input/output port 10 to the third input/output port 9. The restrictor 30 is located between the connection of the actuating line 21 of the spool valve 19 and the connection to the pressure relief valve 27. The second one-way flow restrictor 31 is located in the line 14 connecting the first input/output port 7 to the pressurizing port 13 of the intensifier 12 to control hydraulic flow in a direction from the first input/output port 7 to the intensifier 12. This restrictor 31 is located between the input pressure gauge 28 and the actuating line 20 of the spool valve 19. Finally, the third one-way flow restrictor 32 is located in the line i6 connecting the high pressure port of the intensifier 12 to the second input/output port 8 to control hydraulic flow in a direction from the second input/output port 8 to the intensifier 12.

This restrictor 32 is located between the connection to the output pressure gauge 29 and the connection to the pressure relief valve 27.

In use, the circuit 1 is connected between the tool 3 it is desired to operate and the control valve 4, which will normally be carried by an ROV along with the tanked supply and pump 5. If the circuit 1 is mounted on a panel 2, then the connections can be readily made when the panel 2 has been mounted on the Roy. Ports 7 and 9 are attached to the control valve 4 such that port 7 will be pressurized when it is desired to actuate the tool 3 into using a high pressure input into a first position, for example a "blade down" or cutting position, and port 9 will be pressurized by a relatively "low" pressure input when it is desired to actuate the tool 3 into a second position, for example a "blade up" or retracted position. Similarly, ports 8 and 10 are connected to the tool 3 so that port 8 is connected to the high pressure input of the tool 3 and port 10 is connected to the low pressure input of the tool 3.

Fig. 1 shows the circuit 1 connected in this way when the control valve 4 is in a neutral position when the pump 5 is not operating and no hydraulic fluid is being pumped to either of the input/output ports 7 and 9.

In this neutral position, the pressure relief valve 27 is biased into its closed position. In addition, the spool valve 19 is biased into its first position so that hydraulic fluid can drain from the tool 3 through the circuit 1 to the tanked supply s by various routes, namely (a) through the input/output port 10, down the line ii and through the input/output port 9 to drain low pressure fluid from one side of the tool 3; (b) through the input/output port 8 down the line 16, through the intensifier 12 and out of its tank port 17, through the spool valve 19 and thence via the non-return valve i8 to the input/output port 10 to drain high pressure fluid from the other side of the tool 3; and (c) as a backflow of hydraulic fluid through the pressurizing port 13, of the intensifier 12, down the line 14 and through the input/output port 7.

As shown in Fig. 2, when the control valve 4 is toggled to pump hydraulic fluid to the input/output port 7 to operate the tool 3 in its first mode, then the fluid is pumped along line 14 and supplied first via line 20 to the spool valve 19 to move it into its first position, if it is not already in this position, and then to the pressurizing port 13 of the intensifier 12. The intensifier increases the pressure of the fluid and supplies high pressure fluid to one side of the tool 3 via its pressurizing port 15 and the input/output port 8 of the circuit. This operates the tool 3, for example moving a cutter blade in a cutting direction. The hydraulic fluid on the other side of the tool 3 is returned to the tanked supply 5 through the input/output port 10, down the line ii and out of the circuit 1 via the input/output port 9. It is prevented from actuating the spool valve 19 along line 21 because the spool valve 19 is being actuated from the other side by the higher pressure in the line 20. It is also prevented from entering the spool valve 19 by the non-return valve i8.

When a desired pressure has been reached, high pressure fluid is diverted away from the tool 3 by operation of the relief valve 27, as shown in Fig. 4. This prevents the high pressure fluid from continuing to push the blade of the tool 3 into an anvil against which the blade cuts in order to prevent the blade from being damaged. However, as the tool 3 is still connected to the high pressure supply it remained pressurized and in its first -i_c -more of operation for as long as the hydraulic fluid is pumped through the input/output port 7 to the intensifier. The high pressure fluid that vents through the pressure relief valve 27 flows into the return line ii and is returned to the tanked supply 5 through the input/output port 10.

In order to operate the tool 3 in its second mode of operation, for example to retract a cutting blade, then the control valve 4 is toggled to pump hydraulic fluid to the input/output port 9, as shown in Fig. 3. This cuts off the supply of fluid to the input/output port 7. The line 11 is now pressurized with hydraulic fluid which is supplied initially along line 21 to the spool valve 19. As the line 22 of the spool valve 19 is no longer pressurized, the spool valve 19 is actuated by the pressure in the line 21 against the bias 22 to move into its second position. The line 11 is also supplied with low pressure fluid via the input/output port 10 directly to the other side of the tool 3 to move it into its second more of operation. The hydraulic fluid on the first side of the tool 3 is returned to the tanked supply through the input/output port 8, down the line 16 and into the intensifier 12 through its high pressure port 15. In its second position the spool valve 19 connects the tank port 17 of the intensifier 12 to the line 23 and thence to the line 14 and the first input/output port 7 so that high pressure fluid can drain out of the first side of the tool 3 and the circuit 1. In addition, high pressure fluid in the intensifier 12 can backflow through the pressurizing port 13, down the line 14 and through the input/output port 7.

The supply of pressurized fluid along the line ii also actuates the pressure relief valve 27 into a closed position as the flow of high pressure fluid to its side connected to the line 16 has ceased. This prevents leakage of fluid from the line ii through the valve 27 and resets the valve 27.

It will be appreciated that the control valve 4 can be placed in its neutral position after operation of the tool 3 in either its first or second modes of operation and in neither case is the tool 3 left in a highly pressurized condition as the neutral position always causes high pressure

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fluid to drain from the tool 3 and the circuit 1 back to the tanked supply.

Also, use of the spool valve 19 means that a third draining hose connection to the tanked supply on an ROV is not required. Hence, the aforementioned problem is obviated by use of a circuit in accordance with the present invention.

Claims (1)

1. <claim-text>-12 -CLAIMSAn hydraulic intensifier circuit for use in the actuation of a double-acting hydraulically powered tool, the circuit comprising: first and second input/output ports adapted for connection respectively to a control valve linked to a supply of hydraulic fluid and to the tool for operating the tool in a first mode of operation; third and fourth input/output ports adapted for connection respectively to the control valve and to the tool for operating the tool in a second mode of operation; an hydraulic intensifier having a pressurizing port connected to the first input/output port, a high pressure port connected to the second input/output port and a tank port connected via a non-return valve to a first line connecting the third and fourth input/output ports to one another; and a spool valve connected between the tank port of the hydraulic intensifier on one side and said first and third input/output ports on its other side, the spool valve being actuated (i) into a first position via a pressurizing flow of hydraulic fluid from the first input/output port to the pressurizing port of the intensifier to operate the tool in the first mode wherein the spool valve connects the tank port of the intensifier to the third input/output port via the non-return valve, and (ii) into a second position via a pressurized flow of hydraulic fluid along the first line from the third to the fourth input/output port to operate the tool in the second mode wherein the spool valve connects the tank port of the intensifier to the first input/output port, the spool valve being biased into its first position whereby once a pressurizing flow of hydraulic fluid to the circuit has ceased pressurized hydraulic fluid can drain from the tool and the circuit 1 to the supply -13 - (a) through the third input/output port from said first line and from the tank port through the spool valve and the non-return valve, and (b) through the first input/output port via a backflow of hydraulic fluid from the pressurizing port directly to the first input/output port.</claim-text> <claim-text>2. An hydraulic intensifier circuit as claimed in Claim 1, wherein a pressure relief valve is connected between the high pressure port of the intensifier and said first line connecting the third and fourth input/output ports to one another.</claim-text> <claim-text>3. An hydraulic intensifier circuit as claimed in Claim 2, wherein the pressure relief valve is adapted to operate at a predetermined hydraulic pressure that is at or above the operating pressure required by the tool in its first mode of operation.</claim-text> <claim-text>4. An hydraulic intensifier circuit as claimed in any of Claims 1 to 3, wherein an output pressure gauge is included in the circuit between the high pressure port of the intensifier and the second input/output port.</claim-text> <claim-text>5. An hydraulic intensifier circuit as claimed in any of Claims 1 to 4, wherein an input pressure gauge is included in the circuit between the first input/output port and the pressurizing port of the intensifier.</claim-text> <claim-text>6. An hydraulic intensifier circuit as claimed in any of Claims 1 to 5, wherein a first one-way flow restrictor is included in the circuit in the first line connecting the third and fourth input/output ports to one another to control hydraulic flow in a direction from the fourth to the third input/output port.</claim-text> <claim-text>-14 - 7. An hydraulic intensifier circuit as claimed in Claim 6 when dependent on Claim 2 or Claim 3, wherein the first one-way flow restrictor is located in the first line between a connection thereto for actuation of the spool valve into its second position and a connection to said pressure relief valve.</claim-text> <claim-text>8. An hydraulic intensifier circuit as claimed in any of Claims 1 to 7, wherein a second one-way flow restrictor is included in the circuit in a second line connecting the first input/output port to the pressurizing port of the intensifier to control hydraulic flow in a direction from the first input/output port to the intensifier.</claim-text> <claim-text>9. An hydraulic intensifier circuit as claimed in Claim 8 when dependent on Claim 5, wherein the second one-way flow restrictor is located in the second line between a connection thereto to the input pressure gauge and a connection thereto for actuation of the spool valve into its first position.</claim-text> <claim-text>10. An hydraulic intensifier circuit as claimed in any of Claims 1 to 9, wherein a third one-way flow restrictor is included in the circuit in a third line connecting the high pressure port of the intensifier to the second input/output port to control hydraulic flow in a direction from the second input/output port to the intensifier.</claim-text> <claim-text>11. An hydraulic intensifier circuit as claimed in Claim 10 when dependent on Claims 2 and 4, wherein the third one-way flow restrictor is located in the third line between a connection thereto to the output pressure gauge and a connection to said pressure relief valve.</claim-text> <claim-text>12. An hydraulic intensifier circuit as claimed in any of Claims 1 to 11, wherein the circuit is mounted on a panel.-15 - 13. An hydraulic intensifier circuit for use in the actuation of a double-acting hydraulically powered tool substantially as described herein with reference to the accompanying drawings.</claim-text>