TUBE RUPTURE PROTECTION DEVICE

Abstract

 A tube rupture protection device is disclosed that ensures safety conditions in the event of rupture of a flexible tube connected to a hydraulic actuator of an arm of an actuator, in which the protection device comprises a control valve that in the event of a tube rupture, closes, partially or totally, automatically; the control valve, during normal operation, it adopts a widely open position in which it generates a relatively small load drop, with a consequent energy saving.

Description

Background of the invention

[0001] The invention relates to a tube rupture protection device, in particular a hydraulic protection device that ensures safety conditions in the event of rupture of a (flexible) tube connected to a hydraulic actuator.

[0002] Specifically, but not exclusively, the invention can be applied to the control system of an operating machine (for example an excavating and/or load moving machine), in which the drive can be provided by a linear hydraulic actuator (cylinder), to ensure safe control of the descent in the event of rupture of the flexible tube connected to the linear actuator.

[0003] The prior art comprises various types of tube rupture valves usable for protecting against the rupture of the flexible tube that, in an excavator, connects the hydraulic cylinder to the distributor. The tube rupture valves are configured so as to generate a suitable pressure fall in the event of rupture of the tube.

[0004] Patent publication GB 2514112 A shows a load control valve with a hydraulic fluid inlet and outlet, a pilot line and a conduit that connects the pilot line to the inlet and comprises a flow narrowing and a nonreturn valve that permits flow only in the direction that goes from the pilot line to the inlet.

[0005] Patent publication JP 4890147 B2 shows a control device for controlling the load comprising a check valve arranged between the hydraulic actuator and the tube at risk of rupture, a pilot line for piloting the check valve, a control valve for controlling the pressure of pilot line and a nonreturn valve arranged for preventing transmission of pressure from the tube at risk of rupture to the pressure control valve.

[0006] Patent publication JP 2014206245 A shows a device that reduces the load descent speed and comprises a control valve configured to reduce the control valve opening degree when pressure in the hydraulic actuator supply line is reduced.

[0007] Various aspects of known tube rupture valves are improvable. It is desirable, for example, to prevent relatively great pressure drops during normal operation of the operating machine, to avoid the risk of machine slow-downs, and increases in energy consumption and/or operating temperature increases. It is further desirable to ensure a timely and immediate intervention on the rupture of the tube, and, at the same time, progressive and even operation without jerks and excessive acceleration, maintaining high levels of operating safety and reliability in any possible emergency situation. The ability of the protection device to intervene appropriately in the event of tube rupture, on operating machines of different types and features (for example, for any operating situation, for relatively large work pressure intervals, for tubes of any length and/or diameter, for the multiple configurations that the machines can adopt, etc) is also improvable.

Background of the invention

[0008] One object of the invention is to provide an alternative solution to prior art tube rupture protect devices.

[0009] One object of the invention is to provide a tube rupture protection device for safe control of the descent in the event of rupture of the flexible tube.

[0010] One advantage is to ensure that, in the event of a tube rupture, the descent speed of the operating arm of a machine (excavator) does not exceed a set value (for example twice the speed preceding the rupture).

[0011] One advantage is to enable, in the event of a tube rupture, the descent speed of the operating arm of a machine (excavator) not to be increased with respect to the speed before the rupture, or the descent speed to be decreased after rupture, or the speed to be cancelled after the rupture.

[0012] One advantage is to provide a tube rupture protection device that, during normal operations, generates a relatively reduced pressure fall.

[0013] One advantage is to make available a tube rupture protection device with great versatility, which is for example able to adapt to different types and features of machines and/or to various configurations of a machine.

[0014] One advantage is to devise a tube rupture safety protection device that is constructionally simple and cheap.

[0015] One advantage is to permit optimum controllability of the movable arm of an operating machine, ensuring great stability during movement of the arm.

[0016] One advantage is to ensure good manoeuvrability and optimum comfort for the operator during the various material handling operations.

[0017] One advantage is to reduce energy consumption, obtaining high energy efficiency during the movable arm control step.

[0018] Such objects and advantages, and still others, are achieved by the tube rupture protection device according to one of more of the claims set out below.

[0019] In one embodiment, a tube rupture hydraulic protection device, which is in particular suitable for controlling (limiting) the descent speed in the event of rupture of a tube connected to a hydraulic actuator of a movable element for moving an operating machine, comprises a (pressure and/or flow) control valve arranged on a hydraulic line connected to the tube; the control valve, which is commanded by a pilot line, closes, partially or totally, automatically, in the event of rupture of the tube; the protection device is so configured that the control valve, during normal operation, adopts an open position in which it generates a relatively small load drop, with a consequent energy saving.

Brief description of the drawings

[0020] The invention can be better understood and implemented with reference to the attached drawings that illustrate some non-limiting embodiments thereof, in which:

Figure 1 shows a circuit diagram that includes a first embodiment of a tube rupture safety protection device according to the invention;

Figure 2 shows a circuit diagram that includes a second embodiment of a tube rupture safety protection device according to the invention;

Figure 3 shows a circuit diagram that includes a third embodiment of a tube rupture safety protection device according to the invention;

Figure 4 shows a circuit diagram that includes a fourth embodiment of a tube rupture safety protection device according to the invention;

Figure 5 shows a diagram of a fifth embodiment of a tube rupture safety protection device according to the invention.

Detailed description

[0021] With reference to the aforesaid figures, for the sake of greater clarity, the same elements, even if they belong to different embodiments, have been indicated by the same numbering.

[0022] With 1, a protection device has been indicated for the event of a tube rupture that is suitable for use, in particular, on an operating machine (for example an excavating and/or load moving machine). The protection device 1 is used, in particular, for controlling (limiting) the descent speed of a movable element (arm) in the event of rupture of the (flexible) tube that, normally, connects the directional control valve (distributor) with the hydraulic actuator that controls the movement of the movable element (arm) of the operating machine. The tube rupture protection device 1 may comprise, in particular, a valve unit consisting of a single block (schematized with a dashed line in Figures 1 to 5). This valve unit may comprise, for example, mechanical connecting means, in particular of the flange type, for direct fitting to the body of the hydraulic actuator.

[0023] The protection device 1 may comprise, in particular, a hydraulic line 2 comprising at least one first port P1 intended for connection with a hydraulic actuator C. The hydraulic line 2 may comprise at least one second port P2 intended for the connection with a tube T at risk of rupture.

[0024] The tube rupture protection device 1 may comprise, in particular, a control valve 3 arranged in the hydraulic line 2.

[0025] The control valve 3 may comprise, in particular, at least one first position in which is permits a flow to the first port P1 and prevents a flow to the second port P2. The control valve 3 may comprise, in particular, at least one second position in which it permits a flow to the second port P2.

[0026] The control valve 3 may comprise, in particular, a pressure and/or flow control valve. The control valve 3 may comprise, in particular, a valve of known type that can normally be used in a tube rupture protection device. The control valve 3 may comprise, for example, a control valve (of the pressure and/or flow) with a control of proportional type.

[0027] The control valve 3 may comprise, in particular, a mechanical seal valve, i.e. a valve configured to ensure a mechanical seal with leakage that is virtually nil, for example by the use of specific mechanical components (which are per se known), such as a movable element (piston) and a seat for the movable element with zero leakage.

[0028] The control valve 3 may comprise, in particular, at least one first (ascent) position in which it consents a flow to the first port P1 and prevents a flow to the second port P2. The control valve 3 may comprise, in particular, at least one second (descent) position in which it permits a flow to the second port P2, for example with localized load loss (of a preset amount).

[0029] In other embodiments that are not illustrated, the control valve 3 may comprise types of valve (also of known type).

[0030] The tube rupture protection device 1 may comprise, in particular, a pilot line 4 arranged for piloting the control valve 3. The pilot line 4 may comprise, in particular, at least one third port P3 intended for the connection with at least one element external to the device 1.

[0031] The pilot line 4 may be arranged for piloting the control valve 3 to the first position.

[0032] The tube rupture protection device 1 may comprise, in particular, a discharge line 5 arranged for connecting the pilot line 4 with a fourth port P4 intended for the connection with a drain R. The discharge line 5 may be used, in particular, to discharge at least one part of fluid present in the pilot line 4, when the discharge line 5 is, at least partially, open.

[0033] The protection device 1 may comprise, in particular, a circuit element 6, or hydraulic element, configured and arranged for shutting the discharge line 5 when there is a first pressure (which is relatively high, for example comprised between 5 and 100 bar, or between 10 and 30 bar, in particular equal to about 20 bar) in a portion of the hydraulic line 2 comprised between the second port P2 and the control valve 3 (in the case of an undamaged tube). The circuit element 6 may be configured and arranged for opening, at least partially, the discharge line 5 when there is a second pressure (which is relatively reduced), below the first pressure, in the aforesaid portion of the hydraulic line 2 (in the case of a burst tube). In other words, the circuit element 6 is so configured as to be closed in the steps of normal operation and to be opened automatically (at least partially) in the event of a tube rupture (owing to the drop in pressure that will occur in the aforesaid portion of the hydraulic line 2 comprised between the second port P2 and the control valve 3).

[0034] This circuit element 6 may be, in particular, sensitive to pressure present in the aforesaid portion of the hydraulic line 2 so as to close the discharge line 5 when in the aforesaid portion of the hydraulic line 2 there is a first pressure in the case of an undamaged tube T, i.e. in a situation of normal operation.

[0035] This circuit element 6 may be, in particular, sensitive to pressure present in the aforesaid portion of the hydraulic line 2 so as to open (at least partially) the discharge line 5 when in the aforesaid portion of the hydraulic line 2 there is a second pressure, below the aforesaid first pressure. The second pressure may be due, in particular, in the event of a rupture of the tube T, i.e. in an emergency situation that requires an automatic and immediate intervention for maintaining the system in a safe condition, even if the operator does not promptly intervene on the control device available to him or her.

[0036] The circuit element 6 may comprise, in particular, a first logic element piloted by a pressure coming from the aforesaid portion of the hydraulic line 2. The first logic element may be piloted by elastic means. The first logic element may be drained by the discharge line 5.

[0037] The protection device 1 may comprise, in particular, a service line 7 arranged for connecting the circuit element 6 with the aforesaid portion of the hydraulic line 2. The service line 7 in particular enables the circuit element 6 to be piloted by pressure taken from the hydraulic line 2. The service line 7 is distinct from the discharge line 5.

[0038] The protection device 1 may comprise, in particular, valve means 8 arranged in the discharge line 5, in particular between the circuit element 6 and the pilot line 4. The valve means 8 may comprise, in particular, flow control means arranged for preventing a flow into the discharge line 5 directed to the pilot line 4. The valve means 8 may comprise, as in the specific examples illustrated here, a one-way valve.

[0039] The valve means 8 may be configured to permit a flow to the circuit element 6 and/or to close at least partially the discharge line 5 so as to maintain positive pressure in the pilot line 4.

[0040] The tube rupture protection device 1 may comprise, in particular, throttling means 9 arranged in the pilot line 4, in particular between the third port P3 and the discharge line 5. The throttling means 9 may comprise, for example, an orifice, in particular an adjustable orifice (for example adjustable with a grubscrew).

[0041] The third port P3 may be intended, in particular, for a connection with a control device (for example a joystick) that is operatable by an operator. The third port P3 could be intended, in other embodiments, for the connection with a pressure control valve (for example a proportional pressure-reducing valve). The third port P3 could be intended, in other embodiments, for the connection with a line connected to a chamber of the hydraulic actuator C (for example the chamber opposite the chamber to which the first port P1 is connected).

[0042] The protection device 1 may comprise, in particular, control means 10 (of valve type) piloted by a pressure in the pilot line 4. The control means 10 may be piloted, in particular, so as to close the discharge line 5 when the pressure in the pilot line 4 exceeds a preset value (maximum value). The control means 10 may be piloted, in particular, so as to prevent or limit the discharge of fluid coming from the pilot line 4 through the discharge line 5.

[0043] The control means 10 may comprise, as in the embodiment of Figure 2, a second logic element piloted by a pressure coming from the pilot line 4. The second logic element may be piloted, as in this embodiment, by elastic means (in combination with the pressure of the pilot line 4).

[0044] The control means 10 may be piloted (as in the embodiments of Figures 3 to 5) so as to close the discharge line 5 when a pressure coming from the pilot line 4 falls below a preset value (minimum value) so that the discharge of fluid can occur (only) when the pressure coming from the pilot line 4 is comprised between two positive values (minimum value and maximum value).

[0045] The control means 10 may comprise, as in the embodiments of Figures 3 to 5, at least one three-position valve with at least one central opening position and two outer, or lateral, or end, or closing positions.

[0046] The control means 10 may be arranged in the discharge line 5 and be separated by the control valve 3 (as in the embodiments of Figures 2 and 3). It is possible to provide, as in the embodiments of Figures 4 and 5, for the control means 10 being integrated into at least one portion of the control valve 3.

[0047] The protection device 1 may comprise, as in the embodiment of Figure 5, a bypass line 11 arranged for connecting the second port P2 to the first port P1 bypassing the control valve 3. The protection device 1 may comprise a bypass valve 12 arranged on the bypass line 11. The protection device 1 may comprise an auxiliary (discharge) line 13 arranged for connecting a portion of the hydraulic line 2 (comprised between the control valve 3 and the first port P1) with the fourth port P4 (in particular with a portion of the discharge line 5 comprised between the circuit element 6 and the fourth port P4). The protection device 1 may comprise a valve 14 with "OR" function (for example a selector) arranged on the pilot line 4 to connect the control valve 3 selectively with the third port P3 or with the auxiliary line 13.

[0048] The protection device 1 may comprise, as in the embodiment of Figure 5, a control valve 15 (pressure and/or flow rate control valve, for example a maximum pressure valve) arranged in the auxiliary line 13. The protection device 1 may comprise, in particular, throttling means 16 (for example an orifice, in particular an adjustable orifice).

[0049] The control valve 15 may be used, in particular, to limit the pressure in the hydraulic line 2 (at the first port P1 connected with the actuator C). The control valve 15 can open at least partially, letting fluid pass into the auxiliary line 13, and the throttling means 16 (orifice) can generate a pressure fall that will pilot the control valve 3.

[0050] In these embodiments, the circuit element 6 comprises a logic element. It is possible to provide other embodiments, which are not illustrated, in which the circuit element 6 may comprise a pressure control valve and/or a proportional control valve and/or a maximum pressure valve and/or a nonreturn valve. The circuit element 6 may be configured, in particular, to facilitate a closure of the control valve 3 in the event of an emergency due to the rupture of the tube T, causing a desired reduction of the descent speed, in a controlled manner, further limiting dispersion of the operating fluid exiting the rupture of the tube T. The circuit element 6 can permit, in particular, complete closure of the control valve 3, gradually, i.e. without the risk of generating instability in the handling of the movable element (arm) controlled by the hydraulic actuator C.

[0051] In the embodiments disclosed here, the protection device 1 may belong to a control circuit of the hydraulic actuator C. The control circuit may comprise, as in these embodiments, a directional control valve D of an operating fluid of the actuator and a tube T, at risk of rupture, arranged for connecting the directional control valve D with the hydraulic actuator C. The directional control valve D may be, in particular, of proportional type. The protection device 1 may be arranged between the tube T and the hydraulic actuator C. The tube T may be connected, in particular, with the second port P2 of the protection device 1.

[0052] The directional control valve D (distributor) has been illustrated schematically. The valve D could comprise, for example, four-way and three-position valve, in particular of proportional type, or still other embodiments of valves usable for driving a hydraulic actuator.

[0053] It is possible to provide a control device, which is not illustrated (for example a joystick), that is operatable by an operator, for controlling the directional control valve D, and may be connected to the third port P3 of the device 1 for controlling the control valve 3.

[0054] The aforesaid hydraulic circuit may be used for controlling the safe descent in the event of a tube rupture, of an arm of an operating machine, in particular of an excavation and/or load moving machine.

[0055] The operation of the device 1 is as follows.

[0056] With reference to the embodiment of Figure 1, the control valve 3 is piloted through the pilot line 4, provided with the throttling means 9 (orifice) that causes a localized (adjustable) pressure fall. In the event of rupture of the tube T, the circuit element 6 (logic element) opens and can consequently place the pilot line 4 in communication with the drain R, through the discharge line 5 and the fourth port P4. The pilot line 4 can be discharged when the pressure, in the hydraulic line 2 portion comprised between the control valve 3 and the second port P2, falls below a certain value (presettable, in particular a value selectable in a range comprised between 1 and 100 bar, for example 30 bar).

[0057] It is observed that in particular owing to the valve means 8 (one-directional flow control means) it is possible to maintain a positive pressure (minimum pressure value greater than zero, defined by the valve means 8) in the pilot line 4. The valve means 8 further enables fluid leaks to be prevented from the circuit element 6 to the pilot line 4.

[0058] The operation of the embodiment of Figure 2 is similar to that of the embodiment of Figure 1, although, in this case, the positioning of the control means 10 (for example, a logic element) enables the discharging of the pilot line 4 to be activated only as far as a maximum set piloting pressure value. This maximum value may be selectable, owing to the control means 10, for example the maximum value may be selected in a pressure range comprised between 1 and 100 bar (for example a maximum value of 15 bar, or 50 bar, or other values). Beyond this maximum pressure value, the discharge line 5 remains closed even if the circuit element 6 opens, so that the fluid is not discharged along the discharge line 5 to the fourth port P4 and the pilot line 4 remains active.

[0059] The operation of the embodiment of Figure 3 is similar to that of the embodiment of Figure 2, although, in this case, the control means 10 is configured to keep the discharge line 5 closed below a minimum pressure value, and beyond a maximum value. Basically, the pilot line 4 may be discharged by the discharge line 5 only within a given pressure value range (for example from 5 to 15 bar, or from 10 to 50 bar, etc).

[0060] The operation of the embodiments of Figures 4 and 5, in which the control means 10 is integrated into the piloting piston of the control valve 3, is substantially the same as that of the embodiment of Figure 3.

Claims

1. Tube rupture protection device (1), comprising:

- a hydraulic line (2) comprising at least one first port (P1) intended for the connection with a hydraulic actuator (C) and at least one second port (P2) intended for the connection with a tube (T) at risk of rupture;

- a control valve (3) operating in said hydraulic line (2) and comprising at least one first position in which it allows a flow toward said first port (P1) and prevents a flow toward said second port (P2) and at least one second position in which it allows a flow toward said second port (P2);

- a pilot line (4) arranged to pilot said control valve (3) and comprising at least one third port (P3) intended for the connection with at least one element external to the device (1);

- a discharge line (5) connected to said pilot line (4) and comprising at least one fourth port (P4) intended for the connection with a drain (R) to discharge fluid from said pilot line (4);

- a circuit element (6) arranged to control a discharge flow in said discharge line (5);

- a service line (7) arranged to pilot said circuit element (6) by a pressure coming from a portion of said hydraulic line (2) comprised between said second port (P2) and said control valve (3), said circuit element (6) being piloted to close said discharge line (5) when in said portion of said hydraulic line (2) there is a first pressure, in case of intact tube (T), and to at least partially open said discharge line (5) when in said portion of said hydraulic line there is a second pressure, lower than said first pressure, in case of ruptured tube (T);

- valve means (8) arranged in said discharge line (5) between said circuit element (6) and said pilot line (4).

2. Device according to claim 1, wherein said valve means (8) comprises flow control means arranged to prevent a flow in said discharge line (5) towards said pilot line (4).

3. Device according to claim 1 or 2, wherein said valve means (8) is configured to allow a flow towards said circuit element (6) and/or to at least partially close said discharge line (5) so as to maintain a positive pressure in said pilot line (4).

4. Device according to any one of the preceding claims, wherein said circuit element (6) comprises a first logic element piloted by a pressure in said portion of said hydraulic line (2) and/or piloted by elastic means and/or drained by means of said discharge line (5).

5. Device according to any one of the preceding claims, comprising throttling means (9) arranged in said pilot line (4) between said third port (P3) and said discharge line (5).

6. Device according to any one of the preceding claims, wherein said pilot line (4) is arranged to pilot said control valve (3) towards said first position.

7. Device according to any one of the preceding claims, wherein said third port (P3) is intended for the connection with a control device operable by an operator and/or with a pressure control valve, for example a proportional pressure reducing valve, and/or with a line connected to the hydraulic actuator (C).

8. Device according to any one of the preceding claims, comprising control means (10) piloted by a pressure in said pilot line (4) so as to close said discharge line (5) and prevent a discharge of fluid coming from said pilot line (4) when the pressure in said pilot line (4) exceeds a maximum value.

9. Device according to claim 8, wherein said control means (10) comprises a second logic element piloted by a pressure coming from said pilot line (4) and/or piloted by elastic means.

10. Device according to claim 8, wherein said control means (10) is piloted so as to close said discharge line (5) when a pressure coming from said pilot line (4) falls below a minimum value, whereby the discharge of fluid occurs when the pressure coming from said pilot line (4) is between said minimum value and said maximum value.

11. Device according to claim 10, wherein said control means (10) comprises at least one three-position valve with at least one central opening position and two external closing positions.

12. Device according to any one of claims 8 to 11, wherein said control means (10) is arranged in said discharge line (5) and separated by said control valve (3)

13. Device according to any one of claims 8 to 11, wherein said control means (10) is integrated into at least one portion of said control valve (3).

14. Control circuit of a hydraulic actuator (C), said control circuit comprising a directional control valve (D) of an operating fluid of the actuator, a tube (T) at risk of rupture arranged to connect said directional control valve (D) with said hydraulic actuator (C), a protection device (1) arranged between said tube (T) and said hydraulic actuator (C), said protection device (1) being made according to any one of the preceding claims.

15. Use of a hydraulic circuit for the safe descent control, in the event of tube rupture, of an element of an operating machine, in particular of an excavating and/or load handling machine, said hydraulic control circuit being made according to claim 14.

Drawing