SE534272C2 - SAFETY-vALVE - Google Patents

Description

534 272 the rupture valve releases. Delay can in the western cases cause damage to the equipment and in the worst case that people and animals living in the vicinity die.

An additional problem with dangerous constructions is that the function for these depends on the viscosity of the pressure fluid. An additional problem with existing constructions is that these are fate-dependent for their function. This causes problems in cold weather where the oil is more sluggish than at hot temperatures. If the construction is set according to conditions prevailing at cold temperature, the function of the valve can be significantly impaired at hot temperature. Correspondingly, the function of the valve can be significantly impaired at cold temperature if it is set at hot temperature.

An even further problem with the present designs is that the EU has issued a directive on a new standard for hose break valves for vehicles. A number of known constructions do not meet the requirements of the new standard.

Some types of, for example, electrically controlled systems are designed to detect hose breakage or other types of leakage in hydraulic systems and can be switched off under certain conditions, such as in the event of a break in a line or the like.

Connection of existing types of hose break valves entails an additional problem with the function of the shock absorber being lost. The loss of the vibration damping function can result in accidents.

A more specific problem arises in situations where a lifting device comprises two hydraulic cylinders for maneuvering a bucket or the like. If the hose break valve does not release reliably, one of the pressure cylinders may need to take up the entire load.

Prior art Hose rupture valves and the like are already known in a large number of variants and designs. For example, patent specification EP1 503 1112B1 describes a hose break valve.

The construction differs from the construction according to the present invention.

For example, this is viscosity and fl dependent.

An example of another type of hose break valve is described in the Swedish patent SE412946.

The construction differs substantially from the present invention. 534 272 Also in the patent specification EP0952358 a variant of a hose break valve is described. The valve differs to a significant extent from the construction according to the present invention.

There are also servo-controlled constructions that are intended to indicate hose breakage and prevent damage from occurring in connection with hose breakage. This type of construction is marketed, for example, by the German company Beringer. The construction is expensive and complicated to manufacture. Furthermore, the design of a loader does not fit due to the complicated assembly. For example, pilot lines and the like must be laid. Furthermore, the construction means that functions such as a load lowering function are switched off. OBJECTS OF THE PRESENT INVENTION The main object of the present invention is to provide a substantially improved safety valve, hose rupture valve than prior art constructions.

Another object of the present invention is to provide a safety valve which is inexpensive to manufacture. A further object of the present invention is to provide a safety valve with a substantially smaller delay than previously known constructions. A still further object of the present invention is to provide a hose break valve which means that the function of the vibration damper is not lost when mounting the hose break valve to the system.

Detailed Description of the Invention The invention will be described in more detail below with reference to the accompanying schematic drawings which, by way of example, show the presently preferred embodiments of the invention.

Figure 1 schematically shows a hydraulic diagram for a safety valve in accordance with the present invention.

Referring to the gurus, a safety valve 1, with hose break valve function, is shown in accordance with the present invention. The safety valve 1 comprises a valve block 2, valve housing or the like, which is provided with at least one first port 3 and at least one second port 4. The first port 3 and the second port 4 are connected to each other via at least one channel, such as a flow channel or the like. . At least one line 5 such as a hose, pipe or the like is connected to the first port 3 of the safety valve 1. The line 5 is in turn preferably connected via an intermediate directional valve 6 or the like to a pressure releasing source (not 534 272 shown in figures) such as a hydraulic purge 7 or the hydraulic tank 8. The second port 4 is connected to a hydraulic component 9 such as preferably a hydraulic cylinder .

The safety valve 1 is intended to prevent the backflow of liquid from the hydraulic component 2, such as the hydraulic cylinder shown in the figure, in the event of breakage or leakage on the line 5.

The safety valve 1 is arranged to sense the pressure difference between to the pressure of fate and from the pressure of fate. When the pressure difference between the safety valve to fl fate, the side towards the line 5, and from the fl fate side, the side towards the hydraulic component 9, exceeds a certain level (value), the safety valve fl closes the fate through safety valve 1. The design that enables this function will be described in more detail below.

In alternative embodiments, the valve block may be provided with at least one additional port (connection) 10.

The safety valve 1 comprises a valve block 2 with at least a first port 3 and at least a second port 4. The flow through the safety valve between port 3 and port 4, respectively, is controlled via at least one valve means 11 which is preferably a pilot-controlled pressure valve. The pilot-controlled pressure valve 11 is normally closed. The pilot-controlled pressure valve 11 is opened by pressurizing the pilot line 12.

The unique thing about the present invention is that the pilot line 12 of the pilot-controlled pressure valve (line for controlling the pilot-controlled pressure valve) connects to the first port 3 via a first channel (connection or the like) 13 and it connects to the second port 4 via a second channel (connection or similar) 14. In the first channel 13 there is a first throttle 15. In the second channel 14 there is a second throttle 16. The flow at the throttle 15 is controlled by a pilot-controlled non-return valve 17. The non-return valve is mounted between port 4 and the throttle 16. The pilot line 18 of the pilot-controlled non-return valve 17 connects to channel 14 between the choke 16 and the pilot line 12. When the position is closed, the non-return valve 17 prevents fate from port 4 in the direction of the choke 16. When the pilot line 18 is pressurized, the non-return valve 17 opens.

The first choke 15 has a larger area than the second choke 16. Because the first choke 15 has a larger area than the second choke 16, the volume output per unit time will be higher through the first choke 15 than through the second choke 16. In the event of breakage or leakage of the hose 3 or the line, the pressure in the line 3 will be less than the pressure in the hydraulic cylinder 2. The volume 534 272 discharge via the choke 15 in relation to the discharge via the choke 16 causes a pressure drop in pilot line 12 and pilot line 18. in the pilot line 12 causes the pilot-controlled pressure valve 11 to close. The pressure drop in the pilot line 18 causes the pilot-controlled non-return valve 17 to close. By closing the pilot-controlled non-return valve 17 and the pilot-controlled pressure valve 11, respectively, fl leakage from port 4 to port 3 is prevented. Leakage of hydraulic oil from the pressure side of the hydraulic cylinder is thus prevented in the event of breakage or leakage on the line 3.

The ratio of the cross-sectional area of the second choke 16 to the first choke 15 is preferably in the range 0.3 to 0.7. The cross-sectional area of the second choke thus preferably amounts to between 30 to 70 percent of the cross-sectional area of the first choke. An optimal function is achieved when the ratio between the cross-sectional area of the second and the first choke amounts to about 0.5, i.e. the cross-sectional area of the second choke amounts to about 50 percent of the cross-sectional area of the first choke.

The function of the present invention relates to an indication of differences in the fl fate between the second choke 16 and the first choke 15. The volume fl fate through the first choke 15 should be greater than the volume fl fate through the second choke 16.

The size of the throttles 15 and 16 affects the nature of the function of the safety valve 1.

A slight difference between the cross-sectional areas of the second choke 16 and the cross-sectional areas of the first choke 15, resulting in a difference in the volume genom through the second choke and the first choke, respectively, makes the system slower. Furthermore, fluctuations in pressure are offset by the till fate of the other port.

Flow between port 3 and port 4 is preferably also possible via the non-return valve 19. The non-return valve 19 enables flow in the direction between port 3 and port 4. The non-return valve 19 closes flows in the direction between port 4 and port 3. Both sides of the pilot-controlled pressure valve 11 are pressurized by the construction which is especially important when starting the hydraulic system.

The spring space of the pressure valve communicates with the surrounding atmosphere.

The connection is symbolized in the med gures with position 20. The construction means that the spring force is not added to the pressure in port 4 or port 3. 534 272 In an alternative embodiment of the safety valve in accordance with the present invention, the safety valve also comprises at least a third port (connection) 10. The the third port 10 is connected to the negative side 21 of the hydraulic cylinder 21. Port 4 is connected to the positive side 22 of the hydraulic cylinder 22. The third port 10 communicates via at least one channel 23 with the pilot line 12 (which controls the pilot-controlled pressure valve 11). The flow direction through the channel 23 is controlled by a non-return valve 24. The non-return valve 24 enables the flow from the port 10 towards the pilot line 12 and closes the flow from the pilot line 12 towards the port 9. The construction also includes a throttle 25. The construction is intended to minimize problems associated with low load against hydraulic cylinder.

The safety valve 1 in accordance with the present patent application is particularly suitable for use in hydraulic systems which comprise a function for vibration damping (load damping) or the like. The hydraulic system thereby comprises at least one electric on and off valve 26 and an accumulator 27. The pivot mandrel pair may also comprise a function for damping the damping system consisting of a non-return valve 28 and a throttle 29. The function for vibration damping consists of prior art, so this is not described in more detail. in this patent application.

A possible application for the present invention is that it is used for a lifting device comprising a first hydraulic cylinder and a second hydraulic cylinder. The first hydraulic cylinder is connected to a first pressure line or pressure hose. A first safety valve is connected to the first hydraulic cylinder and a second safety valve is connected to the second hydraulic cylinder. The function of the safety valves eliminates the risk of overloading of the first hydraulic cylinder 9 or the second hydraulic cylinder 30 in the event of a hose breakage.

In the detailed description of the present invention, construction details may have been omitted which are obvious to a person skilled in the art, such obvious construction details are included to the extent required for a satisfactory function of the present invention to be achieved. Although certain preferred embodiments have been described in detail, variations and modifications within the scope of the invention may be apparent to those skilled in the art and all of these are considered to fall within the scope of the appended claims. For example, it is conceivable that the present invention has a safety valve which is directly connected to the hydraulic cylinder or connected via a line. 534 272 Advantages of the Invention With the present, a number of advantages are achieved. The most obvious advantage is that a more efficient hose rupture valve is obtained with the present invention. An additional advantage is that extra hydraulic lines do not have to be laid for the function of the safety valve.

Furthermore, the safety valve does not draw power lines or the like.

The construction becomes safe for any debris in the oil, for example debris from the cylinder.

The rubbish means that the choke with the smaller diameter becomes the one that first risks being clogged again. If the smaller throttle is blocked, the pilot-controlled pressure valve closes.

Debris in the system therefore does not impair the function of the system.

A further advantage of the present system is that the construction does not cause the function of the vibration damper to fall off in connection with a hose break valve being mounted to the system.

Claims (1)

A safety valve (1), of the line rupture valve type, for pressurized fluid systems intended to be connected between at least one line (5) and at least one first hydraulic component (9) such as a hydraulic cylinder, for the purpose of sensing breakage or leakage in the line (5) or the system before the safety valve (1), whose safety valve (1) comprises a valve block (2) provided with at least one first port (3) to which the line (5) is connected and at least one second port (4 ) to which the hydraulic component (9) is connected, the first port (3) and the second port (4) being connected to each other via at least one flow channel, the fate of the flow channel fl is controlled by at least one pilot-controlled pressure valve (1 1) which is controlled by the pressure in at least one pilot line (12) and that the safety valve comprises a non-return valve which allows fate from the first port (3) to the second port (4) past the pilot-controlled pressure valve (11) characterized in that the pilot-controlled pressure valve (11) pilot line (12) connects to the first port (3) via a first channel (13), comprising a first choke (15), and that the pilot valve pilot line (12) connects to the second port (4) via a second channel (14), the second channel (14) of which is provided with, or consists of, at least one second choke (16) and that the flow in the second channel (14), between the second port (4) and the first choke (15) , is controlled by at least one pilot-controlled non-return valve (17), and the cross-sectional area of the first throttle (15) is larger than the cross-sectional area of the second throttle (16) leading to a higher volume through fl through the first throttle (15) relative to the volume through fl through the second the throttle (16). Safety valve (1) according to claim 1, characterized in that the ratio between the cross-sectional area of the second throttle (16) and the first throttle (15) is in the range 0.3 to 0.7. Safety valve (1) according to at least one of the preceding claims, characterized in that the safety valve (1) comprises at least one second port (10) which is connected to the pilot line (12) via at least one channel (23) and that the direction of fate through the channel (23 ) is controlled by at least one non-return valve (24) which allows fl fate from the port (10) towards the pilot line (12) and closes fl the fate from the pilot line (12) towards port (10). 534 272 Safety valve (1) according to at least one of the preceding claims, characterized in that the air space of the pilot-controlled pressure valve (11) is connected to the surrounding atmosphere.