EP3091239A1 - Safety device - Google Patents

Abstract

1. Safety device. 2. Safety device consisting of at least - a valve housing (10), - a pressure supply (P E) - and a tank connection (T E), - Two user connections (P A, T A) and - Two spring-loaded valve pistons (18, 20) which are guided longitudinally within the valve housing (10).   

Description

The invention relates to a safety device in the manner of a hydraulic Tankdruckabsicherung. In agriculture, there is a regular distinction between self-propelled and towed machines. So-called self-propelled vehicles have their own hydraulic system, which is driven directly by the engine of the machine. In towed work machines either the pump of a separate hydraulic system on the machine is driven by the PTO of a tractor or the oil supply of the working machine is taken over directly by the tractor pump.

In the latter case, in which the oil supply is taken over by the tractor, the hydraulic lines of the towed machine are connected to the tractor with so-called quick couplings. Since the couplings often have the same nominal diameters and thus connection geometries, the risk of confusion regarding the pressure supply line and the tank line is quite large despite appropriate labeling. Likewise, it is possible that the connection of one of the lines is forgotten or one of the lines by defective, dirty or improperly mounted couplings during operation independently separates from the hydraulic supply circuit and falls to the ground.

If one of these cases occurs, it is possible that in the hydraulics of the drawn working machine tank pressure quickly builds up, the pressure Pump pressure level (250 bar and more) can achieve. However, many hydraulic components only withstand pressures of between 5 bar and 40 bar on the tank side and could therefore be destroyed.

By the DE 10 2011 118 536 A1 a safety device is known, which is designed in particular as a so-called. Pipe rupture protection, wherein a arranged in a valve housing valve element of a closing valve by means of a control device in an open basic position a fluid-conducting connection between two connection points in the valve housing of the closing valve releases, of which a connection point via a connecting line connected to a hydraulic consumer. In the known solution it is provided that by means of a bypass device which is connected to said connecting line and the closing valve, in case of failure with a corresponding pressure loss against the action of the control device, the valve element in its the fluid-carrying connection between the two connection points of the valve housing blocking position is moved. In this way, a kind of self-adapting closing valve is realized and, in particular, in the event of failure of the pipe break, closing of the safety device occurs immediately and unintentional leakage of the hydraulic circuit in the direction of the environment is avoided with certainty. An overload protection to protect hydraulic consumers from excessive pressure is not achieved with this safety device.

Based on the above-mentioned prior art, the present invention seeks to provide a space-saving building, fast-acting safety device, which makes it possible in the case of misconnection of hydraulic supply lines or forgetting to make the connection, to ensure that in that respect If no hydraulic component connected to a hydraulic circuit is damaged or even destroyed. Furthermore, should ensure the safety device in the manner of a hydraulic tank pressure protection even in normal operation, a safe function of the hydraulic circuit connected to the hydraulic components. A related object solves a safety device with the features of claim 1 in its entirety.

• einem Ventilgehäuse,
• einem Druckversorgungs- sowie einem Tankanschluss,
• zwei Nutzanschlüssen und
• zwei federbelasteten Ventilkolben, die innerhalb des Ventilgehäuses längsverfahrbar geführt sind.

For a functionally reliable operation of the safety device is provided that it is constructed at least of the following components, at least

• a valve housing,
• a pressure supply and a tank connection,
• two utility connections and
• two spring-loaded valve piston, which are guided longitudinally movable within the valve housing.

1. 1. Normalbetrieb; alle Leitungen sind richtig angeschlossen.
2. 2. Druckleitung angeschlossen, Tankleitung nicht angeschlossen oder abgefallen.
3. 3. Druck- und Tankleitung sind miteinander vertauscht.

If, as mentioned above, drawn working machines, such as tillage equipment supplied by a tractor, such as a tractor with oil, so there are three relevant cases in the operation, which must be distinguished:

1. 1. normal operation; all lines are connected correctly.
2. 2. Pressure line connected, tank line not connected or dropped.
3. 3. Pressure and tank line are interchanged.

In the first case, the hydraulic Tankdruckabsicherung according to the feature configuration of claim 1 only a monitoring function and the pressures of supply and tank line are simply passed through.

In the second case, the hydraulic tank pressure protection according to the invention has the task of the pressure supply connection respectively the P-channel when a permissible tank pressure is exceeded, it must be sealed in a seat-tight manner, whereby the tank pressure can then no longer increase.

In the third case takes place with the inventive solution a tank pressure protection by the tank connection respectively the T-channel is sealed seat-tight at a permissible tank pressure is exceeded.

The safety device according to the invention comes, as stated, with little components that can be summarized in blocks in the manner of a kit for the purpose of integrated installation in the hydraulic supply circuit of a working machine, such as a tractor or a tillage implement. Depending on which of the incidents described above is present, one or the other valve piston is used in a controlling manner with regard to the various connections within the valve housing automatically.

The valve housing may be integrally formed; but there is also the possibility of construction in multi-housing technology. In the latter case, the then spatially separated housing parts, each with different connections and one valve piston in a variety of ways can be fluidly connected to each other in order to ensure the function of the safety device as a hydraulic tank pressure protection. The safety device quickly controls the connections to be influenced in the valve housing with the respective valve piston, so that the reaction of the safety device is already present almost at the same time as the malfunction occurs. The fact that the two spring-loaded valve piston can "feel" the pressure changes caused by the disturbance immediately and "process" immediately, the hydraulic components potentially damaging pressure peaks are avoided with certainty. Further advantageous embodiments of the safety device according to the invention are the subject of the dependent claims.

Fig. 1 bis 3

in der Art eines Längsschnittes mit teilweiser Ansicht von Bauteilen (Fig. 1) die erfindungsgemäße Sicherheitsvorrichtung in verschiedenen Betriebszuständen; und

Fig. 4

in der Art eines hydraulischen Schaltplans die Sicherheitsvorrichtung nach den Fig. 1 bis 3.

In the following, the safety device according to the invention will be explained in more detail with reference to an embodiment of the drawing. The show

Fig. 1 to 3

in the manner of a longitudinal section with partial view of components ( Fig. 1 ) the safety device according to the invention in different operating states; and

Fig. 4

in the manner of a hydraulic circuit diagram, the safety device according to the Fig. 1 to 3 ,

The safety device after the Fig. 1 shows a block-like valve housing 10, in the direction of the Fig. 1 seen on the bottom of a pressure supply port P _E and a tank port T _{E are} introduced. On the opposite upper side of the valve housing 10, two useful connections P _A, T _A are present, which open out via corresponding connecting lines into a central control block 12. The pressure supply connection P _E is connected to a stylized reproduced pressure supply source 14, for example in the form of a conventional hydraulic pump. This hydraulic pump 14 is supplied in the usual way from a storage tank T, to which the tank connection T _{E of} the valve housing 10 is connected on the discharge side. The two payload connections P _A , T _A , which are connected to the control block 12, ensure the pressure supply for at least one hydraulic consumer via the port P _A , returning hydraulic oil is returned via the useful port T _A tank side into the valve housing 10.

As further from the Fig. 1 results, the valve housing block 10 is transverse drilled and thus has a continuous horizontal central channel 16. In this central channel 16, two spring-loaded valve piston 18, 20 are provided opposite each other. Both valve pistons 18, 20 are longitudinally displaceable within the valve housing 10 in the region of the central channel 16 and guided independently of each other. Furthermore, both valve pistons 18, 20 are supported on an assignable compression spring 22 or 24 as energy storage. The central channel 16 is divided into different spaces and has a first piston chamber 26, in which the first piston 18 is guided longitudinally movable. In his in the Fig.1 shown position, which corresponds to the normal operation of the safety device, the first valve piston 18 assumes its maximum shifted to the left end position, in which the pressure supply port P _{E is} connected to the working port P _A pressurized. Furthermore, a second valve piston 20 is arranged in a further second piston chamber 28, which is guided on the closure element 62, which in its in Fig. 1 shown open position, the fluid-carrying path between the tank port T _E and the other other useful port T _A from the side of the control block 12 releases. In the locked or closed position of the second valve piston 20 of the pertinent fluid path is then interrupted. The indices E used for the terminals P _E , T _E and P _A , T _A stand for input and A for output.

As further from the Fig. 1 shows that the normal operation of the safety device, both valve piston 18, 20 under the action of their respective compression spring 22, 24 in frontal contact with each other and both valve piston 18, 20 are, as already stated, in its open position within the valve housing 10th

The first valve piston 18 consists of several piston parts, wherein the two adjacent piston parts 30, 32 via a piston rod 34 as another Piston part are firmly connected to each other, wherein preferably the piston rod 34 and the guide 32 made in one piece and with the piston member 30, for example by screwing, are firmly connected. The two substantially cylindrically shaped piston parts 30, 32 have on their mutually facing end faces each have a contact surface 36, 38 which are engageable with each adjacent adjacently abutment surfaces 40, 42 in the valve housing 10, which limit the first piston chamber 26 with. As the Fig. 1 In this case, the contact surface 36 of the second piston part 32 in abutment with the one stop surface 40 in the valve housing 10. To form the pertinent stop surface 40 is a spring chamber 44, in which the first compression spring 22 extends, equal in diameter to the adjacent first piston chamber 26 executed, but discontinued in its penetration. Spring chamber 44 and piston chamber 26 have the same diameter; however, the diameter between these spaces 26 and 44 is reduced.

At his in the direction of the Fig. 1 Seen on the left side, the first piston member 30 has a web-like extension 46 in the manner of a control rod, the free end face in abutment with the opposite free end of the second valve piston 20. The second valve piston 20 is with its piston member 48, the crowned and stepped is executed along a central guide 50 in the valve housing 10 guided längsverfahrbar, and in the event of a malfunction at the pressure supply port P _E and / or the tank port T _E , this piston member 48 spring-loaded get into its closed position, as exemplified in the Fig. 2 and 3 is shown for the safety device according to the invention. In the case of the above-mentioned valve pistons 18, 20, a sealing bevel 52, 54 is provided on the respective end face facing the pressure supply port P _E or the other useful port T _A , which is cylindrical, but preferably designed as a sealing cone or sealing dome, and which is designed to run around correspondingly arranged sealing edges, once cylindrical 56 formed, once formed in the manner of a cone 58, which limit the respective piston chamber 26, 28, each formed a seat-tight closing valve.

The cone-shaped sealing edge 58 divides the second piston chamber 28 into two subspaces, the tank port T _E opening radially into the first subspace and the returning user port T _A coming from the control block 12 into the other subspace. In principle, the first piston chamber 26 can also be subdivided into two subspaces, wherein the pressure supply port P _E opens radially into the one subspace and the pressure-supplying useful port T _A leading to the control block 12 into the other pressure chamber. If the sealing slope 52 of the first valve piston 18 is located on the right-hand cylindrical sealing edge 56, which is part of the second stop surface 42 and bounded by the valve housing 10, then these two subspaces of the first piston chamber 26 are also separated from one another and thus the pressure supply port P _{E of} FIG pressure-supplying utility connection P _A separately.

For further understanding of the function of the safety device is still important to know that the pressure supply source 14 and the tank are on the side of the independently movable machine, such as a tractor, and the output Nutzanschlüsse P _A and T _A plus control block 12 are associated with a working equipment , which can be traversed with the tractor, for example for tillage. The valve block 10 is further constructed in the manner of a cartridge system, ie the individual valve components can be integrated into the block 10 from both sides of the block in a screw-in technique. By means of a spring cap 60, the kit with the compression spring 22 can be closed to the outside. Furthermore, in the direction of the Fig. 1 seen on the left side of the valve housing 10, a block-like conclusion about a screw 62 reached, in addition to a Außengewindestrecke on the free end face carries the guide 50 for the piston part 48 of the second valve piston 20.

When in the Fig. 1 shown normal position of the safety device, which corresponds to the normal operation of the respective work machine is located in the first piston chamber 26, the pump pressure of the pressure supply source or hydraulic pump 14, which is supplied via the pressure supply port P _E in this piston chamber 26. This pump pressure acts in both directions, ie in the direction of the Fig. 1 seen to the left and right, on equal areas on the first valve piston 18 a. The resulting resulting force is thus equal to zero. In the illustrated piston position of both valve pistons 18, 20, the tank pressure is applied via the tank connection T _E in the second piston chamber 28. Also, this tank pressure again affects equally from all sides on the second valve piston 20 and triggers in this respect, no movement. Furthermore, the tank pressure is also on the first valve piston 18, as far as this limits the second piston chamber 28 to the right with its left free end face. As long as the mentioned tank pressure does not exceed the spring pressure applied by the first compression spring 22 to the first valve piston 18, so long as the first piston 18 does not experience any movement and the safety device remains in the in Fig. 1 shown normal operating position.

As is clear from the Fig. 2 gives a little more detail, the first piston member 30 with its control rod-like extension 46 as Aufschraubteil on the in the direction of the Fig. 2 seen left free end of the piston rod 34 screwed. Furthermore, the pertinent first piston part 30 has on the outer peripheral side a sealing and guiding system 64, which on the one hand separates the adjacent fluid passages P _A and T _A and on the other hand allows a low-friction guidance of the first valve piston 18 within the central passage 26 of the valve housing 10. Further, the second piston part 32 has lifted from the first stop surface 40, whereas the so far tracked first piston member 30 with its first sealing slope 52 in abutment with the cylindrically shaped first sealing edge 56 within the valve housing 10. Because of the simpler presentation was in the Fig. 2 and 3 dispensed with the presentation of the control block 12. Furthermore, in the Fig. 2 reproduced a kind of accident for the safety device, in which although the pressure line is connected from the side of the pressure supply source or hydraulic pump 14; However, there is no connected tank line to the tank T or the pertinent tank line has dropped, which is in Fig. 2 Stylized at the end of the connecting line with a cross in the circle indicated.

If, as shown, the tank line at the tank connection T _E drops, then the pressure in the subspace of the second piston chamber 28 immediately increases, into which the tank-side service port T _A discharges and its increased pressure from the pulled working machine in the return line via the control block 12 receives. If this last-mentioned pressure exceeds the pressure force applied by the pressure spring 22, then the first valve piston 18 begins to move against the action of its compression spring 22 and closes as shown in FIG Fig. 2 the fluid-conducting connection between pressure supply connection P _E and pressure supply utility connection P _A seat-tight. Tank side, the pressure is thus limited exclusively by the spring force of the first compression spring 22. The further second valve piston 20 then follows the movement of the first valve piston 18 from left to right due to its second compression spring 24, wherein the piston part 48 of the second valve piston 20 passes under the action of its second compression spring 24 in its closed position, while the tank-side utility T _A from tank connection T _E. As a concomitant with the first valve piston 18 in his in the Fig. 2 shown closed position and thus separated the pressure supply port P _E from the pressure supply utility P _A , no more control pressure passes into the control block 12 and therefore it can not dergestalt thus to a pressure increase come as that would be destroyed at the control block 12 connected equipment or otherwise adversely affected.

The in the Fig. 3 The solution shown now relates to the case, which also occurs in practice, that the pressure and tank supply connections P _E and T _E , as shown, are interchanged. If now the pressure supply source or hydraulic pump 14 is switched on, the fluid pressure obviously rises via the tank connection Tε in the second piston chamber 28. At the same time, in turn, the pressure increases in the subspace of the second piston chamber 28 to which the tank side utility T _{A is} connected, and indeed in any case until the second valve piston 20 in his in the Fig. 3 shown closed position passes. If the pressure in the subspace of the second piston chamber 28 in turn exceeds the pressure applied to the first valve piston 18 by the first compression spring 22, this valve piston 18 shifts in the direction of view Fig. 3 seen from left to right against the action of the spring 22. The second valve piston 20 in turn follows this movement due to its second compression spring 24 and thus closes, as already mentioned, the fluid-carrying connection between the tank connection T _E and tankseitigem Nutzanschluss T _A seat-tight. The pressure in the control block 12, the sake of simplicity in the Fig. 3 is also not shown, is then thus limited by the compression spring 22 of the extent acting as a main piston first valve piston 18. Even if, therefore, high pump pressure should come in the direction of the tank connection T _E , this does not lead to any overloading with regard to the hydraulic consumers of the hydraulic circuit connected to the control block 12, because precisely the second valve closes in a seat-tight manner via the second valve piston 20.

In the direction of the Fig. 1 Seen at the top right is the hydraulic symbol reproducing the hydraulic tank pressure protection as shown with the Fig. 1 to 3 in simplified switching symbolism. In summary, it should be noted that even if the connection of one of the supply lines is forgotten or one of the lines unintentionally and autonomously disconnects during operation due to defective, dirty or improperly mounted couplings, it may lead to a failure of the towed work machine, for example Form of a tillage machine comes; However, at no time, even in normal operation, does a pressure situation arise which would lead to such high pressures as to fear a failure of hydraulic components of the hydraulic supply circuit.

Claims (10)

Safety device consisting of at least a valve housing (10), a pressure supply (P _E ) and a tank connection (T _E ), - Two Nutzanschlüssen (P _A , T _A ) and - Two spring-loaded valve piston (18, 20) which are guided longitudinally movable within the valve housing (10). Safety device according to claim 1, characterized in that the valve housing (10) has a first piston chamber (26) in which a first valve piston (18) is guided longitudinally movable, in its open position, the fluid-carrying path between the pressure supply port (P _E ) and the one user connection (P _A ) releases and locks in its closed position .. Safety device according to claim 1 or 2, characterized in that the valve housing (10) has a further second piston chamber (28) in which a second valve piston (20) is guided longitudinally movable, which in its open position, the fluid-carrying path between the tank port (T _E ) and the other further user connection (T _A ) releases and locks in its closed position. Safety device according to one of the preceding claims, characterized in that in normal operation, both valve pistons (18, 20) under the action of their respective compression spring (22, 24) in frontal contact with each other and are so far in their open position. Safety device according to one of the preceding claims, characterized in that the first valve piston (18) of at least two piston parts (30, 32), which are held by a piston rod part (34) at a distance from each other, and at their mutually facing end faces each have a bearing surface (36, 38) for the system with an adjacently arranged stop surface (40, 42 ) in the valve housing (10) which limits the first piston chamber (26). Safety device according to one of the preceding claims, characterized in that the second valve piston (20) with its piston part (48) along a guide (50) in the valve housing (10) is guided longitudinally movable and in the event of a malfunction at the user port (P _A ) and the tank connection (T _E ) spring loaded in its closed position. Safety device according to one of the preceding claims, characterized in that in the case of the valve pistons (18, 20) a sealing bevel (52, 54) extends on that end face which faces the pressure supply connection (P _E ) or the other utility connection (T _A ) , which with correspondingly arranged sealing edges (56, 58) which delimit the respective piston chamber (26, 28), provide a seat-tight closing valve. Safety device according to one of the preceding claims, characterized in that a first valve piston (18) at its one free end side carries a control rod (46), with which it in normal operation and in the event of a fault, in which the pressure supply port (P _E ) and the tank connection (T _E ) are interchanged with each other, in contact with the second valve piston (20) and in the event of a fault in which the tank connection (T _E ) is not connected to a storage tank (T), at an axial distance the second valve piston (20) is located. Safety device according to one of the preceding claims, characterized in that the valve pistons (18, 20), the piston chambers (26, 28) and the two compression springs (22, 24) are arranged coaxially to one another in the valve housing (10) and that connections (P _E , T _E and P _A , T _A ) transverse to this coaxial arrangement in the valve housing (10) engage in a fluid-carrying. Safety device according to one of the preceding claims, characterized in that the pressure supply port (P _E ) and the tank port (T _E ) on the input side (E) of the valve housing (10) are part of a pressure supply device (14) of a working machine, such as a tractor, and in that the two utility connections (P _A , T _A ) on the outlet side (A) of the valve housing (10) open into a control block (12) leading to a further mobile working machine or tillage equipment which can be moved by means of the tractor.

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