EP3679254B1 - Valve - Google Patents

Description

The invention relates to a valve with the features in the preamble of claim 1.

The use of pressure compensators in hydraulically operating lifting devices is state of the art. The document DE 102 02 607 C1 shows an example of the arrangement of a pressure compensator in a lifting device for lifting and lowering loads to influence the lowering behavior, the pressure compensator being arranged in a return line of a relevant lifting cylinder. Another preferred application is the use in lifting devices that are equipped with a lifting mechanism damping that can be activated or deactivated. A pressure compensator ensures that the accumulator pressure at an associated damping accumulator automatically follows the load pressure of the respective lifting mechanism cylinder, both when the lifting mechanism damping is activated and when the lifting mechanism is deactivated. This ensures that if the lifting mechanism damping is activated, after previously deactivated operation, no uncontrolled lifting or lowering of the lifting mechanism can take place.

the WO 2006/084576 A1 describes valve with the features in the preamble of claim 1 with a valve housing which has a control connection and a fluid inlet and a fluid outlet, and with a Control piston arranged longitudinally displaceably in the valve housing, which, against the action of an energy store, in particular in the form of a compression spring, brings the control piston into at least one position forming a fluid-carrying connection between the fluid inlet and the fluid outlet by means of a control pressure prevailing at the control connection, or blocks this connection, in which Control piston a first orifice is arranged, which connects the control connection with a receiving space for the energy storage fluid-carrying, and wherein a second orifice is arranged in an intermediate part in the valve housing, by means of which the receiving space can be connected to a compensation space.

More valves go out of the DE 36 05 980 A1 , the EP 2 698 545 A2 and the EP 3 309 644 A1 emerged.

Based on this prior art, the invention is based on the object of providing a valve which is characterized by particularly favorable operating behavior as a pressure compensator for use in hydraulically operated lifting devices which are provided with lifting mechanism damping.

According to the invention, this object is achieved by a valve which has the features of claim 1 in its entirety.

According to the characterizing part of claim 1, an essential feature of the invention is that the valve is intended for use as a pressure compensator in hydraulically actuated lifting devices and that the compensation chamber is in fluid communication with the fluid outlet. Due to the arrangement of two diaphragms, which on the one hand lead from the control connection to the receiving space with the spring loading the control piston and, on the other hand, lead from the equalizing chamber leading the pressure of the fluid outlet to the receiving space, the valve represents a kind of piloted pressure compensator the two diaphragms with the spring arranged between them, the control pressure of the pressure compensator generated by the spring is increased. This favors a compact design with a small compression spring in the manner of a so-called cartridge valve, which is particularly suitable for use in lifting devices of mobile units, such as forklifts, truck cranes or the like, in which there is limited installation space available for the hydraulic components.

Since, due to the function of the pressure compensator, the pressure on the damping accumulator follows the load pressure on the lifting cylinder, the damping accumulator is automatically discharged when the lifting cylinder is lowered and is reloaded when it is lifted again. The constant charging process, which also takes place in the deactivated damping mode, i.e. with a functionless damping memory, requires pump power, which costs energy and which reduces the lifting speed. In the prior art, to prevent this effect, an additional switching valve is used between the pump side and the pressure compensator, which blocks this connection in the deactivated damping mode and prevents the accumulator from charging in this mode.

In view of this problem, in a particularly advantageous embodiment of the valve according to the invention, the second diaphragm can be closed by means of a pilot control device which can be controlled by an actuating magnet. If an actuating magnet is used, the closing force of which is greater than the hydraulic force acting on the control piston, the pilot oil flow is prevented when the magnet is actuated and the control piston of the pressure compensator is therefore in the closed position, so that the pressure compensator is blocked. This enables the blocking function, which is usually made available by the additional switching valve, to be integrated into the cartridge of the pressure compensator and enables a corresponding saving in terms of construction effort and installation space for the damping device.

In advantageous exemplary embodiments, the pilot control device has a pilot cone which interacts with a valve seat on the intermediate part and on which two energy stores, in particular in the form of compression springs, act in and against the effective direction of the actuating magnet.

The arrangement can advantageously be made in such a way that the compensation space is at least partially accommodated in the intermediate part, which establishes a fluid-conducting connection to a collecting space as a further part of the compensation space that is permanently connected to the fluid outlet via at least one fluid-conducting connection path Valve housing is in communication.

In advantageous exemplary embodiments, the actuation part of the actuation magnet is guided in a connection part of the actuation magnet provided for connecting the actuation magnet to the valve housing, which, at least partially, takes up one energy store of the pilot control device and connects to the intermediate part, the latter and the connection part being stationary on the valve housing are arranged.

In advantageous embodiments, the control piston is designed as a hollow piston, at least in the area of the control connection and at least in the area in which, at least partially, the energy store is accommodated, with one orifice, designed as a screw-in piece, being inserted into the control piston, the two cavities of which permanently connected to each other in a fluid-carrying manner. When the orifice is designed as a screw-in piece, identical control pistons can be fitted with different orifices for the desired function adjustment.

The control piston can advantageously be provided with a stop part on the side of the intermediate part, which is in one and in the other Stop position can be brought into contact with the valve housing or with the intermediate part.

For the design of the valve in the so-called cartridge design, the arrangement can be made such that the control connection is introduced into the valve housing in the axial direction and the fluid inlet and the fluid outlet reach through the valve housing in the radial direction, the hollow piston on the outer circumference with the valve housing Limited annular space, which in the other stop position of the control piston completely passes over the fluid outlet.

The invention also relates to a device for damping the lifting mechanism, the device having the features of claim 10.

Fig. 1

in Symboldarstellung die Schaltung einer hydraulisch betätigbaren, mit einer Hubwerksdämpfung versehenen Hubeinrichtung;

Fig. 2

einen gegenüber einer praktischen Ausführungsform etwa 3½-fach vergrößert gezeichneten Längsschnitt eines Ausführungsbeispiels des erfindungsgemäßen Ventils, das als Druckwaage bei der Hubeinrichtung von Fig. 1 eingesetzt ist;

Fig. 3

in Symboldarstellung die Schaltung einer hydraulisch betätigbaren, mit einer Hubwerksdämpfung versehenen Hubeinrichtung, die als Druckwaage ein Ventil gemäß einem zweiten Ausführungsbeispiel der Erfindung aufweist; und

Fig. 4

einen Längsschnitt des zweiten Ausführungsbeispiels des erfindungsgemäßen Ventils.

The invention is explained in detail below with reference to the exemplary embodiments shown in the drawing. Show it:

Fig. 1

In a symbolic representation, the circuit of a hydraulically actuated lifting device provided with a lifting mechanism damping;

Fig. 2

a compared to a practical embodiment enlarged approximately 3½ times drawn longitudinal section of an embodiment of the valve according to the invention, which is used as a pressure compensator in the lifting device of Fig. 1 is used;

Fig. 3

In a symbolic representation, the circuit of a hydraulically actuated lifting device provided with a lifting mechanism damping, which has a valve according to a second embodiment of the invention as a pressure compensator; and

Fig. 4

a longitudinal section of the second embodiment of the valve according to the invention.

In Fig. 1 a hydraulically actuated lifting cylinder is denoted by 2, by means of whose working piston 4 a load 6 can be raised and lowered. To control the lifting cylinder 2, its working spaces 8 and 10, which are separate from the working piston 4, are connected to a 4/3-way slide valve 12 which can be controlled by a relevant operator and which has a pressure supply connection P and a tank connection T leading to the tank side. The lifting device is provided with a lifting mechanism damper 14, which is connected to the piston-side working space 8 via a connection point 16 and to the rod-side working space 10 of the lifting cylinder 2 via a connection point 18. According to the prior art, the lifting mechanism damping 14 has a hydropneumatic damping accumulator 20, the oil side 22 of which is connected at a connection point 24 to an accumulator line 26.

In order to bring the lifting device into an operating state with deactivated lifting mechanism damping 14 or an operating state with activated lifting mechanism damping 14, two electrically actuated switching valves 28 and 30 are provided, which can be switched against a mechanical restoring force into an open position to activate the lifting mechanism damping 14. In the open position, the switching valve 28 connects the piston-side working chamber 8 of the lifting cylinder 2 via the connection point 16 with the storage line 26. The other switching valve 30 connects the rod-side working chamber 10 of the lifting cylinder 2 with a return line 32 leading to the tank side T in the open position Fig. 1 , in which the state of the deactivated lifting mechanism damping 14 is shown, the switching valves 28 and 30 are in a switching position in the absence of electrical actuation in which the switching valve 28 with a check valve 34 blocks the fluid flow from the working chamber 8 to the storage line 26, but the fluid flow in allows reverse direction. The other In this switching position, switching valve 30 blocks the fluid flow from the rod-side working chamber 10 of the lifting cylinder 2 to the return line 32 with a check valve 36, but enables the fluid flow in the opposite direction.

In the usual way with lifting mechanism damping, a pressure compensator 38 is inserted between the storage line 26 and the pressure supply connection P, the control connection 40 of which is connected via a control line 42 to the connection point 16, which is connected to the piston-side working chamber 8 of the lifting cylinder 2. The load pressure of the working chamber 8 of the lifting cylinder 2 is therefore applied to the control connection 40 via the control line 42. Since the pressure compensator 38 is connected with its input 44 via a charging line 48 to the pressure supply connection P and with its output 46 to the accumulator line 26, the accumulator pressure of the damping accumulator 20 follows the load pressure of the working chamber 8 of the lifting cylinder 2.

When operating the lifting device with deactivated lifting mechanism damping 14, the piston-side working chamber 8 of the lifting cylinder 2 is connected to the tank side T via the 4/3-way valve 12 during lowering operations. At the in Fig. 1 The switching position shown of the switching valve 28 is therefore discharged via its check valve 34 during each lowering operation of the damping accumulator 20. Since the pressure of the damping accumulator 20 follows the load pressure in the working chamber 8 of the pressure cylinder 2 due to the function of the pressure compensator 38, the damping accumulator 20 is charged again via the charging line 48 with each new lifting process. In order to avoid the successive charging processes of the damping accumulator 20 during successive lowering and lifting operations of the lifting cylinder 2 with deactivated lifting mechanism damping 14, a switching valve 50 is inserted in the prior art in the charging line 48 between pressure compensator 38 and pressure supply connection P, which a charging current when lifting mechanism damping 14 is deactivated towards the Damping memory 20 prevents and only releases the charging line 48 when the lifting mechanism damping 14 is activated. In addition, the charging line 48 is protected against a return flow in the direction of the pressure supply connection P by a check valve 52. The one in the Fig. 1 The diaphragm or throttle shown in the control line 42 and the diaphragm or throttle in the charging line 48 (each without a reference number) are used for improved control and coordination of the hydraulic circuit (likewise Fig. 3 ).

the Fig. 2 shows in a separate representation the design of the pressure compensator 38 according to a first embodiment of the invention. The so-called cartridge design valve has a valve housing 54 with an open end 56 and an end which is closed in a pressure-tight manner by a screwed-in end piece 58. With his in Fig. 2 On the left-hand side of the housing section, the valve housing 54 can be installed in a valve block, not shown, in the manner customary for cartridge cartridges. From the open end 56, a guide cylinder 60 extends in the valve housing 54 to a spring receiving space 62 with an enlarged inner diameter of which the bores 64 closest to the open end 56 connect the fluid inlet 44 ( Fig. 1 ) and the other bores 66 the fluid outlet 46 ( Fig. 1 ) form. The open housing end 56 forms the control connection 40 of the valve.

In the guide cylinder 60, a control piston 68 is guided in a longitudinally displaceable manner, which is designed as a hollow piston and is loaded at its inner end by a compression spring 70 provided as an energy store. The end of the compression spring 70 facing away from the control piston 68 is supported on an intermediate part 72, which on the one hand rests on a step 74 of the valve housing 54 and on the other hand rests on the end piece 58 in Is set in the axial direction and seals the spring receiving space 62 by means of a sealing device 76.

The in Fig. 2 As shown in the depressurized state, the control piston 68 is moved by the compression spring 70 into an end position in which the control piston 68 rests with an end stop part 78 on a housing step located at the end of the spring receiving space 62. In the other end position displaced against the force of the compression spring 70, the control piston 68 rests with the stop part 78 on the intermediate part 72. The control piston 68 has an outer annular space 80 into which the fluid inlet 44 formed by the bores 64 opens and whose axially inner end forms a control edge 82. The in Fig. 2 In the illustrated end position of the control piston 68, the depressurized state shown is the control edge 82 in front of the bores 66, so that the fluid outlet 46 is closed. In the control position of the control piston 68 shifted against the force of the compression spring 70, the control edge 82 exposes the connection to the annular space 80, with the control edge 82 completely traversing the bores 66 of the fluid outlet 46 when the control piston 68 is in the right end position.

The control piston 68 designed as a hollow piston has, in the area adjoining the spring receiving space 62, an area tapered in internal diameter with an internal thread 84 into which a screw-in piece 86 is screwed, in which a first orifice 88 is located, which has the control input 40 the spring receiving space 62 connects. In the intermediate part 72 adjoining the spring receiving space 62, a second panel 90 is formed which connects the spring receiving space 62 with a compensation space 92 located in the intermediate part 72, which in turn is connected via radial bores 94 with a collecting space 96, which is as Annular space between the outer circumference of the intermediate part 72 and the inside of the valve housing 54 is located. The collecting space 96 is above inclined connecting sections 98 in the valve housing 54 Fluid ducts in the valve block, not shown, are connected to the fluid outlet 46 formed by the bores 66, so that the pressure of the damping accumulator 20 is effective on the second diaphragm 90 via the connecting paths 98, the collecting chamber 96 and the compensation chamber 92. The combination of the two orifices 88 and 90 with the compression spring 70 in between forms a type of pilot control for the pressure compensator, the pilot oil flow flowing through the second orifice 90 increasing the control pressure generated by the compression spring 70.

the Fig. 3 shows how the Fig. 1 , the circuit of a hydraulically actuated lifting device, wherein the lifting mechanism damper 14 works with a pressure compensator according to a second embodiment of the valve according to the invention, which is shown in Fig. 4 is shown separately in longitudinal section. The valve housing 54 of the second exemplary embodiment corresponds in construction to the first exemplary embodiment, as are the internal components, such as control piston 54 with first aperture 88, compression spring 70, intermediate part 72 as the closure of spring receiving space 62 and second aperture 90. In contrast to the first exemplary embodiment the compensation space 92 formed in the intermediate part 72 is not closed by a closed end piece 58, but is replaced by a connection part 102 screwed into the valve housing 54 for an actuating magnet 104. Like the end piece 58 of the first exemplary embodiment, the connection part 102 rests on the intermediate part 72 for its axial fixing.

The actuation magnet 104 has an axially displaceable actuation part 106 which, when the magnet 104 is energized, in Fig. 4 moves to the left. The actuating part 106, which is guided displaceably in the connection part 102, extends into a chamber 108 formed in the connection part 102, which forms a continuation of the adjoining compensation space 92 in the intermediate part 72. The actuating part 106 is used to control a pilot cone 110, for which a valve seat 112 is formed on the intermediate part 72. This is located on the intermediate part 72 in front of the access to the second panel 90, so that it can be closed by the pilot cone 110. The free end of the actuating part 106 rests against a pressure piece 114 located in the chamber 108, on which a second compression spring 116 is supported with its one end, the other end of which rests against a pressure plate 118 which has a rearward enlarged diameter Part of the valve cone 110 forms. For resetting the pilot cone 110, that is, lifting off the valve seat 112 when the actuating magnet 104 is not energized, a third compression spring 120 is inserted between the pressure plate 118 and the intermediate part 72, the spring force of which is less than that of the other pressure spring 116 resting on the pressure plate 118.

In this arrangement, the second diaphragm 90 can be closed by means of the pilot cone 110 when the magnet 104 is actuated, or can be released by means of the restoring force of the third compression spring 120 when the electromagnet 104 is not actuated. When the second diaphragm 90 is closed by the actuating magnet 104, the pilot oil flow is prevented, so that the control piston 68 closes the connection between the fluid inlet 44 and the fluid outlet 46. When used as a pressure compensator 38 in the lifting mechanism damping 14, as in Fig. 3 As shown, the valve assumes not only the function of the pressure compensator 38 when the lifting mechanism damping 14 is activated, but also the function of the switching valve 50, which blocks the charging line 48, when the lifting mechanism damping 14 is deactivated Fig. 1 and replaces this.

Claims (11)

1. Valve with a valve housing (54), which has a control connection (40) as well as a fluid inlet (64) and a fluid outlet (66), and with a control piston (68), which is arranged so as to be longitudinally movable in the valve housing (54) and, counter to the action of an energy accumulator (70), in particular in the form of a compression spring, by means of a control pressure prevailing at the control connection (40) brings the control piston (68) into at least one position forming a fluid-conducting connection between the fluid inlet (40) and the fluid outlet (66) or blocks this connection, wherein a first orifice (88) is arranged in the control piston (68), which orifice connects the control connection (40) to a receiving chamber (62) for the energy accumulator (70) in a fluid-conducting manner, and wherein a second orifice (90) is arranged in an intermediate part (72) in the valve housing (54), by means of which the receiving space (62) can be connected to a compensating chamber (92), characterised in that the valve is provided for use as a pressure compensator (38) in hydraulically operable lifting devices (2) and in that the compensating chamber (92) is in fluid-conducting connection (98) with the fluid outlet (66).
2. Valve according to claim 1, characterised in that the second orifice (90) can be closed by means of a pilot control device (110) which can be controlled by an actuating magnet (104).
3. Valve according to claim 2, characterised in that the pilot control device has a pilot control cone (110) which cooperates with a valve seat (112) on the intermediate part (72) and on which two energy accumulators (116, 120), in particular in the form of compression springs, act in and contrary to the direction of action of the actuating magnet (104).
4. Valve according to claim 1 or 2, characterised in that the compensating chamber (92) is accommodated, at least in part, in the intermediate part (72) which establishes a fluid-conducting connection (94) to a collecting chamber (96) as a further part of the compensating chamber (92), which compensating chamber is in permanent fluid-conducting communication with the fluid outlet (66) in the valve housing (54) via at least one fluid-conducting connecting path (98).
5. Valve according to claim 3, characterised in that the actuating part (106) of the actuating magnet (104) is guided in a connection part (102) of the actuating magnet (104) which is provided for connecting the actuating magnet (104) to the valve housing (54), which connection part accommodates, at least in part, the one energy accumulator (116) of the pilot control device (110) and connects to the intermediate part (72).
6. Valve according to claim 5, characterised in that the intermediate part (72) and the connection part (102) are arranged fixedly on the valve housing (54).
7. Valve according to one of the preceding claims, characterised in that the control piston (68), at least in the region of the control connection (40) and at least in the region in which the one energy accumulator (70) is, at least in part, accommodated, is configured as a hollow piston, and in that the one orifice (88), configured as a screw-in piece (86) and inserted into the control piston (68), permanently connects the two cavities thereof to each other in a fluid-conducting manner.
8. Valve according to one of the preceding claims, characterised in that the control piston (68) is provided on the side of the intermediate part (72) with a stop part (78) which in the one stop position and in the other stop position can be brought into contact with the valve housing (54) and with the intermediate part (72) respectively.
9. Valve according to claim 7 and claim 8, characterised in that the control connection (40) is introduced into the valve housing (54) in the axial direction and the fluid inlet (64) and the fluid outlet (66) pass through the valve housing (54) in the radial direction, and in that on the outer circumference the hollow piston with the valve housing (54) delimits an annular space (80) which completely crosses over the fluid outlet (66) in the other stop position of the control piston (68).
10. Device for damping lifting gear having a pressure supply source (P), a pressure accumulator device (20), at least one hydraulic consumer (2), in particular in the form of a hydraulic operating cylinder, and a valve according to one of the preceding claims which with a working chamber (8) of the hydraulic consumer (2) is connected in a fluid-conducting manner to the control connection (40) of the valve, the fluid inlet (64) of which is connected to the pressure supply source (P) and the fluid outlet (66) of which is connected to the pressure accumulator device (20).
11. Valve according to claim 10, characterised in that the one working chamber (8), which is connected to the control connection (40) of the valve, is simultaneously connected via a stop valve (28) into the fluid-conducting connection (26) between the valve and the pressure accumulator device (20), and in that a further working chamber (10) of the hydraulic consumer (2) is connected via a further stop valve (30) to a return line (32) towards the tank side (T).

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