EP3018364B1 - Control device with sliding piston - Google Patents

Description

The invention relates to a control device according to the preamble of patent claim 1.

In a generic, from EP 2 157 320 A1 known control device is set to a pressure-responsive responsive secondary pressure relief valve in the load pressure signal circuit value of the secondary pressure within the same Auslenkhubs the spool from the center position by means of a parallel proportional seat valve disposed in a line leading from the load pressure signal to the tank and actuated by a proportional solenoid. This proportional seat valve requires considerable circuitry, line technology and control technology overhead and to control either the sampling of Auslenkhubs the spool and / or the pressure conditions in the hydraulic consumer.

Such control devices with a proportional directional spool and secondary pressure limiting are well known. For example, the technical information document "The HAWE Universe" under "current product program" of the company HAWE Hydraulik SE, D-81673 Munich, with the printing notice: K 177-00 DE 2009 (see also: info@hawe.de) on the pages 2.1- 29, bottom right, 2.1- 31, top right and 2.1- 33 bottom right, such control devices in which the proportional directional spool a secondary pressure relief valve associated with a deflection or two secondary pressure relief valves for both Auslenkrichtungen the spool. In such control devices, when the proportional directional spool has actuated the hydraulic consumer and the load pressure is increasing, the secondary pressure relief then responds at a constant limit, thereby turning the load pressure signal circuit into a constant pressure system. If, for example, the hydraulic consumer then attacks, unnecessary hydraulic energy is destroyed, which means a significant loss of energy.

This will be explained on the basis of a forest crane with which tree trunks are manipulated. The forest crane has a gripper operated by a hydraulic consumer, with which the gripped tree trunks are held, and further hydraulic consumers for moving the gripper. Since the gripper usually no load-holding valves are installed because of unnecessary costs and deteriorated dynamics of the tree trunks holding gripper would slowly open in the middle position of the gripper-proportional directional spool, since the spool only slider-tight and leakage to the tank occurs. For this reason, for loading or stowing the gripped tree trunks, the motion control is used with the same active gripping function. For example, the crane operator does not press the pedal for the gripping function, provided that the tree trunks are not too heavy, only to reliably hold tree trunks in the gripper. The crane operator makes this intuitively as he moves gripped tree trunks. Here, the pedal deflection, so the deflection of the piston valve from the center position, no longer matters, but there is the constant limit for the maximum force required in this deflection gripping force, as long as the gripper holds the logs pressed together, although a lower gripping force would be sufficient. When so actuated gripping function of the load pressure signal circuit operates as a constant pressure system, whereby hydraulic energy is destroyed. Similar, hydraulic energy-destroying operating situations are also found in hydraulic excavators or similar hydraulic implements.

Further prior art is contained in DE 10 2012 220 445 A1 and EP 0 309 987 A1 ,

The invention has for its object to provide a control device of the type mentioned, with the, e.g. For such in practice more frequently occurring operating situations unnecessary hydraulic energy losses can be minimized. The stated object is solved with the features of claim 1.

In the control device, within a part of the deflection stroke of the piston valve, e.g. a lower limit is set and in another part of the Auslenkhubs a higher limit, each from the load pressure in the load pressure signal circuit as a so-called secondary pressure In this way, a favorable energy loss and Kolbenschieber- hubabhängige, e.g. realized two-stage, secondary pressure limiting in the same direction of deflection, is saved by the hydraulic energy when the higher limit is not necessary. The change of the limit may be in stages or even proportionally according to an appropriate law. The limit is changed by disconnecting a secondary pressure relief valve from the load pressure signal circuit, i. the secondary pressure relief valve sets in a certain part of Auslenkhubs a low limit before within the same Auslenkhubs after disconnecting the secondary pressure relief valve from the load pressure signal circuit, the load pressure further to a higher limit and thus, for example via a feed regulator, the operating pressure of the hydraulic consumer increases, for example until the response of a main system pressure relief valve.

The spool itself allows the limit value to be changed within the same Auslenkhubs because the second or first bypass structure initially a single secondary pressure relief valve can be effective and this is dependent on the load pressure signal circuit or the load pressure signal, or at two for the two Auslenkrichtungen the spool provided secondary pressure relief valves for different limits simultaneously with the first bypass structure both secondary pressure relief valves can be acted upon by the load pressure signal and stroke dependent only the secondary pressure relief valve set to the higher limit.

In an expedient embodiment of the control device, two differently preset secondary pressure relief valves, e.g. for the Auslenkhübe from the center position in both directions, provided, wherein the change of the limit within the same Auslenkhubs by switching from a secondary pressure relief valve to the other or by applying both, depending on the Auslenkhub the spool.

In an expedient embodiment of the control device with two secondary pressure relief valves for the two deflection directions set to different limit values, a first connection pair, preferably a recess pair, is provided in the bore for the spool, of which one connection is connected to a secondary pressure relief valve and a second Connection is connected to the load pressure signal circuit, preferably via a throttle. In the scope of the spool, a first, the first pair of terminals for mutual connection overrunning bridging structure is provided, preferably a group of bridging recesses. Further, in the bore a second pair of connections, preferably a recess pair, provided axially offset from the first terminal pair, of which a terminal is connected to the other secondary pressure relief valve and the other terminal is connected to the load pressure signal circuit, preferably via a throttle. In the scope of the spool, a second bridging structure, preferably a group of indentations, is provided axially offset from the first bridging structure, which pass over the terminals of the second connection pair so that, depending on the deflection stroke, the load pressure signal circuit is connected to a secondary pressure limiting valve is, while the other secondary pressure relief valve is separated from the load pressure signal circuit, and in another part of the same Auslenkhubs the load pressure signal circuit with the other secondary pressure relief valve or both is connected simultaneously. At the same time, when the low limit is set, even the secondary pressure relief valve set to the higher limit can remain connected to the load pressure signal circuit because it will not respond. On the other hand, the set to the low limit secondary pressure relief valve is separated from the load pressure signal circuit or insulated from the fed load pressure signal so that only the set to the higher limit secondary pressure relief valve responds. Alternatively, even for each deflection direction, a plurality of differently set secondary pressure limiting valves and correspondingly many bridging structures could be provided.

Expediently, in each case one connection of each connection pair is connected to a control side of a supply regulator pressure compensator arranged in a pump line to a pump connection of the proportional directional valve. The inlet regulator pressure compensator keeps constant the pressure difference set by the position within the deflection stroke via the spool, depending on the respective limit value.

In an expedient embodiment, the higher limit value acts in an end part of the Auslenkhubs of the spool from the center position, and previously the low limit, so that the hydraulic consumer is acted upon only at the end portion of the Auslenkhubs at full pressure.

In another embodiment, the higher limit in an initial part and an end part of the Auslenkhubs acts from the center position, and the low limit acts in an intermediate part between the initial part and the end part of the Auslenkhubs.

In a further embodiment, for example, over the entire Auslenkhub a deflection direction from the center position continuously acts either the higher or the lower limit. In the case of a forest crane, for example, this can be the deflection stroke, via which the gripper is relieved and / or opened.

In a further embodiment, for example, the low limit value is set by a secondary pressure limiting valve, and the higher limit value is set either at a further secondary pressure limiting valve or corresponds to a pressure in the load pressure signal circuit which is not set by any secondary pressure limiting valve.

Fig. 1

ein Blockschaltbild einer Steuervorrichtung,

Fig. 2

einen Ausschnitt dieser Steuervorrichtung in einer ersten Position eines Schieberkolbens bei dessen Auslenkhub,

Fig. 3

einen Ausschnitt der Steuervorrichtung in einem weiteren Teil des Auslenkhubs des Schieberkolbens,

Fig. 4

eine Detailvariante,

Fig. 5

eine Detailvariante, und

Fig. 6, 7 und 8

Diagramme von Grenzwerten eines Sekundärdrucks über die beiden Auslenkhübe des Kolbenschiebers aus der Mittelstellung,

Embodiments of the subject invention will be explained with reference to the drawing. Show it:

Fig. 1

a block diagram of a control device,

Fig. 2

a detail of this control device in a first position of a spool at the Auslenkhub,

Fig. 3

a detail of the control device in a further part of the Auslenkhubs the spool,

Fig. 4

a detail variant,

Fig. 5

a detail variant, and

FIGS. 6, 7 and 8

Diagrams of limits of a secondary pressure over the two Auslenkhübe the spool from the center position,

Fig. 1 illustrates a control device S for a hydraulic consumer H, for example, a forest crane or excavator, in the non-actuated state, optionally not shown further control devices can be linked to the control device S shown, for example, for further hydraulic consumers.

The control device S comprises a proportional directional spool 1 (4/3-proportional directional spool in the illustrated embodiment, as a non-limiting example) operable by two proportional solenoids and pressure pilot controls, and containing a spool R in a bore V. By means of the proportional directional spool 1 of the hydraulic consumer H is adjusted via working lines A, B in opposite directions, and indeed independent of load and proportionally.

The proportional directional spool valve 1 in the embodiment shown as secondary pressure relief K two secondary pressure relief valves 2, 3 associated with the secondary pressure relief valve 2 for the Auslenkhub for applying the power A to a higher limit P1 ( Fig. 6 to 8 ) is set, however, the secondary pressure relief valve 3 for the opposite Auslenkhub (working line B) to a low limit P2 ( Fig. 6 to 8 ).

The spool R is from the center position shown in a switching position a (act on the working line A, relieve the working line B to a tank line T) adjustable. In the other direction of deflection of the spool T from the center position is a switching position set (working line A to tank line T relieved, working line B applied), in the FIG. 1 is divided into two parts b ', b, although it is the same switching position. It is the secondary pressure relief valve 2 of the switching position b, b 'assigned, however, the secondary pressure relief valve 3 of the switching position a. Furthermore, a feed regulator pressure compensator 4 is provided in a pump line P. The inlet regulator pressure compensator 4 is acted upon on the control side by a spring and a control line 27, and at the closing control side via a control line which branches off from the output side of the inlet regulator pressure compensator 4.

In an embodiment not shown, only a single secondary pressure relief valve 2 or 3 could be provided, or could be provided for each or a deflection several different set secondary pressure relief valves.

In the slide bore V 1 different connections are provided in a housing, not shown, the proportional directional spool. A connection 7 of the working line B is arranged centrally and adjacent thereto a connection 8 of the working line A. For tapping the load pressure in the working line B, a connection 9 is used, whereas for tapping the load pressure in the working line A a connection 10 is located adjacent to this Connection 11 to the tank line T.

Also in the opposite side of the slide bore V more connections are provided, namely a terminal 12 which is connected via a control line 30 to the control line 27, in addition to this a connection 13 which is connected via a control line 25 to the secondary pressure relief valve 2 , then a port 14 connected to a load pressure signal circuit LS, then a port 15a connected to a line 6b to the tank line T, then a port 16 connected to the pump line 5, P from the regulator pressure compensator 4 , and a port 15b, which is connected to a line 6a also to the tank line T, a port 19 which is connected to a control line 28 with a throttle 29 to the control line 27 and the load pressure signal circuit LS. Another connection 17 is connected via a control line 26 to the secondary pressure limiting valve 3. Both secondary pressure relief valves 2, 3 are connected on the output side to the tank line T. Then follows a terminal 18, which is also connected to the control line 27 and aligned with the opposite terminal 11.

In the spool R connections are included, in the section for the switching position b ', b, first, a first bridging structure 20 for connecting the terminals 12, 13, a Channel 21 for connecting the terminals 9, 14, a channel 22 for connecting the terminals 16 and 7, a channel 23 for connecting the terminals 8 and 15b and, as the core of the invention, only for the switching position b, ie not in the part of Shift position portion b ', a second lock-up structure 24 for connecting terminals 17 and 18. The respective lock-up structure 20 and 24 may be formed as a group of bridging recesses in the circumference of the spool T, the groups being axially spaced from each other and are only within part of the length of the section. Alternatively, these could also be control notches or longitudinal grooves. The terminals 12, 13, 17, 18 may be two Einichpaarare.

In the other portion (switch position a) of the spool R connections are also provided, namely a channel 23a for connecting the terminals 7 and 15a, a channel 22a for connecting the terminals 16a and 8, a channel 21a for connecting the terminals 10 and 19. Further is a bridging structure 20 'is provided for the switching position a, with the terminals 17 and 18 are connected in the switching position a.

In the middle position, only the terminals 11, 18 are connected via the spool R in order to relieve at least the control line 27.

Fig. 2 illustrates the switching position b 'of the spool R. Here, the load pressure from the working line B via the channel 21 from the terminal 9 to the terminal 14 and from this in the load pressure signal LS and via the control line 28 and the throttle 29 is transmitted to the control line 27. At the same time, the bridging structure 20 connects the ports 12 and 13 so that the load pressure is transmitted via the control line 30 to the control line 25 and within the initial part of the Auslenkhubs to the secondary pressure relief valve 2.

In this switching position b 'is set with a corresponding increase in the load pressure from the secondary pressure relief valve 2, the higher limit value P1, which also acts in the control line 27. The control line 26 is shut off so that the secondary pressure limiting valve 3 (with the low limit value P2) remains disconnected.

Within an end portion of the same Auslenkhubs the spool R is in Fig. 3 shown switching position b produced. The first bypass structure 20 transfers the pressure from the port 13 into the control line 25 to the secondary pressure limiting valve 2, while at the same time the second bypass structure 24, the load pressure signal from the terminal 14 via the control lines 30, 27 in the control line 26 to the secondary Pressure relief valve 3 transmits. This responds at the low limit P2, whereas then the secondary pressure relief valve 2 does not respond.

In the 4 and 5 Alternative solutions for the function of changing the limit are indicated. Other alternative solutions could use a solenoid valve or a proportional solenoid valve for this function (not shown).

In Fig. 4 is a closing spring 33 of the secondary pressure relief valve 2 (3) associated with a black / white magnet 31 which is switched by a higher-level control device 32, which is informed for example about the position of the spool R within the Auslenkhubs. With the black / white magnet 31, the bias of the closing spring 33 can be changed, which defines two limits.

In Fig. 5 is the secondary pressure relief valve 2 (3) associated with a proportional solenoid 34 which is energized by a higher-level control device 32 and the bias of the closing spring 33 can be changed either in steps or continuously, whereby the limit changes accordingly.

The Fig. 6 to 8 illustrate in diagrams different examples of the secondary pressure limitation K. The secondary pressure 35 is applied vertically and via the opposite Auslenkhübe 36, 37 of the spool R from the center position. These examples are not limiting, but suggest that many variations are possible.

In the one deflection 36 (working line A) is in Fig. 6 the lower limit value P2 is controlled via an initial part 39 of the deflection stroke from the middle position, and the higher limit value P1 only via an end part 40. In the opposite direction of deflection 37 (working line B), however, the higher limit value P1 is set over the entire deflection stroke 38.

In Fig. 7 is set in the deflection 36 via an initial part 42 of the Auslenkhubs the higher limit value P1, and also on the end portion 40. In the intermediate part 41, however, the low limit value P2 is set. In the opposite deflection direction 37, the higher limit value P1 is set over the entire deflection stroke 38.

In Fig. 8 is in Auslenkrichtung 36 as in Fig. 7 method, however, is set in the deflection 37 over the entire Auslenkhub 38, the low limit P2.

If only one secondary pressure limiting valve 2 or 3 is provided for a respective deflection stroke in an embodiment not shown, then this is acted upon in a part of the Auslenkhubs with the load pressure signal, and separated in a further part of the load pressure signal until it becomes higher.

In the case of a forest crane, for example, in the interpretation according to Fig. 6 the gripper is operated via the initial part 39 in accordance with the low limit value P2, which is sufficient to hold gripped tree trunks safely, while the gripper is moved by another hydraulic consumer, not shown. The crane operator intuitively actuates the pedal only so far that it remains in the starting area 39 when moving the gripper filled with the tree trunks. Only if particularly heavy tree trunks are to be kept and the pedal is fully deflected, the hydraulic consumer is operated with the higher limit P1.

Claims (9)

1. Control apparatus (S) for at least one hydraulic consumer (H) with a proportional way valve (1) including a valve piston (R), which is displaceable from a central position in a bore (V) in a housing, and at least one secondary pressure limiting valve (2, 3), with which a threshold value (P1, P2) of a load pressure may be set as a secondary pressure (35) in a load pressure signal circuit (LS), wherein the threshold value (P1, P2) of the secondary pressure (35) on displacement of the valve piston (R) from a central position of the proportional way valve (1) within its displacement stroke (36) may be altered, characterised in that the threshold value (P1, P2) is alterable by isolating the at least one secondary pressure limiting valve (2, 3) from the load pressure signal circuit (LS) within a part of the same deflection stroke.
2. Control apparatus as claimed in Claim 1, characterised in that the threshold value (P1, P2) is alterable in dependence on the displacement stroke of the valve piston (R).
3. Control apparatus as claimed in at least one of the preceding claims, characterised in that two secondary pressure limiting valves (2, 3), preset to different threshold values (P1, P2), are provided for the two displacement strokes from the central position and that the threshold value (P1, P2) is alterable within the same displacement stroke by switching over from one secondary pressure limiting valve (2) to the other secondary pressure limiting valve (3) or pressurising both secondary pressure limiting valves (2, 3).
4. Control apparatus as claimed in Claim 3, characterised in that for at least one displacement stroke in the bore (V), a first pair of connections (12, 13), preferably a pair of tappings, is provided, of which one connection (12) is connected indirectly, preferably via a throttle (29), to the load pressure signal circuit (LS) and the other connection (13) is connected to the one of the two secondary pressure limiting valves (2, 3), set to different threshold values for the two displacement strokes from the central position, that provided in the periphery of the valve piston (R) for the bridging connection of the connections of the first pair of connections (12, 13) there is a first bridging structure (20), which passes over only the first pair of connections (12, 13) in the bore and with which the connections of the first pair of connections (12, 13) are connected together over a portion of the displacement stroke of the valve piston (R) from the central position, that a second pair of connections (17, 18) is provided in the bore (V) axially offset from the first pair of connections (12, 13), of which one connection (18) is connected indirectly, preferably via a throttle (29), to the load pressure signal circuit (LS) and the other connection (17) is connected to the other of the two secondary pressure limiting valves (2, 3), that provided axially offset from the first bridging structure (20) in the periphery of the valve piston (R) for the bridging connection of the connections of the second pair of connections (17, 18) there is a second bridging structure, preferably a group of bridging recesses, passing over only the second pair of connections (17, 18) in the bore, with which within a further portion of the same displacement stroke the connections of the second pair of connections (17, 18) are connected together and simultaneously the connections of the first pair of connections (12, 13) are connected via the first bridging structure (20) so that the load pressure signal circuit (LS) is connected within the one portion of the displacement stroke to one secondary pressure limiting valve and is connected within the further portion of the displacement stroke to both or to other secondary pressure limiting valves (2, 3).
5. Control apparatus as claimed in Claim 4, characterised in that the connection (12, 18) connected indirectly to the load pressure signal circuit (LS), of each pair of connections (12, 13; 17, 18) is connected to an open control side of a feed controller pressure compensator (4) arranged in a pump conduit (P) to a pump connection (16) of the proportional way valve (1).
6. Control apparatus as claimed in at least one of the preceding claims, characterised in that the secondary pressure (35) is raised in an end portion (40) of the same displacement stroke (36) out of the central position from a low threshold value (P2) to a higher threshold value (P1).
7. Control apparatus as claimed in at least one of the preceding claims, characterised in that the secondary pressure (35) is raised in an initial portion (42) and an end portion (40) of the same displacement stroke (36) out of the central position in each case to a higher threshold value (P1) and in an intermediate portion (38, 41) between the initial portion and the end portion a lower threshold value (P2) is set.
8. Control apparatus as claimed in at least one of the preceding claims, characterised in that the secondary pressure (35) within the same displacement stroke from the central position is continuously the higher or the lower threshold value (P1, P2) and that the threshold value (P1, P2) is altered at least once in the opposite displacement stroke.
9. Control apparatus as claimed in at least one of the preceding claims, characterised in that a lower threshold value (P2) is set on one secondary pressure limiting valve (3) and that a higher threshold value (P1) is set either at a further secondary pressure limiting valve (2) or corresponds to a pressure in the load pressure signal circuit (LS) limited by no secondary pressure limiting valve (2 or 3).

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