EP1360419B1 - Distributing valve for the load-independent control of a hydraulic consumer in terms of direction and speed - Google Patents

Abstract

A directional control valve for a hydraulic load has, in a piston bore of a valve housing, a control piston which can be displaced axially in opposite directions from a central position and which has first fine control grooves for opening a connection between a load chamber and a feed chamber. There are second fine control grooves for opening a connection between a load chamber and a discharge chamber of the piston bore under control. In its central position, there is a restricted relief connection from a load chamber to the discharge chamber via the control piston. The restricted relief connection is obtained via a recess in the control piston, independently of the second fine control grooves.

Description

The invention is based on a directional control valve that is used for load-independent control of a hydraulic consumer in terms of direction and speed serves and which has the features from the preamble of claim 1.

Such a directional valve is from the data sheet RD 64282 / 10.99 from the applicant known. The directional valve then has a piston bore in a valve housing one from a central position axially in opposite directions sliding control piston with which the pressure medium paths between an inlet chamber, the pressure medium can be supplied from a pressure medium source, two together connected drainage chambers via which pressure medium can be discharged to a tank is, and two consumer chambers are controllable. The control piston points first fine control grooves for opening a connection between a consumer chamber and the inlet chamber and second fine control grooves for opening a connection between a consumer chamber and a drain chamber on. There are different variants for the directional control valve, which differ in their design of the control piston. In one variant, the Control piston in its central position from all valve chambers against each other. This Variant can also be described as a variant with a locked middle position. at a second variant is a throttled connection in the middle position or residual opening between the two consumer chambers and the drain chambers. This variant can also be used as a variant with a relieved middle position describe.

In practice, the control piston is the variant with a relieved center position compared to the control piston, which in the middle position the existing consumer chambers shuts off, the second fine control grooves extended so far that they protrude into the consumer chambers when the control piston is in the middle position. The disadvantage here is that with valve actuation at the beginning of the opening the first fine control grooves the flow cross-section between the inlet chamber and the one consumer chamber in comparison to the flow cross section between the other consumer chamber and a drain chamber very much is small. A sensitive control and a clamped procedure of the hydraulic Consumer is not possible in this stroke range. Are between that Directional control valve and the hydraulic consumer still check valves or brake valves switched, so there is a high effort for the coordination of these valves to make the flow cross-sections at the directional valve. Another disadvantage is that a control piston with locked middle position a completely new design the second fine control grooves is necessary.

The invention has for its object a directional control valve that features the preamble of claim 1 has to develop so that a sensitive one even at the beginning of the opening of the first fine control grooves Control of the hydraulic consumer is possible and that the effort for the design of the fine control grooves is reduced.

The desired goal can be with a generic directional valve after the Achieve the invention in that, as in the characterizing part of the claim 1, the relief connection is independent of the second fine control grooves via a recess of the control piston and that when the control piston moves in the sense of a connection Consumer chamber with a drain chamber interrupted the relief connection is before the second fine control grooves open a flow cross section. Accordingly, in the variant with a relieved center position, the second fine control grooves nothing to do with the relief of a consumer chamber. Your Interpretation can therefore be based solely on the desired control of the hydraulic dimensions necessary for the consumer. At a given maximum flow rate, the second fine control grooves for the Valve variant with relieved middle position and for the valve variant with locked Middle position be the same.

Advantageous embodiments of a directional control valve according to the invention can be used take from the subclaims.

According to claim 2, the recess is in the central position of the control piston directly to both a consumer chamber and a drain chamber is open and is in the event of a displacement of the control piston from the Locked middle position to one of the chambers. So here is the throttled Relief in a short way through the recess alone.

The recess can be a recess, which in addition to the Known directional valve already provided recesses on the control piston becomes. In a particularly preferred manner, however, according to claim 3 a recess, which also known directional control valves already have, namely a recess, which serves to report a load pressure, slightly So changed that they bring relief to the consumer chamber can.

The relief can take place directly via the recess. This appears in the case of a directional control valve, as is described in DE 38 without a relieved middle position 41 507 C1 or from EP 0 786 598 is known and in which the load message via radial channels of the control piston takes place in the area of the housing webs between the consumer chambers and the drainage chambers are particularly useful. There are there to make the radial channels in the outer mouth area axially only so large that they are both in the middle position of the control piston to the consumer chambers as well as open to the drain chamber.

In the case of a load message, as in the directional control valve according to the data sheet or in a directional control valve known from EP 0 638 730 A1 is obtained according to claims 3, 4 and 5 including the fluid path for the load message and by adjusting the pressure in the consumer chamber tapping radial channel also a relief in a simple manner a consumer chamber.

Two embodiments of a directional control valve according to the invention are in the Drawings shown. The invention is illustrated by the figures in these drawings now explained in more detail.

Figur 1

das erste Ausführungsbeispiel, bei dem die Verbraucherkammern über den Fluidpfad zur Lastmeldung entlastet werden, und

Figur 2

das zweite Ausführungsbeispiel, bei dem die Verbraucherkammern über zusätzliche Ausnehmungen des Steuerkolbens entlastet werden.

Show it

Figure 1

the first embodiment, in which the consumer chambers are relieved via the fluid path for load reporting, and

Figure 2

the second embodiment in which the consumer chambers are relieved via additional recesses in the control piston.

According to the figures, a continuously adjustable directional valve passes through a valve housing 20, that within a load-sensing control for one hydraulic consumer is used, a piston bore 21 through, in which a control piston 22 is axially movable. The length of the spool 22 agrees with the length of the piston bore 21 from one end face 23 to other end face 24 of the valve housing 20. The piston bore 21 is surrounded by five axially spaced control chambers, the inflow of pressure medium to and the drain from a hydraulic consumer serve and their connections to each other controlled by the control piston 22 become. The middle of the five control chambers is the inlet chamber 27. On both sides there is a consumer chamber 28 or this feed chamber 29. An outlet chamber 32 follows each consumer chamber 28 or 29 or 33, which are not closer to one passing through the valve housing 20 tank channel shown is open.

The control piston 22 takes due to two not shown centering springs attached to the end faces 23 and 24 of the valve housing 20 and the piston bore 21 outward-closing lids are housed, one Middle position. In this middle position, two piston collars 34 and 35 lock of the control piston 22, between which there is an inlet chamber 27 Piston neck 36 with circumferential annular groove 37, the two consumer chambers 28 and 29 against the inlet chamber 27. The two piston collars 34 and 35 are so long that they are in the middle position of the control piston, the consumer chambers 28 and 29 also along the housing webs 38 from the drain chambers able to separate. Each piston collar 34 or 35 is followed by another Piston neck 39 or 40 with an annular groove 41 or 42, each in the area a drain chamber is located. Another is connected to the piston neck 40 Piston collar 43 on the spring chamber in the one cover against the drain chamber 33 seals.

The distance between the drain chamber 32 and the end face 23 is greater than the distance between the drain chamber 33 and the end face 24 of the valve housing 20. Between the drain chamber 32 and the end face 23 are in the piston bore 21 has three axially spaced annular chambers 44, 45 and 46, the middle of these three chambers being referred to as the load reporting chamber 45 is because from there the load pressure to an assigned to the directional control valve however, not shown individual pressure compensator and, if the load pressure is the highest is reported to a pump controller. The, from the load reporting chamber 45 viewed from, to the end face 23 of the valve housing 20 lying annular chamber 44 can be connected to the input of a pressure relief valve. Also to the one between the load reporting chamber 45 and the drain chamber 32 Annular chamber 46, a pressure relief valve can be connected. In the shown central position of the control piston 22 extends to the piston neck 39 following piston section from the front side 23 of the valve housing 20 to in the area of the housing web 47 between the annular chamber 46 and the drain chamber 32. A flat annular groove 49 is screwed into this piston section, via the three ring chambers 44, 45 in the central position of the control piston 22 and 46 are interconnected. Between the ring groove 49 and the piston neck 39 there is a piston collar 48, the effective sealing length of which is less than is the width of the annular chamber 46. The piston collar 48 has on the drain chamber 32 facing outer edge two diametrically opposite each other Milling 50 through which the annular chamber 46 and drain chamber 32 with Small opening cross-section are open to each other when the control piston 22 is in its central position. The control piston 22 is out of its central position moved out, the load reporting chamber 45 depending on the direction of movement of the control piston from the annular chamber 44 or from the annular chamber 46 Cut. In addition, regardless of the direction of movement in the middle position of the control piston 22 via the annular chamber 46 existing connection the load reporting chamber 45 to drain chamber 32 closed by the load reporting chamber 45 from the annular chamber 46 or the annular chamber 46 from the drain chamber 32 is separated.

Located on both ends of each of the two piston collars 34 and 35 diametrically opposite each other two fine control grooves 55 and 56, the Cross section becomes larger towards the front edges. The fine control grooves are enough from the front edges only so far into the piston collars that their inner End in the central position of the control piston 22 still a distance from the consumer chambers 28 or 29 has. Are in the central position of the control piston 22 So the consumer chambers via the fine control grooves neither with the inlet chamber 27 still fluidly connected to the adjacent drain chamber 32 or 33.

An axial bore 57 passes through the control piston 22 and connects to the two Ends is closed. The control piston 22 has in the region of the annular groove 49 a narrow radial bore 62 which extends from the outside to the axial bore 57 and which acts as a nozzle or throttle. The axial bore 57 is also two Radial bores 58 and 59 crossed, of which the radial bore 58 through the Piston collar 34 and the radial bore 59 through the piston collar 35 of the control piston 22 passes through. The radial bores 58 and 59 are in the axial Seen direction, are still within the extent of the fine control grooves 55 but offset by 90 degrees to these. They have such a diameter and from the end edge of the respective one facing the inlet chamber 27 Piston collar 34 and 35 such a distance that they are in the middle position of the control piston 22 at a short distance from a consumer chamber 28, 29 would be covered by the wall of the piston bore 21. In which This is the case for the exemplary embodiment according to FIG. 2.

In the embodiment of Figure 1, however, is eccentric on the two opposite mouths of each radial bore 58 and 59 and the radial bores overlying a blind hole 60 or 61 of shallow depth, whose diameter is larger than the diameter of the radial bores. In the The central position of the control piston 22 exists between the blind bores 60 and the consumer chamber 28 and between the blind bores 61 and the consumer chamber 29 a flow cross section.

Thus, in the embodiment of Figure 1 in the middle position of the Control piston 22, the consumer chamber 28 via the blind bores 60 and Radial bore 58 and the consumer chamber 29 via the blind bores 61 and the radial bore 59 as well as the consumer chamber 28 via the axial bore 57, the radial bore 62, via the annular groove 49 of the control piston 22, over the annular chamber 46 of the piston bore 21 and over the cutouts 50 fluidly connected to the drain chamber 32. The connection is over the nozzle action of the radial bore 62 a throttled connection. about the connection can thus be hydraulic fluid in one from the consumer chambers small current flow to the drain chamber 32 and thus to a tank. This relieves the consumer chambers of pressure, so that for example Check or brake valves between the consumer chambers and one hydraulic consumers are arranged to work safely. A burden that is supported on a consumer chamber if there is no check valve, moves slowly.

The consumer chambers are relieved without including the fine tax slots 56, so that they can be designed exactly as with a directional control valve without throttled relief of the middle position. From the spool one Such a directional control valve differs from the control piston 22 of the exemplary embodiment of the invention according to FIG. 1 only through the additional blind bores 60 and 61.

If the control piston 22 moves out of the middle position, in the view according to FIG. 1 For example, moved to the right, the blind holes 60 are covered and the flow area between them and the consumer chamber 28 closed before this consumer chamber via the fine control grooves 56 is connected to the drain chamber 32 on the piston collar 34. Is locked also the connection between the annular groove 49 on the control piston 22 and the Drain chamber 32. The radial bore 59, however, remains to the consumer chamber 29, which is now connected to the inlet chamber 27 via the fine control grooves 55 is open so that a load message is possible. When the control piston moves 22 from the middle position to the left are the blind holes 61 covers and the radial bores 58 remain open to the consumer chamber 28.

In the exemplary embodiment according to FIG. 2, the radial bores 58 and 59 are sufficient except for the outside of the piston collars 34 and 35 and are in the middle position of the control piston 22 covered by the piston bore 21. For the throttled Everyone has discharge of the consumer chambers 28 and 29 in the middle position Piston collar 34 and 35 two opposite, axially extending, Narrow grooves 70 and 71 on the 22 in the central position of the control piston along the housing webs 38 an immediate throttled connection between the consumer chambers and the drainage chambers. In the middle position of the control piston, the grooves 70 and 71 only extend as far into the consumer chambers and the drain chambers into that fluid communication through them interrupted when the control piston 22 moves from the central position before fine control grooves 55 and 56 open to the consumer chambers. In the exemplary embodiment according to FIG. 2, the throttled also takes place Relief for the consumer chambers without the inclusion of fine tax slots 56.

Claims (5)

1. A directional control valve for the control, in particular the load-independent control, of a hydraulic consumer in terms of direction and speed, comprising a control spool (22) which can be displaced axially in opposite directions from a central position in a spool bore (21) of a valve housing (20) with which the pressure medium paths can be controlled between a feed chamber (27), to which pressure medium can be fed from a pressure medium source, a discharge chamber (32, 33), via which pressure medium can be led away to a tank, and two consumer chambers (28, 29), which has first fine control grooves (55) for opening under control a connection between a consumer chamber (28, 29) and the feed chamber (27), and second fine control grooves (56) for opening under control a connection between a consumer chamber (28, 29) and the discharge chamber (32, 33), and via which, in the central position, there is a restricted relief connection from a consumer chamber (28, 29) to the discharge chamber (32, 33),
   characterized by the fact that the relief connection exists via a recess (60, 61, 70, 71) in the control spool (22), independently of the second fine control grooves (56), and that, in the event of displacement of the control spool (22) with the effect of connecting the consumer chamber (28, 29) to the discharge chamber (32, 33), the relief connection is interrupted before the second fine control grooves (56) open a flow cross section.
2. A directional control valve according to claim 1, characterized by the fact that, in the central position of the control spool (22), the recess (70, 71) is directly open both to a consumer chamber (28, 29) and to a discharge chamber (32, 33) and, in the event of displacement of the control spool (22) from the central position, is shut off with respect to one of the chambers (28, 29, 32, 33).
3. A directional control valve according to claim 1 or 2, characterized by the fact that, in the event of displacement of the control spool (22) with the effect of connecting a consumer chamber (28, 29) to the feed chamber (27), the recess (60, 61) remains open to the consumer chamber (28, 29), and that the recess (60, 61) lies in a fluid path serving to feed back a load pressure.
4. A directional control valve according to claim 3, characterized by the fact that the fluid path has a radial bore (58, 59) to tap off the load pressure prevailing in a consumer chamber (28, 29), and that the recess (60, 61) is formed by an enlargement of only the opening region of the radial bore (58, 59).
5. A directional control valve according to claim 3 or 4, characterized by the fact that, in the region of a consumer chamber (28), the control spool (22) has a first spool collar (34) with first fine control grooves (55) and second fine control grooves (56), a first annular groove (41) adjoining the first spool collar (34) in the region of a discharge chamber (32), a further spool collar (48) adjacent to said annular groove (41) and a further annular groove (49) adjacent thereto, that the recess (60) belongs to a first radial duct (58) of the first spool collar (34), that the control spool (22) has an axial bore (57) which is met by the first radial duct (58) and, at an axial distance from the first radial duct (58), is met by a second radial duct (62), which on the outside opens into the further annular groove (49), that, isolated from the discharge chamber (32) by a housing land (47), around the spool bore (21) there runs an annular chamber (46) whose width is greater than the effective width of the further spool collar (48), and that the further spool collar (48) and the annular chamber (46) are located in relation to each other in such a way that, in the central position of the control spool (22), the further annular groove (49) is open to the discharge chamber (32) via the annular chamber (46) but, following a short travel of the control spool (22) from the central position, is isolated from the discharge chamber (32) by the further spool collar (48).

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