EP1024299B1 - Hydraulic directional control valve - Google Patents

Abstract

The distributor incorporates a regulating balance in the form of a plunger (14) which moves in a bore (13) under the effect of a pressure differential created by inlet pressure on one face and a load pressure on the other. In a zone adjacent to the first end (12) of the plunger the bore wall and/or the plunger has at least one calibrated passage (30) designed to establish a link between the plunger end and a lateral orifice (21) in the bore when the plunger is forced into its end position by an extreme load above the normal inlet pressure. This ensures a flow of fluid at a low rate to the orifice and provides for a slow movement of the hydraulic receiver controlled by the distributor.

Description

The present invention relates to improvements made to hydraulic distributors comprising a regulatory balance capable of ensuring most charge pressure detection function high, an anti-saturation function and a flow division independent of the load, this balance comprising a plunger movable in a housing under the action a pressure differential generated by the intake pressure supplied by a hydraulic source applying to a first its ends and by the highest charge pressure applying to its other end, said plunger being clean also to be released, in proportion to the above differential of pressure, a side port of the housing connected to a port of distributor work to deliver hydraulic fluid under the intake pressure reduced by the above differential pressure.

In Figure 1 of the accompanying drawings is shown for example, in cross section, a method of known realization of such a distributor as it appears in FIG. 1 of document FR-A 2 689 575 in the name of the Applicant.

The dispenser comprises a body 1 provided with a orifice P for admission of the pressurized fluid in from a hydraulic source (not shown). In the example shown, said orifice P is constituted under shape of a channel 2 crossing the body 1 transversely on the drawing plane and opening on both sides main of said body serving as support during stacking side by side and one against the other of several distributors. At least one orifice T (formed as of a channel crossing the body 1 transversely to the plane of the drawing and opening onto the two main faces said body) is used for the return of the fluid to a reservoir (not shown). Two working ports A, B are connectable to a hydraulic device or receiver (not represented). A distribution drawer 4 is suitable for slide in a bore 5 which crosses longitudinally the body 1 and opens on two opposite end faces 6, 7 of it. Conventionally, the body 1 and the drawer 4 have passages and / or pipes and / or grooves arranged to cooperate with a view to to establish and / or interrupt the connections between various orifices P, A, B, T of the distributor body according to the axial position occupied by the slide in the bore. The specific arrangements of these passages and / or pipes and / or grooves are determined by the man of the profession in relation to the desired functions for the distributor.

Furthermore, in this specific example, the body 1 has yet another transverse channel 8 extending between the main faces of the body and combined with at minus a pressure selector for transmitting, in a channel 18 located downstream of the distributor drawer 4, strongest (load sensing pressure or LS pressure) of the two pressures constituted respectively by the pressure in said channel upstream of the distributor and the distributor working pressure.

Channel 2 connected to the intake port P opens into the bore 5 of the body in a chamber intake 10 thereof, near which a another room 11 communicates, through a passage 12, with a housing 13 in which is mounted to slide freely seals a plunger 14. The passage 12 opens into the housing 13 at one end of it, here the end lower (corresponding to an end face of the plunger 14, here its lower end), while at its opposite end (here its upper end) the housing 13 opens into a cavity 15 in which can move the head 16 of the plunger 14. The enlarged head 16 relative to the body of the diver, can rest on a shoulder formed at the outlet of the housing 13 in the cavity 15 to retain the plunger 14. A spring 17 is provided in the cavity 15 to repel the plunger 14 against said shoulder so as to fix its position in the absence of pressure. The aforementioned channel 8 leads into the cavity 15, so that the pressure in the channel 3 is also present in cavity 15 and is then exerted on the corresponding end of the plunger 14 (here its upper end).

In addition, the plunger 14 is crossed by a channel axial 18 opening, on one side, into its end face opposite passage 12 and, on the other side, in a canal diametral 19 passing through the plunger 14 and disposed of so as to be closed by the wall of the housing 13 when the plunger 14 is in the rest position imposed by the spring 17 (shown in Figure 1) or in a position not completely raised. Part 28 of the axial channel 18 is arranged in the form of a restriction or a nozzle.

The portion of the drawer 4 which extends, in position neutral, between chambers 10 and 11 by isolating them one on the other is provided with progressivity notches 20 intended to ensure a controlled flow of the fluid hydraulic in the correct direction when the drawer is moved one way or the other.

From the aforementioned housing 13 extend, in two approximately diametrically opposite directions, two conduits 21 in which one or in each of which is arranged a non-return valve 22, the two conduits 21 opening, in bore 5, in two chambers respective 23.

Near bedrooms 23, two bedrooms respective distribution 24 of bore 5 are combined, by conduits 25, to the working orifices orifices distributor A and B respectively.

Finally, beyond the distribution chambers 24, respectively two return chambers 26 of bore 5 are connected, by conduits 27, to the return channel 3 leading to the return orifice T.

The operation of the distributor which has just been described is detailed in the document FR 2 689 575 already cited, to which reference may be made.

Although a distributor arranged as it has just been described gives satisfaction in its general principle of realization, however, it has a drawback in certain operating conditions. Such dispenser is not intended to be used alone, but to be associated with several other distributors of the same type to constitute a distribution device multiple hydraulics. Distributors are then preferably stacked tightly against each other others by their main or large faces, so that the respective P, T and LS conduits (channels 8) all communicate with each other and constitute continuous channels crossing the stack of pa = t in share to ensure the functioning of the multiple distribution.

When, in such a distribution device multiple, a distribution tranche considered (i.e. a unitary distributor) sees its operation inhibited under the action of LS pressure imposed by another installment of the multiple distribution, it may be desirable however, the distribution tranche considered may continue to be maneuvered so that the receiver hydraulic that it controls can be set or maintained in operation, if only with a speed reduced: this can be the case for example for the rotation of a machine turret or for translation of a machine.

In other words, it seems desirable to be able to give a function considered a capacity operational, even reduced or degraded, despite inhibition controlled by the general LS circuit of the multiple distribution device, and this without it being done call for the section under consideration to a priority circuit, including examples are elsewhere known and whose implementation, which complicates the overall arrangement and makes it more expensive, does not does not seem to impose itself in the context considered.

It is therefore a question of giving, to the distribution tranche considered, a pseudo-priority without significant modification of the single dispenser or multiple dispensing device.

The object of the invention is therefore to propose an arrangement that responds to user wishes while requiring only minimal adjustments compared to the structures existing distributors.

For these purposes, a hydraulic distributor as defined in is characterized, being arranged in accordance with the invention, in that the housing wall and / or the plunger, in an area included in the vicinity of the above first end of the plunger, is equipped with at least one calibrated passage suitable for establishing a connection between the abovementioned first end of the plunger and the aforesaid lateral opening when the plunger is pushed back into position extreme under the action of the highest charge pressure exceeding the inlet pressure.

Thanks to this arrangement, when the highest charge pressure high exceeds intake pressure and pushes the plunger back into an extreme position in which should be interrupted the flow of hydraulic fluid from the intake port to the side opening of the housing - and therefore should inhibit the operation of the distributor in favor of another distributor of a multiple distribution device which controls a receiver hydraulics developing the highest load pressure -, the presence of the calibrated passage, however, allows maintaining a hydraulic fluid flow at low flow rate to the orifice lateral: the hydraulic receiver associated with the distributor can then continue to be powered and run, albeit at high speed scaled down.

The presence of the calibrated passage means that the regulator pressure of the distributor balance is no longer exactly the existing pressure differential Δp, between the inlet pressure (P) and the highest charge pressure (LS), as it is conveyed in the LS line and applied to the first end of the plunger.

So we establish a pseudo-priority in favor of the receiver hydraulically controlled by the distributor thus equipped, which receiver can continue to operate at low speed.

Although the calibrated passage may, from a point of view functional, either be provided in the wall of the housing or in the diver, it is however more advantageous, to facilitate machining, that said calibrated passage is machined in the plunger.

Preferably several calibrated passages can be provided and distributed peripherally, advantageously regularly.

In a simple embodiment, each pass is consisting of a notch cut into the wall. However, it can also be a channel with a calibrated restriction.

• la fig. 2 est une vue partielle en coupe, à plus grande échelle, d'une partie du distributeur de la fig. 1 et montrant un mode de réalisation préféré de l'agencement conforme à l'invention ; et
• les fig. 3 à 5 sont des vues partielles en coupe d'une partie de la balance illustrée à la fig. 2 et montrant respectivement plusieurs variantes possibles de réalisation de l'agencement de l'invention.

The invention will be better understood on reading the detailed description which follows of certain embodiments given solely by way of nonlimiting examples. In this description, reference is made to the appended drawings, in which:

• fig. 2 is a partial sectional view, on a larger scale, of a part of the dispenser of FIG. 1 and showing a preferred embodiment of the arrangement according to the invention; and
• fig. 3 to 5 are partial sectional views of part of the scale illustrated in FIG. 2 and respectively showing several possible alternative embodiments of the arrangement of the invention.

Referring first to FIG. 2, on which the same reference numbers have been kept to designate the organs identical to those of FIG. 1, there is shown a view enlarged with a regulatory balance such as that equipping the hydraulic distributor of fig. 1, except that the restriction 28 provided in channel 18 is here provided in a insert 29 inserted in the plunger 14.

The arrangement according to the invention consists in providing, between the passage 12 receiving the fluid under the intake pressure P and the conduit 21 connected to a working orifice A, B, a passage permanent calibrated which ensures a low fluid flow flow rate when plunger 14 is pushed back to inhibition position functional of the distributor under the action of a pressure of highest load LS, prevailing in upper chamber 15, which exceeds the intake pressure P (case illustrated in fig. 2).

In the preferred embodiment shown in FIG. 2 he several calibrated passages 30 are provided in the plunger 14, distributed peripherally and formed here by notches carved into the outer wall of the plunger extending parallel to the axis thereof. This is a mode of simple in terms of structure and which does not requires minimal machining without any difficulty technical. It should be noted in this regard that the realization of such notches can not only be, of course, performed on new materials during the manufacture of these, but may also be done on pre-existing materials so as to provide them with the additional function of pseudo-priority mentioned above.

Other embodiments are also possible.

In fig. 3, the calibrated passages 31 are formed under form of radial channels with restriction, which, from the point manufacturing view, is achievable without major difficulty.

In fig. 4 and 5, the calibrated passages are practiced in the wall of the housing 13 by joining the passage 12 and the conduit 21, either in the form of notches 32 hollowed out in the wall of the housing 13 at the lower end of the plunger 14 (fig. 4), or in the form of restricted channels 33 (fig. 5) dug in the body 1 of the distributor behind the surface of the housing 13. However, the arrangements shown in FIGS. 4 and 5 can pose manufacturing problems in the usual context of monobloc body where the locations to be machined are accessible difficult.

Claims (5)

1. A hydraulic directional control valve having a regulating balance designed to provide a highest load-pressure sensing function, an anti-saturation function and a function whereby the flow is split independently of the load, this balance comprising a plunger (14) which can be displaced in a housing (13) under the action of a differential pressure (Δp) created by the intake pressure (P) supplied by a hydraulic source and applied (at 12) to a first of its ends and by the highest load pressure (LS) applied (at 15) to its other end, said plunger (14) also being designed to open, in proportion to said differential pressure (Δp), a lateral orifice (21) of the housing (13) linked to a working orifice (A, B) of the directional control valve so as to deliver to it hydraulic fluid having the intake pressure (P) less said differential pressure (Δp), characterised in that the wall of the housing (13) and/or the plunger (14) is provided, in a zone locateded in the vicinity of said first end of the plunger, with at least one calibrated passage (30-33) designed to establish a link between said first end of the plunger and said lateral orifice when the plunger is pushed back into an end position under the action of the highest load pressure (LS) exceeding the intake pressure (P),
      whereby, in spite of the excess value of the highest load pressure (LS) intended to inhibit operation of the directional control valve, hydraulic fluid is nevertheless delivered at a low rate to the lateral orifice and allows the hydraulic receiver controlled by said hydraulic directional control valve to be displaced at a low rate.
2. A hydraulic directional control valve as claimed in claim 1, characterised in that the calibrated passage (30, 31) is provided on the plunger (14).
3. A hydraulic directional control valve as claimed in claim 1 or 2, characterised in that several peripherally distributed calibrated passages (30-33) are provided.
4. A hydraulic directional control valve as claimed in anyone of preceding claims, characterised in that each calibrated passage (30, 32) is provided in the form of a notch hollowed into the wall.
5. A hydraulic directional control valve as claimed in anyone of preceding claims, characterised in that each calibrated passage (31, 33) is provided in the form of a passage with a calibrated restriction.

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