EP0306368B1 - Pressure compensator valve for a hydraulic proportional directional valve, and hydraulic directional valve comprising it - Google Patents

Description

The invention relates to a pressure compensating device adapted to equip a hydraulic distributor of the proportional type provided with a pipe for detecting the operating pressure, as well as a hydraulic distributor comprising this pressure compensating device.

• d'une part, en permanence avec la chambre du ressort du tiroir de compensateur, de façon à superposer, à l'action de ce ressort sur le tiroir de compensateur, l'action de la pression régnant dans cette canalisation;
• d'autre part, avec au moins une chambre distributrice du stator, que le tiroir distributeur met alternativement en communication, avec le circuit de retour quand le tiroir est en position neutre de repos, ou avec un circuit d'utilisation, quand le tiroir distributeur alimente ce circuit.

Such a proportional type hydraulic distributor is described by patent FR-2,562,632. This hydraulic distributor comprises: a distributor drawer sliding in the bore of a stator and actuated by at least one pilot pressure, so that the drawer, provided with progressivity notches, moves in front of lights provided in the bore of the stator, while its supply is ensured through a compensating drawer; as well as, inside the stator, a pressure detection pipe which communicates:

• on the one hand, permanently with the spring chamber of the compensator slide, so as to superimpose, on the action of this spring on the compensator slide, the action of the pressure prevailing in this pipe;
• on the other hand, with at least one distributor chamber of the stator, that the distributor drawer alternately puts in communication, with the return circuit when the drawer is in neutral rest position, or with a circuit of use, when the distributor drawer feeds this circuit.

It is known that such taking of information is known by the commercial name of "load sensing". The purpose of such a system is to transmit to a device regulating the pressure of the installation, the highest pressure required by the most loaded device. This allows the circuit pressure to be adjusted to the required fair value for powering the various receiving devices it controls.

For this, the hydraulic distributor according to the aforementioned patent comprises, on the main drawer, a fluid inlet flow which is regulated by a compensator drawer, or compensator drawer, the position of which depends on the value of the pressure of prevailing use in the detection pipeline. Inside this compensator drawer is a non-return valve whose purpose is to prevent a possible reverse movement of a receiver. Such a reverse movement would tend to develop when a receiver is subjected to a force against which it is desired to move, and this more particularly when the supply pump of the circuit has not yet reached the necessary pressure. to defeat this effort.

In general, it can be seen that this structure gives full satisfaction for operation at an average feed rate. On the other hand, when the flow reaches large values, the pressure losses observed through the compensator slide become very large and they affect the efficiency of the distributor.

The present invention aims to avoid these drawbacks by proposing a new organization of the compensator drawer.

The invention proposes for this purpose a pressure compensating device for a proportional type hydraulic distributor comprising a distributor drawer, intended to regulate the supply pressure arriving in a supply chamber of this distributor drawer as a function of the pressure of use delivered by this distributor drawer, comprising a compensating drawer, sliding in a housing of a stator portion communicating with an inlet channel and a feed channel opening into the feed chamber, and subject axially, in one direction, at both the operating pressure and the thrust of a compensating spring and, in the other direction, at the supply pressure, this compensating slide carrying a shutter member adapted to isolate hydraulically the inlet and supply channels and subjected to a return spring carried by this compensating drawer, characterized in that the compensating drawer has a low-cut part, the shutter member being an annular valve adapted to slide without play between two abutments around this low-cut part and inside a cylindrical bore into which the feed channel opens, by defining at the bottom of the housing a chamber containing the return spring which communicates permanently by a pipe with the chamber food.

• la canalisation est ménagée dans la portion statorique entourant le logement du tiroir compensateur,
• ou la canalisation est ménagée dans le clapet annulaire,
• le tiroir compensateur comporte une partie massive de guidage et, entre la partie décolletée et cette partie massive, une portion intermédiaire de diamètre inférieur à celui de l'alésage mais supérieur à celui de la partie décolletée en sorte de former un épaulement formant butée pour le clapet annulaire,
• le tiroir compensateur comporte en une extrémité de la partie décolletée une collerette d'appui sur laquelle prend appui le ressort de rappel du clapet annulaire,
• le clapet annulaire définit une chambre cylindrique adjacente à la partie décolletée, dans laquelle pénètre le ressort de rappel.
• la canalisation reliant la chambre arrière au canal l'alimentation débouche au fond de cette chambre.

According to preferred arrangements of the invention:

• the pipe is formed in the stator portion surrounding the housing of the compensating drawer,
• or the pipe is made in the annular valve,
• the compensating slide has a massive guide part and, between the low-cut part and this solid part, an intermediate portion with a diameter less than that of the bore but greater than that of the low-cut part so as to form a shoulder forming a stop for the annular valve,
• the compensating drawer comprises at one end of the low-cut part a support flange on which the return spring of the annular valve bears,
• the annular valve defines a cylindrical chamber adjacent to the low-cut part, into which the return spring penetrates.
• the pipe connecting the rear chamber to the channel the power supply opens at the bottom of this chamber.

The invention also provides a proportional type hydraulic distributor comprising a drawer distributor sliding in a bore of a stator provided with an annular supply chamber and at least one use channel from which a pressure tapping pipe starts, pilot chambers into which the ends of the drawer penetrate , and a pressure compensating device according to the invention through which feed fluid is supplied to the feed chamber.

• _ la figure 1 est une vue partielle en coupe longitudinale d'un distributeur hydraulique comportant un compensateur de pression conforme à l'invention, en position neutre;
• _ la figure 2 en est une vue partielle analogue en position de fonctionnement; et
• _ la figure 3 est une vue partielle en coupe longitudinale analogue à celle de la figure 1, d'un distributeur selon une variante de réalisation.

Objects, characteristics and advantages of the invention appear from the following description, given by way of nonlimiting example, with reference to the appended drawings in which:

• _ Figure 1 is a partial view in longitudinal section of a hydraulic distributor comprising a pressure compensator according to the invention, in neutral position;
• _ Figure 2 is a similar partial view in the operating position; and
• _ Figure 3 is a partial view in longitudinal section similar to that of Figure 1, of a dispenser according to an alternative embodiment.

The distributor illustrated in the drawings comprises a stator block 1, in the bore 2 of which slides a cylindrical distributor drawer 3. In the usual way, the switching of the hydraulic circuits is effected by displacement of the grooves of the drawer 3 in front of the lights of the stator .

At its right end, for example, the drawer 3 is provided with a spring return device of known type, comprising a helical spring 4, compressed between the cups 5 and 6 and two rings 7 and 8, trapped between two shoulders of the end 9 of the drawer 3, around which they can slide. Thus, in its neutral rest position, the slide 3 is recalled to the configuration illustrated in FIG. 1, while it is pushed to the left (FIG. 2) when a pilot pressure is sent into an opening 10 of a fixed cap 2A linked to the stator. On the contrary, it is pushed to the right when a pilot pressure is sent to the opposite.

In the example illustrated, it has been assumed that the three-position slide 3 is used to control a double-acting hydraulic cylinder 12. For this, one of the sections of the cylinder 12 is connected to a first channel d 'use 13 of the stator 1, while the opposite section of the cylinder 12 is connected to a second pipe for using the stator 1 (not shown).

The distributor receives in an annular chamber 15, the pressure sent by a hydraulic unit 16.

The supply chamber 15 surrounds a sliding drawer 60 that a compression spring 75, housed in a chamber 18, recalls in abutment against the fixed bottom 19 of the housing 60A of this drawer. The spring 75 is also supported on a base 80 whose position is adjustable by a setting screw 81. An inlet channel 73 opens into the housing 60A which consists of a portion in a bore 20 into which opens a supply channel leading to the supply chamber 70

At each of its two ends, the distributor drawer 3 has an axial internal housing marked 29 in the right end.

The housing 29 communicates with the outside of the drawer by two axially offset radial bores referenced respectively 30 and 31. Likewise, the housing at the other end leads to two radial bores.

When the drawer 3 is in its neutral rest position (Figure 1), the bore 31 faces a solid part 34 of the stator which closes it.

Between the holes 30 and 31, the stator defines, in the bore, a solid part 40, in front of which is likely to move a groove 41 of the drawer 3.

Around the drawer 3, in the area around the bore 31 when the drawer 3 is pushed to the left (FIG. 2), there is an annular stator chamber 42.

Similarly, at its opposite end, the drawer 3 has a movable groove in front of a solid part of the stator adjacent to an annular stator chamber (not shown).

The two annular stator chambers are connected by a pipe 46 called "pipe for the detection of the operating pressure" (or, in English, "load sensing") which communicates permanently with the chamber 18 of the spring 17 which recalls the drawer compensator 60.

The groove 41 is adapted to put the pipe 46 in normal communication with a pipe 39 of the fluid return circuit.

Progressivity notches equip the different grooves of the drawer 3, as indicated for example by the reference 50.

Appropriate means of any known type (not shown) are provided for evacuating the fluid from the jack 12 in good time to the fluid return circuit.

The compensating slide comprises a solid solid part 61 for guidance extended by a low-cut part 62 on which and around which an annular valve 63 (or ring) sliding in leaktight manner can slide in the bore 20 and comprising, opposite the solid part 61, a housing 21 around the low-cut part 62. A compression spring 64 is supported on one side on a support flange 76 ending the drawer 60, on the other side on the bottom 66 of the housing 21 of the annular valve 63. Thus, the spring 64 tends to push the annular valve 63 against a shoulder 67 which connects the low-cut part 62 to the rest of the drawer 60. The shoulder 67 constitutes one of the end stops of the valve 63 .

Preferably, this shoulder 67 connects the low-cut part 62 to a second low-cut zone 23 of intermediate diameter between the diameter of the part 62 and the transverse dimension of the part 61.

Balancing channels 51 are provided in the support flange 76.

Furthermore, a pipe 68, here produced in the stator body 65, permanently connects the rear chamber 69 of the annular valve 63 (containing the spring 64) to the pressure prevailing in the supply chamber 70 of the main drawer 3, upstream a throttle 72 which is formed in operation with a distribution groove 71 (Figure 2). Thus, the fluid coming from the supply orifice 73 (arrow 74) in the supply chamber 15 of the compensating slide 60, is directed towards the chamber 70 passing, in the configuration of FIG. 2, through an annular section important. Without modifying the size of the compensating drawer of the prior art, the pressure losses on the passage of the pressure compensating drawer 60 have therefore been significantly reduced.

In the variant of FIG. 3, the communication between the chambers 70 and 69 is made by holes 68 'made in the annular valve.

• _ lorsque l'ensemble est au repos (figure 1), la pression P1 du fluide emprisonné dans la chambre 70 s'applique par la canalisation 68 (ou 68′) dans la chambre 69 où elle engendre un effort qui maintient le clapet annulaire 63 en appui sur l'épaulement 67 du clapet 60. Dans cette position, le passage du fluide est interdit depuis la chambre 70 vers l'orifice d'alimentation 73, où règne la pression d'alimentation ou d'entrée PE: il ne peut donc y avoir d'écoulement inverse.

The operation is as follows:

• _ when the assembly is at rest (Figure 1), the pressure P1 of the fluid trapped in the chamber 70 is applied by the pipeline 68 (or 68 ′) in the chamber 69 where it generates a force which maintains the annular valve 63 resting on the shoulder 67 of the valve 60. In this position, the passage of the fluid is prohibited from the chamber 70 towards the supply orifice 73, where the supply or inlet pressure PE prevails: it cannot so there is reverse flow.

When the pressure difference (PE-P1) applied to the annular valve 63 corresponds to a thrust slightly greater than the setting of the spring 64, the valve 63 comes to the position of FIG. 2, in abutment on the left support flange 76 of the drawer 60. The passage from PE to chamber 70 is wide open, in particular thanks to the small diameter of the intermediate part 23: the fluid flows with reduced pressure drops. Given the differences in section subjected to this PE pressure, the drawer 60 tends to move to the right.

When PE is clearly greater than P1, the slide valve 60 plays its normal regulatory role, taking account of the pressure in the pipe 46. It moves against the action of the spring 75 so as to ensure a constant pressure drop in the notches dispenser drawer 3.

It goes without saying that the foregoing description has been offered only by way of nonlimiting example and that numerous variants can be proposed by those skilled in the art without departing from the scope of the invention.

Thus in particular the distributor could in essence be reduced to what is shown in Figures 1 and 2 (or 3) for the supply of a single-acting cylinder.

Claims (8)

1. A pressure compensating device for a hydraulic distributor of the proportional type comprising a distributor slide valve (3), adapted to control the supply pressure (P₁) entering a supply chamber (70) of the distributor slide valve (3) in relation to the working pressure supplied by this distributor slide valve (3), comprising a compensating slide valve (60) sliding in a housing (60A) in a stator portion (65) communicating with an inlet channel (73) and a supply channel opening into the supply chamber (70), and subjected axially, in one direction, to the working pressure and to the force of a spring (75) simultaneously and, in the other direction, to the supply pressure (P₁), this compensating slide valve (60) carrying a closing element (63) adapted to isolate the inlet channel (73) and supply channel hydraulically and being subject to a return spring (64) carried by this compensating slide valve (60), characterized in that the compensating slide valve (60) comprises an undercut portion (62), the closing element is an annular flap valve (63) adapted to slide without play between two stops (67, 76) around this undercut portion (62) and inside a cylindrical bore (20) into which the supply channel (73) opens, whilst defining at the bottom of the housing (60A) a chamber (69) containing the return spring (64) and in permanent communication with the supply chamber (70) through a channel (68, 68').

2. A device according to claim 1, characterized in that the channel (68) is formed in the stator portion (65) surrounding the housing (60A) of the compensating slide valve (60).

3. A device according to claim 1, characterized in that the channel (68′) is formed in the annular flap valve (63).

4. A device according to any one of claims 1 to 3, characterized in that the compensating slide valve (60) comprises a large solid guiding part (61) and, between the undercut portion (62) and this large solid part (61), an intermediate portion (23) of lesser diameter than that of the bore (20) but greater than that of the undercut portion (62) so as to form a shoulder (67) forming a stop for the annular flap valve (63).

5. A device according to any one of claims 1 to 4, characterized in that the compensating slide valve (60) comprises, at one end of the undercut portion (62), a bearing collar (76) on which the return spring (64) of the annular flap valve (63) bears.

6. A device according to any one of claims 1 to 5, characterized in that the annular flap valve (63) defines a cylindrical rear chamber (69) adjacent to the undercut portion (62) into which the return spring (64) penetrates.

7. A device according to claim 6, characterized in that the channel (68′) connecting the rear chamber (69) to the supply chamber (70) opens at the bottom of this chamber.

8. A hydraulic distributor of proportional type comprising a distributor slide valve (3), sliding in a bore (2) in a stator (1) equipped with an annular supply chamber (70), at least one utilization channel (13) from which a pressure take off channel (29, 30, 31, 46) originates, control chambers into which the ends (9) of the slide valve (3) extend, and a pressure compensating device, in accordance with one of claims 1 to 7, through which supply fluid is led to the supply chamber (70).

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