EP2935905A1

EP2935905A1 - Hydraulic distributor with in-built pressure compensator, and motorized vehicle equipped with such a distributor

Info

Publication number: EP2935905A1
Application number: EP13820798.0A
Authority: EP
Inventors: Christophe Payre; Frédéric Lagors
Original assignee: Fluid-System (Sarl)
Current assignee: Fluid-System
Priority date: 2012-12-18
Filing date: 2013-12-11
Publication date: 2015-10-28
Anticipated expiration: 2033-12-11
Also published as: FR2999623B1; EP2935905B1; WO2014096630A1; FR2999623A1; SI2935905T1

Abstract

The invention relates to a hydraulic distributor comprising: a housing, a metering slide mounted so that it can slide in the housing, at least one pressure compensator mounted so that it can slide in said metering slide. The metering slide and its in-built compensator are configured in such a way as to prevent any return current from an LS line.

Description

HYDRAULIC DISPENSER WITH INTEGRATED PRESSURE BALANCE AND MOTORIZED ENGINE PROVIDED WITH SUCH A DISTRIBUTOR

Description

Technical Field of the Invention

The invention relates to a hydraulic distributor with integrated pressure balance and a motorized machine equipped with such a distributor.

It concerns the technical field of hydraulic distributors comprising dosing drawers and pressure balances, which balances maintain a constant pressure difference across said drawers to maintain a constant flow. This type of distributor is generally characterized by the English term "Flow Sharing" (or "debit sharing" in French). State of the art

Flow Sharing distributors are well known to those skilled in the art and for example described in patent documents EP 2.375.1 14 (REXROTH), FR 2.544.405 (LINDE), or US 5.186.000 (HITACHI).

These Flow Sharing dispensers are composed of a so-called "dosing" drawer allowing more or less to discover a section of fluid passage towards a hydraulic receiver. Downstream of this adjustable section is interposed a pressure balance to maintain an identical pressure difference across the metering slide, regardless of the load conditions of the hydraulic receiver. In fact, the fluid flow through the metering slide is not influenced by the pressure of the hydraulic receiver. In the case of a system comprising a plurality of hydraulic receivers and when said system is unsaturated, that is to say that the total flow rate required for operating all the receivers _(r Q _P E∞ tors) remains below the maximum flow rate of the fluid source under pressure (Q _p0 mpe), then each distributor maintains a constant flow regardless of the load conditions of other receivers. In the case of a saturated system (Qre∞ _P eurs> Q _P om _P e), the distribution of flow rates is established proportionally to the section discovered by each metering slide such that the relative speeds of the receivers are maintained.

The system illustrated in Figure 1 attached repeats the principles outlined above. The system comprises two hydraulic receivers R1 and R2, which consist for example of jacks. Each receiver R1, R2 comprises a first hydraulic chamber 81, 82 connected to a hydraulic circuit C under pressure and another hydraulic chamber 91, 92 connected to a discharge pipe or to a low pressure environment (for example a tank) Re. The receiver R1 is the most loaded, the spring 71 schematically at the end of the rod of the cylinder illustrating this additional load. The circuit C comprises a source of pressurized fluid P (typically a variable flow and pressure pump) supplying two parallel branches respectively connected to each of the hydraulic chambers 81, 82. Each branch comprises in series: a metering slide T1, T2 and a pressure balance B1, B2. An LS charge detection line (Load Sensing) is used to signal the charge pressure to the source of fluid P so that it can continuously adjust its pressure and its flow to the values demanded by the sensors. receivers R1 and R2 that it feeds. The LS line communicates with each balance B1, B2. These are solicited: on one side by the pressure of the fluid at the metering slide T1, T2 and the other side by the pressure in the LS pipe. The receiver R1 being the most charged, its charging pressure is established in the LS line. The balance B2 equilibrates with respect to this pressure, which pressure is established downstream of the metering slide T2 by the regulation of said balance. The upstream pressures to the dosing drawers T1 and T2 being those of the fluid source P, the pressure difference (Apref) at the terminals of these dosing drawers is identical. In fact, the flow rates Q1 and Q2 passing through the dosing drawers T1 and T2, respectively, remain identical, whatever the load conditions of the receivers R1 and R2.

In the aforementioned EP patent 2,375,14 (REXROTH), it is envisaged to integrate pressure balances directly into the distributor housing, downstream of the metering slide. This type of distributor has the advantage of having a single piece directly integrating two components (metering slide and balance) and thus offering two functions. However, these distributors are relatively heavy (because it is necessary to have additional material around pressure balances), complex to be machined, requiring the integration of load-retaining valves whose function is to avoid transfers of pressure. flows from one distributor to another by the LS line.

Patent document FR 2,544,405 (LINDE) partially overcomes this state of affairs. Indeed, the distributor described in this document provides for directly integrating the pressure scales inside the metering slide. More specifically, this document describes a hydraulic distributor comprising a housing provided with: a first orifice opening in a delivery line arranged to be connected to a source of pressurized fluid, - a second orifice connected to a charge line predisposed to be connected to a first hydraulic chamber of a hydraulic receiver, a third orifice opening in a pipe predisposed to be connected to a charge sensing line for signaling the charge pressure to a regulator of the source of pressurized fluid. A flow passage system connects these different orifices.

The metering slide is slidably mounted in the housing to control fluid flows within the passage system, said slide comprising: an active position opening a flow passage between the first port and the second housing port; a neutral position closing said passage.

At least one pressure balance is slidably mounted in a longitudinal bore of the metering slide. This scale is arranged so that, in the active position of the slide, it acts as a throttling point in the flow passage connecting the first orifice and the second orifice of the casing, being stressed: on one side by the pressure of the fluid prevailing in said flow passage, and on the other hand by the pressure prevailing in a portion of the longitudinal bore of said spool which is connected to the third orifice of said housing.

This scale includes a duct opening at a first opening and a second opening, said openings being arranged so that, in the active position of the metering slide: - the first opening is placed in the flow passage connecting the first orifice and the second orifice of the housing, - the second opening is placed in the portion of the longitudinal bore of the metering slide which is connected to the third orifice of the housing, when the pressure of the fluid prevailing in the flow passage connecting the first orifice and the second orifice of said housing is greater than or equal to the pressure prevailing in said portion of the longitudinal bore.

According to a first embodiment presented in the document FR 2.544.405 (LINDE), it is envisaged to integrate a non-return valve ball in the conduit of the balance which connects the two openings. This ball has the function of preventing a return current from occurring when the pressure of the fluid in the flow passage connecting the first orifice and the second orifice of the housing (ie the pressure pressure of the hydraulic receiver) becomes lower. at the pressure prevailing in the portion of the longitudinal bore of the slide which is connected to the third orifice of the housing (ie the pressure in the LS line). However, the introduction of the ball check valve is particularly difficult to achieve.

In an alternative embodiment presented in this same document FR 2.544.405 (LINDE), the duct of the scale is devoid of check valve. It is the front surface of an additional piece that closes the duct when the pressure in the LS line is greater than the load pressure of the hydraulic receiver. This design is even more complex and expensive since it requires the use of an additional room.

The invention aims to remedy this state of affairs. More particularly, an object of the invention is to provide a scale distributor integrated in the metering slide of the type described in the document FR 2.544.405 (LINDE) cited above, in which the design of the scale very simply prevents any flow of fluid. from the LS line to the least heavily loaded portion of the receiver, refraining from using any non-return valve device or any additional parts.

Disclosure of the invention.

The solution proposed by the invention is a hydraulic distributor of the type described above, but in which the second opening of the duct of the balance is closed by an active wall of the longitudinal bore of the metering slide, when the pressure of the fluid prevailing in the passage of flow connecting the first port and the second housing port is less than the pressure in the portion of the longitudinal bore of said drawer which is connected to the third port of the housing.

It is now the combination of the arrangement of the second opening of the balance duct and the configuration of the longitudinal bore of the dispensing metering slide, which makes it possible to avoid any return flow from the LS line. Such a dispenser offers the same functionalities as those of the dispenser described in document FR 2.544.405 (LINDE), but with fewer parts. The design is simpler and the distributor less expensive.

Other characteristics of the dispenser are listed below, each of these characteristics being able to be considered alone or in combination with the remarkable characteristics defined above:

the duct of the balance advantageously comprises a longitudinal bore opening at the first opening and a radial bore opening at level of the second opening, a nozzle being disposed at the junction of said two holes.

the longitudinal bore is extended to open at a third opening in the portion of the longitudinal bore of the metering slide which is connected to the third port of the housing, another nozzle being disposed in the extension of said longitudinal bore.

the housing may further comprise: - a fourth orifice opening into a pipe predisposed to be connected to a discharge pipe or a low-pressure environment, - a flow passage connected to the second orifice of said housing and to said fourth orifice, which passage is configured so that the fluid flows in this passage without crossing the pressure balance.

the pressure balance is preferably solicited by a spring acting on the end of said balance which is located in the portion of the longitudinal bore of the metering slide which is connected to the third orifice of the housing, so that in the absence of any solicitation said balance closes the flow passage for connecting the first port and the second port of said drawer.

Preferably, the pressure exerted by the spring on the balance is negligible compared to the pressure at the first orifice and the pressure at the third orifice, when the metering slide is in the active position.

Longitudinal slits may be provided on the outer wall of the metering slide, which slots are configured to create a nozzle flow passage between the first port and the second port.

According to a preferred embodiment, the hydraulic distributor is such that:

the housing comprises: another third orifice opening into the pipe predisposed to be connected to the charge detection line to signal the pressure of charge to the regulator of the source of pressurized fluid, the fourth opening opening in a pipe predisposed to be connected to a discharge line or a low-pressure environment, - a fifth port opening into a charge line predisposed to be connected to a second hydraulic chamber of the hydraulic receiver, - a passage system of flow connected to said orifices,

the metering slide comprising at least three positions: a first active position opening a flow passage between the first orifice and the second orifice of the housing; a second active position opening a flow passage between the first orifice and the fifth orifice of said housing, and a neutral position closing these passages,

a second pressure balance is slidably mounted in a longitudinal bore of the metering slide, said second scale being arranged so that, in the second active position of said slide, it acts as a throttling point in the connecting flow passage; the first orifice and the fifth orifice of the casing, being stressed: on one side by the pressure of the fluid prevailing in said flow passage, and on the other hand by the pressure prevailing in a portion of the longitudinal bore of said slide which is connected to the other third port of said housing,

o said second scale includes a duct opening at a first opening and a second opening, said openings being arranged so that, in the second active position of the metering slide: - the first opening is placed in the passage flow path connecting the first orifice and the fifth orifice of the housing, - the second opening is placed in the portion of the longitudinal bore of the metering slide which is connected to the other third orifice of the housing, when the pressure of the fluid prevailing in the passage of flow connecting the first orifice and the fifth orifice of said housing is greater than or equal to the pressure prevailing in said portion of the longitudinal bore,

o the second opening of the duct of the second scale is closed by an active wall of the longitudinal bore of the metering slide, when the pressure of the fluid in the flow passage connecting the first orifice and the fifth orifice of the housing is less than the pressure; prevailing in the portion of the longitudinal bore of said drawer which is connected to the other third port of the housing. Another aspect of the invention relates to a motorized machine incorporating a hydraulic circuit comprising: a source of fluid under pressure, at least one hydraulic receiver provided with at least a first hydraulic chamber, a charge detection line predisposed to signaling the charging pressure of said receiver to an adjusting member of said source of pressurized fluid, - a discharge line or a low pressure environment, a hydraulic distributor according to the above described remarkable characteristics being connected to the hydraulic circuit so as to than :

the first orifice is connected to the source of fluid under pressure, the second port is connected to the first hydraulic chamber of the hydraulic receiver,

the third port is connected to the load sensing line. Description of the figures.

Other advantages and characteristics of the invention will appear better on reading the description of a preferred embodiment which follows, with reference to the appended drawings, carried out as indicative and non-limiting examples and in which: Figure 1 above illustrates the operating principle of a dispenser "Flow Shar / ng",

FIG. 2 is a longitudinal sectional view of a hydraulic distributor according to the invention, the metering slide being in the neutral position,

FIG. 3 shows, on an enlarged scale, the position of a portion of the metering slide and the associated pressure balance, in the distributor of FIG.

FIG. 4 is a view in longitudinal section of a hydraulic distributor according to the invention, the metering slide being in the first active position,

FIG. 5 shows, on an enlarged scale, the position of a portion of the metering slide and the associated pressure balance, in the dispenser of FIG. 4,

FIG. 6 is a view in longitudinal section of a hydraulic distributor according to the invention, the metering slide being in the second active position,

FIG. 7 shows, on an enlarged scale, the position of a portion of the metering slide and the associated pressure balance, in the dispenser of FIG. 6,

FIG. 8 is a longitudinal sectional view of two hydraulic distributors in accordance with the invention, said distributors being each connected to a hydraulic receiver, one of which is more loaded than the other,

FIG. 9 shows, on an enlarged scale, the position of a portion of the metering slide and the associated pressure balance, in the least loaded dispenser of FIG. 8,

FIG. 10 shows the slide of FIG. 9 with an alternative embodiment, FIG. 11 schematizes, in the form of a hydraulic symbol, a dispenser according to the invention.

Preferred embodiments of the invention

Referring to Figure 2, the dispenser "Flow Shar / ng" D1 object of the invention comprises: a housing C provided with a longitudinal bore in which slides a metering slide T, inside which slides at least one, preferably two pressure balances B1 and B2. These scales are arranged symmetrically in the metering slide T. These different parts are obtained by molding and / or machining a metallic material, for example stainless steel or aluminum. Any other material that is suitable for those skilled in the art may, however, be envisaged.

The longitudinal piercing of the housing C comprises several orifices 1 to 5. In the accompanying figures, the latter are in the form of radial bores opening into annular grooves made in the main longitudinal bore.

A first port 1 opens into a discharge pipe 10 predisposed to be connected to a source of pressurized fluid P. The latter is typically a pump variable flow and pressure. The pulsed flow rate is for example between 0 L / min and 200 L / min, and the pressure between 10 bar and 380 bar. The fluid discharged from the source P is typically oil, but any other fluid suitable for those skilled in the art and which is adapted to the hydraulic receiver can be used.

A second port 2 opens into a charge line 20 predisposed to be connected to the first hydraulic chamber 81 of the hydraulic receiver R1. In the accompanying figures, the latter consists of a jack comprising a double rod piston 70 and two hydraulic chambers 81, 91. However, the distributor D1 can be associated with any other type of hydraulic receiver: single rod cylinder, hydraulic motor, etc.

A third orifice 3 opens into a pipe predisposed to be connected to a charge detection line LS (for the acronym "Load Sensing"), to signal the charge pressure to a regulator OR of the fluid source under pressure P. The OR element automatically adjusts fluid flow and pressure to the demand of the hydraulic receiver. Another third port 3 'is connected to a parallel branch of the pipe LS.

A fourth port 4 opens into a conduit predisposed to be connected to a discharge line or a low pressure environment 40, which generally consists of a reservoir. Another fourth orifice 4 'is connected to a parallel branch of the pipe 40.

A fifth port 5 opens into a charge line 50 predisposed to be connected to the second hydraulic chamber 91 of the hydraulic receiver R1.

In the embodiment illustrated in the accompanying figures, the first port 1 is positioned substantially in the middle of the main longitudinal bore of the housing. The other orifices are arranged symmetrically with respect to a radial plane passing through this first port 1. From this orifice 1, towards the left end (respectively the right end) of the housing are found: the second orifice 2 (respectively the fifth orifice 5), the fourth orifice 4 (respectively the other fourth orifice 4 ') and the third port 3 (respectively the other third port 3 ').

A passage system connects these different orifices so as to allow fluid circulation at least between: the first orifice 1 and the second orifice 2; the first port 1 and the fifth port 5; the second port 2 and the fourth port 4; the fifth port 5 and the other fourth port 4 '.

The metering slide T is slidably mounted in the housing C to control fluid flows within the aforementioned passage system. Specifically, the drawer T is inserted into the main longitudinal bore of the housing C, the outer diameter of said drawer being adjusted to the inner diameter of said bore. The drawer T comprises one, preferably two longitudinal bores 6, 6 '. The number of holes corresponds to the number of pressure scales that are integrated. The bores 6, 6 'are coaxial with the axis of the main longitudinal bore of the casing C and are arranged symmetrically, on either side of a central radial wall 60 of the drawer T. The longitudinal bores 6, 6' present each a portion 61, 61 'of smaller diameter located near the central radial wall 60 and in which is mounted a pressure balance B1, B2; and a portion of larger diameter 62, 62 'which is remote from said central radial wall 60.

The longitudinal bores 6, 6 'are provided with a plurality of radial channels 601, 601', 602, 602 ', 603, 603' allowing the fluid flows, which channels pass right through the drawer T. More precisely, the first longitudinal bore 6 which is located on the left in the appended figures comprises, from the central radial wall 60 towards the left end of the drawer T: a first channel 601 radial, a second channel 602 which may be slightly oblique or not, and a third channel 603 radial. The first two channels 601 and 602 are arranged at the smaller diameter portion 61 of the longitudinal bore 6, and the third channel 603 in the larger diameter portion 62. Similarly, the second longitudinal bore 6 'which is located to the right in the appended figures comprises, from the central radial wall 60 towards the right end of the drawer T: a first channel 601 'radial, a second channel 602' which may be slightly oblique or not, and a third channel 603 'radial disposed in the larger diameter portion 62 '. These channels 601 ', 602', 603 'are symmetrical with the channels 601, 602, 603. The drawer T comprises at least a first active position opening a flow passage between the first port 1 and the second port 2 of the housing C (Figures 4 and 5) and a neutral position closing said passage (Figures 2 and 3). A second active position is preferably provided to open a flow passage between the first port 1 and the fifth port 5 of the housing C (Figures 6 and 7).

In the first active position illustrated in Figures 4 and 5, the drawer T is moved to the right of the housing C. The first channel 601 is positioned in front of the first port 1 and the second channel 602 is positioned in front of the second port 2. The fluid under pressure can thus feed the first chamber 81 of the receiver R1 via: the pump P, the pipe 10, the first channel 601, the longitudinal bore 6, the second channel 602 and the pipe 20. The third channel 603 is positioned in front of the third port 3 and the outer wall of the drawer T mouth the fourth port 4. The portion 62 of the longitudinal bore 6 is thus connected to the third port 3 and thus to the LS line.

Furthermore, in this first active position and in the preferred case where the drawer T is provided with the second longitudinal hole 6 '(FIG. 4), the other first channel 601' is positioned in front of the fifth orifice 5 and the other second channel 602 'is positioned in front of the other fourth port 4'. The fluid contained in the second chamber 91 of the receiver R1 can therefore be evacuated via: the pipe 50, the other second channel 602 'and the pipe 40. Finally, the cylinder rod of the receiver R1 moves to the right. Note also that in this first active position, the outer wall of the drawer T mouth the other third port 3 '.

In the second active position illustrated in Figures 6 and 7, the drawer T is moved to the left of the housing C. The other first channel 601 'is positioned in front of the first port 1 and the other second channel 602' is positioned in front of the fifth port 5. The pressurized fluid can thus feed the second chamber 91 of the receiver R1 via: the pump P, the pipe 10, the other first channel 601 ', the longitudinal bore 6', the other second channel 602 ' and the conduit 50. The other third channel 603 'is positioned in front of the other third port 3' and the outer wall of the drawer T mouths the other fourth port 4 '. The portion 62 'of the longitudinal bore 6' is connected to the other third port 3 'and therefore to the LS line.

Referring to FIG. 6, in this second active position, it also appears that the first channel 601 is positioned in front of the second orifice 2 and the second channel 602 is positioned in front of the fourth orifice 4. The fluid contained in the first chamber 81 of the receiver R1 can therefore be evacuated via: the pipe 20, the second channel 602 and the pipe 40. Finally, the cylinder rod of the receiver R1 moves to the left. The outer wall of the drawer T mouths the third orifice 3.

In the neutral position shown in Figures 2 and 3, the outer wall of the spool T at least the mouths 1, 3 and subsidiarily 3 ': the fluid can not flow between the orifices 1 and 2 or between the orifices 1 and 5.

In the accompanying figures, the drawer T is moved by means of electromagnets E1, E2 which exert their force on each of its ends. Each electromagnet E1, E2 cooperates with a return spring ER1, ER2, one end of which bears on a fixed part of the housing C, and another end bears on said electromagnet. By energizing the coil of one of the electromagnets E1 or E2, a force proportional to the driving intensity of said coil is generated on the slide T, which moves in the first active position or in the second position. active. In the absence of excitation, the springs ER1, ER2 place the drawer T in the neutral position. When the drawer T moves, a passage section opens between the first port 1 and the first channel 601 (Figure 5) or between the first port 1 and the other first channel 601 '(Figure 7), which allows pressurized fluid to flow to the second port 2 or to the fifth port 5. Whatever the active position, the drawer T is then in equilibrium between the force of the electromagnet E1, respectively E2, and that of the spring ER1, respectively ER2. The displacement of the drawer T is directly proportional to the intensity "I" of the control of the coil of the electromagnet which is excited. Indeed, the force generated by this electromagnet is balanced by that of the associated spring. The section of passage discovered is then proportional to the intensity "I". Instead of actuation by electromagnet, one can consider actuations by mechanical control, hydraulic control, pneumatic control or any other actuating means for moving the drawer T in the housing C.

At least one pressure balance B1 is slidably mounted in the longitudinal bore 6 of the slide T, and more particularly in the smaller diameter portion 61. However, it is preferred to insert another pressure balance B2 into the smaller diameter portion 61 'of the second longitudinal drilling 6 '. Balances B1 and B2 are identical. The outer diameter of each balance B1, B2 is adjusted to the inner diameter of the smaller diameter portion 61, 61 '.

The balance B1, respectively B2, is advantageously solicited by a spring BR1, respectively BR2, one end bears on the electromagnet E1, respectively E2, and another end is supported on said balance. These springs BR1 and BR2 are simple return springs, the pressure they exert on the scales B1 and B2 being negligible compared to the pressure of the fluid flowing in the different passages and in particular that prevailing at the first and third orifices 1, 3 , 3 ', when the drawer T is in an active position. The spring BR1 acts on the end of the balance B1 which is situated in the portion of larger diameter 62. As it appears in FIGS. 2 and 3, in the absence of any stress, the balance B1 is in a position where it closes the flow passage for connecting the first port 1 and the second port 2 of the housing C, in particular by closing the second channel 602. Similarly, the spring BR2 acts on the end of the second balance B2 which is located in the larger diameter portion 62 '. In the absence of any stress, the second balance B2 is in a position where it closes the flow passage for connecting the first port 1 and the fifth port 5, closing the other second channel 602 '(Figure 2) .

When the drawer T is in the first active position, the balance B1 acts as a choke point in the flow passage connecting the first port 1 and the second port 2. Referring more specifically to Figure 5, the balance B1 is configured to open a passage section between the second channel 602 and the second port 2, a shoulder 700 formed on the outer wall of said throttle balance at that section. This shoulder 700 extends to the end of the balance B1 which is vis-à-vis the central wall 60. Referring to Figure 4, we see that in the first active position of the drawer T, the second balance B2 is solicited only by the spring BR2. The balance B2 is in a neutral position where it closes the other second channel 602 '. However, the configuration of the shoulder 700 'allows a fluid flow between the fifth port 5 and the other fourth port 4' around the balance B2, without crossing said scale, which significantly reduces the pressure losses compared to the distributors Flow sharing known from the prior art.

When the drawer T is in the second active position, it is the balance B2 which acts as a throttling point in the flow passage connecting the first orifice 1 and the fifth orifice 5, said balance being configured to open a section of passage between the other second channel 602 'and the fifth port 5 (Figure 7). And in this second active position of the drawer T, the first balance B1 is biased only by the spring BR1, so that it closes the second channel 602. The configuration of the shoulder 700 allows a fluid flow between the second port 2 and the fourth port 4, around the balance B1, without crossing said balance, effectively limiting the losses.

In FIGS. 3 and 5, the first balance B1 includes a duct 701 opening at a first opening 702 and a second opening 703. To simplify the design, the duct 701 consists of a longitudinal bore 7012 opening at the level of the first opening 702 and a radial bore 7013 opening at the second opening 703. The first opening 702 is in particular located on the front face of the end of the balance B1 which is in the extension of the shoulder 700 (c that is, the rightmost end in the figures). The second radial opening 703 is located on the periphery of the balance B1, in a portion which is close to the end biased by the spring BR1 (that is to say towards the left-most end on the figures).

A nozzle G1 is disposed in the conduit 701, at the junction of the longitudinal bore 7012 and the radial bore 7013. Its function is to limit the flow of fluid capable of flowing between the two openings 702 and 703. This nozzle G1 is present the shape of an orifice whose diameter is smaller than that of the holes. For example, if the diameter of the bores 7012, 7013 is about 5 mm, the diameter of the nozzle G1 is about 1.2 mm.

As clearly shown in FIGS. 3 and 5, the longitudinal bore 7012 can be extended to open at a third opening 704. This opening is located on the end face of the end of the balance B1 which is urged by the spring BR1. Another nozzle G2 is disposed in the extension of the bore 7012, at the junction with the radial bore 7013. This nozzle G2 has the function of limiting the flow of fluid capable of flowing between the two openings 702 and 704. This nozzle G2 is advantageously in the form of an orifice whose diameter is smaller than that of the nozzle G1, for example about 0.6 mm.

Similarly, with reference to FIG. 7, the second balance B2 integrates a duct 701 'opening at a first opening 702' and a second opening 703 '. A longitudinal bore 7012 'opens at the first opening 702' and a radial bore 7013 'opens at the second opening 703'. The first opening 702 'is located on the front face of the end of the balance B2 which is in the extension of the shoulder 700'. The second radial opening 703 'is located on the periphery of the balance B2, in a portion which is close to the end biased by the spring BR2. A nozzle G1 'is disposed in the conduit 701' to limit the flow of fluid able to flow between the two openings 702 'and 703'. This nozzle G1 'is identical to the aforementioned nozzle G1. The longitudinal bore 7012 'is advantageously extended to open at a third opening 704' located on the end face of the end of the balance B2 which is biased by the spring BR2. Another nozzle G2 ', identical to the nozzle G2 above, is disposed in the extension of the bore 7012' to limit the flow of fluid capable of flowing between the two openings 702 'and 704'.

With reference to FIGS. 4 to 5, when the slide T moves into the first active position, the pressurized fluid from the pump P flows in the flow passage connecting the first orifice 1 and the second orifice 2 of the casing C This fluid under pressure acts on the shoulder 700 of the balance B1. The pressure of the fluid prevailing in this flow passage is greater than or equal to the pressure prevailing in the portion 62 of the longitudinal bore 6 which is connected to the third orifice 3 (that is to say the pressure in the pipe LS). In fact, the balance B1 is pushed to the left, until it comes into abutment against the electromagnet E1. The opening 704 is closed.

In this first active position of the drawer T: the balance B1 acts as a throttling point in the flow passage connecting the first orifice 1 and the second orifice 2; the first opening 702 is placed in this flow passage; the second opening 703 is placed in the larger diameter portion 62 of the longitudinal bore 6. The charge pressure information (i.e. the pressure in the flow passage connecting the first port 1 and the second port 2) is then transmitted to the line LS via: the first opening 702, the duct 701, the nozzle G1, the second opening 703, the portion 62, the third channel 603 and the third orifice 3. This signal LS is then sent to the adjustment member OR of the pump P and at the other third port 3 '.

In this first active position of the drawer T, the fluid without pressure from the second chamber 91 of the receiver R1 flows in the flow passage connecting the fifth port 5 and the other fourth port 4 'of the housing C, without crossing the second B2 balance. The combined action of the spring BR2 and the nozzle G2 'pushes the second balance B2 to the left, in abutment against the wall 60, the openings 702' and especially 703 'being closed. More particularly, the first opening 702 'is closed by the end face of the central wall 60 and the second opening 703' is closed by the internal active surface of the smaller diameter portion 61 'of the longitudinal bore 6'. The orifice 3 'is in any case closed by the drawer T. In fact, the fluid coming from the pipe LS does not can not flow to the fifth port 5, and therefore to the least loaded branch of the receiver R1.

In the same way, referring to FIGS. 6 and 7, when the slide T moves in the second active position, the pressurized fluid coming from the pump P circulates in the flow passage connecting the first orifice 1 and the fifth orifice 5 of the casing C. This pressurized fluid acts on the shoulder 700 'of the second balance B2, the pressure of the fluid prevailing in this flow passage being greater than or equal to the pressure prevailing in the portion 62' of the longitudinal bore. 6 'which is connected to the other third port 3' (i.e. the pressure in the LS line). In fact, the second balance B2 is pushed to the right, until it comes into abutment against the electromagnet E2. The opening 704 'is closed.

In this second active position: the second balance B2 acts as a throttling point in the flow passage connecting the first orifice 1 and the fifth orifice 5; the first opening 702 'is placed in this flow passage; the second opening 703 'is placed in the portion of larger diameter 62' of the longitudinal bore 6 'which is connected to the other third orifice 3'. The charge pressure information is then transmitted to the LS via: the first opening 702 ', the conduit 701', the nozzle G1 ', the second opening 703', the portion 62 ', the third channel 603' and the other third port 3 '.

In this second active position, the fluid from the first chamber 81 of the receiver R1 flows in the flow passage connecting the second port 2 and the fourth port 4 of the housing C, without crossing the balance B1. The combined action of the spring BR1 and the nozzle G2 pushes the balance B1 to the right, until it abuts against the wall 60, the openings 702 and especially 703 being closed. More particularly, the first opening 702 is closed by the end face of the central wall 60 and the second opening 703 is closed off by the internal active surface of the smaller diameter portion 61 of the longitudinal bore 6. The orifice 3 is in any state In fact, the fluid from the LS pipe can not flow to the second port 2, and therefore to the least loaded branch of the receiver R1.

When the balance B1 or B2 is pushed towards the central wall 60 of the drawer T, it is advantageous for the fluid situated between this wall and the end of said balance to escape so as not to (or hardly) oppose to displacement. Thanks to the clever design of balances B1, B2, this fluid is evacuated towards the portion of larger diameter 62, 62 'via: the first opening 702, 702', the duct 701, 701 ', the nozzle G2, G2' and the third opening 704, 704 '.

FIG. 11 schematizes, in the form of a hydraulic symbol, the distributor D1 which has just been described, simultaneously: in the first position I, in the second active position II and in the neutral position N.

The distributor object of the invention is preferably intended to be installed in a motorized vehicle of the type construction vehicle or agricultural vehicle. This machine generally comprises: a source of pressurized fluid (typically an on-board pump), at least one hydraulic receiver R1 (for example the jack of an excavator or agricultural implement) provided with at least one chamber hydraulic 81, - a charge detection line (or line LS) predisposed to signal the charge pressure of said receiver to an adjusting member of said source of fluid under pressure, - a discharge line 40 or a low pressure environment ( typically a tank). It is sufficient for the assembler to connect: - the first port 1 to the source of fluid under pressure, P; the second orifice 2 to the first hydraulic chamber 81 of the receiver R1; the third ports 3 and 3 'to the LS line; the fourth orifices 4 and 4 'to the discharge line 40 or to the low pressure environment; the fifth port 5 to the second hydraulic chamber 91 of the receiver R1.

The machine may comprise two or more hydraulic receivers operating simultaneously and consist for example of two jacks associated with two particular tools. FIG. 8 schematizes such a mounting where at least a second hydraulic receiver R2 is connected to the hydraulic circuit described above, by means of another distributor D2 connected in parallel. This distributor D2 is identical to the distributor D1. Its first port 1 is connected to the common source of pressurized fluid P; its second orifice 2 to the first hydraulic chamber 82 of the receiver R2; its third ports 3 and 3 'to the common line LS; its fourth orifices 4 and 4 'to the common discharge line 40 or to the low pressure environment; its fifth port 5 to the second hydraulic chamber 92 of the receiver R2.

In this arrangement, the two receivers R1 and R2 are jacks working simultaneously, and whose rods must be moved to the same side (to the right in Figure 8). The receiver R1 is the most loaded receiver, the spring 71 shown schematically at the end of the rod of the cylinder illustrating this additional load. The drawer T1, T2 of each of the distributors is moved to the first position: the flow passage between the orifices 1 and 2 is open in each of the distributors. The receiver R1 being the most loaded, the pressure at the second port 2 of the distributor D1 is greater than that at the second port 2 of the distributor D2. The drawer T1 of the distributor D1, and the balances B1, B2 associated therewith, are in a configuration position to that described with reference to FIG. 5. The highest load pressure (that is to say the pressure in the flow passage connecting the first port 1 and the second port 2 of the distributor D1) is established in the line LS common to the two distributors D1 and D2. The pressure difference ΔΡ at the terminals 1 and 2 of the distributor D1 is therefore equal to APDI = Psource of fluid - PLS. The flow rate through the metering slide T1 is in fact independent of the load.

Figure 9 illustrates in detail the behavior of the distributor D2 at its first balance B1. Its balance B2 is in a position identical to that of the balance B2 of the distributor B1. The pressure of the fluid prevailing in the flow passage connecting the first orifice 1 and the second orifice 2 is less than the pressure prevailing in the portion 62 of the longitudinal bore 6 of said spool T2 (that is to say the pressure prevailing in driving LS). This balance B1 therefore tends to be moved to the right. The second opening 703 is then closed by the internal active wall of the smaller diameter portion 61 of the longitudinal bore 6 of the spool T1: the fluid from the pipe LS can not flow to the second orifice 2 of the receiver R2, and therefore to the least loaded branch.

It is however necessary to maintain a constant pressure difference at terminals 1 and 2 of the distributor D2. Referring to FIG. 9, the balance B1 of the distributor D2, and in particular its shoulder 700, acts as a throttling point in the passage section between the second channel 602 and the second orifice 2, creating a loss of pressure which increases until the pressure at said throttling point is equal to that in the portion 62 of the longitudinal bore 6 of the spool T2 (i.e. the pressure in the LS line). The pressure difference ΔΡ at the terminals 1 and 2 of the distributor D2 is therefore equal to ΔΡϋ2 = Psource fluid - PLS = APDL The flow rate through the metering slide T2 is well independent of the load. In summary, the flow rates through distributors D1 and D2, respectively, remain the same, regardless of the load conditions of the receivers R1 and R2.

The fluid moving around the balance B1 of the distributor D2, and unlike a static fluid, generates hydrodynamic forces (also called jet effects) which tend to want to close said balance. To compensate for these effects, the pressure at the point of constriction in the passage section between the second channel 602 and the second port 2 increases. And the pressure difference ΔΡ at terminals 1 and 2 of the distributor D2 decreases of the order of 1 to 2 bars, resulting in a more or less pronounced drop in the flow of the least loaded slice. This phenomenon is amplified for significant differences in pressure between the slices and for flow rates at the terminals of the large dosers D1, D2. In order to compensate for this drop in flow, and as it appears in FIG. 10, it is advantageous to machine on the metering slide T2 (and T1), regulating slots 6000 acting as a variable nozzle as a function of the travel of the drawer and which act between the orifices 1 and 2 or 1 and 5 in parallel with the action of the balance. These slots 6000 are made on the outer wall of the metering slide, and are longitudinal. They are configured to create a nozzle flow passage between the first port 1 and the second port 2 (respectively the fifth port 5). Thus, these slots 6000 allow to take a small amount of flow on the first pressure port 1 and transfer it to the second port 2 (or to the fifth port 5), bypassing the throttling point in the section passing between the second channel 602 and the second port 2 (or between the other second channel 602 'and the orifice 5). The slots 6000 then make it possible to compensate for the jet effects which causes a drop in the flow rate in the least loaded slice.

In the case of a saturated system, the higher the degree of saturation, the more the pressure difference across the different distributors D1 and D2 decreases, the more the movements slow down, but as this pressure difference remains the same regardless of the Distributor, we keep a proportionality of the flow rates of the distributors.

The invention must be understood as applying to a machine comprises n (n> 2) hydraulic receivers operating simultaneously. The operation is identical to that described above with reference to FIGS. 8 and 9.

The arrangement of the various elements and / or means and / or steps of the invention, in the embodiments described above, should not be understood as requiring such an arrangement in all implementations. In any case, it will be understood that various modifications may be made to these elements and / or means and / or steps, without departing from the spirit and scope of the invention.

Claims

claims

1. Hydraulic distributor comprising:

a housing (C) provided with a longitudinal bore comprising:

a first orifice (1) opening into a discharge pipe (10) predisposed to be connected to a source of pressurized fluid (P),

a second orifice (2) opening into a charge line (20) predisposed to be connected to a first hydraulic chamber (81) of a hydraulic receiver (R1),

a third orifice (3) opening into a pipe predisposed to be connected to a charge detection line (LS) for signaling the charge pressure to a regulator (OR) of the source of pressurized fluid (P),

a flow passage system connected to said orifices,

a metering slide (T) slidably mounted in the housing (C) so as to control fluid flows within the passage system, said slide comprising: an active position (I) opening a flow passage between the first orifice (1) and the second orifice (2) of the housing (C), a neutral position (N) closing said passage,

- At least one pressure balance (B1) slidably mounted in a longitudinal bore (6) of the metering slide (T), said balance being arranged so that, in the active position (I) of said slide, it acts as a point throttling in the flow passage connecting the first orifice (1) and the second orifice (2) of the housing (C), being biased: on one side by the pressure of the fluid in said flow passage, and on the other hand by the pressure in a portion (62) of the longitudinal bore of said slide which is connected to the third orifice (3) of said housing,

said balance (B1) integrates a duct (701) opening at a first opening (702) and a second opening (703), said openings being arranged so that, in the active position (I) of metering slide (T):

the first opening (702) is placed in the flow passage connecting the first orifice (1) and the second orifice (2) of the housing (C),

the second opening (703) is placed in the portion (62) of the longitudinal bore (6) of the metering slide (T) which is connected to the third orifice (3) of the casing (C), when the pressure of the fluid prevailing in the flow passage connecting the first orifice (1) and the second orifice (2) of said housing is greater than or equal to the pressure prevailing in said portion (62) of the longitudinal bore (6),

characterized in that the second opening (703) of the conduit (701) of the balance (B1) is closed off by an active wall (61) of the longitudinal bore (6) of the metering slide (T), when the fluid pressure in the flow passage connecting the first orifice (1) and the second orifice (2) of the casing (C) is less than the pressure prevailing in the portion (62) of the longitudinal bore (6) of said slide which is connected to the third port (3) of the housing (C).

2. Hydraulic distributor according to claim 1, wherein the conduit (701) of the balance (B1) comprises a longitudinal bore (7012) opening at the first opening (702) and a radial bore (7013) opening at the level of the second opening (703), a nozzle (G1) being disposed at the junction of the two said holes.

The hydraulic distributor according to claim 2, wherein the longitudinal bore (7012) extends to open at a third opening (704) located in the portion (62) of the longitudinal bore (6) of the metering slide (T). which is connected to the third orifice (3) of the housing (C), another nozzle (G2) being disposed in the extension of said longitudinal bore.

4. Hydraulic distributor according to one of the preceding claims, wherein the housing (C) comprises:

a fourth orifice (4) opening into a pipe predisposed to be connected to a discharge pipe (40) or a low pressure environment, a flow passage connected to the second orifice (2) of said housing and to said fourth orifice (4). ), which passage is configured so that the fluid flows in this passage without crossing the pressure balance (B1).

5. Hydraulic distributor according to one of the preceding claims, wherein the pressure balance (B1) is biased by a spring (BR1) acting on the end of said balance which is located in the portion (62) of the longitudinal bore ( 6) of the metering slide (T) which is connected to the third orifice (3) of the housing (C), so that the absence of any stress, said balance closes the flow passage for connecting the first port (1) and the second port (2) of said housing.

6. Hydraulic distributor according to claim 5, wherein the pressure exerted by the spring (BR1) on the balance (B1) is negligible compared to the pressure at the first orifice (1) and the pressure at the third level orifice (3), when the metering slide (T) is in the active position (I).

7. Hydraulic distributor according to one of the preceding claims, wherein longitudinal slots (6000) are formed on the outer wall of the metering slide

(T), which slots are configured to create a nozzle flow passage between the first port (1) and the second port (2).

8. Hydraulic distributor according to one of the preceding claims, wherein:

the housing (C) comprises:

o another third orifice (3 ') opening in a pipe predisposed to be connected to the charge detection line (LS) for signaling the charge pressure to the regulator (OR) of the source of fluid under pressure ( P)

o fourth orifices (4, 4 ') opening into a pipe arranged to be connected to a discharge pipe (40) or to a low-pressure environment,

a fifth orifice (5) opening into a charge line (50) predisposed to be connected to a second hydraulic chamber (91) of the hydraulic receiver (R1),

a flow passage system connected to said orifices,

the metering slide (T) comprising at least three positions: a first active position (I) opening a flow passage between the first orifice (1) and the second orifice (2) of the casing (C), a second active position ( II) opening a flow passage between the first orifice (1) and the fifth orifice (5) of said housing and a neutral position (N) closing these passages,

a second pressure balance (B2) is slidably mounted in a longitudinal bore (6 ') of the metering slide (T), said second scale being arranged so that, in the second active position (II) of said slide, it acts as a point throttling in the flow passage connecting the first orifice (1) and the fifth orifice (5) of the casing (C), being biased: on one side by the pressure of the fluid prevailing in said flow passage, and on the other hand by the pressure in a portion (62 ') of the longitudinal bore (6') of said slide which is connected to the other third orifice (3 ') of said housing,

said second scale (B2) includes a duct (701 ') opening at a first opening (702') and a second opening (703 '), said openings being arranged so that in the second position active (II) of the metering slide (T):

the first opening (702 ') is placed in the flow passage connecting the first orifice (1) and the fifth orifice (5) of the housing (C),

the second opening (703 ') is placed in the portion (62') of the longitudinal bore (6) of the metering slide (T) which is connected to the other third orifice (3 ') of the casing (C), when the fluid pressure prevailing in the flow passage connecting the first orifice (1) and the fifth orifice (5) of said housing is greater than or equal to the pressure in said portion (62 ') of the longitudinal bore (6'),

the second opening (703 ') of the duct (701') of the second scale (B2) is closed off by an active wall (61 ') of the longitudinal bore (6') of the metering slide (T), when the pressure of the fluid prevailing in the flow passage connecting the first port (1) and the fifth port (5) of the housing (C) is less than the pressure in the portion (62 ') of the longitudinal bore (6') of said connected drawer at the other third port (3 ') of said housing.

9. Motorized machine incorporating a hydraulic circuit comprising: a source of pressurized fluid (P), at least one hydraulic receiver (R1) provided with at least a first hydraulic chamber (81), a charge detection line. (LS) predisposed to signaling the charge pressure of said receiver to an adjusting member (OR) of said source of pressurized fluid, - a discharge line (40) or a low pressure environment,

characterized in that a hydraulic distributor (D1) according to claim 1 is connected to the hydraulic circuit so that:

its first orifice (1) is connected to the source of pressurized fluid (P), its second orifice (2) is connected to the first hydraulic chamber (81) of the hydraulic receiver (R1),

its third port (3) is connected to the charge detection line (LS).

Motorized machine according to claim 9, wherein the hydraulic receiver (R1) is provided with a second hydraulic chamber (91), and wherein the hydraulic distributor (D1) is in accordance with claim 8, which distributor is connected to the hydraulic circuit so that:

the first port (1) is connected to the source of pressurized fluid (P), the second port (2) is connected to the first hydraulic chamber (81) of the hydraulic receiver (R1),

the third ports (3, 3 ') are connected to the charge detection line (LS),

the fourth orifices (4, 4 ') are connected to the discharge line (40) or to the low pressure environment.

the fifth port (5) is connected to the second hydraulic chamber (91) of the hydraulic receiver (R1).

1 1. Motorized machine according to claim 10, wherein the hydraulic circuit further comprising a second hydraulic receiver (R2) provided with two hydraulic chambers (82, 92), at least one second hydraulic distributor (D2) according to claim 8 being connected to said hydraulic circuit so that:

its first orifice (1) is connected to the source of fluid under pressure (P),

its second orifice (2) is connected to the first hydraulic chamber (82) of the second hydraulic receiver (R2),

its third ports (3, 3 ') are connected to the charge detection line

(LS),

its fourth orifices (4, 4 ') are connected to the discharge line (40) or to the low pressure environment.

its fifth port (5) is connected to the second hydraulic chamber (92) of the second hydraulic receiver (R2).