FR3010325A1 - IMPROVED FILTRATION SYSTEM FOR HYDRAULIC CIRCUIT - Google Patents

Abstract

The present invention provides a hydraulic circuit comprising a feed line (HP), a return line (BP) and a filtration system (3) connected in series on the return line (BP), said filtration system (3) further comprising a filter element (5) and a dispenser (4, 6), said dispenser having a filtration configuration (4A, 6A) in which all or part of the flow of the return line (BP) passes through the element filter (5), and a passage pattern (4B, 6B) in which the filter element (5) is isolated from the return line (BP), said dispenser (4, 6) further comprising a control (45). , 65) adapted to control the passage of the distributor (4, 6) from the passage configuration (4B, 6B) to the filtration configuration (4A, 6A) when the pressure in the return line (BP) is greater than a value pressure threshold.

Description

GENERAL TECHNICAL FIELD The present invention relates to the field of hydraulic circuits, and more specifically the filtration elements of hydraulic circuits.

STATE OF THE ART In closed hydraulic circuits, the filtration is conventionally done: either by sampling the flow on the low pressure branch of the circuit, this withdrawn flow being then reinjected by the feeding circuit, or directly into the closed circuit with a high pressure filter designed to withstand pressures up to 450 bar. These filtration systems, however, have disadvantages. In the case of a flow sampling on the low pressure branch, it requires over-size the feed circuit to compensate for losses generated in pressure and flow. The removal of such a sample does not allow to maintain an effective filtration of the pollution in the circuit. In the case of a filter disposed directly in the closed circuit, the filter must be dimensioned so as to withstand the high pressure within the circuit, and is therefore heavy, expensive and bulky. The present invention aims to provide a filtration system for hydraulic circuit does not have such disadvantages.

PRESENTATION OF THE INVENTION To this end, the present invention proposes a hydraulic circuit comprising a first set of hydraulic devices and a second set of hydraulic devices, said first and second sets being connected by a supply line, a return line, the circuit being characterized in that it further comprises a filtration system connected in series on the return line and comprising an intake port and a discharge port, said filtration system further comprising a filter element; filtration and a dispenser, said dispenser having a filtration configuration in which all or part of the flow of the return line passes through the filter element, and a passage configuration in which the filter element is isolated from the return line, said dispenser further comprising a control adapted to control the passage of the dispenser from the configuration of passage to the configurator filtration unit when the pressure in the return line is greater than a pressure threshold value. The inlet port and the discharge port are typically connected by a non-return valve and the circuit further comprises a selector connected to its inlet port and its discharge port so as to take the most pressure. high, and the distributor comprises a hydraulic control opposing a return element, said hydraulic control being controlled by the selector. The filtration system then typically further comprises a restriction connected to its inlet and discharge port. Said distributor then comprises, for example: a first orifice connected to the inlet orifice; a second orifice connected to the discharge orifice; a third orifice and a fourth orifice connected to the filtration element; dispenser being configured as follows: in filtration configuration, the first and second dispenser openings are respectively connected to the third and fourth dispenser openings, in the passage configuration, the first orifice is connected to the second orifice, while the third and fourth orifices are closed. According to another variant, the dispenser comprises: a first orifice connected to the inlet orifice of the filtration system; a second orifice connected to the filtration element, said dispenser being configured as follows: in filtration configuration, its first orifice and its second orifice are connected, - in passage configuration, its first orifice and its second orifice are closed, the filtration system further comprising a restriction connected to its inlet and its discharge orifice, the control being connected to the inlet of the filtration system. According to a particular embodiment, said filter element comprises a filter and a cooler connected in series. According to a particular embodiment, said filter element further comprises a pressure limiter connected to an ambient pressure tank, said pressure limiter defining a maximum pressure applied to said filter element, ensuring protection of the filtration element against overpressure in case of distributor failure. According to a particular embodiment, the dispenser comprises: a first orifice connected to the inlet orifice of the filtration system; a second orifice connected to the filtration element, said dispenser being configured as follows: in filtration configuration , its first orifice and its second orifice are connected via a non-return valve allowing the passage of only the first orifice to the second orifice, - in passage configuration, its first orifice and its second orifice 5 are closed, the filtration system further comprising a restriction connected to its inlet and its discharge port, the control being connected to the inlet of the filtration system, the circuit further comprising a booster pump, connected to the line 10 supply via a non-return valve, and to the filter element via a non-return valve, so that the feeding of the return line passes beforehand through the element of f iltration. PRESENTATION OF THE FIGURES Other characteristics, objects and advantages of the invention will emerge from the description which follows, which is purely illustrative and nonlimiting, and which should be read with reference to the appended drawings, in which: FIG. An exemplary circuit according to one aspect of the invention, - Figure 2 shows a variant of the circuit shown in Figure 1; - Figure 3 shows another example circuit according to one aspect of the invention; FIG. 4 shows a variant of the example presented in FIG. 3. In all the figures, the elements in common are identified by identical reference numerals. DETAILED DESCRIPTION Figure 1 shows an exemplary circuit according to one aspect of the invention. The circuit shown comprises: - a first set of hydraulic devices 1, - a second set of hydraulic devices 2, said first and second sets being connected by a feed line and a return line.

In the illustrated example, the first set of hydraulic devices 1 comprises a hydraulic pump 11 and a booster pump 12 supplying a booster circuit 13. The booster circuit 13 has a structure well known to those skilled in the art , and includes a set of check valve and pressure limiters, to ensure a booster function of the hydraulic circuit and protection against overpressure. The second set of hydraulic devices 2 comprises a hydraulic motor 21.

An arbitrary direction of circulation of the fluid in the circuit, represented by arrows, is arbitrarily represented. Considering this direction of circulation, the HP supply line of the circuit and the BP return line of the circuit are represented, the HP supply line being connected to the discharge of the hydraulic pump 11 and supplying the second set of hydraulic devices. 2, while the BP return line is connected to the inlet of the hydraulic pump 11 and is at a lower pressure than the HP supply line. The disclosed circuit comprises a filtration system 3. This filtration system 3 comprises an inlet port 31 and a discharge port 32, and is connected in series with the return line BP.

The inlet port 31 and the discharge port 32 of the filtration system 3 are connected by a nonreturn valve 33, configured to be in the direction from the first set of hydraulic devices 1 to the second set of hydraulic devices 2, and blocking in the direction from the second set of hydraulic devices 2 to the first set of hydraulic devices 1. Thus, the check valve 33 is blocking only if the filtration system 3 is on the return line, that is to say the low pressure line of the circuit. In the case where the filtration system 3 is on the supply line, that is to say the high pressure line of the circuit, the nonreturn valve 33 is conducting, which makes a short circuit of the system of filtration 3. The filtration system 3 comprises a distributor 4 and a filtration element 5. The distributor 4 comprises: a first orifice 41 connected to the inlet orifice 31, a second orifice connected to the orifice of discharge 32, a third orifice 43 and a fourth orifice 44 connected to the filtration element 5. The distributor 4 alternates between two configurations: a filtration configuration 4A, in which the first 41 and the second orifice 42 of the distributor are connected respectively to the third 43 and the fourth 44 orifice of the distributor 4, - a passage configuration 4B, in which the first orifice 41 is connected to the second orifice 42, while the third 43 and fourth 44 orifices are closed.

The distributor 4 is controlled by a hydraulic control 45 which is opposed by a return element 46, here a spring.

The return element 46 maintains the distributor 4 by default in its filtration configuration 4A, and the application of a command by the hydraulic control 45 tilts the distributor 4 in its passage configuration 4B.

The hydraulic control 45 is connected to the inlet port 31 of the filtration system 3. The control applied to the distributor 4 by the hydraulic control 45 is therefore equal to the pressure at the inlet port 31 of the filtration system 3 .

The return element 46 exerts a thrust force on the distributor 4. The return element 46 thus defines a pressure threshold value, such that: - When the pressure at the inlet port 31 of the filtration system 3 is less than or equal to the pressure threshold value, the distributor 4 is in filtration configuration 4A. - When the pressure at the inlet port 31 of the filtration system 3 is greater than the pressure threshold value, the distributor 4 is in the passage configuration 4B.

The pressure threshold value defined by the return element 46 is advantageously configured to be greater than the boost pressure of the circuit slightly increased so as to tolerate a variation in pressure.

The threshold value of pressure defined by the return element 46 is thus for example equal to 4 bar. Thus, the filtration system 3 conducts a series connection of the filter element 5 in the return line BP only when the pressure at the inlet port 31 of the filtration system 3 is less than or equal to a threshold value. that is, when the pressure in the BP return line is less than or equal to the threshold value. The filter element 5 is thus protected against too high pressures.

The filtration element 5 comprises a filter 51, typically connected in series with a cooler 52. The filtration element 5 advantageously comprises a pressure limiter 53 connected to an ambient pressure tank R, so as to provide additional protection against the overpressures by defining a maximum pressure in the filter element 5, for example equal to 8 bar. This pressure limiter 53 protects the filtration element 3 against overpressure in the event of failure of the distributor 4. The filtration element 5 furthermore typically comprises a calibrated anti-return valve 54 connected in parallel with the filter 51, so as to perform a short circuit function of the filter 51 if the pressure within the filtration element 5 exceeds the calibration value of the calibrated check valve 54. An anti-return valve 55 is also advantageously arranged upstream of the filter 51 relative to the third orifice 43 of the dispenser 4.

The proposed circuit thus makes it possible to carry out a filtration of the fluid of the hydraulic circuit, without requiring an over-dimensioning of the booster pump 12 or the filter 51. FIG. 2 shows a variant of the embodiment of FIG.

In this variant, the hydraulic control 45 of the distributor 4 is supplied by means of a selector 34 connected to the inlet port 31 and to the discharge port 32 of the filtration system 3, the selector 34 being configured so to take the highest pressure between the pressure at the inlet port 31 and at the discharge port 32 of the filtration system 3. This variant thus makes it possible to drive the distributor 4 by means of the highest pressure among the pressure at the inlet port 31 and the pressure at the discharge port 32 of the filtration system 3, which improves the stability. A restriction 35 is advantageously also connected to the inlet port 31 and the discharge port 32 of the filtration system 3, so as to be connected in parallel with the selector 34. Such a restriction makes it possible to avoid blows in case of reversal of the pressure ratio between the inlet port 31 and the delivery port 32 of the filtration system 3.

The restriction 35 is advantageously calibrated in such a way that the leakage rate it allows to pass is small compared with the flow rate passing through the filtration system 3. According to another variant not shown, the hydraulic control 45 of the distributor 4 is connected at the inlet port 31 and the discharge port 32 of the filtration system 3 by two restrictions connected in parallel. The filtration system 3 is advantageously arranged on the line of the hydraulic circuit which, for the estimated use of the circuit, will be mainly the return line or low-pressure line of the circuit, that is to say the line connected to the admission of the elements delivering a flow or a pressure in the circuit.

For example, considering the circuit shown in Figure 2, the filtration is performed when the fluid flows in the circuit in the direction indicated by the arrows, corresponding for example to a forward operation. In the event of a reversal of direction, corresponding, for example, to a reverse operation, the nonreturn valve 33 is passing and thereby bypasses the distributor 4 and the filtration element 5. The filtration of the circuit is therefore carried out when its majority use.

Figure 3 shows another embodiment of circuit according to one aspect of the invention.

In this embodiment, the filtration system 3 is configured to selectively capture a portion of the flow of the BP return line to filter it. The filter element 5 is connected to the discharge port 32 of the filtration system 3 by an anti-return valve 37, configured to prevent the passage of fluid from the return line BP to the filter element 5. The discharge port 32 and the inlet port 31 of the filtration system 3 are connected by a restriction 36 The filtration system 3 presented comprises a distributor 6 with two orifices 61, 62 and two configurations 6A and 6B. The first orifice 61 is connected to the inlet orifice 31 of the filtration system 3. The second orifice 62 is connected to the filtration element 5. The distributor 6 has: A filtration configuration 6A in which its first orifice 61 and its second orifice 62 are connected, - a passage configuration 6B in which its first orifice 61 and its second orifice 62 are closed. A control 65 to which a return spring 66 opposes controls the passage of the distributor 6 from its filtration configuration 6A to its passage configuration 6B when the pressure between the restriction 36 and the inlet 31 of the filtration system 3 exceeds a threshold value. The return spring 66 maintains the distributor 6 by default in its filtration configuration 6A, and defines the pressure threshold value from which the control 65 switches the distributor 6 from its filtration configuration 6A to its passage configuration 6B. As indicated above, the pressure threshold value defined by the return element 66 is advantageously configured to be greater than the boost pressure of the circuit slightly increased so as to tolerate a variation in pressure. The threshold value of pressure defined by the return element 66 is thus for example equal to 5 bar.

In operation, the restriction 36 limits the flow through the BP return line, and is calibrated so that a portion of the flow of the return line BP passes through the filtration system 3 if the pressure does not exceed the threshold value set. In case of overpressure, the filter element 5 is protected by the tilting of the distributor 6 which isolates it from the return line BP. This embodiment is thus simplified with respect to the embodiments presented in the preceding figures, and makes it possible to obtain a very stable control of the distributor 6.

FIG. 4 shows a variant of the circuit presented previously in FIG. 3. In this variant, the booster pump 12 is connected on the one hand to the HP supply line of the hydraulic circuit, and on the other hand to the filter 51 25 of the filter element 5. The connection of the booster pump 12 to the supply line HP of the hydraulic circuit is carried out by means of a non-return valve, thus ensuring that the booster pump 12 is not exposed to the oil pressure of the HP supply line.

The booster pump 12 is also connected to a tank R at ambient pressure by means of a booster pressure limiter 71 thus ensuring protection of the booster pump 12 against overpressures. The booster pump 12 is furthermore connected to the filter 51 of the filtering element 5 via a non-return valve 72 thus ensuring that the flow goes only from the booster pump 12 to the booster element. filtration 5, not in the opposite direction. The distributor 6 also comprises an anti-return valve 67 allowing passage only in one direction in configuration 6A, that is to say from the return line BP to the filter element 5, thus ensuring that the flow rate of the booster pump 12 passes through the filter element before being injected into the return line BP. This variant thus ensures a filtration of the feed rate injected into the return line BP of the hydraulic circuit, in addition to a calibrated filtration 15 of the flow rate of the return line BP as previously described with reference to FIG. 3. The proposed circuit Thus, it is possible to filter inside the loop of the closed circuit without using an exchange function and thus without requiring an over-dimensioning of the booster pump 12, while using a low-pressure filter which is more economical in terms of price, mass and footprint that a filter sized to be used at high pressure. A large proportion of the flow is filtered internally to the circuit, which provides superior filtration quality and thus improves the service life of the system.

Claims (8)

REVENDICATIONS1. A hydraulic circuit comprising a first set of hydraulic apparatuses (1) and a second set of hydraulic apparatuses (2), said first (1) and second (2) sets being connected by - a supply line (HP), - a return line (BP), the circuit being characterized in that it further comprises a filtration system (3) mounted in series on the return line (BP) and comprising an inlet port (31) and an orifice discharge device (32), said filtration system (3) further comprising a filter element (5) and a distributor (4, 6), said dispenser having a filtration configuration (4A, 6A) in which all or part of the flow rate of the return line (BP) passes through the filter element (5), and a passage pattern (4B, 6B) in which the filter element (5) is isolated from the return line (BP), said dispenser (4, 6) further comprising a control (45, 65) adapted to control the passage of the dispenser (4, 6) d e the passage configuration (4B, 6B) to the filtration configuration (4A, 6A) when the pressure in the return line (BP) is greater than a pressure threshold value. The circuit of claim 1, wherein said filter element (5) comprises a filter (51) and a cooler (52) connected in series. 3. Circuit according to one of claims 1 or 2, wherein said filter element (5) further comprises a pressure limiter (53) connected to a tank at ambient pressure (R), said pressure limiter (53). defining a maximum pressure applied to said filter element (5). 4. Circuit according to one of claims 1 to 3, wherein the inlet port (31) and the discharge port (32) are connected by a non-return valve (33) and the circuit further comprises a selector (34) connected to its inlet port (31) and its delivery port (32) so as to take the highest pressure, and the distributor (4) comprises a hydraulic control (45) opposing a return element (46), said hydraulic control being controlled by the selector (34). 5. Circuit according to claim 4, wherein the filtration system (3) further comprises a restriction (35) connected to its inlet port (31) and its discharge port (32). 6. Circuit according to one of claims 4 or 5, wherein said distributor (4) comprises: - a first port (41) connected to the inlet port (31), - a second port (42) connected to the discharge port (32), - a third port (43) and a fourth port (44) connected to the filter element (5), said distributor (4) being configured as follows: - in the filtration configuration ( 4A), the first (41) and the second (42) dispenser ports (4) are respectively connected to the third (43) and fourth (44) dispenser ports (4), in the passage configuration (4B), the first port (41) is connected to the second port (42) while the third (43) and fourth (44) ports are closed. 7. Circuit according to one of claims 1 to 3, wherein the distributor (6) comprises - a first orifice (61) connected to the inlet (31) of the filtration system (3), - a second orifice (62) connected to the filter element (5), said distributor (6) being configured as follows: - in filtration configuration (6A), its first orifice (61) and its second orifice (62) are connected, in passage configuration (6B), its first orifice (61) and its second orifice (62) are closed, the filtration system (3) further comprising a restriction (36) connected to its inlet (31) and at its discharge port (32), the control (65) being connected to the inlet (31) of the filtration system (3). 8. Circuit according to one of claims 1 to 3, wherein the distributor (6) comprises - a first port (61) connected to the inlet (31) of the filtration system (3), - a second orifice (62) connected to the filter element (5), said dispenser (6) being configured as follows: - in filtration configuration (6A), its first orifice (61) and its second orifice (62) are connected via a non-return valve (67) allowing the passage of only the first orifice (61) to the second orifice (62), - in the passage configuration (6B), its first orifice (61) and its second orifice (62) are closed, the filtration system (3) further comprising a restriction (36) connected to its inlet (31) and its discharge port (32), the control (65) being connected to the orifice inlet (31) of the filtration system (3), the circuit further comprising a booster pump (12), connected to the feed line (HP) via a check valve, and to the filter element (5) via an anti-return valve (72), so that the feeding of the return line (BP) passes beforehand through the filter element (5).