EP3163076A1 - Hydraulic machine with two displacements and safety valve - Google Patents

Abstract

The machine comprises distribution ducts respectively connected to a first, a second and a third enclosure (40, 42, 44) and a displacement selector (21) capable of being controlled to adopt a large displacement configuration in which the second enclosure (42) is connected to one of the main lines (2) while the first and third chambers (40, 44) are connected to the other main line (1), and a small displacement configuration in which the second and third speakers (42, 44) are connected to one of the main lines (2) while the first chamber is connected to the other main line (1). The machine comprises a safety valve (150) comprising at least a first channel (56) connected to said one main line (2) and a second channel (58) connected to the third chamber (44). The safety valve is controllable, when the displacement selector (21) is controlled in large displacement, in a first configuration isolating the first and second channels (56, 58) and to be controlled, when the displacement selector is controlled in small displacement, in a second configuration connecting the first and second tracks (56, 58).

Description

• deux séries de conduits de distribution ayant chacune un premier et un deuxième groupe de conduits de distribution, le premier groupe de conduits de distribution de la première série étant relié à une première enceinte, les deuxièmes groupes de conduits de distribution des première et deuxième série étant reliés à une deuxième enceinte, et le premier groupe de conduits de distribution de la deuxième série étant relié à une troisième enceinte,
• un sélecteur de cylindrée apte à être commandé pour adopter une configuration de grande cylindrée dans laquelle la deuxième enceinte est reliée à l'une des conduites principales, tandis que la première et la troisième enceinte sont reliées à l'autre conduite principale, et une configuration de petite cylindrée dans laquelle la deuxième et la troisième enceinte sont reliées à l'une des conduites principales, tandis que la première enceinte est reliée à l'autre conduite principale.

The present disclosure relates to a hydraulic machine having at least two active operating displacements and adapted to be connected to two main conduits, respectively supply and exhaust, the machine comprising:

• two series of distribution ducts each having a first and a second group of distribution ducts, the first group of distribution ducts of the first series being connected to a first chamber, the second groups of distribution ducts of the first and second series being connected to a second enclosure, and the first group of distribution ducts of the second series being connected to a third enclosure,
• a controllable displacement selector for adopting a large displacement configuration in which the second chamber is connected to one of the main lines, while the first and third chambers are connected to the other main line, and a configuration small displacement in which the second and the third chamber are connected to one of the main pipes, while the first chamber is connected to the other main pipe.

The first and second series of distribution ducts respectively define a first and a second sub-machine. In large displacement, the two sub-machines are active because their two groups of respective distribution ducts are respectively connected to the supply and to the exhaust. In small displacement, only the first sub-machine is active, the two groups of distribution ducts of the second series, that is to say of the second sub-machine being connected to the same main pipe.

A hydraulic machine of this type, in this case a hydraulic motor, is known from the document FR 2,673,684 .

To change the displacement of the engine, the displacement selector must be controlled to switch from one to the other of the aforementioned configurations. In general, the displacement selector comprises a slide that moves between a first position corresponding to the large displacement configuration, in which it connects the first and third speakers together by isolating them from the second chamber, and a second position which corresponds to in the configuration of small displacement, in which it connects the second and third speakers together isolating them from the first speaker. Thus, according to the configuration of the displacement selector, that is to say in particular according to the position of the drawer of this selector, the third enclosure is connected either with the first enclosure or with the second enclosure. However, it may happen that, during this transition from one configuration to another, the displacement selector is blocked so that the third enclosure would then be isolated from both the first and the second enclosure. If the machine operates in such a blocking situation, the pressure in the third chamber may rise, under the effect of the fluid discharged into this chamber which can not escape from it because of the isolation of this enclosure .

Furthermore, it has been indicated that, in the small-displacement configuration, the second and third enclosures are connected to one of the main pipes, while the first enclosure is connected to the other of the main pipes. Thus, the hydraulic machine has a preferred operating direction in small displacement, since all the distribution ducts of the second series are then connected to the same main pipe by the connection between the second and third speakers. If this machine is a motor, this preferred direction in small displacement corresponds to that in which the main pipe to which is connected the first enclosure in a small displacement configuration is a main supply line. Indeed, in this case, the distribution ducts of the second series are all connected to the exhaust pipe by the connection between the second and third speakers. On the other hand, in the opposite direction, the distribution ducts of the second series are all connected to the feed in small displacement configuration so that the sub-engine corresponding to this second series of distribution ducts is inactivated since all its ducts dispensers are put at the same pressure, but it can exert a resistant torque on the engine. In addition, depending on the configuration of the displacement selector, the high pressure in the second and third speakers can cause a partial displacement of the selector up to isolate the third speaker of the first and second speakers, and can thus lead to an increase in significant pressure in this third chamber since the fluid that is repressed can not escape.

To prevent the increase of the pressure in the third enclosure from causing degradation of the machine, it is possible to choose to connect a pressure limiter to this third enclosure. In a manner known per se, a pressure limiter is a valve calibrated at a given trigger pressure, from which it opens to connect the enclosure it protects to an evacuation, in particular to a tank without overpressure.

However, pressure limiters are expensive and relatively bulky valves. In addition, the more the machine is designed to withstand high pressures and flow rates, the greater the cost and the size of the pressure relief devices used to protect it against overpressure become important.

Thus, according to a first aspect, the invention aims to improve the state of the art by avoiding as much as possible to damage the machine under the effect of overpressure, particularly in the third enclosure, with the aid of a solution which is substantially free from the aforementioned drawbacks.

• deux séries de conduits de distribution ayant chacune un premier et un deuxième groupe de conduits de distribution, le premier groupe de conduits de distribution de la première série étant relié à une première enceinte, les deuxième groupes de conduits de distribution des première et deuxième séries étant reliés à une deuxième enceinte, et le premier groupe de conduits de distribution de la deuxième série étant relié à une troisième enceinte,
• un sélecteur de cylindrée apte à être commandé pour adopter une configuration de grande cylindrée dans laquelle la deuxième enceinte est reliée à l'une des conduites principales, tandis que la première et la troisième enceinte sont reliées à l'autre conduite principale, et une configuration de petite cylindrée dans laquelle la deuxième et la troisième enceinte sont reliées à ladite une des conduites principales, tandis que la première enceinte est reliée à ladite autre conduite principale ;

la machine comporte en outre une valve de sécurité comprenant au moins une première voie reliée à l'une des conduites principales et une deuxième voie reliée à la troisième enceinte, ladite valve de sécurité étant apte à être commandée, lorsque le sélecteur de cylindrée est commandé vers la configuration de grande cylindrée, dans une première configuration dans laquelle la première et la deuxième voies sont isolées l'une de l'autre, et à être commandée, lorsque le sélecteur de cylindrée est commandé vers la configuration de petite cylindrée, dans une deuxième configuration dans laquelle la première et la deuxième voies sont reliées.Thus, according to one aspect, the invention a hydraulic machine having at least two active operating displacements and adapted to be connected to two main lines, respectively supply and exhaust,
the machine comprising:

• two series of distribution ducts each having a first and a second group of distribution ducts, the first group of distribution ducts of the first series being connected to a first chamber, the second groups of distribution ducts of the first and second series being connected to a second enclosure, and the first group of distribution ducts of the second series being connected to a third enclosure,
• a controllable displacement selector for adopting a large displacement configuration in which the second chamber is connected to one of the main lines, while the first and third chambers are connected to the other main line, and a configuration small displacement in which the second and the third chamber are connected to said one of the main lines, while the first chamber is connected to said other main line;

the machine further comprises a safety valve comprising at least a first channel connected to one of the main lines and a second channel connected to the third chamber, said safety valve being able to be controlled, when the displacement selector is controlled to the large displacement configuration, in a first configuration in which the first and second tracks are isolated from each other, and to be controlled, when the displacement selector is controlled to the small displacement configuration, in a second configuration in which the first and second channels are connected.

Thus, the safety valve is simply a valve that can be controlled between the first and second configurations above, without having to be tared at a particular pressure. Thus, this valve is both significantly less expensive and significantly less bulky than a pressure limiter.

However, the safety valve avoids dangerous overpressures that can occur when the displacement selector is controlled to the small displacement configuration but that we are in a particular situation in which the machine operates in non-preferential direction in small displacement , or in which, although operating in a preferred direction in small displacement, the feed pressure becomes greater than the exhaust pressure (in particular by a hydrodynamic braking phenomenon, as when the machine is a driving motor of a vehicle that travels forward and downhill), or in which the selector is partially blocked during the passage from large to small displacement. Indeed, as soon as the displacement selector is controlled towards its small displacement configuration, the safety valve connects the third enclosure to the main pipe to which its first track is connected, which, even in the particular situations mentioned above, avoids the isolation of this third enclosure and therefore avoids excessive overpressure in the latter.

Optionally, the safety valve further comprises a third channel connected to said other main line and the second and third channels are connected in the first configuration of said safety valve.

Thus, the second channel, and therefore the third speaker, is connected to one or the other of the main ducts depending on whether the selector displacement is controlled towards its small displacement configuration or towards its large displacement configuration. Thus, if in addition to the situations mentioned above, the displacement selector is blocked when it is controlled towards its large displacement configuration from its small displacement configuration, the third enclosure is not isolated because it is connected to said other main pipe. In addition, this is consistent with the fact that, in large displacement, the third chamber must anyway be connected to said other main line by the displacement selector, if the latter operates normally.

Optionally, said one of the main lines to which is connected the first channel of the safety valve is the main pipe used for the exhaust in the preferred direction of operation of the machine.

Optionally, in the second configuration of the safety valve, the first and second channels are connected to said one of the main lines by a non-return valve allowing only the flow of fluid in the direction from the second way to the first way .

In this case, it is when the pressure at the second channel, that is to say in the third enclosure, becomes greater than the pressure at the first channel, that is to say in said one of the main pipes , that the fluid flows from the third enclosure. Thus, when said main pipe is used for the supply (for example, in small displacement and non-preferential direction of operation), the connection between the first and the second channel of the safety valve does not cause a drop in pressure. 'food.

For example, the check valve may be located between the first channel and said one of the main lines, in which case the first channel is permanently connected to said one of the main lines by this valve.

Optionally, the displacement selector is hydraulically controlled and comprises a selection control chamber connected to a displacement control duct for soliciting passage between one of the large displacement and small displacement configurations, and the other of said configurations, and a reverse displacement control, able to solicit the passage of said other configurations of large displacement and small displacement at said one of said configurations.

The reverse displacement control may comprise another hydraulic control chamber, connected to another control duct, or other means, in particular a return means, such as a spring of antagonistic effect to that of the power supply. from the control room.

Optionally, the safety valve is hydraulically controlled and comprises a safety control chamber connected to a safety pilot conduit for urging the passage of one of the first and second configurations to the other of the first and second configurations, as well as an inverse safety command for urging the passage of said other of the first and second configurations to said one of the first and second configurations.

The reverse safety control may comprise another safety control chamber, connected to another control duct to have an effect antagonistic to that of the aforementioned safety control chamber, or a return means such as a spring, of antagonistic effect to that of the fluid supply of the safety control chamber.

Optionally, the cubic capacity control duct and the safety pilot duct are interconnected.

Thus, the control of the displacement selector and that of the safety valve are naturally carried out under the same conditions, in a synchronized manner.

Optionally, the machine comprises an internal fluid distributor comprising the two series of distribution ducts.

Optionally, the displacement selector is disposed in the internal fluid distributor.

Thus, the inner dispenser housing portion may be of standard or substantially standard type, suitable for several machines, while it is the internal fluid distributor and its displacement selector that would be specifically designed for a given machine.

Optionally, the displacement selector comprises a spool movable in a bore of the internal fluid distributor, and the first, second and third enclosures respectively comprise first, second and third grooves of this bore.

Optionally, the safety valve is disposed in a housing portion of the internal distributor.

As indicated above, the safety valve is a very simple valve and of modest dimensions, and it can therefore be easily integrated with a standard or almost standard part of the internal distributor housing.

• la figure 1 est une vue en coupe axiale d'une machine hydraulique conforme à l'invention, montrant le sélecteur de cylindrée dans la configuration de grande cylindrée ;
• la figure 2 est un agrandissement de la partie distribution de la machine de la figure 1, dans laquelle se trouvent le sélecteur de cylindrée et la valve de sécurité.
• la figure 3 est une vue conforme à la figure 2, montrant le sélecteur de cylindrée dans la configuration de petite cylindrée ;
• la figure 4 est une vue analogue aux figures 2 et 3, montrant le sélecteur de cylindrée dans une configuration intermédiaire pouvant générer une pression excessive dans la troisième enceinte ;
• la figure 5 est une vue en section dans le plan V-V de la figure 2, montrant une partie de la machine équipée d'une valve de sécurité selon un premier mode de réalisation, cette valve étant représentée dans une première configuration ;
• la figure 6 est une vue de la partie VI de la figure 5, montrant la valve de sécurité dans sa deuxième configuration ;
• la figure 7 est un schéma hydraulique de la machine de la figure 1 équipée de la valve de sécurité selon le premier mode de réalisation ;
• les figures 8 et 9 sont des vues analogues aux figures 5 et 6, montrant la valve de sécurité selon un deuxième mode de réalisation ;
• la figure 10 est une vue en section dans le plan X-X de la figure 8 ; et
• la figure 11 est un schéma hydraulique de la machine hydraulique de la figure 1, équipée de la valve de sécurité selon le deuxième mode de réalisation.

The invention will be better understood and its advantages will appear better on reading the detailed description which follows, of embodiments shown by way of non-limiting examples. The description refers to the accompanying drawings in which:

• the figure 1 is an axial sectional view of a hydraulic machine according to the invention, showing the displacement selector in the large displacement configuration;
• the figure 2 is an enlargement of the dispensing part of the machine the figure 1 , in which are the displacement selector and the safety valve.
• the figure 3 is a view according to the figure 2 , showing the displacement selector in the small displacement configuration;
• the figure 4 is a view similar to figures 2 and 3 , showing the displacement selector in an intermediate configuration that can generate excessive pressure in the third enclosure;
• the figure 5 is a sectional view in the VV plane of the figure 2 , showing a part of the machine equipped with a safety valve according to a first embodiment, this valve being represented in a first configuration;
• the figure 6 is a view of part VI of the figure 5 , showing the safety valve in its second configuration;
• the figure 7 is a hydraulic diagram of the machine the figure 1 equipped with the safety valve according to the first embodiment;
• the Figures 8 and 9 are views similar to Figures 5 and 6 showing the safety valve according to a second embodiment;
• the figure 10 is a sectional view in the XX plane of the figure 8 ; and
• the figure 11 is a hydraulic diagram of the hydraulic machine of the figure 1 equipped with the safety valve according to the second embodiment.

The hydraulic machine represented on the figure 1 is of the fixed casing and rotary cylinder block type. However, it is understood that the invention could also be applied to a hydraulic machine of the type with rotating housing and fixed cylinder block. In the example shown, the machine, motor or pump, is of the radial piston type.

This machine comprises a fixed housing in three parts, 2A, 2B and 2C, assembled by 2D screws. A corrugated reaction cam 4 is formed in the part 2B of the housing. The machine comprises a cylinder block 6 which is mounted in relative rotation about an axis 10 with respect to the cam 4 and which comprises a plurality of radial cylinders 12, which can be supplied with fluid under pressure and inside. of which are slidably mounted radial pistons 14. In this case, the cylinder block 6 rotates a shaft 5 which cooperates with grooves 7. This shaft carries an outlet flange 9.

The machine further comprises an internal fluid distributor 16 which is integral with the housing with respect to the rotation about the axis 10. In other words, the internal distributor and the cam do not rotate relative to each other. to the other. The internal distributor 16 is housed inside the crankcase portion 2C, which is also referred to as a "distribution cover". This portion 2C may be of a block having a bell-shaped shape, or be closed at its axial end opposite the cylinder block, by an attached plate.

Referring also to the figure 2 , which shows the part of the machine comprising the internal distributor 16 and its distribution cover 2C, it can be seen that the internal distributor has a radial distribution face 16A into which delivery ducts, such as the ducts S1G1 and S12G2, open. The internal distributor 16 also has an outer axial face 16B which has a first main groove 18 and a second main groove 20, which serve respectively to feed and exhaust the fluid or vice versa. It will be considered in the following that, in the preferred direction of operation of the machine, the groove 18 is a feed groove and the groove 20 is an exhaust groove. The axial face internal 2C 'of the distribution cover 2C which cooperates with the aforementioned face 16B, has main grooves 18', 20 'respectively opposite the grooves 18 and 20. These grooves 18' and 20 'communicate with the main supply lines or exhaust, respectively 1 and 2, which are drilled in the wall of the distribution cover 2C.

The machine comprises a displacement selector 21 comprising an axial bore 22 made in the internal distributor 16. This axial bore is in species centered on the axis 10. The displacement selector also comprises a main spool 24 which is axially movable in the bore 22 and a secondary slide 24 'which comprises an internal piston 25 disposed inside the main spool 24 and an outer skirt 26, integral with the piston and forming a return around the end 24A of the main spool 24.

The displacement selector 21 is hydraulically controlled and comprises a selection control chamber 28 connected to a displacement control duct 30 which is shown in phantom on the Figures 2 to 4 . In this case, this displacement control duct 30 is formed by a bore of the internal distributor 16 which connects the chamber 28, formed at the end 22A of the bore 22 opposite the cylinder block, to a buffer groove 32 formed on the internal axial periphery 2C 'of the distribution cover, this groove 32 being connected to a pilot bore 3 of this distribution cover. At its opposite end to the main spool 24, the control chamber 28 is closed, in this case by a cover 34 retained at the end 22A of the bore, for example by a circlip or any other means. In the example shown, the bore 22 passes axially through the internal distributor 16 from one side to the other and the bottom wall of the chamber 28 is therefore formed by the attached cover 34. It could of course be understood that the bore is not through and that the bottom wall of the control chamber is formed by a solid wall portion of the inner manifold 16.

It is understood that the fluid supply of the selection control chamber 28 tends to move the drawers 24 and 24 'of the displacement selector in the axial direction F indicated on the figure 2 .

On the opposite side of the bore 22, that is to say at its end 22B located towards the cylinder block, is disposed a return spring 36 of effect opposite to that of the fluid filling of the chamber 28. This spring 26 is supported, on the one hand, on a shoulder of the skirt 26 or on the piston 25 and, on the other hand, on a bottom cup 38 located at the end 22B of the bore. The spring tends to permanently push the skirt 26 in the axial direction G indicated on the figure 2 .

The skirt 26 is integral with the piston 25, via an inner flange 26A that has this skirt, and which is secured to the outer periphery of the piston 25, for example by a means such as a circlip. The spring 36 thus tends constantly to move the assembly of the secondary slide 24 'formed by the skirt 26 and the piston 25 in the direction G. Furthermore, this assembly is mounted to slide axially relative to the slide 24, the piston 25 being axially movable inside this drawer and the skirt 26 surrounding the end 24A of this drawer.

However, this travel is limited by stops. Indeed, the head 25A of the piston 25 opposite the skirt 26 forms a radially projecting flange adapted to cooperate with a shoulder 24B of the slide 24 to, when the piston 25 is moved in the direction F, also cause a displacement of the drawer 24 in the same direction F by the abutment of the collar against this shoulder 24B.

In contrast, the secondary slide 24 'formed by the piston 25 and the skirt 26 also has a stop adapted to abut with the end 24A of the main spool 24 for, when the secondary slide 24' is moved in the direction G, abut against this end 24A and thus also move the main spool 24 in the direction G. In this case, the aforementioned abutment is formed by the face of the flange 26A of the skirt 26 which is opposite the spring 36.

Finally, the main spool 24 has a bore 27 which communicates the outer periphery of this spool 24 with the space formed between the shoulder 24B of its inner periphery 24 and the head 25A of the piston 25.

The bore 22 has three grooves, namely a first groove 40 connected to the main groove 18 by a bore 41, a second groove 42 connected to the groove 20 by a bore 43, and a third groove 44 which, in this case , is located between the grooves 40 and 42. These first, second and third grooves respectively form the first, second and third speakers within the meaning of this presentation. The different distribution ducts are respectively connected to these grooves. Thus, the conduits of distribution have two sets of distribution ducts each having a first and a second group of distribution ducts. The distribution ducts of the first group of distribution ducts of the first series, like the duct S1G1, are connected to the first groove 40. The distribution ducts of the second groups of distribution ducts of the first and second series, to Like the duct S12G2, are connected to the second groove 42. Finally, the distribution ducts of the first group of distribution ducts of the second series, like the duct S2G1, only primed on the Figures 2 to 4 , are connected to the third groove 44.

Thus, the two sets of distribution ducts each correspond to a sub-machine. A sub-machine corresponding to one series, is active when the first group of ducts of the series and the second group of ducts of the series are set to two different pressures, respectively to the supply and to the exhaust or vice versa.

So, in the configuration illustrated on the figures 1 and 2 , the machine is in large displacement, the two series being active. Indeed, in this configuration, the first groove 40 and the third groove 44 are interconnected by the connecting groove 23 of the slide 24 and are thus both connected to the main groove 18, itself connected to the main pipe 1, for example supply, while the second groove 42 of the bore is isolated from the first and third groove and is connected to the main groove 20, for example connected to the exhaust. In this case, the first group of conduits of the first series is connected to the main pipe 1 while the second group of conduits of the first series is connected to the main pipe 2, so that the sub-machine corresponding to this first series is active. At the same time, the first group of conduits of the first series is also connected to the main pipe 1 while the second group of conduits of the second series is also connected to the main pipe 2, so that the second sub-machine corresponding at the second series is also active.

On the other hand, the configuration represented on the figure 3 is a small displacement configuration. Indeed, in this configuration, the fluid supply of the chamber 28 has pushed the piston 25 into the F direction and this piston has driven the slide 24 in the same direction F until the abutment of its end flange 24C against a shoulder located at the end 22A of the bore. In this situation, the second and third grooves 42 and 44 of the bore 22 communicate with each other by the connecting groove 23 of the slide 24, while the first groove 40 is isolated from the grooves 42 and 44. In this situation, the first grooves and second groups of distribution ducts of the first series remain respectively connected to the main pipe 1 and the main pipe 2. The sub-machine corresponding to the first series of distribution ducts is therefore active. In contrast, the two groups of distribution ducts of the second series are connected to the main pipe 2, by the connection of the grooves 42 and 44, so that the second sub-machine corresponding to the second series is inactive. In this configuration of small displacement and in the preferred direction of operation of the machine, in which the main pipe 2 is an exhaust pipe, the main spool 24 and the secondary spool 24 'formed by the piston 25 and the skirt 26 are in the position shown on the figure 3 .

However, if the pressure in main lines 1 and 2 is reversed, the configuration shown in figure 4 . This reversal of the pressure in the main lines 1 and 2 may for example be due to operation of the machine in reverse, that is to say in non-preferential operating direction in which the main pipe 2 serves to high pressure supply while the main pipe 1 serves the exhaust. This pressure reversal may also be due to operation in "engine braking", for example when the hydraulic machine is a hydraulic drive motor of a vehicle, traveling downhill. In this case, the pressure in the main pipe 2 used for the exhaust momentarily becomes greater than the pressure in the main pipe 1 which is used for feeding. The selection control of the displacement remains active, so that the slide 24 remains in the position represented on the figure 3 . However, the high pressure in the main pipe 2 and therefore in the groove 42 of the bore 22 feeds, via the hole 27 of the slide 24, the chamber 27 'located between the shoulder 24B of the slide 24 and the head 25A of the piston 25. This has the effect of moving the secondary slide 24 'formed by the piston 25 and the skirt 26 in the direction G, until the flange 26A of the skirt 26 come into abutment against the end 24A of the slide 24, that is to say in the position represented on the figure 4 . In this position, the skirt 26 insulates the groove 42 relative to the groove 44, the latter also remaining isolated from the groove 40 by the wall of the main spool 24. Thus, the conduits of the first group of distribution ducts of the second S2G1 series, which are connected to the enclosure 44, are isolated from other distribution channels. This isolation of the groove 44 or, if the secondary slide 24 'is only partially displaced in the direction G, the restriction of the connection between the grooves 42 and 44, is in principle to avoid putting the groove 44 too much high pressure resistant and to limit the braking torque delivered during the mode of operation "engine brake", as set out in particular in the document WO 2011/048327 . However, this situation is prolonged, insofar as the fluid discharged into the distribution ducts connected to this groove 44 by the pistons of the machine can not escape, the pressure in these ducts and in this groove 44 can become very high principle.

The configuration represented on the figure 4 may also occur if, during a control of passage of the large displacement configuration represented on the figures 1 and 2 to the small-displacement configuration shown on the figure 3 , the secondary slide 24 'formed by the piston 25 and the skirt 26 is locked relative to the main spool 24 without being able to move relative to it in the direction of the arrow F as desired. In this case, under the effect of the pressure in the control chamber 28, the drawers 24 and 24 'move from the position shown on the figure 2 to that of the figure 4 , so that the third groove 44 and the distribution ducts of the first group of the second series which are connected to it can be subjected to very high pressures.

To prevent this pressure from damaging the machine, it includes a safety valve 50.

As we see better on the figure 5 , this safety valve 50 comprises a bore 52 formed in the distribution cover 2C and a slide 54 movable in this bore. The bore 52 is in this case made transversely to the axis 10. The safety valve comprises a first channel 56 connected to the main pipe 2 and a second channel 58 connected to the third groove 44 of the bore 22 the displacement selector. In this case, as can be seen for example in the figure 2 , this groove 44 is connected to the outer axial face 16B of the internal distributor 16 by a bore 44 'of this distributor. This bore 44 'opens into an enclosure 44 "delimited by two seals 17 between the outer face 16B and the inner face 2C' of the dispensing cover.The bore 44 'is shown in its entirety for the sake of clarity of the drawing and explanations which However, it is understood that it is in fact not secant with the bore 43, these two holes being for example in different planes.This enclosure 44 "comprises a shoulder 17 'which forms a thrust surface and balancing for, under the effect of the pressure in the chamber 44 ", contribute to pushing the radial face 16A of the internal distributor 16 against the communication face 6A (see figure 1 ) of the cylinder block 6 in which the cylinder ducts 13 which communicate with the distribution ducts during the relative rotation of the cylinder block and the cam open. In this respect, it will be noted that the grooves 18 and 20 may also have thrust and balance surfaces, and that the machine may comprise additional thrust and balance means of the internal distributor 16, such as the springs 15 arranged between the bottom of the distribution cover 2C and the face facing the internal distributor 16.

As we see on the Figures 2 to 4 , the bore 52 of the safety valve communicates with the enclosure 44 "by a bore 58, which forms the second channel of the safety valve 50. The first channel 56 of this valve comprises a bore which communicates with the main pipe 2. In this case, this communication is performed via a check valve 60 arranged in a bore 62 connected to the main pipe 2. This bore 62 is in this case made transversely to the axis 10 and closed by a plug 64 on the external face of the distribution cover 2 C. The non-return valve is, in a manner known per se, screwed to the end of the bore 62 opposite the plug 64, and comprises a movable closure member such as a ball 66 continuously recalled by a spring 68 against a seat 70. Thus, the communication between the main pipe 2 and the first channel 56 of the safety valve is normally closed and opens only when the pressure in the way 56, and so da ns the throat 44 of the internal distributor, becomes greater than the pressure in the main pipe 2.

In this case, the holes 56 and 58 forming the first and second channels of the safety valve 50 are formed of the closed axial holes, on the side opposite the bore 52, by plugs 56 'and 58' respectively.

In this case, the safety valve 50 is hydraulically controlled and comprises a safety control chamber 72 connected to a safety piloting duct 74 to urge the displacement of the drawer 54 in the direction I indicated on the figure 5 when the chamber 72 is supplied with fluid. The safety valve 50 also comprises a reverse safety control, to urge the drawer to move in the opposite direction J to the direction I. In the present case, this reverse safety control comprises a spring 76 disposed at the end of the bore 52 opposed to the safety control chamber 72. This end is in this case closed by a plug 78, the spring 76 bearing between the plug 78 and a shoulder of the slide 54.

The figure 5 shows the safety valve in a first configuration, in which the first and second channels 56 and 58 are isolated from each other. This first configuration is obtained by the return effect of the spring 76, the safety control chamber 72 then not being supplied with fluid, in particular when the displacement selector 21 is itself controlled in its large displacement configuration. .

On the other hand, on the figure 6 , the chamber 72 is supplied with fluid, and it can be seen that the slide 54 has moved in the direction I against the return force of the spring 76, so as to communicate the tracks 56 and 58 by a groove 54 'of the drawer 54.

In the first configuration, the channels 56 and 58 are isolated, so that the safety valve does not interfere with the communication between the groove 44 of the displacement selector and the other grooves of this selector. This first configuration is in particular obtained when the displacement selector is controlled towards its large displacement configuration represented on the figure 2 , in which the grooves 40 and 44 communicate with each other while the groove 42 is isolated.

The safety valve is controlled in its second configuration shown on the figure 6 when the displacement selector is commanded to its small-capacity configuration shown on the figure 3 . In this second configuration, the communication between the channels 56 and 58 communicates the third groove 44 of the displacement selector with the main pipe 2, via the non-return valve 60. If, while the safety valve is in this second configuration , the pressure in the groove 44 increases because of the positioning of the displacement selector in the configuration shown in the figure 4 this increase in pressure in the groove 44 and thus in the channels 56 and 58 opens the non-return valve 50 to establish a communication between the groove 44 and the second main pipe 2. In this case, the excess pressure is avoided since the fluid can be put under the pressure of the main pipe 2.

We note on the figure 5 that the safety piloting duct 74 is connected to the pilot bore 30 described with reference to the figure 2 . As indicated then, this bore 30 serves to supply the displacement control pipe 30 of the displacement selector via the buffer groove 32. In fact, the pilot lines 30 and 74 could simply be both connected to the buffer groove 32, this groove being moreover supplied by pilot bore 3.

On the Figures 5 and 6 , that the safety valve 50 comprises a drainage pipe 80, which is located on the side of the bore 52 opposite the safety control chamber 72 and which is connected to the internal space of the machine housing.

The figure 7 illustrates the operating diagram of the machine with the safety valve 50 which has just been described. FIG. 2 shows the two sub-machines SM1 and SM2 respectively corresponding to the two series of distribution lines, the displacement selector 21 and the safety valve 50. This figure also shows the distribution conduits S1G1 of the first group of the first series connected to the groove 40, the distribution ducts S2G1 of the first group of the second series connected to the third groove 44 and the distribution ducts S12G2 of the second group of the first and second series connected to the second groove 42. The first channel 56 of the valve 50 is connected to the main pipe 2 (in this case, this connection is represented by a connection of the first channel 56 to the second groove 42 which is itself permanently connected to the pipe 2 via the displacement selector 21) and its second channel 58 is connected to the distribution ducts S2G1 connected to the third groove 44. On the figure 7 , the displacement selector 21 is in its configuration of large displacement C1, the grooves 40 and 44 being connected to the main pipe 1 while the groove 42 is connected to the main pipe 2. In this configuration of large displacement, the valve of security 50 is in its first configuration, the channels 56 and 58 being isolated.

The control of the displacement selector in its small displacement configuration by the supply of the chamber 28 in principle passes this displacement selector in its configuration of small displacement C2, in which only the groove 40 is connected to the main pipe 1, while the grooves 42 and 44 are connected to the main pipe 2.

However, for the reasons given in reference to the figure 4 , the selector can adopt an intermediate configuration C3, in which only the groove 40 is connected to the main pipe 1, while only the groove 42 is connected to the main pipe 2 and the groove 44 is isolated. However, the control of the displacement selector 21 to its small displacement configuration by the supply of the chamber 28 has also caused the supply of the safety control chamber 72, thus passing the safety valve 50 in its second position. , in which the first and second channels 56 and 58 communicate, thereby communicating the third groove 44 of the displacement selector with the main pipe 2 (in this case via the groove 42 permanently connected to this main pipe 2), via the check valve 160.

With reference to Figures 8 to 10 , the safety valve 150 is now described according to a second embodiment. This valve 150 comprises a bore 152, made in this case transversely to the axis 10 in the distribution cover 2C, and a slide 154 movable in this bore.

According to this embodiment, the safety valve 150 comprises three channels, namely a first channel 156 connected to the main line 2, a second channel 158 connected to the groove 44 of the displacement selector and a third channel 159 connected to the first main line 1. The connection between the channel 158 and the groove 44 can be carried out in the same way as the connection between the channel 56 of the safety valve according to the first mode of realization at this groove 44. The connection of the third channel 159 to the first main pipe 1 can be direct, via a hole 159 'of the distribution cover 2C. The connection between the channel 156 and the second main pipe 2 can be achieved via a non-return valve 160 shown in FIG. figure 10 . This valve is disposed in a bore 162 of the distribution cap 2C closed by a plug 164, and comprises a movable closure member 166 permanently biased by a spring 168 against a seat 170. The bore 162 connects the first channel 156 of the valve safety device to the main pipe 2, via the grooves 20 and 20 'of the outer axial face of the inner distributor 16 and the inner axial face of the distribution cover 2C. It will be understood that this non-return valve 160 opens to connect the track 156 to the second main pipe 2 when the pressure in the track 156 becomes greater than the pressure in this main pipe. The channel 156 is formed by a bore which is in this case substantially parallel to the axis 10, and which is closed by a stopper 156 'on the opposite side to the bore 152. A drainage duct 180 similar to the conduit 80 of FIG. the figure 5 can be expected.

The safety valve 150 is hydraulically controlled and comprises a safety control chamber 172 connected to a safety piloting duct 174, itself connected to the pilot bore 3. As in the first embodiment, the piloting duct safety 174 is thus connected to the displacement control conduit 30 via the buffer groove 32. In this case, the fluid supply of the safety control chamber 172 has the effect of moving the drawer 154 in the direction I for the move from his first position represented on the figure 8 , corresponding to the first configuration of the safety valve, to its second position represented on the figure 9 , corresponding to the second configuration of the safety valve. The control of the safety valve comprises a reverse safety control, comprising in this case a return spring 176 which tends to permanently push the slide 154 to its first position in the direction J. The spring 176 is supported by on the one hand, on a plug 178 for closing the bore 152 and, on the other hand, on a shoulder of the slide 154.

In the first configuration of the safety valve 150 shown in the figure 8 , the drawer 154 communicates between them the second and third channels 158 and 159, via a groove 154 'of this drawer. In this first configuration, however, the first channel 156 is isolated from the channels 158 and 159. This first configuration is obtained by default under the effect of the return of the spring 176, in particular when the displacement selector 21 is controlled in its configuration. large displacement. In this first configuration, the communication between the channels 158 and 159 actually contributes to communicate the groove 44 of the displacement selector with the groove 40, which corresponds to the desired situation in large displacement configuration.

In its second configuration represented on the figure 9 , the safety valve 150 makes the first and second channels 156 and 158 communicate with each other via the groove 154 ', while the third channel 159 is isolated from the channels 156 and 158. Thus, the groove 44 of the displacement selector is connected to the second main pipe 2, in this case via the non-return valve 160. An excess of pressure in the groove 44 is thus avoided by this communication.

The hydraulic circuit of the machine equipped with the safety valve according to this second embodiment is represented on the figure 11 . This figure has identified two sub-machines SM1 and SM2 whose distribution ducts S12G2 of the second group of the first and second series are connected to the second groove 42 of the displacement selector 21, while the distribution ducts S1G1 of the first group of the first series are connected to the first groove 40 and the distribution ducts S2G1 of the first group of the second series are connected to the third groove 44.

The figure 11 illustrates the situation in which the displacement selector is controlled in its large displacement configuration C1. The grooves 40 and 44 are thus connected to the first main pipe 1, while the groove 42 is connected to the second main pipe 2. The safety valve 150 is then in its first configuration, in which its second and third tracks 158 and 159 are connected and are isolated from the third channel 156.

When the displacement selector is in its configuration of small displacement C2, only the groove 40 is connected to the main pipe 1, while the grooves 42 and 44 are connected to the main pipe 2.

However, for the reasons given in reference to the figure 4 , the displacement selector can, despite the control of this selector to its configuration of small displacement, adopt the intermediate configuration C3 above. This control of the displacement selector to its small large displacement configuration by the supply of the chamber 28 has also caused the supply of the safety control chamber 172, thus passing the safety valve 150 in its second position, in which the first and second channels 156 and 158 communicate, being isolated from the third channel 159. Thus, the third groove 44 of the displacement selector communicates with the main pipe 2 (in this case via the groove 42 permanently connected to this main line 2), via the non-return valve 160.

Claims (11)

Hydraulic machine having at least two active operating displacements and capable of being connected to two main lines (1, 2), respectively supply and exhaust, the machine comprising: two series of distribution ducts each having a first and a second group of distribution ducts, the first group of distribution ducts of the first series (S1G1) being connected to a first chamber (40), the second groups of ducts of distribution of the first and second series (S12G2) being connected to a second enclosure (42), and the first group of distribution ducts of the second series (S2G1) being connected to a third enclosure (44), a selector of displacement (21) that can be controlled to adopt a configuration of large displacement (C1) in which the second chamber (42) is connected to one of the main ducts (2), while the first and third enclosure (40, 44) are connected to the other main pipe (1), and a small displacement configuration (C2) in which the second and third enclosures (42, 44) are connected to one of the main pipes (2). ), while the first enclosure (40) is connected to said other main pipe (1), characterized in that it further comprises a safety valve (50, 150) comprising at least a first channel (56, 156) connected to said one of the main lines (2) and a second channel (58, 158) connected at the third chamber (44), said safety valve being controllable, when the displacement selector (21) is controlled to the large displacement configuration, in a first configuration in which the first and second channels (56, 58, 156, 158) are isolated from one another, and to be controlled, when the displacement selector is controlled to the small displacement configuration, in a second configuration in which the first and second channels (56, 58, 156, 158) are connected. Machine according to claim 1, characterized in that the safety valve (150) further comprises a third track (159) connected to said other main pipe (1) and in that the second and third tracks (158, 159) are connected in the first configuration of said safety valve. Machine according to claim 1 or 2, characterized in that said one of the main lines (2) to which is connected the first channel (56, 156) of the safety valve (50, 150) is the main pipe which serves exhaust in preferential direction of operation of the machine. Machine according to one of Claims 1 to 3, characterized in that in the second configuration of the safety valve (50, 150) the first and second channels (56, 58, 156, 158) are connected to said one of the main lines by a non-return valve (60, 160) allowing only the flow of fluid in the direction from the second channel to the first channel. Machine according to any one of claims 1 to 4, characterized in that the displacement selector (21) is hydraulically controlled and comprises a selection control chamber (28) connected to a displacement control duct (30) for soliciting the passage between one of the configurations of large displacement and small displacement, and the other of said configurations, and a reverse displacement control (36), adapted to solicit the passage of said other configurations of large displacement and small displacing said one of said configurations. Machine according to any one of claims 1 to 5, characterized in that the safety valve (50, 150) is hydraulically controlled and comprises a safety control chamber (72, 172) connected to a safety piloting duct ( 74, 174) for biasing the passage of one of the first and second configurations to the other of the first and second configurations, and an inverse safety control (76, 176) for urging the passage of said other of the first and second configurations. second configurations to said one of the first and second configurations. Machine according to claims 5 and 6, characterized in that the displacement control duct (30) and the safety pilot duct (74, 174) are interconnected. Machine according to any one of claims 1 to 7, characterized in that it comprises an internal fluid distributor (16) comprising the two series of distribution ducts (S1G1, S2G1, S12G2). Machine according to claim 8, characterized in that the displacement selector (21) is arranged in the internal fluid distributor (16). Machine according to claim 9, characterized in that the displacement selector (21) comprises a slide (24, 24 ') movable in a bore (22) of the internal fluid distributor (16), and in that the first, second and third enclosures respectively comprise a first, a second and a third groove (40, 42, 44) of this bore. Machine according to any one of claims 8 to 10, characterized in that the safety valve (50, 150) is arranged in a housing portion (2C) of the inner distributor (16).

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