FR2490290A1 - HYDRAULIC DEVICE FOR CONTROLLING COMMUNICATION - Google Patents

Abstract

HYDRAULIC DEVICE FOR COMMANDING A COMMUNICATION. HYDRAULIC DEVICE WHICH INCLUDES A PILOT VALVE AND A SWITCHING VALVE CHARACTERIZED IN THAT A CONTROLLER 25 OF THE PILOT VALVE 9 IS CONSTITUTED BY A STAGE DRAWER, WHILE THE FRONT FACE OF THE CONTROL PISTON 19 IS LOADED BY THE PREVIOUS PRESSURE IN THE SUPPLY TANK IN THE CENTRAL REGION OF THE DRAWER, PROVIDED FOR TWO PISTONS 27, 28 THE DIAMETERS OF WHICH RESPECTIVELY CORRESPOND TO THOSE OF THE PISTONS AT THE ADJACENT ENDS, ON THE TWO MUTUALLY OPPOSED SIDES OF THE TWO CONTROL PISTONS 27, 28 CONTROL 38, 39 WHICH COOPERATE WITH THE CONTROL EDGES 40, 41 OF THE ENCLOSURE 23 IN WHICH IS LODGED ITS DRAWER.

Description

I

  The present invention relates to a device

  tif for controlling a communication between a source of pressurized fluid and a supply tank, on the one hand, and an accumulator on the other hand, which comprises a pilot valve whose control member can be loaded by the pressure of the accumulator and a controllable switching valve

  by said pilot valve, the control member of the valve

  pilot selectively connecting a control conduit leading to the switching valve with the source of pressurized fluid

  or with the feed tank.

  In a hydraulic device of the above type, the pilot valve is in the form of a seat valve which can be held open by means of a piston loaded by the pressure of the source of fluid under pressure. This pilot valve can occupy different positions, which has the effect of

  consequence, in particular, in the case of a source of

  under pressure with a very low flow per unit time,

  uncertain opening and closing actions of

  emulator of the fluid source under pressure (see the brochure

  RD 264I0 / I2.77 of the Applicant).

  The present invention aims to achieve

  be a device ensuring communication and isolation

  the accumulator. The invention reaches the goals

  that it is fixed in that the control organ of the valve-

  The pilot is in the form of a stepped spool whose end face of the end-piston having a larger diameter is loaded by the pressure in the accumulator while the end face of the smaller-diameter control piston is loaded. is charged by the pressure in the supply tank, in that in the central region of said drawer are provided two additional central control pistons whose diameter respectively corresponds to that of the pistons

  adjacent end, and that at the mutually opposite side

  the two control pistons are provided with control edges

  which cooperate with the control edges of the envelope in the-

which is housed said drawer.

  It should be noted that the control member of the pilot valve does not occupy a particular control position that is to say that the connection between the pump and the accumulator

  is either fully open or fully closed. We are

  thus reads a communication and a secure isolation between

  the source of pressurized fluid or the feed tank

  tion and use. During the passage of the pressure of the pump to the pressure of the accumulator and vice versa, the drawer

  performs a fast switching movement and thus acts

  IO me a flip flop. By a judicious choice of the diameter of the control pistons, the difference of pressures which determines

  switching can be chosen at will.

  Another feature of the invention provides that the front face of the drawer which is in communication with the feed tank I5 has a blind hole which extends

  up to the connecting element connecting the control piston of the

  relatively large tremit to the adjacent central control piston,

  this blind hole being connected at this point with a transverse channel

  sal opening on the outside and in that the wall of an annular channel or a groove which is in connection with the control conduit forms the control edges of the envelope or the ribs

of the valve.

  According to another feature of the invention, the amount of pressurized fluid supplying the accumulator per unit of time is limited to a degree corresponding to the free section of the constriction. For this purpose, the invention is

  characterized in that the switching valve is connected directly

  at the source of fluid under pressure, while the valve

  pilot is connected to it through a throttling. In the case of using an adjustable throttle, the free flow section can be chosen at will. The fluid that is

  directed towards the battery, flows back to the circuit of use

  or to the feed tank.

  Other features and advantages of the invention

  will be apparent from the following description given

  By way of non-limiting example, with reference to the appended drawing in which: FIG. I is a block diagram of a device according to the invention, and FIG. 2 is a large scale longitudinal section

  through an essential component of this device.

  Referring to the drawing there is shown a pump I which I0 is connected by conduits 2 to 4 to an accumulator. In the duct 4 is inserted a non-return valve 6 opening towards the accumulator 5. To a PI point of the conduit 3 is connected to a switching valve 7 which has the structure of a valve with two inputs and two outputs, which has a proportional action I5. In the illustrated control position of the switching valve 7, its connection points PI and VI are isolated from each other, these points being connected together in the other control position, while in the positions

  intermediaries, a strangulation action occurs.

  A duct 8 connects the duct 3 to a point P2 of a pilot valve 9 which has the structure of a three-way valve.

  entrances and two exits, and which operates as a bistable

  and has, in addition to the connection point P2, two other connection points T2 and D. The points P2 and T2 can be

  alternatively put in communication with the point D. In the pos.

  represented by the control member of the pilot valve 9, the point P2 is connected to the point D.

  Both valves 7 and 9 have their dis-

  tributors controlled by a fluid under pressure whose control members are respectively subjected to the action of a spring

  I0 or II which tends to maintain this organ in the position

sented;

  The point D of the pilot valve 9 is connected by a

  I2 at the side of the switching valve 7 next to the spring I0

  so that the pressure prevailing in the conduit I2 solicits the

  the control valve of the switching valve 7 in the same direc-

  the spring I0. The opposite side of the switching valve 7 is connected, by means of a conduit I3, to a conduit 2 connected to the pump I. The side of the pilot valve 9 which is opposite the spring II es-connected by a conduit I4, connected to a point

  connection piece S and which, preferably, comprises a choke

  variable) to the accumulator 5 on the side of the valve 6 opposite the pump I, so that the pressure in the conduit I4 exerts on the control member of the pilot valve, by the point

  6, a force opposing that of the spring II.

  The other side of the pilot valve 9 is connected by a point of

  connection T3 and one conduit I5, to another conduit I7

  I0 weaving a feed tank I6 led to which is also connected the point T2 of the pilot valve 9. The point VI of the switching valve 7 is connected, via a conduit I8, to a connection point P4 of a four-way valve and three

  outputs I9 can be operated at will, for example, manually.

  I5, which constitutes the control valve allowing the user to control a double-acting actuating cylinder 20. The point T4 of the dispensing valve I9 is connected to the conduit I7 and the actuating cylinder 20 is connected, of share

  and on the other hand, to the use connections V4 and V5 of the valve dis-

tribe I9.

  In the illustrated position of the control member of the dispensing valve 7, the connection between the pump I and the cylinder 20 is closed so that the pump I delivers into the accumulator 5. The internal pressure of the accumulator 5 acting via the conduit I4, at the point S of the pilot valve 9, whose control member, when this pressure reaches a certain limit, moves against the spring force

  I thus abruptly communicating the point of connection

  line D with the point T2 and hence with the reservoir of

I6 power supply.

  In the illustrated position of the control member of the pilot valve 9, the pressure of the pump I is applied by the conduit I2 to the left side, according to the drawing, of the switching valve 7. Since the force of the I0 spring acts in the same direction, it is clear that the control member of the switching valve 7 retains the position shown

  until the pressure in duct I2 is suf-

  for the pressure that the pump I exerts, through the conduit I3

  on the control member of the switching valve 7,

  passes the joint force of the spring I0 and that exerted on the control member of the valve 7 by the pressure prevailing

  in the conduit I2. In these circumstances, a progressive link

  it is established between the pump I and the dispensing valve I9 through intermediate throttle positions of the control member of the switching valve I. After that, the actuating cylinder 20 can be controlled in a controlled manner.

  classic by means of this-valve dispenser.

  If appropriate, a variable constriction 2I could be interposed in the conduit 3. This constriction limits to a

  predetermined maximum the amount of fluid under pressure is

  per unit of time, to the accumulator 5. Pressurized fluid that is not required to charge the accumulator 5

  I5 can be used by the actuating cylinder 20.

  FIG. 2 illustrates a preferred embodiment of

  pilot valve 9. It includes a cover 22 which

  is attached to an envelope or body 23. The body 23 is per-

  The slide 25 comprises four control pistons 26 to 29 which are connected by intermediate connecting elements 30 to 32. The control pistons 26, 27 on one side and the pistons 28 and 29 on the other side respectively have the same diameter, the diameter of the pistons 26,27 being larger than that of the pistons 28, 29. The piston 26

  advances inside the lid 22 and presents, to its ex-

  free end, a support flange 33. Between this flange and the front face of the body 23 of the valve is interposed a spring

  34 which urges the control member 25 towards the inte-

  The opposite end face of the drawer 25

  has a blind hole 35 which extends to the connecting member

  its 30 and communicates with the outer face of this connecting element 30 through a transverse channel 36. The bore 24

  has a groove 37 whose opposite walls perpendicularly

  -res to the longitudinal axis of the bore 24, are equidistant from opposite faces of the control pistons 27, 28 on which have been provided the control edges 38,39. The transition between the bore 24 and the groove 37 is defined by edges of

command 40.4I.

  In the cover 22 opens a connecting channel 42 which communicates with the connection point S terminating

  5. Another connection channel 43 which communicates with

  that with the connection point D, is connected to the groove 37.

  A third connecting channel 44, communicating with the point of

  connection P2, is connected to the bore 24 in the region

  between the two pistons 28, 29 the bore 24 being connected in the region of the free end face of the piston 29, with a connecting channel 45 communicating with the connection points

IO T2 and T3.

  The drawer 25 has been shown in a correct position

  corresponding to that in which the accumulator 5 is empty.

  In this position, the connecting channels 43 and 44 are connected together. As the pressure rises in the accumulator 5, the spool 25 is moved towards the connecting channel 45,

  against the force of the spring 34. As a result, the edge of

  Minder 38 of the piston 27 passes in front of the control edge 40 of the body 23 of the valve at the same time as the control edge 39 of the piston 28 meets the control edge 41 of the casing 23 of the valve. When the movement of the spool 25 continues, against the force of the spring 34, the connecting channel 43 is put in communication by the transverse channel 36, the blind hole 35 and the following part of the bore 24, with the channel of

  link 45, which completes the charging operation of the accumula-

5.

  Pistons 27 and 28 have different diameters.

  It contains in the groove 37 an action surface resulting from the difference of these two diameters and which, during the loading

  the accumulator is subjected to the pressure of the pump and

  that the accumulator has been charged, to the action of the prevailing pressure

  in the supply tank. At the moment of the passing of

  the pressure of the pump at the pressure of the supply tank in the groove 37, the force exerted on said action surface decreases rapidly in the groove 37, so that under the action of the pressure in the accumulator 5, the slide 25 moves even faster towards the connecting channel 45. It can thus be seen that with a constant pressure in the accumulator 5, the lowering of the pressure in the groove 37a has the effect, due to its isolation of the pressure of pump I and its

  connection to the feed tank I6, to produce a

  additional placement of the drawer 25. When the pressure drops in the accumulator, the drawer 25 must be moved

  in the opposite direction of the distance so traveled,

  that the throat 37 is again loaded by the pressure of the pump. The difference in the diameters of the pistons 27 and 28 determines a pressure difference which, at the time of calculation

  of the pilot valve can be chosen freely. This difference

  This pressure ensures a reliable opening and closing of the pilot valve, in particular, in the case where the pump I 10 discharges only very small quantities of fluid per unit.

  time to charge the battery 5.

  The non-return valve 6, the switching valve 7

  the pilot valve 9 and the throttle 2I are housed in a housing

  The spigot 25 could be divided between the pistons 27 and 28. In this case, a relatively weak spring is interposed, which tends to hold the two parts together. tiroi, in the portion of the bore 24 adjacent the piston 29 and instead of the blind hole 35 and the transverse channel 36 of the slide 25, is provided in the body 23 of the valve, a channel connecting the connecting channel 45 with the space between the pistons 26

and 27.

  Of course, the invention is not limited to the embodiment which has just been described and which has been shown, it will be possible to make many modifications of details without

  to get out, for that, from the scope of the invention.

Claims (1)

Hydraulic device for controlling a communication between a source of pressurized fluid and a supply tank, on the one hand, and an accumulator, on the other hand, which comprises a pilot valve whose control member can to be charged by the pressure of the accumulator and a switching valve controllable by said pilot valve, the control member of the pilot valve selectively connecting a control conduit leading to the switching valve IO with the source of the fluid under pressure or with the supply tank, characterized in that the control member (25) of the pilot valve (9) is in the form of a staged slide, the front face of the piston of end control (26) having a larger diameter is charged by the pressure in the accumulator (5) while the front face of the smaller diameter control piston (29) is loaded by the prevailing pressure. da ns the supply tank, in that in the central region of said drawer are provided two additional central control pistons (27, 28) whose diameter corresponds respectively to that of the adjacent end pistons and in that at the mutually the opposite of the two control pistons (27, 28) are provided control edges (38, 39) which cooperate with the control edges (140, 41) of the casing (23) in which is housed said drawer.   20 - Device according to claim I, characterized   in that the front face of the drawer (25) which is in communication with   the supply tank has a blind hole (35) which extends to the connecting member (30) connecting the relatively large end control piston (26) to the adjacent central control piston (27) , this blind hole being connected at this point with a transverse channel (36) opening outwards and in that the wall of an annular channel or groove (37) which is connected with the conduit of control (I2) forms the control edges of the envelope or body (23) of the valve.   3 - Device according to claim I or 2 characterized in that the switching valve (7) is connected directly to the source of fluid under pressure (I), while the pilot valve (9) is connected thereto to through a constriction (2I).   Device according to claim 1 or   vendication 3, characterized in that the slide (25) is divided transversely between its two central pistons (27, 28),   in that on the front face of said drawer connected with the   IO feed (I6) acts a spring that tends to hold its two parts assembled and that the space delimited by the one of the two control pistons (26, 27) which is the most   remote from the connection to the supply tank,   by a channel in the envelope or in the body   I5 (23) with the supply tank.