FR2475758A1 - FLOW REGULATOR FOR HYDRAULIC CIRCUITS - Google Patents

Abstract

THE REGULATOR INCLUDES A MOBILE DRAWER 9 PROVIDED SO AS TO OPEN A FIRST PASSAGE PORT 21 BETWEEN A SUPPLY DUCT 13, WHICH CONNECTS A SOURCE OF PRESSURIZED FLUID TO THE REGULATOR AND A USER DUCT 14 WHICH CONNECTS THE REGULATOR TO A DEVICE OF USE, AND A SECOND PASSAGE OPENING BETWEEN THE OPERATION DUCT AND AN EXHAUST DUCT 15, THE REGULATOR BEING PROVIDED WITH MEANS INTENDED TO MAINTAIN SENSITIVELY CONSTANT THE PRESSURE DIFFERENCE BETWEEN A FIRST ZONE 40 IN THE DUCT. SUPPLY 13 AND A SECOND ZONE 41 IN THE USE DUCT 14 AND THE PRESSURE DIFFERENCE BETWEEN THE SECOND ZONE 41 AND A THIRD ZONE 42 OF THE EXHAUST DUCT 15 SO AS TO AVOID THE FLOW FROM BEING AFFECTED BY PRESSURE VARIATIONS FLUID BETWEEN A ZONE LOCATED UPSTREAM AND A ZONE LOCATED DOWNSTREAM FROM THE REGULATOR.

Description

The present invention relates to a regulator with electromagnetic control

  for hydraulic circuits, designed to control both the supply rate of a fluid

  from a source of pressurized fluid to a dispo-

  user and the evacuation rate from the device

  User sitive towards the evacuation proper.

  It is an object of the invention to create a regulator of this type in which the control of the flow rate is not affected by the pressure variations which may possibly appear between a zone situated upstream and a zone situated

downstream compared to the regulator itself.

The regulator according to the invention is characterized in that it essentially comprises:

a feed chamber which communicates via

  medium of a supply line with the source, a use chamber which communicates via a use line with the user device, an evacuation chamber which communicates via a line discharge with discharge, said chambers being formed in a body of the valve; a slide valve or slide valve movable axially inside said body and provided with a first valve member whose function is to regulate the opening of a first passage orifice between the supply and use chambers, and a second valve member, the function of which is to regulate the opening of a second orifice for passage between the use and discharge chambers, while an elastic force exerted by a spring acts on the drawer and a force generated by the fluid is brought to act on an active surface of the drawer;

  a first and a second interception organ respectively

  in the supply line and in the discharge line to adjust the pressure difference

  upstream and downstream of said interception bodies, the open-

  ture of the first interception member being controlled by first means which detect the pressure of the fluid in a first predefined zone along the supply line and in a second predefined zone along the use line and which vary the respective opening when there is variation in the difference between the two pressures and

of the flow passing through it, the opening of the second information organ

  terception being controlled by second means which detects

  try the pressure of the fluid in the second predefined zone along the use pipe and in a third predefined zone along the discharge pipe which vary the respective opening when there is variation in the

  difference between the two pressures and the flow through it.

  The regulator of the invention is described in more detail below for an embodiment, reference being made to the appended drawings, in which:

  - Figure 1 is a schematic view of a hy-

in which the regulator is inserted according to the pre-

invention; and - Figures 2 and 3 are schematic sectional views

  of the regulator of the invention, in two operating positions-

different.

  The regulator according to the invention, indicated by the ref-

  rence 1 in FIG. 1, is suitable for being inserted into a hydraulic circuit of the type shown in the figure for controlling the flow rate of a circulating supply fluid

between a source of pressurized fluid, such as an accumulator-

  hydraulic head 2 and a user device 3; the regulation

  also provided for controlling the flow rate of the fluid which is discharged from this user device towards a

drain tank 4.

  The regulator, shown schematically in the figures

  gures 2 and 3, comprises a body 8 in a cavity from which a drawer or slide valve 9 can move; the surface

lateral of the latter practically defines, with the over-

  face of the cavity, three chambers, namely: a supply chamber 10, a use chamber 11 and a discharge chamber 12, each communicating respectively with a supply line 13, a use line 14 and an evacuation pipe 15. The first of these pipes

  is designed to be able to be connected to the hydraulic accumulator

link 2 via a tube section 16 (FIG. 1), the second to be in communication with the user device 3 via a tube section 17, and the third can be put into communication with the

  tank 4 via a section of tube 18.

  The supply chamber 10 and the use chamber

  tion 11 can be connected through

di.aire of an orifice 21, the opening of which is regulated by a valve member 22 formed on the slide 9 (which is constituted in the present embodiment by a conical surface); the use chamber 11 and the discharge chamber 12

can be put into reciprocal communication via the

medial of an orifice 23 (FIG. 3) whose opening is re-adjusted by a valve member 24 also formed on the

drawer 9.

  - On the right end of the drawer 9 as provided in Figures 2 and 3 is applied the force exerted by a helical spring 25 disposed between the bottom of a seat 26 of the drawer and a shoulder 27 of the body 8, the another end of the drawer 9 is provided with an active surface 28 penetrating into a cavity 29 of the body 8 and closing this cavity. Via a pipe 32 in which is mounted

  a throttle device 33 provided with a diameter bore

  predetermined meter (and in any case lower than that of the pipe), the cavity 29 communicates with the supply line 13. In addition, the cavity 29 communicates with the evacuation by means of a pipe 34 in which is disposed a ball or any other similar body 35 intended to cooperate with an associated seat and adjust a passage orifice in the pipe, said ball being able to be pushed against the

  seat by a rod 38 of an electromagnet 39.

  On the route of the operating pipe 14 and the pipe. evacuation 15 are respectively arranged a first and a second interception members 36 and 37 whose

  function is to adjust, in a manner which will be described below

  afterwards, the pressure difference upstream and downstream of said

  interception bodies. The opening of the first inter-

  ception 36 is controlled and adjusted by first means capable of detecting the pressure of the fluid in a first predefined zone 40 along the supply line 13 and in a second predefined zone 41 along the use line 14 and varying the relative opening as a function of the variation in the difference between the two pressures; the opening of the second interception member 37 is controlled l2t adjusted by second means capable of detecting the pressure of the fluid in the second predefined zone 41 and in a third predefined zone 42 along the evacuation pipe 15 and making vary the relative opening as a function of the variation of the difference between the two pressures and of the flow which passes through it. In the embodiment shown, these means comprise a rod 43 movable axially in a corresponding bore of the body 8 and provided with a head 44 which comes to bear against a ball 45 intended to cooperate with a corresponding seat; a helical spring 46 capable of pushing the rod to the left, as seen in Figures 2 and 3, is disposed between the head 44 and a shoulder of the body 8; as clearly shown in the figures, each assembly formed by the rod and the ball which corresponds to it is provided with two active surfaces 47, 48, those of the intercepting member 36 being exposed to the pressures of the fluid in the first and second zones 40 and 41 respectively, and those of the intercepting member 37 being exposed to the pressures of the fluid in said second and third zones 41 and 42. In the embodiment shown, the cross section of contact of the ball with the pipes 41 and 42 has dimensions such that the active surfaces 47 and 48 have the same area, and that, therefore, if in the two zones 40 and 41, or 41 and 42, the same pressure prevails, the resultant applied by said pressures on each rod becomes zero: consequently, the rod is pushed, to the left in the figures, only by the action of the spring 46 which

associated with it.

  A pipe section 52 parallel to the supply pipe 14, connects the second zone 41 to a fourth zone 53 downstream of the intercepting member 36; along this pipe section is inserted a non-return valve 54 capable of allowing the fluid coming from the fourth zone 53 to pass to the second zone and preventing

  the passage of the fluid in reverse direction.

  The operation of the flow regulator described is as follows:

  It will be assumed that the feed rate between the accumulator

  reader 2 and user device 3 need to be set.

  If this flow must be the maximum flow permitted by the regulator

  tor, the electromagnet 39 will be maintained in a position in which its rod 38: - is brought into its end-of-travel position on the left, which means that the orifice communicating with the pipe 34 and controlled by the ball 35 remains completely open. Under these conditions, the fluid coming from the supply line 13 (FIG. 2) and which reaches the regulator enters the cavity 29 via the line 32 and the bore of the throttling element inserted in this line, and it can flow freely from the cavity 29 in the direction of the evacuation pipe 34; the pressure which builds up in said cavity is practically zero in

  reason for the passage of the fluid through the bore of the foreign element

  regulation 33, and also of free evacuation through the pipe

  34. It follows that from the fact that no force acts primarily

  tick on the active surface 28 of the drawer 9, the latter occupies the position shown in FIG. 2 under the action of the

  helical spring 25; the orifice 21 between the supply chamber

  tation 10 and the operating chamber 11 is completely open and leaves free passage for the fluid between the first and the second chamber and between the latter and the device

of use, via line 14 of the regulation

flow rate reader.

If the feed rate has to be reduced, the operator acts on the electromagnet 39 so as to move the rod 38 to the right (as seen in FIG. 2) and close the line 34 according to the degree of desired closure by means of the ball 35. It is clear that the reduction in the passage orifice in the pipe 34 gives rise to an increase in pressure in the cavity 29, with the consequence that the result of the pressure forces which acts on the active surface 28 increases and that, as a result, the drawer is caused to move to the right while overcoming the reaction

  elastic of the coil spring 25. At each degree of closing

  ture of the orifice for passage of the pipe 34 therefore corresponds to a well-defined opening of the orifice 21 and, consequently, a well-defined flow rate of the fluid flowing in

the regulator.

  The fluid which flows from the use chamber 11 towards the user device passes through the first

6 2475758

  interceptor 36 whose opening depends on the pressures of the respective fluid pa and pu prevailing in the first and second zones 40 and 41 of the supply line 13

  and the operating line 14. In fact, the fluid generated

  dre on the active surfaces 47 and 48 of the intercepting member 36 the resultants Ra, Ru whose value, if S designates the area of these supposedly equal surfaces, is

R P S

a a Ru P S (1)

  If F denotes the force exerted by the spring 46 in a posi-

  tion of general equilibrium of the rod 43, we have in said posi-

tion S (P a Pu) S Ap = F (2) Consequently, it is clear that the pressure variation Ap between the two zones 40 and 41 depends on the force F exerted by the spring 46, and it follows that when '' we choose the latter correctly, we can obtain a variation A

  predetermined between said zones, variation which remains substantial

  aunt while feeding and usage conditions may vary. In fact, if it is assumed for example that Pu has a tendency to decrease, it results from it according to equation (2) that there is equilibrium of the forces on the rod 43 whose resultant acts so as to move the said rod to the right (Figure 2); to this new condition thus obtained corresponds a bringing together of the ball 45 relative to its seat and of

  this makes a higher degree of closure of the organ of inter-

  ception 36 which results in a reduction in the cross-section of the current passing through said member, and therefore an increase in the pressure in the zone 41. However, this increase in pressure tends to bring back the rod 43, according to equation (2 ), in its initial equilibrium position. A similar result (return to the initial equilibrium position of the rod 43) would be obtained by supposing an increase in the pressure t

  or any variation in pressure pa.

  Thus, the intercepting member 36, whatever the variations in pa and Pu, tends to return to its original equilibrium position, with the consequence that the jump or pressure difference Ap between the two zones 40 and 41 remains constant. A displacement relative to this position gives rise to variations in surface in section of the intercepting member 36 which produce variations in the pressure pu such that there is automatic return to said

pos it: Lorn.

  It is clear that because the difference Ap of the pressure between the zones 40 and 41, and therefore between the supply chamber 10 and the use chamber 11, is kept constant, the result is that the controlled flow by the regulator depends only on the position occupied by the slide 9 as a function of the determined control pressure

using the electromagnet 39.

  If the regulator is used to control the evacuation rate, the passage in the evacuation pipe 34 is closed, by acting on the electromagnet 39, until an increase in the pressure in the cavity 29, which brings the drawer 9 into a position similar to that shown in FIG. 3 in which the valve element 24 opens the orifice 23 between the use chamber 11 and the evacuation chamber; the position shown in Figure 3 is that of the end of travel of the slide in which the discharge orifice is fully open; in this position, and as can be clearly seen in FIG. 3, the drawer closes the orifice 21 (FIG. 2) between the supply chamber 10

and the operating chamber 11.

  The adjustment of the discharge orifice 23 can be obtained

by acting on the electromagnet 39 according to sem-

similar to those described for opening the feed hole

  mentation 21. The fluid arrives from the user device 3 (FIG. 1) in the pipe 14 (FIG. 3) of the regulator, crosses the pipe section 52 by opening the valve.

  of no return 54, first enters the user chamber

  tion 11 then into the evacuation chamber 12 passing through the orifice 23, then to flow towards the evacuation passing through the evacuation pipe 15 in which is

  inserted the interceptor 37.

During the evacuation of the fluid, the pressure variation Ap between the pressure pu defined above which prevails in the zone 41 and the pressure ps which prevails in the zone 42 along the evacuation pipe 15 is kept constant from the made

  of the action of the interception unit 37, the functioning of which

which is completely similar to that of the

  terception 36, will not be described in more detail. Thus, even during evacuation, possible variations in the conditions of the user device and evacuation have no influence on the flow rate of the fluid which circulates in the regulator and depends only on the position occupied.

by drawer 9.

It is clear that modifications and variants can be made to the embodiment of the present invention described and illustrated, both in its form and in the arrangement of its different parts, without departing from the scope. of said invention. In particular, the interception bodies 46, 47 may have

  a structure different from that which has been described, provided that

tion that they include means to detect

  fluid pressure in two different zones and prede-

  finished along the supply and use lines or along the use and discharge lines, and

  to modify the respective openings according to the varia-

  tion of the difference between said pressures and of the flow rate which passes through them, so as to ensure a pressure difference

  constant between the two predefined zones.

at

Claims (7)

1. Flow regulator suitable for being inserted between a source of pressurized fluid and a user device of said fluid, and between the user device and the evacua-   tion so as to control the flow of fluid from the source to the user device and from the user device to the discharge, characterized in that it comprises: a supply chamber (10) which communicates via a supply line (13) with the source, a use chamber (11) which communicates via a use line (14) with the user device, an evacuation chamber (12) which communicates via a discharge line (15) with the discharge, said chambers being formed in a valve body; a slide valve (9) or slide valve movable axially inside the body (8) and provided with a first valve member (22) whose function is to regulate the opening of a   first passage orifice (21) between the supply chambers   tation (10) and use (11), and a second valve member (24) whose function is to regulate the opening of a   second passage orifice (23) between the user chambers   tion (11) and evacuation (12), while an elastic force exerted by a spring (25) acts on the slide (9) and a force generated by the fluid is caused to act on an active surface ( 28) of the drawer; a first (36) and a second (37) intercepting member, respectively arranged in the use pipe (11) and in the discharge pipe (15) to keep constant the pressure difference upstream and the approval of these bodies   interception, the opening of said first interceptor   tion (36) being controlled by first means which detects   try the fluid pressure in a first zone (40) pre- defined along the supply line (13) and in a second zone (41) predefined along the use line (14) and which cause the respective opening to vary when there is variation in the difference between both   pressures and flow passing through said opening, the   verture of the second interception member (37) being controlled by second means which detect the pressure of the fluid in the second predefined zone (41) along the use pipe (14) and in a third predefined zone (42) along the discharge pipe (15) and which vary the respective opening when there is variation in the difference between said two pressures and the flow rate which passes through the said opening.   2. Current regulator according to claim 1, characterized in that the first means comprise a first movable member (43, 44, 45) in a corresponding seat of the body, provided with two active surfaces (47, 48), one of which   (47) is exposed to the fluid of the first zone (40) and the other   tre (48) is exposed to the fluid of the second zone; (41), the or-   movable gane being subjected to the stress of a spring (46)   and connected to the first interception member (36). 3. Current regulator according to claim 1, characterized in that the second means comprise a second movable member (43, 44, 45) in a corresponding seat of the body, provided with two active surfaces (47, 48), one of which (47) is exposed to the fluid of the second zone (41) and the other (48) is exposed to the fluid of the third zone (42), the movable member being subjected to the stress of a spring (46) and   connected to the second interception member (37).   4. Current regulator according to any one of previous claims, characterized in that each   of said first and second interception members (36, 37) comprises a ball (45) suitable for closing a corresponding seat constituted respectively in the use pipe (14)   and in the discharge pipe (15).   5. Current regulator according to any one of   claims 2 to 4, characterized in that each of   springs (46) of said first and second means normally tend to push the respective movable member in a direction which   keeps the corresponding interception device open.   6. Current regulator according to any one of   previous claims, characterized in that the pipe   use (14) includes a clean pipe section (52)   to put the second zone (41) into communication with a   third zone ((53) along the use line (14) and downstream of the second zone (41), a non-return valve (54) being provided in the line (52) to remain closed there when the fluid passes through the use line (14) and flows from the use chamber (11) towards the user device and to remain open, on the other hand when the fluid passes through the use line (14) and s flows in the opposite direction. 7. Current regulator according to any one of previous claims, characterized in that the surface active (28) of the drawer (9) forms the surface of a cavity (29) in the body which is in communication with both the supply line (14) via a strut   regulation (33) and with the evacuation, a third   electromechanically controlled terception being inserted between said cavity and the evacuation, this member being adapted to vary the opening of the passage orifice between the cavity and the evacuation so as to vary in a controlled manner the pressure of the fluid contained in said cavity   and controlling the movement of said drawer (9).